Validation

github.com/ThalesIgnite/crypto11

Package crypto11 enables access to cryptographic keys from PKCS#11 using Go crypto API. PKCS#11 tokens are accessed via Context objects. Each Context connects to one token. Context objects are created by calling Configure or ConfigureFromFile. In the latter case, the file should contain a JSON representation of a Config. There is support for generating DSA, RSA and ECDSA keys. These keys can be found later using FindKeyPair. All three key types implement the crypto.Signer interface and the RSA keys also implement crypto.Decrypter. RSA keys obtained through FindKeyPair will need a type assertion to be used for decryption. Assert either crypto.Decrypter or SignerDecrypter, as you prefer. Symmetric keys can also be generated. These are found later using FindKey. See the documentation for SecretKey for further information. Note that PKCS#11 session handles must not be used concurrently from multiple threads. Consumers of the Signer interface know nothing of this and expect to be able to sign from multiple threads without constraint. We address this as follows. 1. When a Context is created, a session is created and the user is logged in. This session remains open until the Context is closed, to ensure all object handles remain valid and to avoid repeatedly calling C_Login. 2. The Context also maintains a pool of read-write sessions. The pool expands dynamically as needed, but never beyond the maximum number of r/w sessions supported by the token (as reported by C_GetInfo). If other applications are using the token, a lower limit should be set in the Config. 3. Each operation transiently takes a session from the pool. They have exclusive use of the session, meeting PKCS#11's concurrency requirements. Sessions are returned to the pool afterwards and may be re-used. Behaviour of the pool can be tweaked via Config fields: - PoolWaitTimeout controls how long an operation can block waiting on a session from the pool. A zero value means there is no limit. Timeouts occur if the pool is fully used and additional operations are requested. - MaxSessions sets an upper bound on the number of sessions. If this value is zero, a default maximum is used (see DefaultMaxSessions). In every case the maximum supported sessions as reported by the token is obeyed. The PKCS1v15DecryptOptions SessionKeyLen field is not implemented and an error is returned if it is nonzero. The reason for this is that it is not possible for crypto11 to guarantee the constant-time behavior in the specification. See https://github.com/thalesignite/crypto11/issues/5 for further discussion. Symmetric crypto support via cipher.Block is very slow. You can use the BlockModeCloser API but you must call the Close() interface (not found in cipher.BlockMode). See https://github.com/ThalesIgnite/crypto11/issues/6 for further discussion.

v1.2.5 • 3 years ago

github.com/kataras/golog

CBSD 3-Clause License Copyright (c) 2017-2022, Gerasimos (Makis) Maropoulos (kataras2006@hotmail.com) All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. /* Package golog provides an easy to use foundation for your logging operations. Source code and other details for the project are available at GitHub: 0.1.12 The only requirement is the Go Programming Language Example code: Golog has a default, package-level initialized instance for you, however you can choose to create and use a logger instance for a specific part of your application. Example Code: Golog sets colors to levels when its `Printer.Output` is actual a compatible terminal which can renders colors, otherwise it will downgrade itself to a white foreground. Golog has functions to print a formatted log too. Example Code: Golog takes a simple `io.Writer` as its underline Printer's Output. Example Code: You can even override the default line braker, "\n", by using the `golog#NewLine` function at startup. Example Code: Golog is a leveled logger, therefore you can set a level and print whenever the print level is valid with the set-ed one. Available built'n levels are: Below you'll learn a way to add a custom level or modify an existing level. The default colorful text(or raw text for unsupported outputs) for levels can be overridden by using the `golog#ErrorText, golog#WarnText, golog#InfoText and golog#DebugText` functions. Example Code: Golog gives you the power to add or modify existing levels is via Level Metadata. Example Code: The logger's level can be changed via passing one of the level constants to the `Level` field or by passing its string representation to the `SetLevel` function. Example Code: Transaction with your favorite, but deprecated logger is easy. Golog offers two basic interfaces, the `ExternalLogger` and the `StdLogger` that can be directly used as arguments to the `Install` function in order to adapt an external logger. Outline: Example Code: Example Code: But you should have a basic idea of the golog package 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:

v0.1.12 • 7 months ago

github.com/fasthttp/websocket

Package websocket implements the WebSocket protocol defined in RFC 6455. The Conn type represents a WebSocket connection. A server application calls the Upgrader.Upgrade method from an HTTP request handler to get a *Conn: net/http valyala/fasthttp Call the connection's WriteMessage and ReadMessage methods to send and receive messages as a slice of bytes. This snippet of code shows how to echo messages using these methods: In above snippet of code, p is a []byte and messageType is an int with value websocket.BinaryMessage or websocket.TextMessage. An application can also send and receive messages using the io.WriteCloser and io.Reader interfaces. To send a message, call the connection NextWriter method to get an io.WriteCloser, write the message to the writer and close the writer when done. To receive a message, call the connection NextReader method to get an io.Reader and read until io.EOF is returned. This snippet shows how to echo messages using the NextWriter and NextReader methods: The WebSocket protocol distinguishes between text and binary data messages. Text messages are interpreted as UTF-8 encoded text. The interpretation of binary messages is left to the application. This package uses the TextMessage and BinaryMessage integer constants to identify the two data message types. The ReadMessage and NextReader methods return the type of the received message. The messageType argument to the WriteMessage and NextWriter methods specifies the type of a sent message. It is the application's responsibility to ensure that text messages are valid UTF-8 encoded text. The WebSocket protocol defines three types of control messages: close, ping and pong. Call the connection WriteControl, WriteMessage or NextWriter methods to send a control message to the peer. Connections handle received close messages by calling the handler function set with the SetCloseHandler method and by returning a *CloseError from the NextReader, ReadMessage or the message Read method. The default close handler sends a close message to the peer. Connections handle received ping messages by calling the handler function set with the SetPingHandler method. The default ping handler sends a pong message to the peer. Connections handle received pong messages by calling the handler function set with the SetPongHandler method. The default pong handler does nothing. If an application sends ping messages, then the application should set a pong handler to receive the corresponding pong. The control message handler functions are called from the NextReader, ReadMessage and message reader Read methods. The default close and ping handlers can block these methods for a short time when the handler writes to the connection. The application must read the connection to process close, ping and pong messages sent from the peer. If the application is not otherwise interested in messages from the peer, then the application should start a goroutine to read and discard messages from the peer. A simple example is: Connections support one concurrent reader and one concurrent writer. Applications are responsible for ensuring that no more than one goroutine calls the write methods (NextWriter, SetWriteDeadline, WriteMessage, WriteJSON, EnableWriteCompression, SetCompressionLevel) concurrently and that no more than one goroutine calls the read methods (NextReader, SetReadDeadline, ReadMessage, ReadJSON, SetPongHandler, SetPingHandler) concurrently. The Close and WriteControl methods can be called concurrently with all other methods. Web browsers allow Javascript applications to open a WebSocket connection to any host. It's up to the server to enforce an origin policy using the Origin request header sent by the browser. The Upgrader calls the function specified in the CheckOrigin field to check the origin. If the CheckOrigin function returns false, then the Upgrade method fails the WebSocket handshake with HTTP status 403. If the CheckOrigin field is nil, then the Upgrader uses a safe default: fail the handshake if the Origin request header is present and the Origin host is not equal to the Host request header. The deprecated package-level Upgrade function does not perform origin checking. The application is responsible for checking the Origin header before calling the Upgrade function. Connections buffer network input and output to reduce the number of system calls when reading or writing messages. Write buffers are also used for constructing WebSocket frames. See RFC 6455, Section 5 for a discussion of message framing. A WebSocket frame header is written to the network each time a write buffer is flushed to the network. Decreasing the size of the write buffer can increase the amount of framing overhead on the connection. The buffer sizes in bytes are specified by the ReadBufferSize and WriteBufferSize fields in the Dialer and Upgrader. The Dialer uses a default size of 4096 when a buffer size field is set to zero. The Upgrader reuses buffers created by the HTTP server when a buffer size field is set to zero. The HTTP server buffers have a size of 4096 at the time of this writing. The buffer sizes do not limit the size of a message that can be read or written by a connection. Buffers are held for the lifetime of the connection by default. If the Dialer or Upgrader WriteBufferPool field is set, then a connection holds the write buffer only when writing a message. Applications should tune the buffer sizes to balance memory use and performance. Increasing the buffer size uses more memory, but can reduce the number of system calls to read or write the network. In the case of writing, increasing the buffer size can reduce the number of frame headers written to the network. Some guidelines for setting buffer parameters are: Limit the buffer sizes to the maximum expected message size. Buffers larger than the largest message do not provide any benefit. Depending on the distribution of message sizes, setting the buffer size to a value less than the maximum expected message size can greatly reduce memory use with a small impact on performance. Here's an example: If 99% of the messages are smaller than 256 bytes and the maximum message size is 512 bytes, then a buffer size of 256 bytes will result in 1.01 more system calls than a buffer size of 512 bytes. The memory savings is 50%. A write buffer pool is useful when the application has a modest number writes over a large number of connections. when buffers are pooled, a larger buffer size has a reduced impact on total memory use and has the benefit of reducing system calls and frame overhead. Per message compression extensions (RFC 7692) are experimentally supported by this package in a limited capacity. Setting the EnableCompression option to true in Dialer or Upgrader will attempt to negotiate per message deflate support. If compression was successfully negotiated with the connection's peer, any message received in compressed form will be automatically decompressed. All Read methods will return uncompressed bytes. Per message compression of messages written to a connection can be enabled or disabled by calling the corresponding Conn method: Currently this package does not support compression with "context takeover". This means that messages must be compressed and decompressed in isolation, without retaining sliding window or dictionary state across messages. For more details refer to RFC 7692. Use of compression is experimental and may result in decreased performance.

v1.5.10 • 5 months ago

github.com/mna/pigeon

Command pigeon generates parsers in Go from a PEG grammar. From Wikipedia [0]: Its features and syntax are inspired by the PEG.js project [1], while the implementation is loosely based on [2]. Formal presentation of the PEG theory by Bryan Ford is also an important reference [3]. An introductory blog post can be found at [4]. The pigeon tool must be called with PEG input as defined by the accepted PEG syntax below. The grammar may be provided by a file or read from stdin. The generated parser is written to stdout by default. The following options can be specified: If the code blocks in the grammar (see below, section "Code block") are golint- and go vet-compliant, then the resulting generated code will also be golint- and go vet-compliant. The generated code doesn't use any third-party dependency unless code blocks in the grammar require such a dependency. The accepted syntax for the grammar is formally defined in the grammar/pigeon.peg file, using the PEG syntax. What follows is an informal description of this syntax. Identifiers, whitespace, comments and literals follow the same notation as the Go language, as defined in the language specification (http://golang.org/ref/spec#Source_code_representation): The grammar must be Unicode text encoded in UTF-8. New lines are identified by the \n character (U+000A). Space (U+0020), horizontal tabs (U+0009) and carriage returns (U+000D) are considered whitespace and are ignored except to separate tokens. A PEG grammar consists of a set of rules. A rule is an identifier followed by a rule definition operator and an expression. An optional display name - a string literal used in error messages instead of the rule identifier - can be specified after the rule identifier. E.g.: The rule definition operator can be any one of those: A rule is defined by an expression. The following sections describe the various expression types. Expressions can be grouped by using parentheses, and a rule can be referenced by its identifier in place of an expression. The choice expression is a list of expressions that will be tested in the order they are defined. The first one that matches will be used. Expressions are separated by the forward slash character "/". E.g.: Because the first match is used, it is important to think about the order of expressions. For example, in this rule, "<=" would never be used because the "<" expression comes first: The sequence expression is a list of expressions that must all match in that same order for the sequence expression to be considered a match. Expressions are separated by whitespace. E.g.: A labeled expression consists of an identifier followed by a colon ":" and an expression. A labeled expression introduces a variable named with the label that can be referenced in the code blocks in the same scope. The variable will have the value of the expression that follows the colon. E.g.: The variable is typed as an empty interface, and the underlying type depends on the following: For terminals (character and string literals, character classes and the any matcher), the value is []byte. E.g.: For predicates (& and !), the value is always nil. E.g.: For a sequence, the value is a slice of empty interfaces, one for each expression value in the sequence. The underlying types of each value in the slice follow the same rules described here, recursively. E.g.: For a repetition (+ and *), the value is a slice of empty interfaces, one for each repetition. The underlying types of each value in the slice follow the same rules described here, recursively. E.g.: For a choice expression, the value is that of the matching choice. E.g.: For the optional expression (?), the value is nil or the value of the expression. E.g.: Of course, the type of the value can be anything once an action code block is used. E.g.: An expression prefixed with the ampersand "&" is the "and" predicate expression: it is considered a match if the following expression is a match, but it does not consume any input. An expression prefixed with the exclamation point "!" is the "not" predicate expression: it is considered a match if the following expression is not a match, but it does not consume any input. E.g.: The expression following the & and ! operators can be a code block. In that case, the code block must return a bool and an error. The operator's semantic is the same, & is a match if the code block returns true, ! is a match if the code block returns false. The code block has access to any labeled value defined in its scope. E.g.: An expression followed by "*", "?" or "+" is a match if the expression occurs zero or more times ("*"), zero or one time "?" or one or more times ("+") respectively. The match is greedy, it will match as many times as possible. E.g. A literal matcher tries to match the input against a single character or a string literal. The literal may be a single-quoted single character, a double-quoted string or a backtick-quoted raw string. The same rules as in Go apply regarding the allowed characters and escapes. The literal may be followed by a lowercase "i" (outside the ending quote) to indicate that the match is case-insensitive. E.g.: A character class matcher tries to match the input against a class of characters inside square brackets "[...]". Inside the brackets, characters represent themselves and the same escapes as in string literals are available, except that the single- and double-quote escape is not valid, instead the closing square bracket "]" must be escaped to be used. Character ranges can be specified using the "[a-z]" notation. Unicode classes can be specified using the "[\pL]" notation, where L is a single-letter Unicode class of characters, or using the "[\p{Class}]" notation where Class is a valid Unicode class (e.g. "Latin"). As for string literals, a lowercase "i" may follow the matcher (outside the ending square bracket) to indicate that the match is case-insensitive. A "^" as first character inside the square brackets indicates that the match is inverted (it is a match if the input does not match the character class matcher). E.g.: The any matcher is represented by the dot ".". It matches any character except the end of file, thus the "!." expression is used to indicate "match the end of file". E.g.: Code blocks can be added to generate custom Go code. There are three kinds of code blocks: the initializer, the action and the predicate. All code blocks appear inside curly braces "{...}". The initializer must appear first in the grammar, before any rule. It is copied as-is (minus the wrapping curly braces) at the top of the generated parser. It may contain function declarations, types, variables, etc. just like any Go file. Every symbol declared here will be available to all other code blocks. Although the initializer is optional in a valid grammar, it is usually required to generate a valid Go source code file (for the package clause). E.g.: Action code blocks are code blocks declared after an expression in a rule. Those code blocks are turned into a method on the "*current" type in the generated source code. The method receives any labeled expression's value as argument (as any) and must return two values, the first being the value of the expression (an any), and the second an error. If a non-nil error is returned, it is added to the list of errors that the parser will return. E.g.: Predicate code blocks are code blocks declared immediately after the and "&" or the not "!" operators. Like action code blocks, predicate code blocks are turned into a method on the "*current" type in the generated source code. The method receives any labeled expression's value as argument (as any) and must return two opt, the first being a bool and the second an error. If a non-nil error is returned, it is added to the list of errors that the parser will return. E.g.: State change code blocks are code blocks starting with "#". In contrast to action and predicate code blocks, state change code blocks are allowed to modify values in the global "state" store (see below). State change code blocks are turned into a method on the "*current" type in the generated source code. The method is passed any labeled expression's value as an argument (of type any) and must return a value of type error. If a non-nil error is returned, it is added to the list of errors that the parser will return, note that the parser does NOT backtrack if a non-nil error is returned. E.g: The "*current" type is a struct that provides four useful fields that can be accessed in action, state change, and predicate code blocks: "pos", "text", "state" and "globalStore". The "pos" field indicates the current position of the parser in the source input. It is itself a struct with three fields: "line", "col" and "offset". Line is a 1-based line number, col is a 1-based column number that counts runes from the start of the line, and offset is a 0-based byte offset. The "text" field is the slice of bytes of the current match. It is empty in a predicate code block. The "state" field is a global store, with backtrack support, of type "map[string]any". The values in the store are tied to the parser's backtracking, in particular if a rule fails to match then all updates to the state that occurred in the process of matching the rule are rolled back. For a key-value store that is not tied to the parser's backtracking, see the "globalStore". The values in the "state" store are available for read access in action and predicate code blocks, any changes made to the "state" store will be reverted once the action or predicate code block is finished running. To update values in the "state" use state change code blocks ("#{}"). IMPORTANT: The "globalStore" field is a global store of type "map[string]any", which allows to store arbitrary values, which are available in action and predicate code blocks for read as well as write access. It is important to notice, that the global store is completely independent from the backtrack mechanism of PEG and is therefore not set back to its old state during backtrack. The initialization of the global store may be achieved by using the GlobalStore function (http://godoc.org/github.com/mna/pigeon/test/predicates#GlobalStore). Be aware, that all keys starting with "_pigeon" are reserved for internal use of pigeon and should not be used nor modified. Those keys are treated as internal implementation details and therefore there are no guarantees given in regards of API stability. With options -support-left-recursion pigeon supports left recursion. E.g.: Supports indirect recursion: The implementation is based on the [Left-recursive PEG Grammars][9] article that links to [Left Recursion in Parsing Expression Grammars][10] and [Packrat Parsers Can Support Left Recursion][11] papers. References: pigeon supports an extension of the classical PEG syntax called failure labels, proposed by Maidl et al. in their paper "Error Reporting in Parsing Expression Grammars" [7]. The used syntax for the introduced expressions is borrowed from their lpeglabel [8] implementation. This extension allows to signal different kinds of errors and to specify, which recovery pattern should handle a given label. With labeled failures it is possible to distinguish between an ordinary failure and an error. Usually, an ordinary failure is produced when the matching of a character fails, and this failure is caught by ordered choice. An error (a non-ordinary failure), by its turn, is produced by the throw operator and may be caught by the recovery operator. In pigeon, the recovery expression consists of the regular expression, the recovery expression and a set of labels to be matched. First, the regular expression is tried. If this fails with one of the provided labels, the recovery expression is tried. If this fails as well, the error is propagated. E.g.: To signal a failure condition, the throw expression is used. E.g.: For concrete examples, how to use throw and recover, have a look at the examples "labeled_failures" and "thrownrecover" in the "test" folder. The implementation of the throw and recover operators work as follows: The failure recover expression adds the recover expression for every failure label to the recovery stack and runs the regular expression. The throw expression checks the recovery stack in reversed order for the provided failure label. If the label is found, the respective recovery expression is run. If this expression is successful, the parser continues the processing of the input. If the recovery expression is not successful, the parsing fails and the parser starts to backtrack. If throw and recover expressions are used together with global state, it is the responsibility of the author of the grammar to reset the global state to a valid state during the recovery operation. The parser generated by pigeon exports a few symbols so that it can be used as a package with public functions to parse input text. The exported API is: See the godoc page of the generated parser for the test/predicates grammar for an example documentation page of the exported API: http://godoc.org/github.com/mna/pigeon/test/predicates. Like the grammar used to generate the parser, the input text must be UTF-8-encoded Unicode. The start rule of the parser is the first rule in the PEG grammar used to generate the parser. A call to any of the Parse* functions returns the value generated by executing the grammar on the provided input text, and an optional error. Typically, the grammar should generate some kind of abstract syntax tree (AST), but for simple grammars it may evaluate the result immediately, such as in the examples/calculator example. There are no constraints imposed on the author of the grammar, it can return whatever is needed. When the parser returns a non-nil error, the error is always of type errList, which is defined as a slice of errors ([]error). Each error in the list is of type *parserError. This is a struct that has an "Inner" field that can be used to access the original error. So if a code block returns some well-known error like: The original error can be accessed this way: By default the parser will continue after an error is returned and will cumulate all errors found during parsing. If the grammar reaches a point where it shouldn't continue, a panic statement can be used to terminate parsing. The panic will be caught at the top-level of the Parse* call and will be converted into a *parserError like any error, and an errList will still be returned to the caller. The divide by zero error in the examples/calculator grammar leverages this feature (no special code is needed to handle division by zero, if it happens, the runtime panics and it is recovered and returned as a parsing error). Providing good error reporting in a parser is not a trivial task. Part of it is provided by the pigeon tool, by offering features such as filename, position, expected literals and rule name in the error message, but an important part of good error reporting needs to be done by the grammar author. For example, many programming languages use double-quotes for string literals. Usually, if the opening quote is found, the closing quote is expected, and if none is found, there won't be any other rule that will match, there's no need to backtrack and try other choices, an error should be added to the list and the match should be consumed. In order to do this, the grammar can look something like this: This is just one example, but it illustrates the idea that error reporting needs to be thought out when designing the grammar. Because the above mentioned error types (errList and parserError) are not exported, additional steps have to be taken, ff the generated parser is used as library package in other packages (e.g. if the same parser is used in multiple command line tools). One possible implementation for exported errors (based on interfaces) and customized error reporting (caret style formatting of the position, where the parsing failed) is available in the json example and its command line tool: http://godoc.org/github.com/mna/pigeon/examples/json Generated parsers have user-provided code mixed with pigeon code in the same package, so there is no package boundary in the resulting code to prevent access to unexported symbols. What is meant to be implementation details in pigeon is also available to user code - which doesn't mean it should be used. For this reason, it is important to precisely define what is intended to be the supported API of pigeon, the parts that will be stable in future versions. The "stability" of the version 1.0 API attempts to make a similar guarantee as the Go 1 compatibility [5]. The following lists what part of the current pigeon code falls under that guarantee (features may be added in the future): The pigeon command-line flags and arguments: those will not be removed and will maintain the same semantics. The explicitly exported API generated by pigeon. See [6] for the documentation of this API on a generated parser. The PEG syntax, as documented above. The code blocks (except the initializer) will always be generated as methods on the *current type, and this type is guaranteed to have the fields pos (type position) and text (type []byte). There are no guarantees on other fields and methods of this type. The position type will always have the fields line, col and offset, all defined as int. There are no guarantees on other fields and methods of this type. The type of the error value returned by the Parse* functions, when not nil, will always be errList defined as a []error. There are no guarantees on methods of this type, other than the fact it implements the error interface. Individual errors in the errList will always be of type *parserError, and this type is guaranteed to have an Inner field that contains the original error value. There are no guarantees on other fields and methods of this type. The above guarantee is given to the version 1.0 (https://github.com/mna/pigeon/releases/tag/v1.0.0) of pigeon, which has entered maintenance mode (bug fixes only). The current master branch includes the development toward a future version 2.0, which intends to further improve pigeon. While the given API stability should be maintained as far as it makes sense, breaking changes may be necessary to be able to improve pigeon. The new version 2.0 API has not yet stabilized and therefore changes to the API may occur at any time. References:

v1.3.0 • 2 months ago

github.com/libvirt/libvirt-go

Package libvirt provides a Go binding to the libvirt C library Through conditional compilation it supports libvirt versions 1.2.0 onwards. This is done automatically, with no requirement to use magic Go build tags. If an API was not available in the particular version of libvirt this package was built against, an error will be returned with a code of ERR_NO_SUPPORT. This is the same code seen if using a new libvirt library to talk to an old libvirtd lacking the API, or if a hypervisor does not support a given feature, so an application can easily handle all scenarios together. The Go binding is a fairly direct mapping of the underling C API which seeks to maximise the use of the Go type system to allow strong compiler type checking. The following rules describe how APIs/constants are mapped from C to Go For structs, the 'vir' prefix and 'Ptr' suffix are removed from the name. e.g. virConnectPtr in C becomes 'Connect' in Go. For structs which are reference counted at the C level, it is neccessary to explicitly release the reference at the Go level. e.g. if a Go method returns a '* Domain' struct, it is neccessary to call 'Free' on this when no longer required. The use of 'defer' is recommended for this purpose If multiple goroutines are using the same libvirt object struct, it may not be possible to determine which goroutine should call 'Free'. In such scenarios each new goroutine should call 'Ref' to obtain a private reference on the underlying C struct. All goroutines can call 'Free' unconditionally with the final one causing the release of the C object. For methods, the 'vir' prefix and object name prefix are remove from the name. The C functions become methods with an object receiver. e.g. 'virDomainScreenshot' in C becomes 'Screenshot' with a 'Domain *' receiver. For methods which accept a 'unsigned int flags' parameter in the C level, the corresponding Go parameter will be a named type corresponding to the C enum that defines the valid flags. For example, the ListAllDomains method takes a 'flags ConnectListAllDomainsFlags' parameter. If there are not currently any flags defined for a method in the C API, then the Go method parameter will be declared as a "flags uint32". Callers should always pass the literal integer value 0 for such parameters, without forcing any specific type. This will allow compatibility with future updates to the libvirt-go binding which may replace the 'uint32' type with a enum type at a later date. For enums, the VIR_ prefix is removed from the name. The enums get a dedicated type defined in Go. e.g. the VIR_NODE_SUSPEND_TARGET_MEM enum constant in C, becomes NODE_SUSPEND_TARGET_MEM with a type of NodeSuspendTarget. Methods accepting or returning virTypedParameter arrays in C will map the parameters into a Go struct. The struct will contain two fields for each possible parameter. One boolean field with a suffix of 'Set' indicates whether the parameter has a value set, and the other custom typed field provides the parameter value. This makes it possible to distinguish a parameter with a default value of '0' from a parameter which is 0 because it isn't supported by the hypervisor. If the C API defines additional typed parameters, then the corresponding Go struct will be extended to have further fields. e.g. the GetMemoryStats method in Go (which is backed by virNodeGetMemoryStats in C) will return a NodeMemoryStats struct containing the typed parameter values. Every method that can fail will include an 'error' object as the last return value. This will be an instance of the Error struct if an error occurred. To check for specific libvirt error codes, it is neccessary to cast the error. To connect to libvirt

v7.4.0+incompatible • 3 years ago

gopkg.in/jackc/pgx.v2

Package pgx is a PostgreSQL database driver. pgx provides lower level access to PostgreSQL than the standard database/sql It remains as similar to the database/sql interface as possible while providing better speed and access to PostgreSQL specific features. Import github.com/jack/pgx/stdlib to use pgx as a database/sql compatible driver. pgx implements Query and Scan in the familiar database/sql style. pgx also implements QueryRow in the same style as database/sql. Use Exec to execute a query that does not return a result set. Connection pool usage is explicit and configurable. In pgx, a connection can be created and managed directly, or a connection pool with a configurable maximum connections can be used. Also, the connection pool offers an after connect hook that allows every connection to be automatically setup before being made available in the connection pool. This is especially useful to ensure all connections have the same prepared statements available or to change any other connection settings. It delegates Query, QueryRow, Exec, and Begin functions to an automatically checked out and released connection so you can avoid manually acquiring and releasing connections when you do not need that level of control. pgx maps between all common base types directly between Go and PostgreSQL. In particular: pgx can map nulls in two ways. The first is Null* types that have a data field and a valid field. They work in a similar fashion to database/sql. The second is to use a pointer to a pointer. pgx maps between int16, int32, int64, float32, float64, and string Go slices and the equivalent PostgreSQL array type. Go slices of native types do not support nulls, so if a PostgreSQL array that contains a null is read into a native Go slice an error will occur. pgx includes an Hstore type and a NullHstore type. Hstore is simply a map[string]string and is preferred when the hstore contains no nulls. NullHstore follows the Null* pattern and supports null values. pgx includes built-in support to marshal and unmarshal between Go types and the PostgreSQL JSON and JSONB. pgx encodes from net.IPNet to and from inet and cidr PostgreSQL types. In addition, as a convenience pgx will encode from a net.IP; it will assume a /32 netmask for IPv4 and a /128 for IPv6. pgx includes support for the common data types like integers, floats, strings, dates, and times that have direct mappings between Go and SQL. Support can be added for additional types like point, hstore, numeric, etc. that do not have direct mappings in Go by the types implementing ScannerPgx and Encoder. Custom types can support text or binary formats. Binary format can provide a large performance increase. The natural place for deciding the format for a value would be in ScannerPgx as it is responsible for decoding the returned data. However, that is impossible as the query has already been sent by the time the ScannerPgx is invoked. The solution to this is the global DefaultTypeFormats. If a custom type prefers binary format it should register it there. Note that the type is referred to by name, not by OID. This is because custom PostgreSQL types like hstore will have different OIDs on different servers. When pgx establishes a connection it queries the pg_type table for all types. It then matches the names in DefaultTypeFormats with the returned OIDs and stores it in Conn.PgTypes. See example_custom_type_test.go for an example of a custom type for the PostgreSQL point type. pgx also includes support for custom types implementing the database/sql.Scanner and database/sql/driver.Valuer interfaces. []byte passed as arguments to Query, QueryRow, and Exec are passed unmodified to PostgreSQL. In like manner, a *[]byte passed to Scan will be filled with the raw bytes returned by PostgreSQL. This can be especially useful for reading varchar, text, json, and jsonb values directly into a []byte and avoiding the type conversion from string. Transactions are started by calling Begin or BeginIso. The BeginIso variant creates a transaction with a specified isolation level. Use CopyFrom to efficiently insert multiple rows at a time using the PostgreSQL copy protocol. CopyFrom accepts a CopyFromSource interface. If the data is already in a [][]interface{} use CopyFromRows to wrap it in a CopyFromSource interface. Or implement CopyFromSource to avoid buffering the entire data set in memory. CopyFrom can be faster than an insert with as few as 5 rows. pgx can listen to the PostgreSQL notification system with the WaitForNotification function. It takes a maximum time to wait for a notification. The pgx ConnConfig struct has a TLSConfig field. If this field is nil, then TLS will be disabled. If it is present, then it will be used to configure the TLS connection. This allows total configuration of the TLS connection. pgx defines a simple logger interface. Connections optionally accept a logger that satisfies this interface. The log15 package (http://gopkg.in/inconshreveable/log15.v2) satisfies this interface and it is simple to define adapters for other loggers. Set LogLevel to control logging verbosity.

v2.11.0 • 7 years ago

github.com/cockroachdb/apd/v3

Package apd implements arbitrary-precision decimals. apd implements much of the decimal specification from the General Decimal Arithmetic (http://speleotrove.com/decimal/) description, which is refered to here as GDA. This is the same specification implemented by pythons decimal module (https://docs.python.org/2/library/decimal.html) and GCCs decimal extension. Panic-free operation. The math/big types don’t return errors, and instead panic under some conditions that are documented. This requires users to validate the inputs before using them. Meanwhile, we’d like our decimal operations to have more failure modes and more input requirements than the math/big types, so using that API would be difficult. apd instead returns errors when needed. Support for standard functions. sqrt, ln, pow, etc. Accurate and configurable precision. Operations will use enough internal precision to produce a correct result at the requested precision. Precision is set by a "context" structure that accompanies the function arguments, as discussed in the next section. Good performance. Operations will either be fast enough or will produce an error if they will be slow. This prevents edge-case operations from consuming lots of CPU or memory. Condition flags and traps. All operations will report whether their result is exact, is rounded, is over- or under-flowed, is subnormal (https://en.wikipedia.org/wiki/Denormal_number), or is some other condition. apd supports traps which will trigger an error on any of these conditions. This makes it possible to guarantee exactness in computations, if needed. SQL scan and value methods are implemented. This allows the use of Decimals as placeholder parameters and row result Scan destinations. apd has two main types. The first is Decimal which holds the values of decimals. It is simple and uses a big.Int with an exponent to describe values. Most operations on Decimals can’t produce errors as they work directly on the underlying big.Int. Notably, however, there are no arithmetic operations on Decimals. The second main type is Context, which is where all arithmetic operations are defined. A Context describes the precision, range, and some other restrictions during operations. These operations can all produce failures, and so return errors. Context operations, in addition to errors, return a Condition, which is a bitfield of flags that occurred during an operation. These include overflow, underflow, inexact, rounded, and others. The Traps field of a Context can be set which will produce an error if the corresponding flag occurs. An example of this is given below.

v3.2.1 • last year

github.com/aws/aws-sdk-go-v2/service/ivschat

Package ivschat provides the API client, operations, and parameter types for Amazon Interactive Video Service Chat. The Amazon IVS Chat control-plane API enables you to create and manage Amazon IVS Chat resources. You also need to integrate with the Amazon IVS Chat Messaging API, to enable users to interact with chat rooms in real time. The API is an AWS regional service. For a list of supported regions and Amazon IVS Chat HTTPS service endpoints, see the Amazon IVS Chat information on the Amazon IVS pagein the AWS General Reference. This document describes HTTP operations. There is a separate messaging API for managing Chat resources; see the Amazon IVS Chat Messaging API Reference. Notes on terminology: You create service applications using the Amazon IVS Chat API. We refer to these as applications. You create front-end client applications (browser and Android/iOS apps) using the Amazon IVS Chat Messaging API. We refer to these as clients. The following resources are part of Amazon IVS Chat: LoggingConfiguration — A configuration that allows customers to store and record sent messages in a chat room. See the Logging Configuration endpoints for more information. Room — The central Amazon IVS Chat resource through which clients connect to and exchange chat messages. See the Room endpoints for more information. A tag is a metadata label that you assign to an AWS resource. A tag comprises a key and a value, both set by you. For example, you might set a tag as topic:nature to label a particular video category. See Best practices and strategies in Tagging Amazon Web Services Resources and Tag Editor for details, including restrictions that apply to tags and "Tag naming limits and requirements"; Amazon IVS Chat has no service-specific constraints beyond what is documented there. Tags can help you identify and organize your AWS resources. For example, you can use the same tag for different resources to indicate that they are related. You can also use tags to manage access (see Access Tags). The Amazon IVS Chat API has these tag-related operations: TagResource, UntagResource, and ListTagsForResource. The following resource supports tagging: Room. At most 50 tags can be applied to a resource. Your Amazon IVS Chat applications (service applications and clients) must be authenticated and authorized to access Amazon IVS Chat resources. Note the differences between these concepts: Authentication is about verifying identity. Requests to the Amazon IVS Chat API must be signed to verify your identity. Authorization is about granting permissions. Your IAM roles need to have permissions for Amazon IVS Chat API requests. Users (viewers) connect to a room using secure access tokens that you create using the CreateChatTokenoperation through the AWS SDK. You call CreateChatToken for every user’s chat session, passing identity and authorization information about the user. HTTP API requests must be signed with an AWS SigV4 signature using your AWS security credentials. The AWS Command Line Interface (CLI) and the AWS SDKs take care of signing the underlying API calls for you. However, if your application calls the Amazon IVS Chat HTTP API directly, it’s your responsibility to sign the requests. You generate a signature using valid AWS credentials for an IAM role that has permission to perform the requested action. For example, DeleteMessage requests must be made using an IAM role that has the ivschat:DeleteMessage permission. For more information: Authentication and generating signatures — See Authenticating Requests (Amazon Web Services Signature Version 4)in the Amazon Web Services General Reference. Managing Amazon IVS permissions — See Identity and Access Managementon the Security page of the Amazon IVS User Guide. Amazon Resource Names (ARNs) ARNs uniquely identify AWS resources. An ARN is required when you need to specify a resource unambiguously across all of AWS, such as in IAM policies and API calls. For more information, see Amazon Resource Namesin the AWS General Reference.

v1.16.6 • 3 days ago

github.com/decred/dcrd/blockchain/v4

Package blockchain implements Decred block handling and chain selection rules. The Decred block handling and chain selection rules are an integral, and quite likely the most important, part of Decred. At its core, Decred is a distributed consensus of which blocks are valid and which ones will comprise the main block chain (public ledger) that ultimately determines accepted transactions, so it is extremely important that fully validating nodes agree on all rules. At a high level, this package provides support for inserting new blocks into the block chain according to the aforementioned rules. It includes functionality such as rejecting duplicate blocks, ensuring blocks and transactions follow all rules, and best chain selection along with reorganization. Since this package does not deal with other Decred specifics such as network communication or wallets, it provides a notification system which gives the caller a high level of flexibility in how they want to react to certain events such as newly connected main chain blocks which might result in wallet updates. Before a block is allowed into the block chain, it must go through an intensive series of validation rules. The following list serves as a general outline of those rules to provide some intuition into what is going on under the hood, but is by no means exhaustive: This package supports headers-first semantics such that block data can be processed out of order so long as the associated header is already known. The headers themselves, however, must be processed in the correct order since headers that do not properly connect are rejected. In other words, orphan headers are not allowed. The processing code always maintains the best chain as the branch tip that has the most cumulative proof of work, so it is important to keep that in mind when considering errors returned from processing blocks. Notably, due to the ability to process blocks out of order, and the fact blocks can only be fully validated once all of their ancestors have the block data available, it is to be expected that no error is returned immediately for blocks that are valid enough to make it to the point they require the remaining ancestor block data to be fully validated even though they might ultimately end up failing validation. Similarly, because the data for a block becoming available makes any of its direct descendants that already have their data available eligible for validation, an error being returned does not necessarily mean the block being processed is the one that failed validation. Errors returned by this package have full support for the standard library errors.Is and errors.As methods and are either the raw errors provided by underlying calls or of type blockchain.RuleError, possibly wrapped in a blockchain.MultiError. This allows the caller to differentiate between unexpected errors, such as database errors, versus errors due to rule violations through errors.As. In addition, callers can programmatically determine the specific rule violation by making use of errors.Is with any of the wrapped error kinds.

v4.1.1 • last year

github.com/andersfylling/disgord

Package disgord provides Go bindings for the documented Discord API, and allows for a stateful Client using the Session interface, with the option of a configurable caching system or bypass the built-in caching logic all together. Create a Disgord client to get access to the REST API and gateway functionality. In the following example, we listen for new messages and respond with "hello". Session interface: https://pkg.go.dev/github.com/andersfylling/disgord?tab=doc#Session You don't have to use a callback function, channels are supported too! Never close a channel without removing the handler from Disgord, as it will cause a panic. You can control the lifetime of a handler or injected channel by in injecting a controller: disgord.HandlerCtrl. Since you are the owner of the channel, disgord will never close it for you. Disgord handles sharding for you automatically; when starting the bot, when discord demands you to scale up your shards (during runtime), etc. It also gives you control over the shard setup in case you want to run multiple instances of Disgord (in these cases you must handle scaling yourself as Disgord can not). Sharding is done behind the scenes, so you do not need to worry about any settings. Disgord will simply ask Discord for the recommended amount of shards for your bot on startup. However, to set specific amount of shards you can use the `disgord.ShardConfig` to specify a range of valid shard IDs (starts from 0). starting a bot with exactly 5 shards Running multiple instances each with 1 shard (note each instance must use unique shard ids) Handle scaling options yourself You can inject your own cache implementation. By default a read only LFU implementation is used, this should be sufficient for the average user. But you can overwrite certain methods as well! Say you dislike the implementation for MESSAGE_CREATE events, you can embed the default cache and define your own logic: > Note: if you inject your own cache, remember that the cache is also responsible for initiating the objects. > See disgord.CacheNop Whenever you call a REST method from the Session interface; the cache is always checked first. Upon a cache hit, no REST request is executed and you get the data from the cache in return. However, if this is problematic for you or there exist a bug which gives you bad/outdated data, you can bypass it by using Disgord flags. In addition to disgord.IgnoreCache, as shown above, you can pass in other flags such as: disgord.SortByID, disgord.OrderAscending, etc. You can find these flags in the flag.go file. `disgord_diagnosews` will store all the incoming and outgoing JSON data as files in the directory "diagnose-report/packets". The file format is as follows: unix_clientType_direction_shardID_operationCode_sequenceNumber[_eventName].json

v0.36.2 • 2 years ago

github.com/minio/selfupdate

Package update provides functionality to implement secure, self-updating Go programs (or other single-file targets). For complete updating solutions please see Equinox (https://equinox.io) and go-tuf (https://github.com/flynn/go-tuf). This example shows how to update a program remotely from a URL. Go binaries can often be large. It can be advantageous to only ship a binary patch to a client instead of the complete program text of a new version. This example shows how to update a program with a bsdiff binary patch. Other patch formats may be applied by implementing the Patcher interface. Updating executable code on a computer can be a dangerous operation unless you take the appropriate steps to guarantee the authenticity of the new code. While checksum verification is important, it should always be combined with signature verification (next section) to guarantee that the code came from a trusted party. selfupdate validates SHA256 checksums by default, but this is pluggable via the Hash property on the Options struct. This example shows how to guarantee that the newly-updated binary is verified to have an appropriate checksum (that was otherwise retrieved via a secure channel) specified as a hex string. Cryptographic verification of new code from an update is an extremely important way to guarantee the security and integrity of your updates. Verification is performed by validating the signature of a hash of the new file. This means nothing changes if you apply your update with a patch. This example shows how to add signature verification to your updates. To make all of this work an application distributor must first create a public/private key pair and embed the public key into their application. When they issue a new release, the issuer must sign the new executable file with the private key and distribute the signature along with the selfupdate. In order to update a Go application with selfupdate, you must distribute it as a single executable. This is often easy, but some applications require static assets (like HTML and CSS asset files or TLS certificates). In order to update applications like these, you'll want to make sure to embed those asset files into the distributed binary with a tool like go-bindata (my favorite): https://github.com/jteeuwen/go-bindata Mechanisms and protocols for determining whether an update should be applied and, if so, which one are out of scope for this package. Please consult go-tuf (https://github.com/flynn/go-tuf) or Equinox (https://equinox.io) for more complete solutions. selfupdate only works for self-updating applications that are distributed as a single binary, i.e. applications that do not have additional assets or dependency files. Updating application that are distributed as multiple on-disk files is out of scope, although this may change in future versions of this library.

v0.6.0 • 2 years ago

github.com/vrischmann/envconfig

Package envconfig implements a configuration reader which reads each value from an environment variable. The basic idea is that you define a configuration struct, like this: Once you have that, you need to initialize the configuration: Then it's just a matter of setting the environment variables when calling your binary: Your conf struct must follow the following rules: By default, envconfig generates all possible keys based on the field chain according to a flexible naming scheme. The field chain is how you access your field in the configuration struct. For example: With that struct, you access the name field via the chain *Shard.Name* The default naming scheme takes that and transforms it into the following: It can handles more complicated cases, with multiple words in one field name. It needs to be in the correct case though, for example: With that struct, you access the name field via the chain *Cassandra.SSLCert* or *Cassandra.SslKey* The default naming scheme takes that and transforms it into the following: And, if that is not good enough for you, you always have the option to use a custom key: Now envconfig will only ever checks the environment variable _cassandraMyName_. There are three types of content for a single variable: Example of a valid slice value: The format for a struct is as follow: Example of a valid struct value: Example of a valid slice of struct values: For bytes slices, you generally don't want to type out a comma-separated list of byte values. For this use case, we support base64 encoded values. Here's an example: This will decode DATA to FOOBAR and put that into conf.Data. Sometimes you don't absolutely need a value. Here's how we tell envconfig a value is optional: Sometimes you want a field to be skipped entirely. Often times you have configuration keys which almost never changes, but you still want to be able to change them. In such cases, you might want to provide a default value. Here's to do this with envconfig: You can of course combine multiple options. The syntax is simple enough, separate each option with a comma. For example: This would give you the default timeout of 1 minute, and lookup the myTimeout environment variable. envconfig supports the following list of types: Notably, we don't (yet) support complex types simply because I had no use for it yet. When the standard types are not enough, you will want to use a custom unmarshaler for your types. You do this by implementing Unmarshaler on your type. Here's an example:

v1.3.0 • 4 years ago

github.com/google/go-replayers/grpcreplay

Package grpcreplay supports the capture and replay of gRPC calls. Its main goal is to improve testing. Once you capture the calls of a test that runs against a real service, you have an "automatic mock" that can be replayed against the same test, yielding a unit test that is fast and flake-free. To record a sequence of gRPC calls to a file, create a Recorder and pass its DialOptions to grpc.Dial: It is essential to close the Recorder when the interaction is finished. There is also a NewRecorderWriter function for capturing to an arbitrary io.Writer. To replay a captured file, create a Replayer and ask it for a (fake) connection. We don't actually have to dial a server. (Since we're reading the file and not writing it, we don't have to be as careful about the error returned from Close). A test might use random or time-sensitive values, for instance to create unique resources for isolation from other tests. The test therefore has initial values, such as the current time, or a random seed, that differ from run to run. You must record this initial state and re-establish it on replay. To record the initial state, serialize it into a []byte and pass it as the second argument to NewRecorder: On replay, get the bytes from Replayer.Initial: Recorders and replayers have support for running callbacks before messages are written to or read from the replay file. A Recorder has a BeforeFunc that can modify a request or response before it is written to the replay file. The actual RPCs sent to the service during recording remain unaltered; only what is saved in the replay file can be changed. A Replayer has a BeforeFunc that can modify a request before it is sent for matching. Example uses for these callbacks include customized logging, or scrubbing data before RPCs are written to the replay file. If requests are modified by the callbacks during recording, it is important to perform the same modifications to the requests when replaying, or RPC matching on replay will fail. A common way to analyze and modify the various messages is to use a type switch. A nondeterministic program may invoke RPCs in a different order each time it is run. The order in which RPCs are called during recording may differ from the order during replay. The replayer matches incoming to recorded requests by method name and request contents, so nondeterminism is only a concern for identical requests that result in different responses. A nondeterministic program whose behavior differs depending on the order of such RPCs probably has a race condition: since both the recorded sequence of RPCs and the sequence during replay are valid orderings, the program should behave the same under both. The same is not true of streaming RPCs. The replayer matches streams only by method name, since it has no other information at the time the stream is opened. Two streams with the same method name that are started concurrently may replay in the wrong order. Besides the differences in replay mentioned above, other differences may cause issues for some programs. We list them here. The Replayer delivers a response to an RPC immediately, without waiting for other incoming RPCs. This can violate causality. For example, in a Pub/Sub program where one goroutine publishes and another subscribes, during replay the Subscribe call may finish before the Publish call begins. For streaming RPCs, the Replayer delivers the result of Send and Recv calls in the order they were recorded. No attempt is made to match message contents. At present, this package does not record or replay stream headers and trailers, or the result of the CloseSend method.

v1.3.0 • 4 months ago

gitee.com/opengauss/openGauss-connector-go-pq

Package pq is a pure Go Postgres driver for the database/sql package. In most cases clients will use the database/sql package instead of using this package directly. For example: You can also connect to a database using a URL. For example: Similarly to libpq, when establishing a connection using pq you are expected to supply a connection string containing zero or more parameters. A subset of the connection parameters supported by libpq are also supported by pq. Additionally, pq also lets you specify run-time parameters (such as search_path or work_mem) directly in the connection string. This is different from libpq, which does not allow run-time parameters in the connection string, instead requiring you to supply them in the options parameter. For compatibility with libpq, the following special connection parameters are supported: Valid values for sslmode are: See http://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING for more information about connection string parameters. Use single quotes for values that contain whitespace: A backslash will escape the next character in values: Note that the connection parameter client_encoding (which sets the text encoding for the connection) may be set but must be "UTF8", matching with the same rules as Postgres. It is an error to provide any other value. In addition to the parameters listed above, any run-time parameter that can be set at backend start time can be set in the connection string. For more information, see http://www.postgresql.org/docs/current/static/runtime-config.html. Most environment variables as specified at http://www.postgresql.org/docs/current/static/libpq-envars.html supported by libpq are also supported by pq. If any of the environment variables not supported by pq are set, pq will panic during connection establishment. Environment variables have a lower precedence than explicitly provided connection parameters. The pgpass mechanism as described in http://www.postgresql.org/docs/current/static/libpq-pgpass.html is supported, but on Windows PGPASSFILE must be specified explicitly. database/sql does not dictate any specific format for parameter markers in query strings, and pq uses the Postgres-native ordinal markers, as shown above. The same marker can be reused for the same parameter: pq does not support the LastInsertId() method of the Result type in database/sql. To return the identifier of an INSERT (or UPDATE or DELETE), use the Postgres RETURNING clause with a standard Query or QueryRow call: For more details on RETURNING, see the Postgres documentation: For additional instructions on querying see the documentation for the database/sql package. Parameters pass through driver.DefaultParameterConverter before they are handled by this package. When the binary_parameters connection option is enabled, []byte values are sent directly to the backend as data in binary format. This package returns the following types for values from the PostgreSQL backend: All other types are returned directly from the backend as []byte values in text format. pq may return errors of type *pq.Error which can be interrogated for error details: See the pq.Error type for details. You can perform bulk imports by preparing a statement returned by pq.CopyIn (or pq.CopyInSchema) in an explicit transaction (sql.Tx). The returned statement handle can then be repeatedly "executed" to copy data into the target table. After all data has been processed you should call Exec() once with no arguments to flush all buffered data. Any call to Exec() might return an error which should be handled appropriately, but because of the internal buffering an error returned by Exec() might not be related to the data passed in the call that failed. CopyIn uses COPY FROM internally. It is not possible to COPY outside of an explicit transaction in pq. Usage example: PostgreSQL supports a simple publish/subscribe model over database connections. See http://www.postgresql.org/docs/current/static/sql-notify.html for more information about the general mechanism. To start listening for notifications, you first have to open a new connection to the database by calling NewListener. This connection can not be used for anything other than LISTEN / NOTIFY. Calling Listen will open a "notification channel"; once a notification channel is open, a notification generated on that channel will effect a send on the Listener.Notify channel. A notification channel will remain open until Unlisten is called, though connection loss might result in some notifications being lost. To solve this problem, Listener sends a nil pointer over the Notify channel any time the connection is re-established following a connection loss. The application can get information about the state of the underlying connection by setting an event callback in the call to NewListener. A single Listener can safely be used from concurrent goroutines, which means that there is often no need to create more than one Listener in your application. However, a Listener is always connected to a single database, so you will need to create a new Listener instance for every database you want to receive notifications in. The channel name in both Listen and Unlisten is case sensitive, and can contain any characters legal in an identifier (see http://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS for more information). Note that the channel name will be truncated to 63 bytes by the PostgreSQL server. You can find a complete, working example of Listener usage at https://godoc.org/gitee.com/opengauss/openGauss-connector-go-pq/example/listen. If you need support for Kerberos authentication, add the following to your main package: This package is in a separate module so that users who don't need Kerberos don't have to download unnecessary dependencies. When imported, additional connection string parameters are supported:

v1.0.7 • last week

github.com/decred/dcrd/peer

Package peer provides a common base for creating and managing Decred network peers. This package builds upon the wire package, which provides the fundamental primitives necessary to speak the Decred wire protocol, in order to simplify the process of creating fully functional peers. In essence, it provides a common base for creating concurrent safe fully validating nodes, Simplified Payment Verification (SPV) nodes, proxies, etc. A quick overview of the major features peer provides are as follows: All peer configuration is handled with the Config struct. This allows the caller to specify things such as the user agent name and version, the decred network to use, which services it supports, and callbacks to invoke when decred messages are received. See the documentation for each field of the Config struct for more details. A peer can either be inbound or outbound. The caller is responsible for establishing the connection to remote peers and listening for incoming peers. This provides high flexibility for things such as connecting via proxies, acting as a proxy, creating bridge peers, choosing whether to listen for inbound peers, etc. NewOutboundPeer and NewInboundPeer functions must be followed by calling Connect with a net.Conn instance to the peer. This will start all async I/O goroutines and initiate the protocol negotiation process. Once finished with the peer call Disconnect to disconnect from the peer and clean up all resources. WaitForDisconnect can be used to block until peer disconnection and resource cleanup has completed. In order to do anything useful with a peer, it is necessary to react to decred messages. This is accomplished by creating an instance of the MessageListeners struct with the callbacks to be invoke specified and setting the Listeners field of the Config struct specified when creating a peer to it. For convenience, a callback hook for all of the currently supported decred messages is exposed which receives the peer instance and the concrete message type. In addition, a hook for OnRead is provided so even custom messages types for which this package does not directly provide a hook, as long as they implement the wire.Message interface, can be used. Finally, the OnWrite hook is provided, which in conjunction with OnRead, can be used to track server-wide byte counts. It is often useful to use closures which encapsulate state when specifying the callback handlers. This provides a clean method for accessing that state when callbacks are invoked. The QueueMessage function provides the fundamental means to send messages to the remote peer. As the name implies, this employs a non-blocking queue. A done channel which will be notified when the message is actually sent can optionally be specified. There are certain message types which are better sent using other functions which provide additional functionality. Of special interest are inventory messages. Rather than manually sending MsgInv messages via Queuemessage, the inventory vectors should be queued using the QueueInventory function. It employs batching and trickling along with intelligent known remote peer inventory detection and avoidance through the use of a most-recently used algorithm. In addition to the bare QueueMessage function previously described, the PushAddrMsg, PushGetBlocksMsg, PushGetHeadersMsg, and PushRejectMsg functions are provided as a convenience. While it is of course possible to create and send these message manually via QueueMessage, these helper functions provided additional useful functionality that is typically desired. For example, the PushAddrMsg function automatically limits the addresses to the maximum number allowed by the message and randomizes the chosen addresses when there are too many. This allows the caller to simply provide a slice of known addresses, such as that returned by the addrmgr package, without having to worry about the details. Next, the PushGetBlocksMsg and PushGetHeadersMsg functions will construct proper messages using a block locator and ignore back to back duplicate requests. Finally, the PushRejectMsg function can be used to easily create and send an appropriate reject message based on the provided parameters as well as optionally provides a flag to cause it to block until the message is actually sent. A snapshot of the current peer statistics can be obtained with the StatsSnapshot function. This includes statistics such as the total number of bytes read and written, the remote address, user agent, and negotiated protocol version. This package provides extensive logging capabilities through the UseLogger function which allows a slog.Logger to be specified. For example, logging at the debug level provides summaries of every message sent and received, and logging at the trace level provides full dumps of parsed messages as well as the raw message bytes using a format similar to hexdump -C. This package supports all improvement proposals supported by the wire package. (https://godoc.org/github.com/decred/dcrd/wire#hdr-Bitcoin_Improvement_Proposals) This example demonstrates the basic process for initializing and creating an outbound peer. Peers negotiate by exchanging version and verack messages. For demonstration, a simple handler for version message is attached to the peer.

v1.2.1 • last year

gopkg.in/go-playground/validator.v10

Package validator implements value validations for structs and individual fields based on tags. It can also handle Cross-Field and Cross-Struct validation for nested structs and has the ability to dive into arrays and maps of any type. see more examples https://github.com/go-playground/validator/tree/v9/_examples Doing things this way is actually the way the standard library does, see the file.Open method here: The authors return type "error" to avoid the issue discussed in the following, where err is always != nil: Validator only InvalidValidationError for bad validation input, nil or ValidationErrors as type error; so, in your code all you need to do is check if the error returned is not nil, and if it's not check if error is InvalidValidationError ( if necessary, most of the time it isn't ) type cast it to type ValidationErrors like so err.(validator.ValidationErrors). Custom Validation functions can be added. Example: Cross-Field Validation can be done via the following tags: If, however, some custom cross-field validation is required, it can be done using a custom validation. Why not just have cross-fields validation tags (i.e. only eqcsfield and not eqfield)? The reason is efficiency. If you want to check a field within the same struct "eqfield" only has to find the field on the same struct (1 level). But, if we used "eqcsfield" it could be multiple levels down. Example: Multiple validators on a field will process in the order defined. Example: Bad Validator definitions are not handled by the library. Example: Baked In Cross-Field validation only compares fields on the same struct. If Cross-Field + Cross-Struct validation is needed you should implement your own custom validator. Comma (",") is the default separator of validation tags. If you wish to have a comma included within the parameter (i.e. excludesall=,) you will need to use the UTF-8 hex representation 0x2C, which is replaced in the code as a comma, so the above will become excludesall=0x2C. Pipe ("|") is the 'or' validation tags deparator. If you wish to have a pipe included within the parameter i.e. excludesall=| you will need to use the UTF-8 hex representation 0x7C, which is replaced in the code as a pipe, so the above will become excludesall=0x7C Here is a list of the current built in validators: Tells the validation to skip this struct field; this is particularly handy in ignoring embedded structs from being validated. (Usage: -) This is the 'or' operator allowing multiple validators to be used and accepted. (Usage: rbg|rgba) <-- this would allow either rgb or rgba colors to be accepted. This can also be combined with 'and' for example ( Usage: omitempty,rgb|rgba) When a field that is a nested struct is encountered, and contains this flag any validation on the nested struct will be run, but none of the nested struct fields will be validated. This is useful if inside of your program you know the struct will be valid, but need to verify it has been assigned. NOTE: only "required" and "omitempty" can be used on a struct itself. Same as structonly tag except that any struct level validations will not run. Allows conditional validation, for example if a field is not set with a value (Determined by the "required" validator) then other validation such as min or max won't run, but if a value is set validation will run. This tells the validator to dive into a slice, array or map and validate that level of the slice, array or map with the validation tags that follow. Multidimensional nesting is also supported, each level you wish to dive will require another dive tag. dive has some sub-tags, 'keys' & 'endkeys', please see the Keys & EndKeys section just below. Example #1 Example #2 Keys & EndKeys These are to be used together directly after the dive tag and tells the validator that anything between 'keys' and 'endkeys' applies to the keys of a map and not the values; think of it like the 'dive' tag, but for map keys instead of values. Multidimensional nesting is also supported, each level you wish to validate will require another 'keys' and 'endkeys' tag. These tags are only valid for maps. Example #1 Example #2 This validates that the value is not the data types default zero value. For numbers ensures value is not zero. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. The field under validation must be present and not empty only if any of the other specified fields are present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Examples: The field under validation must be present and not empty only if all of the other specified fields are present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Example: The field under validation must be present and not empty only when any of the other specified fields are not present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Examples: The field under validation must be present and not empty only when all of the other specified fields are not present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. Example: This validates that the value is the default value and is almost the opposite of required. For numbers, length will ensure that the value is equal to the parameter given. For strings, it checks that the string length is exactly that number of characters. For slices, arrays, and maps, validates the number of items. For numbers, max will ensure that the value is less than or equal to the parameter given. For strings, it checks that the string length is at most that number of characters. For slices, arrays, and maps, validates the number of items. For numbers, min will ensure that the value is greater or equal to the parameter given. For strings, it checks that the string length is at least that number of characters. For slices, arrays, and maps, validates the number of items. For strings & numbers, eq will ensure that the value is equal to the parameter given. For slices, arrays, and maps, validates the number of items. For strings & numbers, ne will ensure that the value is not equal to the parameter given. For slices, arrays, and maps, validates the number of items. For strings, ints, and uints, oneof will ensure that the value is one of the values in the parameter. The parameter should be a list of values separated by whitespace. Values may be strings or numbers. For numbers, this will ensure that the value is greater than the parameter given. For strings, it checks that the string length is greater than that number of characters. For slices, arrays and maps it validates the number of items. Example #1 Example #2 (time.Time) For time.Time ensures the time value is greater than time.Now.UTC(). Same as 'min' above. Kept both to make terminology with 'len' easier. Example #1 Example #2 (time.Time) For time.Time ensures the time value is greater than or equal to time.Now.UTC(). For numbers, this will ensure that the value is less than the parameter given. For strings, it checks that the string length is less than that number of characters. For slices, arrays, and maps it validates the number of items. Example #1 Example #2 (time.Time) For time.Time ensures the time value is less than time.Now.UTC(). Same as 'max' above. Kept both to make terminology with 'len' easier. Example #1 Example #2 (time.Time) For time.Time ensures the time value is less than or equal to time.Now.UTC(). This will validate the field value against another fields value either within a struct or passed in field. Example #1: Example #2: Field Equals Another Field (relative) This does the same as eqfield except that it validates the field provided relative to the top level struct. This will validate the field value against another fields value either within a struct or passed in field. Examples: Field Does Not Equal Another Field (relative) This does the same as nefield except that it validates the field provided relative to the top level struct. Only valid for Numbers and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: Example #2: This does the same as gtfield except that it validates the field provided relative to the top level struct. Only valid for Numbers and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: Example #2: This does the same as gtefield except that it validates the field provided relative to the top level struct. Only valid for Numbers and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: Example #2: This does the same as ltfield except that it validates the field provided relative to the top level struct. Only valid for Numbers and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date: Example #1: Example #2: This does the same as ltefield except that it validates the field provided relative to the top level struct. This does the same as contains except for struct fields. It should only be used with string types. See the behavior of reflect.Value.String() for behavior on other types. This does the same as excludes except for struct fields. It should only be used with string types. See the behavior of reflect.Value.String() for behavior on other types. For arrays & slices, unique will ensure that there are no duplicates. For maps, unique will ensure that there are no duplicate values. For slices of struct, unique will ensure that there are no duplicate values in a field of the struct specified via a parameter. This validates that a string value contains ASCII alpha characters only This validates that a string value contains ASCII alphanumeric characters only This validates that a string value contains unicode alpha characters only This validates that a string value contains unicode alphanumeric characters only This validates that a string value contains a basic numeric value. basic excludes exponents etc... for integers or float it returns true. This validates that a string value contains a valid hexadecimal. This validates that a string value contains a valid hex color including hashtag (#) This validates that a string value contains a valid rgb color This validates that a string value contains a valid rgba color This validates that a string value contains a valid hsl color This validates that a string value contains a valid hsla color This validates that a string value contains a valid email This may not conform to all possibilities of any rfc standard, but neither does any email provider accept all possibilities. This validates that a string value contains a valid file path and that the file exists on the machine. This is done using os.Stat, which is a platform independent function. This validates that a string value contains a valid url This will accept any url the golang request uri accepts but must contain a schema for example http:// or rtmp:// This validates that a string value contains a valid uri This will accept any uri the golang request uri accepts This validataes that a string value contains a valid URN according to the RFC 2141 spec. This validates that a string value contains a valid base64 value. Although an empty string is valid base64 this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag. This validates that a string value contains a valid base64 URL safe value according the the RFC4648 spec. Although an empty string is a valid base64 URL safe value, this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag. This validates that a string value contains a valid bitcoin address. The format of the string is checked to ensure it matches one of the three formats P2PKH, P2SH and performs checksum validation. Bitcoin Bech32 Address (segwit) This validates that a string value contains a valid bitcoin Bech32 address as defined by bip-0173 (https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) Special thanks to Pieter Wuille for providng reference implementations. This validates that a string value contains a valid ethereum address. The format of the string is checked to ensure it matches the standard Ethereum address format Full validation is blocked by https://github.com/golang/crypto/pull/28 This validates that a string value contains the substring value. This validates that a string value contains any Unicode code points in the substring value. This validates that a string value contains the supplied rune value. This validates that a string value does not contain the substring value. This validates that a string value does not contain any Unicode code points in the substring value. This validates that a string value does not contain the supplied rune value. This validates that a string value starts with the supplied string value This validates that a string value ends with the supplied string value This validates that a string value contains a valid isbn10 or isbn13 value. This validates that a string value contains a valid isbn10 value. This validates that a string value contains a valid isbn13 value. This validates that a string value contains a valid UUID. Uppercase UUID values will not pass - use `uuid_rfc4122` instead. This validates that a string value contains a valid version 3 UUID. Uppercase UUID values will not pass - use `uuid3_rfc4122` instead. This validates that a string value contains a valid version 4 UUID. Uppercase UUID values will not pass - use `uuid4_rfc4122` instead. This validates that a string value contains a valid version 5 UUID. Uppercase UUID values will not pass - use `uuid5_rfc4122` instead. This validates that a string value contains only ASCII characters. NOTE: if the string is blank, this validates as true. This validates that a string value contains only printable ASCII characters. NOTE: if the string is blank, this validates as true. This validates that a string value contains one or more multibyte characters. NOTE: if the string is blank, this validates as true. This validates that a string value contains a valid DataURI. NOTE: this will also validate that the data portion is valid base64 This validates that a string value contains a valid latitude. This validates that a string value contains a valid longitude. This validates that a string value contains a valid U.S. Social Security Number. This validates that a string value contains a valid IP Address. This validates that a string value contains a valid v4 IP Address. This validates that a string value contains a valid v6 IP Address. This validates that a string value contains a valid CIDR Address. This validates that a string value contains a valid v4 CIDR Address. This validates that a string value contains a valid v6 CIDR Address. This validates that a string value contains a valid resolvable TCP Address. This validates that a string value contains a valid resolvable v4 TCP Address. This validates that a string value contains a valid resolvable v6 TCP Address. This validates that a string value contains a valid resolvable UDP Address. This validates that a string value contains a valid resolvable v4 UDP Address. This validates that a string value contains a valid resolvable v6 UDP Address. This validates that a string value contains a valid resolvable IP Address. This validates that a string value contains a valid resolvable v4 IP Address. This validates that a string value contains a valid resolvable v6 IP Address. This validates that a string value contains a valid Unix Address. This validates that a string value contains a valid MAC Address. Note: See Go's ParseMAC for accepted formats and types: This validates that a string value is a valid Hostname according to RFC 952 https://tools.ietf.org/html/rfc952 This validates that a string value is a valid Hostname according to RFC 1123 https://tools.ietf.org/html/rfc1123 Full Qualified Domain Name (FQDN) This validates that a string value contains a valid FQDN. This validates that a string value appears to be an HTML element tag including those described at https://developer.mozilla.org/en-US/docs/Web/HTML/Element This validates that a string value is a proper character reference in decimal or hexadecimal format This validates that a string value is percent-encoded (URL encoded) according to https://tools.ietf.org/html/rfc3986#section-2.1 This validates that a string value contains a valid directory and that it exists on the machine. This is done using os.Stat, which is a platform independent function. NOTE: When returning an error, the tag returned in "FieldError" will be the alias tag unless the dive tag is part of the alias. Everything after the dive tag is not reported as the alias tag. Also, the "ActualTag" in the before case will be the actual tag within the alias that failed. Here is a list of the current built in alias tags: Validator notes: A collection of validation rules that are frequently needed but are more complex than the ones found in the baked in validators. A non standard validator must be registered manually like you would with your own custom validation functions. Example of registration and use: Here is a list of the current non standard validators: This package panics when bad input is provided, this is by design, bad code like that should not make it to production.

v10.23.0 • 5 days ago

github.com/deanishe/awgo

Package aw is a "plug-and-play" workflow development library/framework for Alfred 3 & 4 (https://www.alfredapp.com/). It requires Go 1.13 or later. It provides everything you need to create a polished and blazing-fast Alfred frontend for your project. As of AwGo 0.26, all applicable features of Alfred 4.1 are supported. The main features are: AwGo is an opinionated framework that expects to be used in a certain way in order to eliminate boilerplate. It *will* panic if not run in a valid, minimally Alfred-like environment. At a minimum the following environment variables should be set to meaningful values: NOTE: AwGo is currently in development. The API *will* change and should not be considered stable until v1.0. Until then, be sure to pin a version using go modules or similar. Be sure to also check out the _examples/ subdirectory, which contains some simple, but complete, workflows that demonstrate the features of AwGo and useful workflow idioms. Typically, you'd call your program's main entry point via Workflow.Run(). This way, the library will rescue any panic, log the stack trace and show an error message to the user in Alfred. In the Script box (Language = "/bin/bash"): To generate results for Alfred to show in a Script Filter, use the feedback API of Workflow: You can set workflow variables (via feedback) with Workflow.Var, Item.Var and Modifier.Var. See Workflow.SendFeedback for more documentation. Alfred requires a different JSON format if you wish to set workflow variables. Use the ArgVars (named for its equivalent element in Alfred) struct to generate output from Run Script actions. Be sure to set TextErrors to true to prevent Workflow from generating Alfred JSON if it catches a panic: See ArgVars for more information. New() creates a *Workflow using the default values and workflow settings read from environment variables set by Alfred. You can change defaults by passing one or more Options to New(). If you do not want to use Alfred's environment variables, or they aren't set (i.e. you're not running the code in Alfred), use NewFromEnv() with a custom Env implementation. A Workflow can be re-configured later using its Configure() method. See the documentation for Option for more information on configuring a Workflow. AwGo can check for and install new versions of your workflow. Subpackage update provides an implementation of the Updater interface and sources to load updates from GitHub or Gitea releases, or from the URL of an Alfred `metadata.json` file. See subpackage update and _examples/update. AwGo can filter Script Filter feedback using a Sublime Text-like fuzzy matching algorithm. Workflow.Filter() sorts feedback Items against the provided query, removing those that do not match. See _examples/fuzzy for a basic demonstration, and _examples/bookmarks for a demonstration of implementing fuzzy.Sortable on your own structs and customising the fuzzy sort settings. Fuzzy matching is done by package https://godoc.org/go.deanishe.net/fuzzy AwGo automatically configures the default log package to write to STDERR (Alfred's debugger) and a log file in the workflow's cache directory. The log file is necessary because background processes aren't connected to Alfred, so their output is only visible in the log. It is rotated when it exceeds 1 MiB in size. One previous log is kept. AwGo detects when Alfred's debugger is open (Workflow.Debug() returns true) and in this case prepends filename:linenumber: to log messages. The Config struct (which is included in Workflow as Workflow.Config) provides an interface to the workflow's settings from the Workflow Environment Variables panel (see https://www.alfredapp.com/help/workflows/advanced/variables/#environment). Alfred exports these settings as environment variables, and you can read them ad-hoc with the Config.Get*() methods, and save values back to Alfred/info.plist with Config.Set(). Using Config.To() and Config.From(), you can "bind" your own structs to the settings in Alfred: See the documentation for Config.To and Config.From for more information, and _examples/settings for a demo workflow based on the API. The Alfred struct provides methods for the rest of Alfred's AppleScript API. Amongst other things, you can use it to tell Alfred to open, to search for a query, to browse/action files & directories, or to run External Triggers. See documentation of the Alfred struct for more information. AwGo provides a basic, but useful, API for loading and saving data. In addition to reading/writing bytes and marshalling/unmarshalling to/from JSON, the API can auto-refresh expired cache data. See Cache and Session for the API documentation. Workflow has three caches tied to different directories: These all share (almost) the same API. The difference is in when the data go away. Data saved with Session are deleted after the user closes Alfred or starts using a different workflow. The Cache directory is in a system cache directory, so may be deleted by the system or "system maintenance" tools. The Data directory lives with Alfred's application data and would not normally be deleted. Subpackage util provides several functions for running script files and snippets of AppleScript/JavaScript code. See util for documentation and examples. AwGo offers a simple API to start/stop background processes via Workflow's RunInBackground(), IsRunning() and Kill() methods. This is useful for running checks for updates and other jobs that hit the network or take a significant amount of time to complete, allowing you to keep your Script Filters extremely responsive. See _examples/update and _examples/workflows for demonstrations of this API.

v0.29.1 • 3 years ago

robpike.io/ivy

Ivy is an interpreter for an APL-like language. It is a plaything and a work in progress. Unlike APL, the input is ASCII and the results are exact (but see the next paragraph). It uses exact rational arithmetic so it can handle arbitrary precision. Values to be input may be integers (3, -1), rationals (1/3, -45/67) or floating point values (1e3, -1.5 (representing 1000 and -3/2)). Some functions such as sqrt are irrational. When ivy evaluates an irrational function, the result is stored in a high-precision floating-point number (default 256 bits of mantissa). Thus when using irrational functions, the values have high precision but are not exact. Unlike in most other languages, operators always have the same precedence and expressions are evaluated in right-associative order. That is, unary operators apply to everything to the right, and binary operators apply to the operand immediately to the left and to everything to the right. Thus, 3*4+5 is 27 (it groups as 3*(4+5)) and iota 3+2 is 1 2 3 4 5 while 3+iota 2 is 4 5. A vector is a single operand, so 1 2 3 + 3 + 3 4 5 is (1 2 3) + 3 + (3 4 5), or 7 9 11. As a special but important case, note that 1/3, with no intervening spaces, is a single rational number, not the expression 1 divided by 3. This can affect precedence: 3/6*4 is 2 while 3 / 6*4 is 1/8 since the spacing turns the / into a division operator. Use parentheses or spaces to disambiguate: 3/(6*4) or 3 /6*4. Ivy has complex numbers, which are constructed using the unary or binary j operator. As with rationals, the token 1j2 (the representation of 1+2i) is a single token. The individual parts can be rational, so 1/2j-3/2 is the complex number 0.5-1.5i and scans as a single value. Indexing uses [] notation: x[1], x[1; 2], and so on. Indexing by a vector selects multiple elements: x[1 2] creates a new item from x[1] and x[2]. An empty index slot is a shorthand for all the elements along that dimension, so x[] is equivalent to x, and x[;3] gives the third column of two-dimensional array x. Only a subset of APL's functionality is implemented, but all numerical operations are supported. Semicolons separate multiple statements on a line. Variables are alphanumeric and are assigned with the = operator. Assignment is an expression. After each successful expression evaluation, the result is stored in the variable called _ (underscore) so it can be used in the next expression. The APL operators, adapted from https://en.wikipedia.org/wiki/APL_syntax_and_symbols, and their correspondence are listed here. The correspondence is incomplete and inexact. Unary operators Binary operators Operators and axis indicator Type-converting operations The constants e (base of natural logarithms) and pi (π) are pre-defined to high precision, about 3000 decimal digits truncated according to the floating point precision setting. Strings are vectors of "chars", which are Unicode code points (not bytes). Syntactically, string literals are very similar to those in Go, with back-quoted raw strings and double-quoted interpreted strings. Unlike Go, single-quoted strings are equivalent to double-quoted, a nod to APL syntax. A string with a single char is just a singleton char value; all others are vectors. Thus “, "", and ” are empty vectors, `a`, "a", and 'a' are equivalent representations of a single char, and `ab`, `a` `b`, "ab", "a" "b", 'ab', and 'a' 'b' are equivalent representations of a two-char vector. Unlike in Go, a string in ivy comprises code points, not bytes; as such it can contain only valid Unicode values. Thus in ivy "\x80" is illegal, although it is a legal one-byte string in Go. Strings can be printed. If a vector contains only chars, it is printed without spaces between them. Chars have restricted operations. Printing, comparison, indexing and so on are legal but arithmetic is not, and chars cannot be converted automatically into other singleton values (ints, floats, and so on). The unary operators char and code enable transcoding between integer and char values. Users can define unary and binary operators, which then behave just like built-in operators. Both a unary and a binary operator may be defined for the same name. The syntax of a definition is the 'op' keyword, the operator and formal arguments, an equals sign, and then the body. The names of the operator and its arguments must be identifiers. For unary operators, write "op name arg"; for binary write "op leftarg name rightarg". The final expression in the body is the return value. Operators may have recursive definitions; see the paragraph about conditional execution for an example. The body may be a single line (possibly containing semicolons) on the same line as the 'op', or it can be multiple lines. For a multiline entry, there is a newline after the '=' and the definition ends at the first blank line (ignoring spaces). Conditional execution is done with the ":" binary conditional return operator, which is valid only within the code for a user-defined operator. The left operand must be a scalar. If it is non-zero, the right operand is returned as the value of the function. Otherwise, execution continues normally. The ":" operator has a lower precedence than any other operator; in effect it breaks the line into two separate expressions. Example: average of a vector (unary): Example: n largest entries in a vector (binary): Example: multiline operator definition (binary): Example: primes less than N (unary): Example: greatest common divisor (binary): On mobile platforms only, due to I/O restrictions, user-defined operators must be presented on a single line. Use semicolons to separate expressions: To declare an operator but not define it, omit the equals sign and what follows. Within a user-defined operator body, identifiers are local to the invocation if they are assigned before being read, and global if read before being written. To write to a global without reading it first, insert an unused read. To remove the definition of a unary or binary user-defined operator, Ivy accepts a number of special commands, introduced by a right paren at the beginning of the line. Most report the current value if a new value is not specified. For these commands, numbers are always read and printed base 10 and must be non-negative on input.

v0.3.6 • 2 months ago

github.com/decred/dcrd/peer/v3

Package peer provides a common base for creating and managing Decred network peers. This package builds upon the wire package, which provides the fundamental primitives necessary to speak the Decred wire protocol, in order to simplify the process of creating fully functional peers. In essence, it provides a common base for creating concurrent safe fully validating nodes, Simplified Payment Verification (SPV) nodes, proxies, etc. A quick overview of the major features peer provides are as follows: All peer configuration is handled with the Config struct. This allows the caller to specify things such as the user agent name and version, the decred network to use, which services it supports, and callbacks to invoke when decred messages are received. See the documentation for each field of the Config struct for more details. A peer can either be inbound or outbound. The caller is responsible for establishing the connection to remote peers and listening for incoming peers. This provides high flexibility for things such as connecting via proxies, acting as a proxy, creating bridge peers, choosing whether to listen for inbound peers, etc. NewOutboundPeer and NewInboundPeer functions must be followed by calling Connect with a net.Conn instance to the peer. This will start all async I/O goroutines and initiate the protocol negotiation process. Once finished with the peer call Disconnect to disconnect from the peer and clean up all resources. WaitForDisconnect can be used to block until peer disconnection and resource cleanup has completed. In order to do anything useful with a peer, it is necessary to react to decred messages. This is accomplished by creating an instance of the MessageListeners struct with the callbacks to be invoke specified and setting the Listeners field of the Config struct specified when creating a peer to it. For convenience, a callback hook for all of the currently supported decred messages is exposed which receives the peer instance and the concrete message type. In addition, a hook for OnRead is provided so even custom messages types for which this package does not directly provide a hook, as long as they implement the wire.Message interface, can be used. Finally, the OnWrite hook is provided, which in conjunction with OnRead, can be used to track server-wide byte counts. It is often useful to use closures which encapsulate state when specifying the callback handlers. This provides a clean method for accessing that state when callbacks are invoked. The QueueMessage function provides the fundamental means to send messages to the remote peer. As the name implies, this employs a non-blocking queue. A done channel which will be notified when the message is actually sent can optionally be specified. There are certain message types which are better sent using other functions which provide additional functionality. Of special interest are inventory messages. Rather than manually sending MsgInv messages via Queuemessage, the inventory vectors should be queued using the QueueInventory function. It employs batching and trickling along with intelligent known remote peer inventory detection and avoidance through the use of a most-recently used algorithm. In addition to the bare QueueMessage function previously described, the PushAddrMsg, PushGetBlocksMsg, and PushGetHeadersMsg functions are provided as a convenience. While it is of course possible to create and send these messages manually via QueueMessage, these helper functions provided additional useful functionality that is typically desired. For example, the PushAddrMsg function automatically limits the addresses to the maximum number allowed by the message and randomizes the chosen addresses when there are too many. This allows the caller to simply provide a slice of known addresses, such as that returned by the addrmgr package, without having to worry about the details. Finally, the PushGetBlocksMsg and PushGetHeadersMsg functions will construct proper messages using a block locator and ignore back to back duplicate requests. A snapshot of the current peer statistics can be obtained with the StatsSnapshot function. This includes statistics such as the total number of bytes read and written, the remote address, user agent, and negotiated protocol version. This package provides extensive logging capabilities through the UseLogger function which allows a slog.Logger to be specified. For example, logging at the debug level provides summaries of every message sent and received, and logging at the trace level provides full dumps of parsed messages as well as the raw message bytes using a format similar to hexdump -C. This package supports all improvement proposals supported by the wire package. This example demonstrates the basic process for initializing and creating an outbound peer. Peers negotiate by exchanging version and verack messages. For demonstration, a simple handler for version message is attached to the peer.

v3.1.3 • last week

github.com/cavaliergopher/grab

github.com/ThalesIgnite/crypto11

github.com/santhosh-tekuri/jsonschema/v2

github.com/decred/dcrd/blockchain/standalone/v2

github.com/decred/dcrd/blockchain/v3

github.com/kataras/golog

gopkg.in/fatih/set.v0

github.com/ltns35/ozzo-validation/v4

github.com/fasthttp/websocket

gopkg.in/go-ozzo/ozzo-validation.v1

gopkg.in/go-ozzo/ozzo-validation.v2

gopkg.in/go-ozzo/ozzo-validation.v4

github.com/go-ozzo/ozzo-VALIdation

gopkg.in/go-ozzo/ozzo-validation.v3

github.com/mna/pigeon

github.com/libvirt/libvirt-go

github.com/decred/dcrd/addrmgr/v2

github.com/decred/dcrd/blockchain/stake/v4

github.com/decred/dcrd/gcs/v3

github.com/go-openapi/validate

github.com/gbrlsnchs/jwt/v3

gopkg.in/jackc/pgx.v2

github.com/offchainlabs/arbitrum/packages/arb-validator-core

github.com/cockroachdb/apd/v3

github.com/decred/dcrd/blockchain/v2

github.com/aws/aws-sdk-go-v2/service/ivschat

github.com/awesome-gocui/gocui

github.com/decred/dcrd/blockchain/v4

github.com/andersfylling/disgord

github.com/minio/selfupdate

github.com/oleksandr/bonjour

github.com/vrischmann/envconfig

github.com/wagslane/go-password-validator

github.com/google/go-replayers/grpcreplay

gitee.com/opengauss/openGauss-connector-go-pq

github.com/decred/dcrd/peer

gopkg.in/go-playground/validator.v10

github.com/deanishe/awgo

github.com/santhosh-tekuri/jsonschema/v3

gopkg.in/mholt/archiver.v3

robpike.io/ivy

github.com/mholt/binding

github.com/decred/dcrd/peer/v3

github.com/kevinburke/twilio-go

github.com/decred/dcrwallet/validate

github.com/bytedance/go-tagexpr

github.com/azure/go-autorest/autorest/validation

github.com/decred/dcrd/blockchain/stake/v5

github.com/wundergraph/graphql-go-tools

github.com/decred/dcrd/gcs/v4