Data Display

Package iris provides a beautifully expressive and easy to use foundation for your next website, API, or distributed app. Source code and other details for the project are available at GitHub: 8.5.9 Final The only requirement is the Go Programming Language, at least version 1.8 but 1.9 is highly recommended. Iris takes advantage of the vendor directory feature wisely: https://docs.google.com/document/d/1Bz5-UB7g2uPBdOx-rw5t9MxJwkfpx90cqG9AFL0JAYo. You get truly reproducible builds, as this method guards against upstream renames and deletes. A simple copy-paste and `go get ./...` to resolve two dependencies: https://github.com/kataras/golog and the https://github.com/iris-contrib/httpexpect will work for ever even for older versions, the newest version can be retrieved by `go get` but this file contains documentation for an older version of Iris. Follow the instructions below: 1. install the Go Programming Language: https://golang.org/dl 2. clear yours previously `$GOPATH/src/github.com/kataras/iris` folder or create new 3. download the Iris v8.5.9 (final): https://github.com/kataras/iris/archive/v8.zip 4. extract the contents of the `iris-v8` folder that's inside the downloaded zip file to your `$GOPATH/src/github.com/kataras/iris` 5. navigate to your `$GOPATH/src/github.com/kataras/iris` folder if you're not already there and open a terminal/command prompt, execute the command: `go get ./...` and you're ready to GO:) Example code: You can start the server(s) listening to any type of `net.Listener` or even `http.Server` instance. The method for initialization of the server should be passed at the end, via `Run` function. Below you'll see some useful examples: UNIX and BSD hosts can take advandage of the reuse port feature. Example code: That's all with listening, you have the full control when you need it. Let's continue by learning how to catch CONTROL+C/COMMAND+C or unix kill command and shutdown the server gracefully. In order to manually manage what to do when app is interrupted, we have to disable the default behavior with the option `WithoutInterruptHandler` and register a new interrupt handler (globally, across all possible hosts). Example code: Access to all hosts that serve your application can be provided by the `Application#Hosts` field, after the `Run` method. But the most common scenario is that you may need access to the host before the `Run` method, there are two ways of gain access to the host supervisor, read below. First way is to use the `app.NewHost` to create a new host and use one of its `Serve` or `Listen` functions to start the application via the `iris#Raw` Runner. Note that this way needs an extra import of the `net/http` package. Example Code: Second, and probably easier way is to use the `host.Configurator`. Note that this method requires an extra import statement of "github.com/kataras/iris/core/host" when using go < 1.9, if you're targeting on go1.9 then you can use the `iris#Supervisor` and omit the extra host import. All common `Runners` we saw earlier (`iris#Addr, iris#Listener, iris#Server, iris#TLS, iris#AutoTLS`) accept a variadic argument of `host.Configurator`, there are just `func(*host.Supervisor)`. Therefore the `Application` gives you the rights to modify the auto-created host supervisor through these. Example Code: Read more about listening and gracefully shutdown by navigating to: All HTTP methods are supported, developers can also register handlers for same paths for different methods. The first parameter is the HTTP Method, second parameter is the request path of the route, third variadic parameter should contains one or more iris.Handler executed by the registered order when a user requests for that specific resouce path from the server. Example code: In order to make things easier for the user, iris provides functions for all HTTP Methods. The first parameter is the request path of the route, second variadic parameter should contains one or more iris.Handler executed by the registered order when a user requests for that specific resouce path from the server. Example code: A set of routes that are being groupped by path prefix can (optionally) share the same middleware handlers and template layout. A group can have a nested group too. `.Party` is being used to group routes, developers can declare an unlimited number of (nested) groups. Example code: iris developers are able to register their own handlers for http statuses like 404 not found, 500 internal server error and so on. Example code: With the help of iris's expressionist router you can build any form of API you desire, with safety. Example code: Iris has first-class support for the MVC pattern, you'll not find these stuff anywhere else in the Go world. Example Code: Iris web framework supports Request data, Models, Persistence Data and Binding with the fastest possible execution. Characteristics: All HTTP Methods are supported, for example if want to serve `GET` then the controller should have a function named `Get()`, you can define more than one method function to serve in the same Controller struct. Persistence data inside your Controller struct (share data between requests) via `iris:"persistence"` tag right to the field or Bind using `app.Controller("/" , new(myController), theBindValue)`. Models inside your Controller struct (set-ed at the Method function and rendered by the View) via `iris:"model"` tag right to the field, i.e User UserModel `iris:"model" name:"user"` view will recognise it as `{{.user}}`. If `name` tag is missing then it takes the field's name, in this case the `"User"`. Access to the request path and its parameters via the `Path and Params` fields. Access to the template file that should be rendered via the `Tmpl` field. Access to the template data that should be rendered inside the template file via `Data` field. Access to the template layout via the `Layout` field. Access to the low-level `iris.Context` via the `Ctx` field. Get the relative request path by using the controller's name via `RelPath()`. Get the relative template path directory by using the controller's name via `RelTmpl()`. Flow as you used to, `Controllers` can be registered to any `Party`, including Subdomains, the Party's begin and done handlers work as expected. Optional `BeginRequest(ctx)` function to perform any initialization before the method execution, useful to call middlewares or when many methods use the same collection of data. Optional `EndRequest(ctx)` function to perform any finalization after any method executed. Inheritance, recursively, see for example our `mvc.SessionController/iris.SessionController`, it has the `mvc.Controller/iris.Controller` as an embedded field and it adds its logic to its `BeginRequest`. Source file: https://github.com/kataras/iris/blob/v8/mvc/session_controller.go. Read access to the current route via the `Route` field. Support for more than one input arguments (map to dynamic request path parameters). Register one or more relative paths and able to get path parameters, i.e Response via output arguments, optionally, i.e Where `any` means everything, from custom structs to standard language's types-. `Result` is an interface which contains only that function: Dispatch(ctx iris.Context) and Get where HTTP Method function(Post, Put, Delete...). Iris has a very powerful and blazing fast MVC support, you can return any value of any type from a method function and it will be sent to the client as expected. * if `string` then it's the body. * if `string` is the second output argument then it's the content type. * if `int` then it's the status code. * if `bool` is false then it throws 404 not found http error by skipping everything else. * if `error` and not nil then (any type) response will be omitted and error's text with a 400 bad request will be rendered instead. * if `(int, error)` and error is not nil then the response result will be the error's text with the status code as `int`. * if `custom struct` or `interface{}` or `slice` or `map` then it will be rendered as json, unless a `string` content type is following. * if `mvc.Result` then it executes its `Dispatch` function, so good design patters can be used to split the model's logic where needed. The example below is not intended to be used in production but it's a good showcase of some of the return types we saw before; Another good example with a typical folder structure, that many developers are used to work, can be found at: https://github.com/kataras/iris/tree/v8/_examples/mvc/overview. By creating components that are independent of one another, developers are able to reuse components quickly and easily in other applications. The same (or similar) view for one application can be refactored for another application with different data because the view is simply handling how the data is being displayed to the user. If you're new to back-end web development read about the MVC architectural pattern first, a good start is that wikipedia article: https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller. Follow the examples at: https://github.com/kataras/iris/tree/v8/_examples/#mvc At the previous example, we've seen static routes, group of routes, subdomains, wildcard subdomains, a small example of parameterized path with a single known parameter and custom http errors, now it's time to see wildcard parameters and macros. iris, like net/http std package registers route's handlers by a Handler, the iris' type of handler is just a func(ctx iris.Context) where context comes from github.com/kataras/iris/context. Iris has the easiest and the most powerful routing process you have ever meet. At the same time, iris has its own interpeter(yes like a programming language) for route's path syntax and their dynamic path parameters parsing and evaluation, We call them "macros" for shortcut. How? It calculates its needs and if not any special regexp needed then it just registers the route with the low-level path syntax, otherwise it pre-compiles the regexp and adds the necessary middleware(s). Standard macro types for parameters: if type is missing then parameter's type is defaulted to string, so {param} == {param:string}. If a function not found on that type then the "string"'s types functions are being used. i.e: Besides the fact that iris provides the basic types and some default "macro funcs" you are able to register your own too!. Register a named path parameter function: at the func(argument ...) you can have any standard type, it will be validated before the server starts so don't care about performance here, the only thing it runs at serve time is the returning func(paramValue string) bool. Example Code: A path parameter name should contain only alphabetical letters, symbols, containing '_' and numbers are NOT allowed. If route failed to be registered, the app will panic without any warnings if you didn't catch the second return value(error) on .Handle/.Get.... Last, do not confuse ctx.Values() with ctx.Params(). Path parameter's values goes to ctx.Params() and context's local storage that can be used to communicate between handlers and middleware(s) goes to ctx.Values(), path parameters and the rest of any custom values are separated for your own good. Run Static Files Example code: More examples can be found here: https://github.com/kataras/iris/tree/v8/_examples/beginner/file-server Middleware is just a concept of ordered chain of handlers. Middleware can be registered globally, per-party, per-subdomain and per-route. Example code: iris is able to wrap and convert any external, third-party Handler you used to use to your web application. Let's convert the https://github.com/rs/cors net/http external middleware which returns a `next form` handler. Example code: Iris supports 5 template engines out-of-the-box, developers can still use any external golang template engine, as `context/context#ResponseWriter()` is an `io.Writer`. All of these five template engines have common features with common API, like Layout, Template Funcs, Party-specific layout, partial rendering and more. Example code: View engine supports bundled(https://github.com/jteeuwen/go-bindata) template files too. go-bindata gives you two functions, asset and assetNames, these can be setted to each of the template engines using the `.Binary` func. Example code: A real example can be found here: https://github.com/kataras/iris/tree/v8/_examples/view/embedding-templates-into-app. Enable auto-reloading of templates on each request. Useful while developers are in dev mode as they no neeed to restart their app on every template edit. Example code: Note: In case you're wondering, the code behind the view engines derives from the "github.com/kataras/iris/view" package, access to the engines' variables can be granded by "github.com/kataras/iris" package too. Each one of these template engines has different options located here: https://github.com/kataras/iris/tree/v8/view . This example will show how to store and access data from a session. You don’t need any third-party library, but If you want you can use any session manager compatible or not. In this example we will only allow authenticated users to view our secret message on the /secret page. To get access to it, the will first have to visit /login to get a valid session cookie, which logs him in. Additionally he can visit /logout to revoke his access to our secret message. Example code: Running the example: Sessions persistence can be achieved using one (or more) `sessiondb`. Example Code: More examples: In this example we will create a small chat between web sockets via browser. Example Server Code: Example Client(javascript) Code: Running the example: But you should have a basic idea of the framework by now, we just scratched the surface. If you enjoy what you just saw and want to learn more, please follow the below links: Examples: Middleware: Home Page:

Package geomaps provides the API client, operations, and parameter types for Amazon Location Service Maps V2. Capabilities include: Access to comprehensive base map data, allowing you to tailor the map display to your specific needs. Multiple pre-designed map styles suited for various application types, such as navigation, logistics, or data visualization. Generation of static map images for scenarios where interactive maps aren't suitable, such as: Embedding in emails or documents Displaying in low-bandwidth environments Creating printable maps Enhancing application performance by reducing client-side rendering

Package spew implements a deep pretty printer for Go data structures to aid in debugging. A quick overview of the additional features spew provides over the built-in printing facilities for Go data types are as follows: There are two different approaches spew allows for dumping Go data structures: This section demonstrates how to quickly get started with spew. See the sections below for further details on formatting and configuration options. To dump a variable with full newlines, indentation, type, and pointer information use Dump, Fdump, or Sdump: Alternatively, if you would prefer to use format strings with a compacted inline printing style, use the convenience wrappers Printf, Fprintf, etc with %v (most compact), %+v (adds pointer addresses), %#v (adds types), or %#+v (adds types and pointer addresses): Configuration of spew is handled by fields in the ConfigState type. For convenience, all of the top-level functions use a global state available via the spew.Config global. It is also possible to create a ConfigState instance that provides methods equivalent to the top-level functions. This allows concurrent configuration options. See the ConfigState documentation for more details. The following configuration options are available: Indent String to use for each indentation level for Dump functions. It is a single space by default. A popular alternative is "\t". MaxDepth Maximum number of levels to descend into nested data structures. There is no limit by default. DisableMethods Disables invocation of error and Stringer interface methods. Method invocation is enabled by default. DisablePointerMethods Disables invocation of error and Stringer interface methods on types which only accept pointer receivers from non-pointer variables. Pointer method invocation is enabled by default. DisablePointerAddresses DisablePointerAddresses specifies whether to disable the printing of pointer addresses. This is useful when diffing data structures in tests. DisableCapacities DisableCapacities specifies whether to disable the printing of capacities for arrays, slices, maps and channels. This is useful when diffing data structures in tests. ContinueOnMethod Enables recursion into types after invoking error and Stringer interface methods. Recursion after method invocation is disabled by default. SortKeys Specifies map keys should be sorted before being printed. Use this to have a more deterministic, diffable output. Note that only native types (bool, int, uint, floats, uintptr and string) and types which implement error or Stringer interfaces are supported with other types sorted according to the reflect.Value.String() output which guarantees display stability. Natural map order is used by default. SpewKeys Specifies that, as a last resort attempt, map keys should be spewed to strings and sorted by those strings. This is only considered if SortKeys is true. Simply call spew.Dump with a list of variables you want to dump: You may also call spew.Fdump if you would prefer to output to an arbitrary io.Writer. For example, to dump to standard error: A third option is to call spew.Sdump to get the formatted output as a string: See the Dump example for details on the setup of the types and variables being shown here. Byte (and uint8) arrays and slices are displayed uniquely like the hexdump -C command as shown. Spew provides a custom formatter that implements the fmt.Formatter interface so that it integrates cleanly with standard fmt package printing functions. The formatter is useful for inline printing of smaller data types similar to the standard %v format specifier. The custom formatter only responds to the %v (most compact), %+v (adds pointer addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb combinations. Any other verbs such as %x and %q will be sent to the the standard fmt package for formatting. In addition, the custom formatter ignores the width and precision arguments (however they will still work on the format specifiers not handled by the custom formatter). The simplest way to make use of the spew custom formatter is to call one of the convenience functions such as spew.Printf, spew.Println, or spew.Printf. The functions have syntax you are most likely already familiar with: See the Index for the full list convenience functions. Double pointer to a uint8: Pointer to circular struct with a uint8 field and a pointer to itself: See the Printf example for details on the setup of variables being shown here. Since it is possible for custom Stringer/error interfaces to panic, spew detects them and handles them internally by printing the panic information inline with the output. Since spew is intended to provide deep pretty printing capabilities on structures, it intentionally does not return any errors.

Package cgi implements the common gateway interface (CGI) for Caddy 2, a modern, full-featured, easy-to-use web server. It has been forked from the fantastic work of Kurt Jung who wrote that plugin for Caddy 1. This plugin lets you generate dynamic content on your website by means of command line scripts. To collect information about the inbound HTTP request, your script examines certain environment variables such as PATH_INFO and QUERY_STRING. Then, to return a dynamically generated web page to the client, your script simply writes content to standard output. In the case of POST requests, your script reads additional inbound content from standard input. The advantage of CGI is that you do not need to fuss with server startup and persistence, long term memory management, sockets, and crash recovery. Your script is called when a request matches one of the patterns that you specify in your Caddyfile. As soon as your script completes its response, it terminates. This simplicity makes CGI a perfect complement to the straightforward operation and configuration of Caddy. The benefits of Caddy, including HTTPS by default, basic access authentication, and lots of middleware options extend easily to your CGI scripts. CGI has some disadvantages. For one, Caddy needs to start a new process for each request. This can adversely impact performance and, if resources are shared between CGI applications, may require the use of some interprocess synchronization mechanism such as a file lock. Your server's responsiveness could in some circumstances be affected, such as when your web server is hit with very high demand, when your script's dependencies require a long startup, or when concurrently running scripts take a long time to respond. However, in many cases, such as using a pre-compiled CGI application like fossil or a Lua script, the impact will generally be insignificant. Another restriction of CGI is that scripts will be run with the same permissions as Caddy itself. This can sometimes be less than ideal, for example when your script needs to read or write files associated with a different owner. Serving dynamic content exposes your server to more potential threats than serving static pages. There are a number of considerations of which you should be aware when using CGI applications. CGI scripts should be located outside of Caddy's document root. Otherwise, an inadvertent misconfiguration could result in Caddy delivering the script as an ordinary static resource. At best, this could merely confuse the site visitor. At worst, it could expose sensitive internal information that should not leave the server. Mistrust the contents of PATH_INFO, QUERY_STRING and standard input. Most of the environment variables available to your CGI program are inherently safe because they originate with Caddy and cannot be modified by external users. This is not the case with PATH_INFO, QUERY_STRING and, in the case of POST actions, the contents of standard input. Be sure to validate and sanitize all inbound content. If you use a CGI library or framework to process your scripts, make sure you understand its limitations. An error in a CGI application is generally handled within the application itself and reported in the headers it returns. Your CGI application can be executed directly or indirectly. In the direct case, the application can be a compiled native executable or it can be a shell script that contains as its first line a shebang that identifies the interpreter to which the file's name should be passed. Caddy must have permission to execute the application. On Posix systems this will mean making sure the application's ownership and permission bits are set appropriately; on Windows, this may involve properly setting up the filename extension association. In the indirect case, the name of the CGI script is passed to an interpreter such as lua, perl or python. This module needs to be installed (obviously). Refer to the Caddy documentation on how to build Caddy with plugins/modules. The basic cgi directive lets you add a handler in the current caddy router location with a given script and optional arguments. The matcher is a default caddy matcher that is used to restrict the scope of this directive. The directive can be repeated any reasonable number of times. Here is the basic syntax: For example: When a request such as https://example.com/report or https://example.com/report/weekly arrives, the cgi middleware will detect the match and invoke the script named /usr/local/cgi-bin/report. The current working directory will be the same as Caddy itself. Here, it is assumed that the script is self-contained, for example a pre-compiled CGI application or a shell script. Here is an example of a standalone script, similar to one used in the cgi plugin's test suite: The environment variables PATH_INFO and QUERY_STRING are populated and passed to the script automatically. There are a number of other standard CGI variables included that are described below. If you need to pass any special environment variables or allow any environment variables that are part of Caddy's process to pass to your script, you will need to use the advanced directive syntax described below. Beware that in Caddy v2 it is (currently) not possible to separate the path left of the matcher from the full URL. Therefore if you require your CGI program to know the SCRIPT_NAME, make sure to pass that explicitly: In order to specify custom environment variables, pass along one or more environment variables known to Caddy, or specify more than one match pattern for a given rule, you will need to use the advanced directive syntax. That looks like this: For example, The script_name subdirective helps the cgi module to separate the path to the script from the (virtual) path afterwards (which shall be passed to the script). env can be used to define a list of key=value environment variable pairs that shall be passed to the script. pass_env can be used to define a list of environment variables of the Caddy process that shall be passed to the script. If your CGI application runs properly at the command line but fails to run from Caddy it is possible that certain environment variables may be missing. For example, the ruby gem loader evidently requires the HOME environment variable to be set; you can do this with the subdirective pass_env HOME. Another class of problematic applications require the COMPUTERNAME variable. The pass_all_env subdirective instructs Caddy to pass each environment variable it knows about to the CGI excutable. This addresses a common frustration that is caused when an executable requires an environment variable and fails without a descriptive error message when the variable cannot be found. These applications often run fine from the command prompt but fail when invoked with CGI. The risk with this subdirective is that a lot of server information is shared with the CGI executable. Use this subdirective only with CGI applications that you trust not to leak this information. buffer_limit is used when a http request has Transfer-Endcoding: chunked. The Go CGI Handler refused to handle these kinds of requests, see https://github.com/golang/go/issues/5613. In order to work around this the chunked request is buffered by caddy and sent to the CGI application as a whole with the correct CONTENT_LENGTH set. The buffer_limit setting marks a threshold between buffering in memory and using a temporary file. Every request body smaller than the buffer_limit is buffered in-memory. It accepts all formats supported by go-humanize. Default: 4MiB. (An example of this is git push if the objects to push are larger than the http.postBuffer) With the unbuffered_output subdirective it is possible to instruct the CGI handler to flush output from the CGI script as soon as possible. By default, the output is buffered into chunks before it is being written to optimize the network usage and allow to determine the Content-Length. When unbuffered, bytes will be written as soon as possible. This will also force the response to be written in chunked encoding. If you run into unexpected results with the CGI plugin, you are able to examine the environment in which your CGI application runs. To enter inspection mode, add the subdirective inspect to your CGI configuration block. This is a development option that should not be used in production. When in inspection mode, the plugin will respond to matching requests with a page that displays variables of interest. In particular, it will show the replacement value of {match} and the environment variables to which your CGI application has access. For example, consider this example CGI block: When you request a matching URL, for example, the Caddy server will deliver a text page similar to the following. The CGI application (in this case, wapptclsh) will not be called. This information can be used to diagnose problems with how a CGI application is called. To return to operation mode, remove or comment out the inspect subdirective. In this example, the Caddyfile looks like this: Note that a request for /show gets mapped to a script named /usr/local/cgi-bin/report/gen. There is no need for any element of the script name to match any element of the match pattern. The contents of /usr/local/cgi-bin/report/gen are: The purpose of this script is to show how request information gets communicated to a CGI script. Note that POST data must be read from standard input. In this particular case, posted data gets stored in the variable POST_DATA. Your script may use a different method to read POST content. Secondly, the SCRIPT_EXEC variable is not a CGI standard. It is provided by this middleware and contains the entire command line, including all arguments, with which the CGI script was executed. When a browser requests the response looks like When a client makes a POST request, such as with the following command the response looks the same except for the following lines: This small example demonstrates how to write a CGI program in Go. The use of a bytes.Buffer makes it easy to report the content length in the CGI header. When this program is compiled and installed as /usr/local/bin/servertime, the following directive in your Caddy file will make it available: The module is written in a way that it expects the scripts you want it to execute to actually exist. A non-existing or non-executable file is considered a setup error and will yield a HTTP 500. If you want to make sure, only existing scripts are executed, use a more specific matcher, as explained in the Caddy docs. Example: When calling a url like /cgi/foo/bar.pl it will check if the local file ./app/foo/bar.pl exists and only then it will proceed with calling the CGI.

Package tview implements rich widgets for terminal based user interfaces. The widgets provided with this package are useful for data exploration and data entry. The package implements the following widgets: The package also provides Application which is used to poll the event queue and draw widgets on screen. The following is a very basic example showing a box with the title "Hello, world!": First, we create a box primitive with a border and a title. Then we create an application, set the box as its root primitive, and run the event loop. The application exits when the application's Stop() function is called or when Ctrl-C is pressed. If we have a primitive which consumes key presses, we call the application's SetFocus() function to redirect all key presses to that primitive. Most primitives then offer ways to install handlers that allow you to react to any actions performed on them. You will find more demos in the "demos" subdirectory. It also contains a presentation (written using tview) which gives an overview of the different widgets and how they can be used. Throughout this package, colors are specified using the tcell.Color type. Functions such as tcell.GetColor(), tcell.NewHexColor(), and tcell.NewRGBColor() can be used to create colors from W3C color names or RGB values. Almost all strings which are displayed can contain color tags. Color tags are W3C color names or six hexadecimal digits following a hash tag, wrapped in square brackets. Examples: A color tag changes the color of the characters following that color tag. This applies to almost everything from box titles, list text, form item labels, to table cells. In a TextView, this functionality has to be switched on explicitly. See the TextView documentation for more information. Color tags may contain not just the foreground (text) color but also the background color and additional flags. In fact, the full definition of a color tag is as follows: Each of the three fields can be left blank and trailing fields can be omitted. (Empty square brackets "[]", however, are not considered color tags.) Colors that are not specified will be left unchanged. A field with just a dash ("-") means "reset to default". You can specify the following flags (some flags may not be supported by your terminal): Examples: In the rare event that you want to display a string such as "[red]" or "[#00ff1a]" without applying its effect, you need to put an opening square bracket before the closing square bracket. Note that the text inside the brackets will be matched less strictly than region or colors tags. I.e. any character that may be used in color or region tags will be recognized. Examples: You can use the Escape() function to insert brackets automatically where needed. When primitives are instantiated, they are initialized with colors taken from the global Styles variable. You may change this variable to adapt the look and feel of the primitives to your preferred style. This package supports unicode characters including wide characters. Many functions in this package are not thread-safe. For many applications, this may not be an issue: If your code makes changes in response to key events, it will execute in the main goroutine and thus will not cause any race conditions. If you access your primitives from other goroutines, however, you will need to synchronize execution. The easiest way to do this is to call Application.QueueUpdate() or Application.QueueUpdateDraw() (see the function documentation for details): One exception to this is the io.Writer interface implemented by TextView. You can safely write to a TextView from any goroutine. See the TextView documentation for details. You can also call Application.Draw() from any goroutine without having to wrap it in QueueUpdate(). And, as mentioned above, key event callbacks are executed in the main goroutine and thus should not use QueueUpdate() as that may lead to deadlocks. All widgets listed above contain the Box type. All of Box's functions are therefore available for all widgets, too. All widgets also implement the Primitive interface. The tview package is based on https://github.com/gdamore/tcell. It uses types and constants from that package (e.g. colors and keyboard values). This package does not process mouse input (yet).

Package tview implements rich widgets for terminal based user interfaces. The widgets provided with this package are useful for data exploration and data entry. The package implements the following widgets: The package also provides Application which is used to poll the event queue and draw widgets on screen. The following is a very basic example showing a box with the title "Hello, world!": First, we create a box primitive with a border and a title. Then we create an application, set the box as its root primitive, and run the event loop. The application exits when the application's Application.Stop function is called or when Ctrl-C is pressed. You will find more demos in the "demos" subdirectory. It also contains a presentation (written using tview) which gives an overview of the different widgets and how they can be used. Throughout this package, styles are specified using the tcell.Style type. Styles specify colors with the tcell.Color type. Functions such as tcell.GetColor, tcell.NewHexColor, and tcell.NewRGBColor can be used to create colors from W3C color names or RGB values. The tcell.Style type also allows you to specify text attributes such as "bold" or "underline" or a URL which some terminals use to display hyperlinks. Almost all strings which are displayed may contain style tags. A style tag's content is always wrapped in square brackets. In its simplest form, a style tag specifies the foreground color of the text. Colors in these tags are W3C color names or six hexadecimal digits following a hash tag. Examples: A style tag changes the style of the characters following that style tag. There is no style stack and no nesting of style tags. Style tags are used in almost everything from box titles, list text, form item labels, to table cells. In a TextView, this functionality has to be switched on explicitly. See the TextView documentation for more information. A style tag's full format looks like this: Each of the four fields can be left blank and trailing fields can be omitted. (Empty square brackets "[]", however, are not considered style tags.) Fields that are not specified will be left unchanged. A field with just a dash ("-") means "reset to default". You can specify the following flags to turn on certain attributes (some flags may not be supported by your terminal): Use uppercase letters to turn off the corresponding attribute, for example, "B" to turn off bold. Uppercase letters have no effect if the attribute was not previously set. Setting a URL allows you to turn a piece of text into a hyperlink in some terminals. Specify a dash ("-") to specify the end of the hyperlink. Hyperlinks must only contain single-byte characters (e.g. ASCII) and they may not contain bracket characters ("[" or "]"). Examples: In the rare event that you want to display a string such as "[red]" or "[#00ff1a]" without applying its effect, you need to put an opening square bracket before the closing square bracket. Note that the text inside the brackets will be matched less strictly than region or colors tags. I.e. any character that may be used in color or region tags will be recognized. Examples: You can use the Escape() function to insert brackets automatically where needed. When primitives are instantiated, they are initialized with colors taken from the global Styles variable. You may change this variable to adapt the look and feel of the primitives to your preferred style. Note that most terminals will not report information about their color theme. This package therefore does not support using the terminal's color theme. The default style is a dark theme and you must change the Styles variable to switch to a light (or other) theme. This package supports all unicode characters supported by your terminal. If your terminal supports mouse events, you can enable mouse support for your application by calling Application.EnableMouse. Note that this may interfere with your terminal's default mouse behavior. Mouse support is disabled by default. Many functions in this package are not thread-safe. For many applications, this is not an issue: If your code makes changes in response to key events, the corresponding callback function will execute in the main goroutine and thus will not cause any race conditions. (Exceptions to this are documented.) If you access your primitives from other goroutines, however, you will need to synchronize execution. The easiest way to do this is to call Application.QueueUpdate or Application.QueueUpdateDraw (see the function documentation for details): One exception to this is the io.Writer interface implemented by TextView. You can safely write to a TextView from any goroutine. See the TextView documentation for details. You can also call Application.Draw from any goroutine without having to wrap it in Application.QueueUpdate. And, as mentioned above, key event callbacks are executed in the main goroutine and thus should not use Application.QueueUpdate as that may lead to deadlocks. It is also not necessary to call Application.Draw from such callbacks as it will be called automatically. All widgets listed above contain the Box type. All of Box's functions are therefore available for all widgets, too. Please note that if you are using the functions of Box on a subclass, they will return a *Box, not the subclass. This is a Golang limitation. So while tview supports method chaining in many places, these chains must be broken when using Box's functions. Example: You will need to call Box.SetBorder separately: All widgets also implement the Primitive interface. The tview package's rendering is based on version 2 of https://github.com/ales999/tcell. It uses types and constants from that package (e.g. colors, styles, and keyboard values).

Package jsonapi provides a serializer and deserializer for jsonapi.org spec payloads. You can keep your model structs as is and use struct field tags to indicate to jsonapi how you want your response built or your request deserialized. What about my relationships? jsonapi supports relationships out of the box and will even side load them in your response into an "included" array--that contains associated objects. jsonapi uses StructField tags to annotate the structs fields that you already have and use in your app and then reads and writes jsonapi.org output based on the instructions you give the library in your jsonapi tags. Example structs using a Blog > Post > Comment structure, jsonapi Tag Reference Value, primary: "primary,<type field output>" This indicates that this is the primary key field for this struct type. Tag value arguments are comma separated. The first argument must be, "primary", and the second must be the name that should appear in the "type" field for all data objects that represent this type of model. Value, attr: "attr,<key name in attributes hash>[,<extra arguments>]" These fields' values should end up in the "attribute" hash for a record. The first argument must be, "attr', and the second should be the name for the key to display in the "attributes" hash for that record. The following extra arguments are also supported: "omitempty": excludes the fields value from the "attribute" hash. "iso8601": uses the ISO8601 timestamp format when serialising or deserialising the time.Time value. Value, relation: "relation,<key name in relationships hash>" Relations are struct fields that represent a one-to-one or one-to-many to other structs. jsonapi will traverse the graph of relationships and marshal or unmarshal records. The first argument must be, "relation", and the second should be the name of the relationship, used as the key in the "relationships" hash for the record. Use the methods below to Marshal and Unmarshal jsonapi.org json payloads. Visit the readme at https://github.com/google/jsonapi

Package jsonapi provides a serializer and deserializer for jsonapi.org spec payloads. You can keep your model structs as is and use struct field tags to indicate to jsonapi how you want your response built or your request deserialized. What about my relationships? jsonapi supports relationships out of the box and will even side load them in your response into an "included" array--that contains associated objects. jsonapi uses StructField tags to annotate the structs fields that you already have and use in your app and then reads and writes jsonapi.org output based on the instructions you give the library in your jsonapi tags. Example structs using a Blog > Post > Comment structure, jsonapi Tag Reference Value, primary: "primary,<type field output>" This indicates that this is the primary key field for this struct type. Tag value arguments are comma separated. The first argument must be, "primary", and the second must be the name that should appear in the "type" field for all data objects that represent this type of model. Value, attr: "attr,<key name in attributes hash>[,<extra arguments>]" These fields' values should end up in the "attribute" hash for a record. The first argument must be, "attr', and the second should be the name for the key to display in the "attributes" hash for that record. The following extra arguments are also supported: "omitempty": excludes the fields value from the "attribute" hash. "iso8601": uses the ISO8601 timestamp format when serialising or deserialising the time.Time value. Value, relation: "relation,<key name in relationships hash>" Relations are struct fields that represent a one-to-one or one-to-many to other structs. jsonapi will traverse the graph of relationships and marshal or unmarshal records. The first argument must be, "relation", and the second should be the name of the relationship, used as the key in the "relationships" hash for the record. Use the methods below to Marshal and Unmarshal jsonapi.org json payloads. Visit the readme at https://github.com/google/jsonapi

Package template implements data-driven templates for generating textual output. To generate HTML output, see html/template, which has the same interface as this package but automatically secures HTML output against certain attacks. Templates are executed by applying them to a data structure. Annotations in the template refer to elements of the data structure (typically a field of a struct or a key in a map) to control execution and derive values to be displayed. Execution of the template walks the structure and sets the cursor, represented by a period '.' and called "dot", to the value at the current location in the structure as execution proceeds. The input text for a template is UTF-8-encoded text in any format. "Actions"--data evaluations or control structures--are delimited by "{{" and "}}"; all text outside actions is copied to the output unchanged. Once parsed, a template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved. Here is a trivial example that prints "17 items are made of wool". More intricate examples appear below. By default, all text between actions is copied verbatim when the template is executed. For example, the string " items are made of " in the example above appears on standard output when the program is run. However, to aid in formatting template source code, if an action's left delimiter (by default "{{") is followed immediately by a minus sign and white space, all trailing white space is trimmed from the immediately preceding text. Similarly, if the right delimiter ("}}") is preceded by white space and a minus sign, all leading white space is trimmed from the immediately following text. In these trim markers, the white space must be present: "{{- 3}}" is like "{{3}}" but trims the immediately preceding text, while "{{-3}}" parses as an action containing the number -3. For instance, when executing the template whose source is the generated output would be For this trimming, the definition of white space characters is the same as in Go: space, horizontal tab, carriage return, and newline. Here is the list of actions. "Arguments" and "pipelines" are evaluations of data, defined in detail in the corresponding sections that follow. An argument is a simple value, denoted by one of the following. A boolean, string, character, integer, floating-point, imaginary or complex constant in Go syntax. These behave like Go's untyped constants. Note that, as in Go, whether a large integer constant overflows when assigned or passed to a function can depend on whether the host machine's ints are 32 or 64 bits. The keyword nil, representing an untyped Go nil. The character '.' (period): . The result is the value of dot. A variable name, which is a (possibly empty) alphanumeric string preceded by a dollar sign, such as $piOver2 or $ The result is the value of the variable. Variables are described below. The name of a field of the data, which must be a struct, preceded by a period, such as .Field The result is the value of the field. Field invocations may be chained: .Field1.Field2 Fields can also be evaluated on variables, including chaining: $x.Field1.Field2 The name of a key of the data, which must be a map, preceded by a period, such as .Key The result is the map element value indexed by the key. Key invocations may be chained and combined with fields to any depth: .Field1.Key1.Field2.Key2 Although the key must be an alphanumeric identifier, unlike with field names they do not need to start with an upper case letter. Keys can also be evaluated on variables, including chaining: $x.key1.key2 The name of a niladic method of the data, preceded by a period, such as .Method The result is the value of invoking the method with dot as the receiver, dot.Method(). Such a method must have one return value (of any type) or two return values, the second of which is an error. If it has two and the returned error is non-nil, execution terminates and an error is returned to the caller as the value of Execute. Method invocations may be chained and combined with fields and keys to any depth: .Field1.Key1.Method1.Field2.Key2.Method2 Methods can also be evaluated on variables, including chaining: $x.Method1.Field The name of a niladic function, such as fun The result is the value of invoking the function, fun(). The return types and values behave as in methods. Functions and function names are described below. A parenthesized instance of one the above, for grouping. The result may be accessed by a field or map key invocation. print (.F1 arg1) (.F2 arg2) (.StructValuedMethod "arg").Field Arguments may evaluate to any type; if they are pointers the implementation automatically indirects to the base type when required. If an evaluation yields a function value, such as a function-valued field of a struct, the function is not invoked automatically, but it can be used as a truth value for an if action and the like. To invoke it, use the call function, defined below. A pipeline is a possibly chained sequence of "commands". A command is a simple value (argument) or a function or method call, possibly with multiple arguments: A pipeline may be "chained" by separating a sequence of commands with pipeline characters '|'. In a chained pipeline, the result of each command is passed as the last argument of the following command. The output of the final command in the pipeline is the value of the pipeline. The output of a command will be either one value or two values, the second of which has type error. If that second value is present and evaluates to non-nil, execution terminates and the error is returned to the caller of Execute. A pipeline inside an action may initialize a variable to capture the result. The initialization has syntax where $variable is the name of the variable. An action that declares a variable produces no output. Variables previously declared can also be assigned, using the syntax If a "range" action initializes a variable, the variable is set to the successive elements of the iteration. Also, a "range" may declare two variables, separated by a comma: in which case $index and $element are set to the successive values of the array/slice index or map key and element, respectively. Note that if there is only one variable, it is assigned the element; this is opposite to the convention in Go range clauses. A variable's scope extends to the "end" action of the control structure ("if", "with", or "range") in which it is declared, or to the end of the template if there is no such control structure. A template invocation does not inherit variables from the point of its invocation. When execution begins, $ is set to the data argument passed to Execute, that is, to the starting value of dot. Here are some example one-line templates demonstrating pipelines and variables. All produce the quoted word "output": During execution functions are found in two function maps: first in the template, then in the global function map. By default, no functions are defined in the template but the Funcs method can be used to add them. Predefined global functions are named as follows. The boolean functions take any zero value to be false and a non-zero value to be true. There is also a set of binary comparison operators defined as functions: For simpler multi-way equality tests, eq (only) accepts two or more arguments and compares the second and subsequent to the first, returning in effect (Unlike with || in Go, however, eq is a function call and all the arguments will be evaluated.) The comparison functions work on any values whose type Go defines as comparable. For basic types such as integers, the rules are relaxed: size and exact type are ignored, so any integer value, signed or unsigned, may be compared with any other integer value. (The arithmetic value is compared, not the bit pattern, so all negative integers are less than all unsigned integers.) However, as usual, one may not compare an int with a float32 and so on. Each template is named by a string specified when it is created. Also, each template is associated with zero or more other templates that it may invoke by name; such associations are transitive and form a name space of templates. A template may use a template invocation to instantiate another associated template; see the explanation of the "template" action above. The name must be that of a template associated with the template that contains the invocation. When parsing a template, another template may be defined and associated with the template being parsed. Template definitions must appear at the top level of the template, much like global variables in a Go program. The syntax of such definitions is to surround each template declaration with a "define" and "end" action. The define action names the template being created by providing a string constant. Here is a simple example: This defines two templates, T1 and T2, and a third T3 that invokes the other two when it is executed. Finally it invokes T3. If executed this template will produce the text By construction, a template may reside in only one association. If it's necessary to have a template addressable from multiple associations, the template definition must be parsed multiple times to create distinct *Template values, or must be copied with Template.Clone or Template.AddParseTree. Parse may be called multiple times to assemble the various associated templates; see ParseFiles, ParseGlob, Template.ParseFiles and Template.ParseGlob for simple ways to parse related templates stored in files. A template may be executed directly or through Template.ExecuteTemplate, which executes an associated template identified by name. To invoke our example above, we might write, or to invoke a particular template explicitly by name,

Package jsonapi provides a serializer and deserializer for jsonapi.org spec payloads. You can keep your model structs as is and use struct field tags to indicate to jsonapi how you want your response built or your request deserialized. What about my relationships? jsonapi supports relationships out of the box and will even side load them in your response into an "included" array--that contains associated objects. jsonapi uses StructField tags to annotate the structs fields that you already have and use in your app and then reads and writes jsonapi.org output based on the instructions you give the library in your jsonapi tags. Example structs using a Blog > Post > Comment structure, jsonapi Tag Reference Value, primary: "primary,<type field output>" This indicates that this is the primary key field for this struct type. Tag value arguments are comma separated. The first argument must be, "primary", and the second must be the name that should appear in the "type" field for all data objects that represent this type of model. Value, attr: "attr,<key name in attributes hash>[,<extra arguments>]" These fields' values should end up in the "attribute" hash for a record. The first argument must be, "attr', and the second should be the name for the key to display in the "attributes" hash for that record. The following extra arguments are also supported: "omitempty": excludes the fields value from the "attribute" hash. "iso8601": uses the ISO8601 timestamp format when serialising or deserialising the time.Time value. Value, relation: "relation,<key name in relationships hash>" Relations are struct fields that represent a one-to-one or one-to-many to other structs. jsonapi will traverse the graph of relationships and marshal or unmarshal records. The first argument must be, "relation", and the second should be the name of the relationship, used as the key in the "relationships" hash for the record. Use the methods below to Marshal and Unmarshal jsonapi.org json payloads. Visit the readme at https://github.com/companyinfo/jsonapi

Package telnet provides TELNET and TELNETS client and server implementations in a style similar to the "net/http" library that is part of the Go standard library, including support for "middleware"; TELNETS is secure TELNET, with the TELNET protocol over a secured TLS (or SSL) connection. ListenAndServe starts a (un-secure) TELNET server with a given address and handler. ListenAndServeTLS starts a (secure) TELNETS server with a given address and handler, using the specified "cert.pem" and "key.pem" files. Example TELNET Client: DialToAndCall creates a (un-secure) TELNET client, which connects to a given address using the specified caller. Example TELNETS Client: DialToAndCallTLS creates a (secure) TELNETS client, which connects to a given address using the specified caller. If you are communicating over the open Internet, you should be using (the secure) TELNETS protocol and ListenAndServeTLS. If you are communicating just on localhost, then using just (the un-secure) TELNET protocol and telnet.ListenAndServe may be OK. If you are not sure which to use, use TELNETS and ListenAndServeTLS. The previous 2 exaple servers were very very simple. Specifically, they just echoed back whatever you submitted to it. If you typed: ... it would send back: (Exactly the same data you sent it.) A more useful TELNET server can be made using the "github.com/karimrc/go-telnet/telsh" sub-package. The `telsh` sub-package provides "middleware" that enables you to create a "shell" interface (also called a "command line interface" or "CLI") which most people would expect when using TELNET OR TELNETS. For example: Note that in the example, so far, we have registered 2 commands: `date` and `animate`. For this to actually work, we need to have code for the `date` and `animate` commands. The actual implemenation for the `date` command could be done like the following: Note that your "real" work is in the `dateHandlerFunc` func. And the actual implementation for the `animate` command could be done as follows: Again, note that your "real" work is in the `animateHandlerFunc` func. If you are using the telnet.ListenAndServeTLS func or the telnet.Server.ListenAndServeTLS method, you will need to supply "cert.pem" and "key.pem" files. If you do not already have these files, the Go soure code contains a tool for generating these files for you. It can be found at: So, for example, if your `$GOROOT` is the "/usr/local/go" directory, then it would be at: If you run the command: ... then you get the help information for "generate_cert.go". Of course, you would replace or set `$GOROOT` with whatever your path actually is. Again, for example, if your `$GOROOT` is the "/usr/local/go" directory, then it would be: To demonstrate the usage of "generate_cert.go", you might run the following to generate certificates that were bound to the hosts `127.0.0.1` and `localhost`: If you are not sure where "generate_cert.go" is on your computer, on Linux and Unix based systems, you might be able to find the file with the command: (If it finds it, it should output the full path to this file.) You can make a simple (un-secure) TELNET client with code like the following: You can make a simple (secure) TELNETS client with code like the following: The TELNET protocol is best known for providing a means of connecting to a remote computer, using a (text-based) shell interface, and being able to interact with it, (more or less) as if you were sitting at that computer. (Shells are also known as command-line interfaces or CLIs.) Although this was the original usage of the TELNET protocol, it can be (and is) used for other purposes as well. The TELNET protocol came from an era in computing when text-based shell interface where the common way of interacting with computers. The common interface for computers during this era was a keyboard and a monochromatic (i.e., single color) text-based monitors called "video terminals". (The word "video" in that era of computing did not refer to things such as movies. But instead was meant to contrast it with paper. In particular, the teletype machines, which were typewriter like devices that had a keyboard, but instead of having a monitor had paper that was printed onto.) In that era, in the early days of office computers, it was rare that an individual would have a computer at their desk. (A single computer was much too expensive.) Instead, there would be a single central computer that everyone would share. The style of computer used (for the single central shared computer) was called a "mainframe". What individuals would have at their desks, instead of their own compuer, would be some type of video terminal. The different types of video terminals had named such as: • VT52 • VT100 • VT220 • VT240 ("VT" in those named was short for "video terminal".) To understand this era, we need to go back a bit in time to what came before it: teletypes. Terminal codes (also sometimes called 'terminal control codes') are used to issue various kinds of commands to the terminal. (Note that 'terminal control codes' are a completely separate concept for 'TELNET commands', and the two should NOT be conflated or confused.) The most common types of 'terminal codes' are the 'ANSI escape codes'. (Although there are other types too.) ANSI escape codes (also sometimes called 'ANSI escape sequences') are a common type of 'terminal code' used to do things such as: • moving the cursor, • erasing the display, • erasing the line, • setting the graphics mode, • setting the foregroup color, • setting the background color, • setting the screen resolution, and • setting keyboard strings. One of the abilities of ANSI escape codes is to set the foreground color. Here is a table showing codes for this: (Note that in the `[]byte` that the first `byte` is the number `27` (which is the "escape" character) where the third and fouth characters are the **not** number literals, but instead character literals `'3'` and whatever.) Another of the abilities of ANSI escape codes is to set the background color. (Note that in the `[]byte` that the first `byte` is the number `27` (which is the "escape" character) where the third and fouth characters are the **not** number literals, but instead character literals `'4'` and whatever.) In Go code, if I wanted to use an ANSI escape code to use a blue background, a white foreground, and bold, I could do that with the ANSI escape code: Note that that start with byte value 27, which we have encoded as hexadecimal as \x1b. Followed by the '[' character. Coming after that is the sub-string "44", which is the code that sets our background color to blue. We follow that with the ';' character (which separates codes). And the after that comes the sub-string "37", which is the code that set our foreground color to white. After that, we follow with another ";" character (which, again, separates codes). And then we follow it the sub-string "1", which is the code that makes things bold. And finally, the ANSI escape sequence is finished off with the 'm' character. To show this in a more complete example, our `dateHandlerFunc` from before could incorporate ANSI escape sequences as follows: Note that in that example, in addition to using the ANSI escape sequence "\x1b[44;37;1m" to set the background color to blue, set the foreground color to white, and make it bold, we also used the ANSI escape sequence "\x1b[0m" to reset the background and foreground colors and boldness back to "normal".

Package apns provide a Apple Push Notification service provider. Apple Push Notification service (APNs) is the centerpiece of the remote notifications feature. It is a robust and highly efficient service for propagating information to iOS (and, indirectly, watchOS), tvOS, and macOS devices. On initial activation, a device establishes an accredited and encrypted IP connection with APNs and receives notifications over this persistent connection. If a notification for an app arrives when that app is not running, the device alerts the user that the app has data waiting for it. You provide your own server to generate remote notifications for the users of your app. This server, known as the provider, has three main responsibilities. It: For each notification, the provider: On receiving the HTTP/2 request, APNs delivers the notification payload to your app on the user's device. Apple Push Notification service includes a default Quality of Service (QoS) component that performs a store-and-forward function. If APNs attempts to deliver a notification but the destination device is offline, APNs stores the notification for a limited period of time and delivers it to the device when the device becomes available. This mechanism stores only one recent notification per device, per app: if you send multiple notifications while a device is offline, a new notification causes the previous notification to be discarded. If a device remains offline for a long time, all notifications that were being stored for it are discarded; when the device goes back online, none of the notifications are displayed. When a device is online, all the notifications you send are delivered and available to the user. However, you can avoid showing duplicate notifications by employing a collapse identifier across multiple, identical notifications. The APNs request header key for the collapse identifier is "apns-collapse-id". For example, a news service that sends the same headline twice in a row could employ the same collapse identifier for both push notification requests. APNs would then take care of coalescing these requests into a single notification for delivery to a device. To ensure secure communication, APNs servers employ connection certificates, certification authority (CA) certificates, and cryptographic keys (private and public) to validate connections to, and identities of, providers and devices. APNs regulates the entry points between providers and devices using two levels of trust: connection trust and device token trust. Connection trust establishes certainty that APNs is connected to an authorized provider, owned by a company that Apple has agreed to deliver notifications for. You must take steps to ensure connection trust exists between your provider servers and APNs. APNs also uses connection trust with each device to ensure the legitimacy of the device. Connection trust with the device is handled automatically by APNs. Device token trust ensures that notifications are routed only between legitimate start and end points. A device token is an opaque, unique identifier assigned to a specific app on a specific device. Each app instance receives its unique token when it registers with APNs. The app must share this token with its provider, to allow the provider to employ the token when communicating with APNs. Each notification that your provider sends to APNs must include the device token, which ensures that the notification is delivered only to the app-device combination for which it is intended. Important: To protect user privacy, do not attempt to use a device token to identify a device. Device tokens can change after updating the operating system, and always change when a device's data and settings are erased. Whenever the system delivers a device token to an instance of your app, the app must forward it to your provider servers to allow further push notifications to the device. A provider using the HTTP/2-based APNs Provider API can use JSON web tokens (JWT) to validate the provider's connection with APNs. In this scheme, the provider does not require a certificate-plus-private key to establish connection. Instead, you provision a public key to be retained by Apple, and a private key which you retain and protect. Your providers then use your private key to generate and sign JWT authentication tokens. Each of your push requests must include an authentication token. Important: To establish TLS sessions with APNs, you must ensure that a GeoTrust Global CA root certificate is installed on each of your providers. You can download this certificate from the GeoTrust Root Certificates website: https://www.geotrust.com/resources/root-certificates/. The HTTP/2-based provider connection is valid for delivery to one specific app, identified by the topic (the app bundle ID) specified in the certificate. Depending on how you configure and provision your APNs Transport Layer Security (TLS) certificate, the trusted connection can also be valid for delivery of remote notifications to other items associated with your app, including Apple Watch complications and voice-over-Internet Protocol (VoIP) services. APNs delivers these notifications even when those items are running in the background. APNs maintains a certificate revocation list; if a provider's certificate is on the revocation list, APNs can revoke provider trust (that is, APNs can refuse the TLS initiation connection).

Package dataurl parses Data URL Schemes according to RFC 2397 (http://tools.ietf.org/html/rfc2397). Data URLs are small chunks of data commonly used in browsers to display inline data, typically like small images, or when you use the FileReader API of the browser. A dataurl looks like: Or, with base64 encoding: Common functions are Decode and DecodeString to obtain a DataURL, and DataURL.String() and DataURL.WriteTo to generate a Data URL string.

Package tview implements rich widgets for terminal based user interfaces. The widgets provided with this package are useful for data exploration and data entry. The package implements the following widgets: The package also provides Application which is used to poll the event queue and draw widgets on screen. The following is a very basic example showing a box with the title "Hello, world!": First, we create a box primitive with a border and a title. Then we create an application, set the box as its root primitive, and run the event loop. The application exits when the application's Stop() function is called or when Ctrl-C is pressed. If we have a primitive which consumes key presses, we call the application's SetFocus() function to redirect all key presses to that primitive. Most primitives then offer ways to install handlers that allow you to react to any actions performed on them. You will find more demos in the "demos" subdirectory. It also contains a presentation (written using tview) which gives an overview of the different widgets and how they can be used. Throughout this package, colors are specified using the tcell.Color type. Functions such as tcell.GetColor(), tcell.NewHexColor(), and tcell.NewRGBColor() can be used to create colors from W3C color names or RGB values. Almost all strings which are displayed can contain color tags. Color tags are W3C color names or six hexadecimal digits following a hash tag, wrapped in square brackets. Examples: A color tag changes the color of the characters following that color tag. This applies to almost everything from box titles, list text, form item labels, to table cells. In a TextView, this functionality has to be switched on explicitly. See the TextView documentation for more information. Color tags may contain not just the foreground (text) color but also the background color and additional flags. In fact, the full definition of a color tag is as follows: Each of the three fields can be left blank and trailing fields can be omitted. (Empty square brackets "[]", however, are not considered color tags.) Colors that are not specified will be left unchanged. A field with just a dash ("-") means "reset to default". You can specify the following flags (some flags may not be supported by your terminal): Examples: In the rare event that you want to display a string such as "[red]" or "[#00ff1a]" without applying its effect, you need to put an opening square bracket before the closing square bracket. Note that the text inside the brackets will be matched less strictly than region or colors tags. I.e. any character that may be used in color or region tags will be recognized. Examples: You can use the Escape() function to insert brackets automatically where needed. When primitives are instantiated, they are initialized with colors taken from the global Styles variable. You may change this variable to adapt the look and feel of the primitives to your preferred style. This package supports unicode characters including wide characters. Many functions in this package are not thread-safe. For many applications, this may not be an issue: If your code makes changes in response to key events, it will execute in the main goroutine and thus will not cause any race conditions. If you access your primitives from other goroutines, however, you will need to synchronize execution. The easiest way to do this is to call Application.QueueUpdate() or Application.QueueUpdateDraw() (see the function documentation for details): One exception to this is the io.Writer interface implemented by TextView. You can safely write to a TextView from any goroutine. See the TextView documentation for details. You can also call Application.Draw() from any goroutine without having to wrap it in QueueUpdate(). And, as mentioned above, key event callbacks are executed in the main goroutine and thus should not use QueueUpdate() as that may lead to deadlocks. All widgets listed above contain the Box type. All of Box's functions are therefore available for all widgets, too. All widgets also implement the Primitive interface. There is also the Focusable interface which is used to override functions in subclassing types. The tview package is based on https://maunium.net/go/tcell. It uses types and constants from that package (e.g. colors and keyboard values). This package does not process mouse input (yet).

This library allows a Go application to draw arbitrary graphics to the Linux Framebuffer. This allows one to create graphical applications without the need for a monolithic display manager like X. Because the framebuffer offers direct access to a chunk of memory mapped pixel data, it is strongly advised to keep all actual drawing operations confined to the thread that initialized the framebuffer.

Package sexprs implements Ron Rivest's canonical S-expressions (c.f. http://people.csail.mit.edu/rivest/Sexp.txt or rivest-draft.txt in this package) in Go. I'm indebted to Inferno's sexprs(2), whose API I first accidentally, and then deliberately, mimicked. I've copied much of its style, only making it more Go-like. Canonical S-expressions are a compact, easy-to-parse, ordered, hashable data representation ideal for cryptographic operations. They are simpler and more compact than either JSON or XML. An S-expression is composed of lists and atoms. An atom is a string of bytes, with an optional display hint, also a byte string. A list can contain zero or more atoms or lists. There are two representations of an S-expression: the canonical representation is a byte-oriented, packed representation, while the advanced representation is string-oriented and more traditional in appearance. The S-expression ("foo" "bar" ["bin"]"baz quux") is canonically: Among the valid advanced representations are: and: There is also a transport encoding (intended for use in 7-bit transport modes), delimited with {}:

Package jsonapi provides a serializer and deserializer for jsonapi.org spec payloads. You can keep your model structs as is and use struct field tags to indicate to jsonapi how you want your response built or your request deserialzied. What about my relationships? jsonapi supports relationships out of the box and will even side load them in your response into an "included" array--that contains associated objects. jsonapi uses StructField tags to annotate the structs fields that you already have and use in your app and then reads and writes jsonapi.org output based on the instructions you give the library in your jsonapi tags. Example structs using a Blog > Post > Comment structure, jsonapi Tag Reference Value, primary: "primary,<type field output>" This indicates that this is the primary key field for this struct type. Tag value arguments are comma separated. The first argument must be, "primary", and the second must be the name that should appear in the "type" field for all data objects that represent this type of model. Value, attr: "attr,<key name in attributes hash>[,<extra arguments>]" These fields' values should end up in the "attribute" hash for a record. The first argument must be, "attr', and the second should be the name for the key to display in the "attributes" hash for that record. The following extra arguments are also supported: "omitempty": excludes the fields value from the "attribute" hash. "iso8601": uses the ISO8601 timestamp format when serialising or deserialising the time.Time value. Value, relation: "relation,<key name in relationships hash>" Relations are struct fields that represent a one-to-one or one-to-many to other structs. jsonapi will traverse the graph of relationships and marshal or unmarshal records. The first argument must be, "relation", and the second should be the name of the relationship, used as the key in the "relationships" hash for the record. Use the methods below to Marshal and Unmarshal jsonapi.org json payloads. Visit the readme at https://github.com/google/jsonapi

Package jsonapi provides a serializer and deserializer for jsonapi.org spec payloads. You can keep your model structs as is and use struct field tags to indicate to jsonapi how you want your response built or your request deserialzied. What about my relationships? jsonapi supports relationships out of the box and will even side load them in your response into an "included" array--that contains associated objects. jsonapi uses StructField tags to annotate the structs fields that you already have and use in your app and then reads and writes jsonapi.org output based on the instructions you give the library in your jsonapi tags. Example structs using a Blog > Post > Comment structure, jsonapi Tag Reference Value, primary: "primary,<type field output>" This indicates that this is the primary key field for this struct type. Tag value arguments are comma separated. The first argument must be, "primary", and the second must be the name that should appear in the "type" field for all data objects that represent this type of model. Value, attr: "attr,<key name in attributes hash>[,<extra arguments>]" These fields' values should end up in the "attribute" hash for a record. The first argument must be, "attr', and the second should be the name for the key to display in the the "attributes" hash for that record. The following extra arguments are also supported: "omitempty": excludes the fields value from the "attribute" hash. "iso8601": uses the ISO8601 timestamp format when serialising or deserialising the time.Time value. Value, relation: "relation,<key name in relationships hash>" Relations are struct fields that represent a one-to-one or one-to-many to other structs. jsonapi will traverse the graph of relationships and marshal or unmarshal records. The first argument must be, "relation", and the second should be the name of the relationship, used as the key in the "relationships" hash for the record. Use the methods below to Marshal and Unmarshal jsonapi.org json payloads. Visit the readme at https://github.com/google/jsonapi

Package goaseprite is an Aseprite JSON loader written in Golang. The package is basically written around using goaseprite.Load() to load in your exported file's JSON data, and then using that to play and get the data necessary to display the animations.

Package tview implements rich widgets for terminal based user interfaces. The widgets provided with this package are useful for data exploration and data entry. The package implements the following widgets: The package also provides Application which is used to poll the event queue and draw widgets on screen. The following is a very basic example showing a box with the title "Hello, world!": First, we create a box primitive with a border and a title. Then we create an application, set the box as its root primitive, and run the event loop. The application exits when the application's Stop() function is called or when Ctrl-C is pressed. If we have a primitive which consumes key presses, we call the application's SetFocus() function to redirect all key presses to that primitive. Most primitives then offer ways to install handlers that allow you to react to any actions performed on them. You will find more demos in the "demos" subdirectory. It also contains a presentation (written using tview) which gives an overview of the different widgets and how they can be used. Throughout this package, colors are specified using the tcell.Color type. Functions such as tcell.GetColor(), tcell.NewHexColor(), and tcell.NewRGBColor() can be used to create colors from W3C color names or RGB values. Almost all strings which are displayed can contain color tags. Color tags are W3C color names or six hexadecimal digits following a hash tag, wrapped in square brackets. Examples: A color tag changes the color of the characters following that color tag. This applies to almost everything from box titles, list text, form item labels, to table cells. In a TextView, this functionality has to be switched on explicitly. See the TextView documentation for more information. Color tags may contain not just the foreground (text) color but also the background color and additional flags. In fact, the full definition of a color tag is as follows: Each of the three fields can be left blank and trailing fields can be omitted. (Empty square brackets "[]", however, are not considered color tags.) Colors that are not specified will be left unchanged. A field with just a dash ("-") means "reset to default". You can specify the following flags (some flags may not be supported by your terminal): Examples: In the rare event that you want to display a string such as "[red]" or "[#00ff1a]" without applying its effect, you need to put an opening square bracket before the closing square bracket. Note that the text inside the brackets will be matched less strictly than region or colors tags. I.e. any character that may be used in color or region tags will be recognized. Examples: You can use the Escape() function to insert brackets automatically where needed. When primitives are instantiated, they are initialized with colors taken from the global Styles variable. You may change this variable to adapt the look and feel of the primitives to your preferred style. This package supports unicode characters including wide characters. Many functions in this package are not thread-safe. For many applications, this may not be an issue: If your code makes changes in response to key events, it will execute in the main goroutine and thus will not cause any race conditions. If you access your primitives from other goroutines, however, you will need to synchronize execution. The easiest way to do this is to call Application.QueueUpdate() or Application.QueueUpdateDraw() (see the function documentation for details): One exception to this is the io.Writer interface implemented by TextView. You can safely write to a TextView from any goroutine. See the TextView documentation for details. You can also call Application.Draw() from any goroutine without having to wrap it in QueueUpdate(). And, as mentioned above, key event callbacks are executed in the main goroutine and thus should not use QueueUpdate() as that may lead to deadlocks. All widgets listed above contain the Box type. All of Box's functions are therefore available for all widgets, too. All widgets also implement the Primitive interface. There is also the Focusable interface which is used to override functions in subclassing types. The tview package is based on https://git.parallelcoin.io/dev/tview. It uses types and constants from that package (e.g. colors and keyboard values). This package does not process mouse input (yet).

Package goncurses is a new curses (ncurses) library for the Go programming language. It implements all the ncurses extension libraries: form, menu and panel. Minimal operation would consist of initializing the display: It is important to always call End() before your program exits. If you fail to do so, the terminal will not perform properly and will either need to be reset or restarted completely. CAUTION: Calls to ncurses functions are normally not atomic nor reentrant and therefore extreme care should be taken to ensure ncurses functions are not called concurrently. Specifically, never write data to the same window concurrently nor accept input and send output to the same window as both alter the underlying C data structures in a non safe manner. Ideally, you should structure your program to ensure all ncurses related calls happen in a single goroutine. This is probably most easily achieved via channels and Go's built-in select. Alternatively, or additionally, you can use a mutex to protect any calls in multiple goroutines from happening concurrently. Failure to do so will result in unpredictable and undefined behaviour in your program. The examples directory contains demontrations of many of the capabilities goncurses can provide.

A dynamic and extensible music library organizer Demlo is a music library organizer. It can encode, fix case, change folder hierarchy according to tags or file properties, tag from an online database, copy covers while ignoring duplicates or those below a quality threshold, and much more. It makes it possible to manage your libraries uniformly and dynamically. You can write your own rules to fit your needs best. Demlo aims at being as lightweight and portable as possible. Its major runtime dependency is the transcoder FFmpeg. The scripts are written in Lua for portability and speed while allowing virtually unlimited extensibility. Usage: For usage options, see: First Demlo creates a list of all input files. When a folder is specified, all files matching the extensions from the 'extensions' variable will be appended to the list. Identical files are appended only once. Next all files get analyzed: - The audio file details (tags, stream properties, format properties, etc.) are stored into the 'input' variable. The 'output' variable gets its default values from 'input', or from an index file if specified from command-line. If no index has been specified and if an attached cuesheet is found, all cuesheet details are appended accordingly. Cuesheet tags override stream tags, which override format tags. Finally, still without index, tags can be retrieved from Internet if the command-line option is set. - If a prescript has been specified, it gets executed. It makes it possible to adjust the input values and global variables before running the other scripts. - The scripts, if any, get executed in the lexicographic order of their basename. The 'output' variable is transformed accordingly. Scripts may contain rules such as defining a new file name, new tags, new encoding properties, etc. You can use conditions on input values to set the output properties, which makes it virtually possible to process a full music library in one single run. - If a postscript has been specified, it gets executed. It makes it possible to adjust the output of the script for the current run only. - Demlo makes some last-minute tweaking if need be: it adjusts the bitrate, the path, the encoding parameters, and so on. - A preview of changes is displayed. - When applying changes, the covers get copied if required and the audio file gets processed: tags are modified as specified, the file is re-encoded if required, and the output is written to the appropriate folder. When destination already exists, the 'exist' action is executed. The program's default behaviour can be changed from the user configuration file. (See the 'Files' section for a template.) Most command-line flags default value can be changed. The configuration file is loaded on startup, before parsing the command-line options. Review the default value of the CLI flags with 'demlo -h'. If you wish to use no configuration file, set the environment variable DEMLORC to ".". Scripts can contain any safe Lua code. Some functions like 'os.execute' are not available for security reasons. It is not possible to print to the standard output/error unless running in debug mode and using the 'debug' function. See the 'sandbox.go' file for a list of allowed functions and variables. Lua patterns are replaced by Go regexps. See https://github.com/google/re2/wiki/Syntax. Scripts have no requirements at all. However, to be useful, they should set values of the 'output' table detailed in the 'Variables' section. You can use the full power of the Lua to set the variables dynamically. For instance: 'input' and 'output' are both accessible from any script. All default functions and variables (excluding 'output') are reset on every script call to enforce consistency. Local variables are lost from one script call to another. Global variables are preserved. Use this feature to pass data like options or new functions. 'output' structure consistency is guaranteed at the start of every script. Demlo will only extract the fields with the right type as described in the 'Variables' section. Warning: Do not abuse of global variables, especially when processing non-fixed size data (e.g. tables). Data could grow big and slow down the program. By default, when the destination exists, Demlo will append a suffix to the output destination. This behaviour can be changed from the 'exist' action specified by the user. Demlo comes with a few default actions. The 'exist' action works just like scripts with the following differences: - Any change to 'output.path' will be skipped. - An additional variable is accessible from the action: 'existinfo' holds the file details of the existing files in the same fashion as 'input'. This allows for comparing the input file and the existing destination. The writing rules can be tweaked the following way: Word of caution: overwriting breaks Demlo's rule of not altering existing files. It can lead to undesired results if the overwritten file is also part of the (yet to be processed) input. The overwrite capability can be useful when syncing music libraries however. The user scripts should be generic. Therefore they may not properly handle some uncommon input values. Tweak the input with temporary overrides from command-line. The prescript and postscript defined on command-line will let you run arbitrary code that is run before and after all other scripts, respectively. Use global variables to transfer data and parameters along. If the prescript and postscript end up being too long, consider writing a demlo script. You can also define shell aliases or use wrapper scripts as convenience. The 'input' table describes the file: Bitrate is in bits per seconds (bps). That is, for 320 kbps you would specify The 'time' is the modification time of the file. It holds the sec seconds and nsec nanoseconds since January 1, 1970 UTC. The entry 'streams' and 'format' are as returned by It gives access to most metadata that FFmpeg can return. For instance, to get the duration of the track in seconds, query the variable 'input.format.duration'. Since there may be more than one stream (covers, other data), the first audio stream is assumed to be the music stream. For convenience, the index of the music stream is stored in 'audioindex'. The tags returned by FFmpeg are found in streams, format and in the cuesheet. To make tag queries easier, all tags are stored in the 'tags' table, with the following precedence: You can remove a tag by setting it to 'nil' or the empty string. This is equivalent, except that 'nil' saves some memory during the process. The 'output' table describes the transformation to apply to the file: The 'parameters' array holds the CLI parameters passed to FFmpeg. It can be anything supported by FFmpeg, although this variable is supposed to hold encoding information. See the 'Examples' section. The 'embeddedcovers', 'externalcovers' and 'onlinecover' variables are detailed in the 'Covers' section. The 'write' variable is covered in the 'Existing destination' section. The 'rmsrc' variable is a boolean: when true, Demlo removes the source file after processing. This can speed up the process when not re-encoding. This option is ignored for multi-track files. For convenience, the following shortcuts are provided: Demlo provides some non-standard Lua functions to ease scripting. Display a message on stderr if debug mode is on. Return lowercase string without non-alphanumeric characters nor leading zeros. Return the relation coefficient of the two input strings. The result is a float in 0.0...1.0, 0.0 means no relation at all, 1.0 means identical strings. A format is a container in FFmpeg's terminology. 'output.parameters' contains CLI flags passed to FFmpeg. They are meant to set the stream codec, the bitrate, etc. If 'output.parameters' is {'-c:a', 'copy'} and the format is identical, then taglib will be used instead of FFmpeg. Use this rule from a (post)script to disable encoding by setting the same format and the copy parameters. This speeds up the process. The official scripts are usually very smart at guessing the right values. They might make mistakes however. If you are unsure, you can (and you are advised to) preview the results before proceeding. The 'diff' preview is printed to stderr. A JSON preview of the changes is printed to stdout if stdout is redirected. The initial values of the 'output' table can be completed with tags fetched from the MusicBrainz database. Audio files are fingerprinted for the queries, so even with initially wrong file names and tags, the right values should still be retrieved. The front album cover can also be retrieved. Proxy parameters will be fetched automatically from the 'http_proxy' and 'https_proxy' environment variables. As this process requires network access it can be quite slow. Nevertheless, Demlo is specifically optimized for albums, so that network queries are used for only one track per album, when possible. Some tracks can be released on different albums: Demlo tries to guess it from the tags, but if the tags are wrong there is no way to know which one it is. There is a case where the selection can be controlled: let's assume we have tracks A, B and C from the same album Z. A and B were also released in album Y, whereas C was release in Z only. Tags for A will be checked online; let's assume it gets tagged to album Y. B will use A details, so album Y too. Then C does not match neither A's nor B's album, so another online query will be made and it will be tagged to album Z. This is slow and does not yield the expected result. Now let's call Tags for C will be queried online, and C will be tagged to Z. Then both A and B will match album Z so they will be tagged using C details, which is the desired result. Conclusion: when using online tagging, the first argument should be the lesser known track of the album. Demlo can set the output variables according to the values set in a text file before calling the script. The input values are ignored as well as online tagging, but it is still possible to access the input table from scripts. This 'index' file is formatted in JSON. It corresponds to what Demlo outputs when printing the JSON preview. This is valid JSON except for the missing beginning and the missing end. It makes it possible to concatenate and to append to existing index files. Demlo will automatically complete the missing parts so that it becomes valid JSON. The index file is useful when you want to edit tags manually: You can redirect the output to a file, edit the content manually with your favorite text editor, then run Demlo again with the index as argument. See the 'Examples' section. This feature can also be used to interface Demlo with other programs. Demlo can manage embedded covers as well as external covers. External covers are queried from files matching known extensions in the file's folder. Embedded covers are queried from static video streams in the file. Covers are accessed from The embedded covers are indexed numerically by order of appearance in the streams. The first cover will be at index 1 and so on. This is not necessarily the index of the stream. 'inputcover' is the following structure: 'format' is the picture format. FFmpeg makes a distinction between format and codec, but it is not useful for covers. The name of the format is specified by Demlo, not by FFmpeg. Hence the 'jpeg' name, instead of 'mjpeg' as FFmpeg puts it. 'width' and 'height' hold the size in pixels. 'checksum' can be used to identify files uniquely. For performance reasons, only a partial checksum is performed. This variable is typically used for skipping duplicates. Cover transformations are specified in 'outputcover' has the following structure: The format is specified by FFmpeg this time. See the comments on 'format' for 'inputcover'. 'parameters' is used in the same fashion as 'output.parameters'. User configuration: This must be a Lua file. See the 'demlorc' file provided with this package for an exhaustive list of options. Folder containing the official scripts: User script folder: Create this folder and add your own scripts inside. This folder takes precedence over the system folder, so scripts with the same name will be found in the user folder first. The following examples will not proceed unless the '-p' command-line option is true. Important: you _must_ use single quotes for the runtime Lua command to prevent expansion. Inside the Lua code, use double quotes for strings and escape single quotes. Show default options: Preview changes made by the default scripts: Use 'alternate' script if found in user or system script folder (user folder first): Add the Lua file to the list of scripts. This feature is convenient if you want to write scripts that are too complex to fit on the command-line, but not generic enough to fit the user or system script folders. Remove all script from the list, then add '30-case' and '60-path' scripts. Note that '30-case' will be run before '60-path'. Do not use any script but '60-path'. The file content is unchanged and the file is renamed to a dynamically computed destination. Demlo performs an instant rename if destination is on the same device. Otherwise it copies the file and removes the source. Use the default scripts (if set in configuration file), but do not re-encode: Set 'artist' to the value of 'composer', and 'title' to be preceded by the new value of 'artist', then apply the default script. Do not re-encode. Order in runtime script matters. Mind the double quotes. Set track number to first number in input file name: Use the default scripts but keep original value for the 'artist' tag: 1) Preview default scripts transformation and save it to an index. 2) Edit file to fix any potential mistake. 3) Run Demlo over the same files using the index information only. Same as above but generate output filename according to the custom '61-rename' script. The numeric prefix is important: it ensures that '61-rename' will be run after all the default tag related scripts and after '60-path'. Otherwise, if a change in tags would occur later on, it would not affect the renaming script. Retrieve tags from Internet: Same as above but for a whole album, and saving the result to an index: Only download the cover for the album corresponding to the track. Use 'rmsrc' to avoid duplicating the audio file. Change tags inplace with entries from MusicBrainz: Set tags to titlecase while casing AC-DC correctly: To easily switch between formats from command-line, create one script per format (see 50-encoding.lua), e.g. ogg.lua and flac.lua. Then Add support for non-default formats from CLI: Overwrite existing destination if input is newer: ffmpeg(1), ffprobe(1), http://www.lua.org/pil/contents.html

package tlang implements data-driven templates for generating textual output. To generate HTML output, see package html/template, which has the same interface as this package but automatically secures HTML output against certain attacks. Templates are executed by applying them to a data structure. Annotations in the template refer to elements of the data structure (typically a field of a struct or a key in a map) to control execution and derive values to be displayed. Execution of the template walks the structure and sets the cursor, represented by a period '.' and called "dot", to the value at the current location in the structure as execution proceeds. The input text for a template is UTF-8-encoded text in any format. "Actions"--data evaluations or control structures--are delimited by "{{" and "}}"; all text outside actions is copied to the output unchanged. Except for raw strings, actions may not span newlines, although comments can. Once parsed, a template may be executed safely in parallel, although if parallel executions share a Writer the output may be interleaved. Here is a trivial example that prints "17 items are made of wool". More intricate examples appear below. By default, all text between actions is copied verbatim when the template is executed. For example, the string " items are made of " in the example above appears on standard output when the program is run. However, to aid in formatting template source code, if an action's left delimiter (by default "{{") is followed immediately by a minus sign and white space, all trailing white space is trimmed from the immediately preceding text. Similarly, if the right delimiter ("}}") is preceded by white space and a minus sign, all leading white space is trimmed from the immediately following text. In these trim markers, the white space must be present: "{{- 3}}" is like "{{3}}" but trims the immediately preceding text, while "{{-3}}" parses as an action containing the number -3. For instance, when executing the template whose source is the generated output would be For this trimming, the definition of white space characters is the same as in Go: space, horizontal tab, carriage return, and newline. Here is the list of actions. "Arguments" and "pipelines" are evaluations of data, defined in detail in the corresponding sections that follow. An argument is a simple value, denoted by one of the following. Arguments may evaluate to any type; if they are pointers the implementation automatically indirects to the base type when required. If an evaluation yields a function value, such as a function-valued field of a struct, the function is not invoked automatically, but it can be used as a truth value for an if action and the like. To invoke it, use the call function, defined below. A pipeline is a possibly chained sequence of "commands". A command is a simple value (argument) or a function or method call, possibly with multiple arguments: A pipeline may be "chained" by separating a sequence of commands with pipeline characters '|'. In a chained pipeline, the result of each command is passed as the last argument of the following command. The output of the final command in the pipeline is the value of the pipeline. The output of a command will be either one value or two values, the second of which has type error. If that second value is present and evaluates to non-nil, execution terminates and the error is returned to the caller of Execute. A pipeline inside an action may initialize a variable to capture the result. The initialization has syntax where $variable is the name of the variable. An action that declares a variable produces no output. Variables previously declared can also be assigned, using the syntax If a "range" action initializes a variable, the variable is set to the successive elements of the iteration. Also, a "range" may declare two variables, separated by a comma: in which case $index and $element are set to the successive values of the array/slice index or map key and element, respectively. Note that if there is only one variable, it is assigned the element; this is opposite to the convention in Go range clauses. A variable's scope extends to the "end" action of the control structure ("if", "with", or "range") in which it is declared, or to the end of the template if there is no such control structure. A template invocation does not inherit variables from the point of its invocation. When execution begins, $ is set to the data argument passed to Execute, that is, to the starting value of dot. Here are some example one-line templates demonstrating pipelines and variables. All produce the quoted word "output": During execution functions are found in two function maps: first in the template, then in the global function map. By default, no functions are defined in the template but the Funcs method can be used to add them. Predefined global functions are named as follows. The boolean functions take any zero value to be false and a non-zero value to be true. There is also a set of binary comparison operators defined as functions: For simpler multi-way equality tests, eq (only) accepts two or more arguments and compares the second and subsequent to the first, returning in effect (Unlike with || in Go, however, eq is a function call and all the arguments will be evaluated.) The comparison functions work on any values whose type Go defines as comparable. For basic types such as integers, the rules are relaxed: size and exact type are ignored, so any integer value, signed or unsigned, may be compared with any other integer value. (The arithmetic value is compared, not the bit pattern, so all negative integers are less than all unsigned integers.) However, as usual, one may not compare an int with a float32 and so on. Each template is named by a string specified when it is created. Also, each template is associated with zero or more other templates that it may invoke by name; such associations are transitive and form a name space of templates. A template may use a template invocation to instantiate another associated template; see the explanation of the "template" action above. The name must be that of a template associated with the template that contains the invocation. When parsing a template, another template may be defined and associated with the template being parsed. Template definitions must appear at the top level of the template, much like global variables in a Go program. The syntax of such definitions is to surround each template declaration with a "define" and "end" action. The define action names the template being created by providing a string constant. Here is a simple example: This defines two templates, T1 and T2, and a third T3 that invokes the other two when it is executed. Finally it invokes T3. If executed this template will produce the text By construction, a template may reside in only one association. If it's necessary to have a template addressable from multiple associations, the template definition must be parsed multiple times to create distinct *Template values, or must be copied with the Clone or AddParseTree method. Parse may be called multiple times to assemble the various associated templates; see the ParseFiles and ParseGlob functions and methods for simple ways to parse related templates stored in files. A template may be executed directly or through ExecuteTemplate, which executes an associated template identified by name. To invoke our example above, we might write, or to invoke a particular template explicitly by name,

Package tview implements rich widgets for terminal based user interfaces. The widgets provided with this package are useful for data exploration and data entry. The package implements the following widgets: The package also provides Application which is used to poll the event queue and draw widgets on screen. The following is a very basic example showing a box with the title "Hello, world!": First, we create a box primitive with a border and a title. Then we create an application, set the box as its root primitive, and run the event loop. The application exits when the application's Stop() function is called or when Ctrl-C is pressed. If we have a primitive which consumes key presses, we call the application's SetFocus() function to redirect all key presses to that primitive. Most primitives then offer ways to install handlers that allow you to react to any actions performed on them. You will find more demos in the "demos" subdirectory. It also contains a presentation (written using tview) which gives an overview of the different widgets and how they can be used. Throughout this package, colors are specified using the tcell.Color type. Functions such as tcell.GetColor(), tcell.NewHexColor(), and tcell.NewRGBColor() can be used to create colors from W3C color names or RGB values. Almost all strings which are displayed can contain color tags. Color tags are W3C color names or six hexadecimal digits following a hash tag, wrapped in square brackets. Examples: A color tag changes the color of the characters following that color tag. This applies to almost everything from box titles, list text, form item labels, to table cells. In a TextView, this functionality has to be switched on explicitly. See the TextView documentation for more information. Color tags may contain not just the foreground (text) color but also the background color and additional flags. In fact, the full definition of a color tag is as follows: Each of the three fields can be left blank and trailing fields can be omitted. (Empty square brackets "[]", however, are not considered color tags.) Colors that are not specified will be left unchanged. A field with just a dash ("-") means "reset to default". You can specify the following flags (some flags may not be supported by your terminal): Examples: In the rare event that you want to display a string such as "[red]" or "[#00ff1a]" without applying its effect, you need to put an opening square bracket before the closing square bracket. Note that the text inside the brackets will be matched less strictly than region or colors tags. I.e. any character that may be used in color or region tags will be recognized. Examples: You can use the Escape() function to insert brackets automatically where needed. When primitives are instantiated, they are initialized with colors taken from the global Styles variable. You may change this variable to adapt the look and feel of the primitives to your preferred style. This package supports unicode characters including wide characters. Many functions in this package are not thread-safe. For many applications, this may not be an issue: If your code makes changes in response to key events, it will execute in the main goroutine and thus will not cause any race conditions. If you access your primitives from other goroutines, however, you will need to synchronize execution. The easiest way to do this is to call Application.QueueUpdate() (see its documentation for details): One exception to this is the io.Writer interface implemented by TextView. You can safely write to a TextView from any goroutine. See the TextView documentation for details. All widgets listed above contain the Box type. All of Box's functions are therefore available for all widgets, too. All widgets also implement the Primitive interface. There is also the Focusable interface which is used to override functions in subclassing types. The tview package is based on https://github.com/gdamore/tcell. It uses types and constants from that package (e.g. colors and keyboard values). This package does not process mouse input (yet).

Package dataurl parses Data URL Schemes according to RFC 2397 (http://tools.ietf.org/html/rfc2397). Data URLs are small chunks of data commonly used in browsers to display inline data, typically like small images, or when you use the FileReader API of the browser. A dataurl looks like: Or, with base64 encoding: Common functions are Decode and DecodeString to obtain a DataURL, and DataURL.String() and DataURL.WriteTo to generate a Data URL string.

Package jsonapi provides a serializer and deserializer for jsonapi.org spec payloads. You can keep your model structs as is and use struct field tags to indicate to jsonapi how you want your response built or your request deserialzied. What about my relationships? jsonapi supports relationships out of the box and will even side load them in your response into an "included" array--that contains associated objects. jsonapi uses StructField tags to annotate the structs fields that you already have and use in your app and then reads and writes jsonapi.org output based on the instructions you give the library in your jsonapi tags. Example structs using a Blog > Post > Comment structure, jsonapi Tag Reference Value, primary: "primary,<type field output>" This indicates that this is the primary key field for this struct type. Tag value arguments are comma separated. The first argument must be, "primary", and the second must be the name that should appear in the "type" field for all data objects that represent this type of model. Value, attr: "attr,<key name in attributes hash>[,<extra arguments>]" These fields' values should end up in the "attribute" hash for a record. The first argument must be, "attr', and the second should be the name for the key to display in the the "attributes" hash for that record. The following extra arguments are also supported: "omitempty": excludes the fields value from the "attribute" hash. "iso8601": uses the ISO8601 timestamp format when serialising or deserialising the time.Time value. Value, relation: "relation,<key name in relationships hash>" Relations are struct fields that represent a one-to-one or one-to-many to other structs. jsonapi will traverse the graph of relationships and marshal or unmarshal records. The first argument must be, "relation", and the second should be the name of the relationship, used as the key in the "relationships" hash for the record. Use the methods below to Marshal and Unmarshal jsonapi.org json payloads. Visit the readme at https://github.com/google/jsonapi

Package badgedata provides a collection of methods to retreive, store and re-display data from other websites. The intent is to use the displayed data with badgen.net.