mako-tree

mako-tree

The build tree structure used internally by mako

Overview

When working with mako build hooks, the first 2 arguments will be the current file and the build tree respectively. Currently, both of those APIs are contained in this module, as they tightly coupled and don't make much sense on their own. (at least at the current time)

Throughout the "analyze" phase, a tree is being built up, starting from the list of entry files. Each file being processed adds any direct dependencies, which will then recursively be processed to find more dependencies. Each vertex in the graph corresponds to some sort of input file.

During the "build" phase, the tree may be trimmed down, such as the case where the entire dependency chain for a JS file will be combined into a single output file. By the end of the build, each vertex in the graph corresponds to an output file.

API

As mako continues to be developed and evolve, some documentation and guides dedicated to plugin authors will surface. For now, the following is purely the API available to both the file and tree parameters in plugins/hooks.

The Tree constructor (documented below) is the primary export for the module. It must be used with the new keyword.

var Tree = require('mako-tree');
var tree = new Tree();

Tree() (constructor)

Each instance represents a build tree. Internally, a graph is used to manage the relationships between all the files being tracked.

NOTE: All paths are assumed to be absolute, this library makes no attempt to set a base/root directory and maintain relative paths.

Tree#hasFile(location)

Returns a Boolean reflecting if the file at the given location exists in this tree.

Tree#addFile(location)

Adds a file at the given location to the tree, if it is not already present, and returns the corresponding File instance.

Tree#getFile(location)

Returns the File instance for the file at the given location. It is assumed to already be part of the graph, and will throw an error if not found.

Tree#removeFile(location)

Removes the file at the given location from the tree. To successfully remove a file, it must not be depended on by another file. This is mostly a plumbing function, and plugin authors are likely going to use removeDependency() instead.

Tree#isSource(location)

Returns a Boolean telling whether or not the file at location is an entry file. (in other words, is not a dependency)

Tree#getEntries()

Returns an Array of all the entry files in this graph. (in other words, files that are at the end of the dependency chains)

Tree#hasDependency(parent, child)

Returns a Boolean reflecting if the dependency relationship between parent and child already exists in the tree.

Tree#addDependency(parent, child)

Adds a new dependency relationship to the graph setting parent as depending on child. If child is not already part of the tree, it will be added. (however, if parent is not in the tree, that is assumed to be an error) This will return the File instance for the child file.

Tree#removeDependency(parent, child)

Removes the specified dependency relationship, basically saying that parent no longer depends on child)

NOTE: If no other files depend on child, it will be removed from the tree. This allows plugins to only concern themselves with the relationships they are aware of, leaving the overall tree management to mako.

Tree#moveDependency(from, to, child)

A helper for moving a dependency on child from one parent to another, which is more explicit than manually adding and removing the dependency links. (which must be done in the right order due to the automatic cleanup behavior of removing dependencies)

An example use case: after inlining a tree of CSS files, the images/fonts/etc will need to be moved from being dependencies of the input files, to the single output file.

Tree#dependenciesOf(file, [recursive])

Returns an Array of files that are dependencies of the given file.

By default, it will only return the direct descendants, but adding recursive will return a flat list of all the files down the entire dependency chain.

Tree#dependantsOf(file, [recursive])

Returns an Array of files that depend on the given file.

By default, it will only return the direct ancestors, but adding recursive will return a flat list of all the files up the entire dependency chain.

Tree#topologicalOrder()

Returns an Array of files that can be processed in an order that respects all the dependencies.

File(location) (constructor)

Each instance represents a file in the overall build.

File#path

The absolute path to where this file exists on disk.

File#type

The current file type associated with this file. This value is used to determine what plugins/hooks need to be invoked at various stages.

When initialized, it will simply reflect the extension of File#path. However, some plugins may need to modify this value if they end up changing how it should be interpreted. For example, a CoffeeScript plugin would switch from "coffee" to "js".

File#contents

This holds the current contents of the file. When first read, this property should be set, and subsequent changes to the source code should apply to this property.

File#isEntry()

Short-hand for tree.isEntry(file.path).

File#hasDependency(child)

Short-hand for tree.hasDependency(file.path, child).

File#addDependency(child)

Short-hand for tree.addDependency(file.path, child).

File#removeDependency(child)

Short-hand for tree.removeDependency(file.path, child).

File#dependencies([recursive])

Short-hand for tree.dependenciesOf(file.path, recursive).

File#dependants([recursive])

Short-hand for tree.dependantsOf(file.path, recursive).