Class Sass::Plugin::StalenessChecker
In: lib/sass/plugin/staleness_checker.rb
Parent: Object

The class handles `.s[ca]ss` file staleness checks via their mtime timestamps.

To speed things up two level of caches are employed:

  • A class-level dependency cache which stores @import paths for each file. This is a long-lived cache that is reused by every StalenessChecker instance.
  • Two short-lived instance-level caches, one for file mtimes and one for whether a file is stale during this particular run. These are only used by a single StalenessChecker instance.

Usage:

  • For a one-off staleness check of a single `.s[ca]ss` file, the class-level {stylesheet_needs_update?} method should be used.
  • For a series of staleness checks (e.g. checking all files for staleness) a StalenessChecker instance should be created, and the instance-level \{stylesheet_needs_update?} method should be used. the caches should make the whole process significantly faster. WARNING: It is important not to retain the instance for too long, as its instance-level caches are never explicitly expired.

Methods

Constants

DELETED = 1.0/0.0

Attributes

dependencies_cache  [RW]  @private

Public Class methods

Creates a new StalenessChecker for checking the staleness of several stylesheets at once.

[Source]

    # File lib/sass/plugin/staleness_checker.rb, line 35
35:       def initialize
36:         @dependencies = self.class.dependencies_cache
37: 
38:         # Entries in the following instance-level caches are never explicitly expired.
39:         # Instead they are supposed to automaticaly go out of scope when a series of staleness checks
40:         # (this instance of StalenessChecker was created for) is finished.
41:         @mtimes, @dependencies_stale = {}, {}
42:       end

Returns whether or not a given CSS file is out of date and needs to be regenerated.

The distinction between this method and the instance-level \{stylesheet_needs_update?} is that the instance method preserves mtime and stale-dependency caches, so it‘s better to use when checking multiple stylesheets at once.

@param css_file [String] The location of the CSS file to check. @param template_file [String] The location of the Sass or SCSS template

  that is compiled to `css_file`.

[Source]

    # File lib/sass/plugin/staleness_checker.rb, line 66
66:       def self.stylesheet_needs_update?(css_file, template_file)
67:         new.stylesheet_needs_update?(css_file, template_file)
68:       end

Public Instance methods

Returns whether or not a given CSS file is out of date and needs to be regenerated.

@param css_file [String] The location of the CSS file to check. @param template_file [String] The location of the Sass or SCSS template

  that is compiled to `css_file`.

[Source]

    # File lib/sass/plugin/staleness_checker.rb, line 50
50:       def stylesheet_needs_update?(css_file, template_file)
51:         template_file, css_mtime = File.expand_path(template_file), mtime(css_file)
52: 
53:         css_mtime == DELETED || dependency_updated?(css_mtime).call(template_file)
54:       end

[Validate]