84 lines
3.5 KiB
Ruby
84 lines
3.5 KiB
Ruby
require 'middleman-core/extension'
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module Middleman
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# The Extensions module is used to handle global registration and loading of Middleman Extensions.
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#
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# The application-facing extension API ({Middleman::CoreExtensions::Extensions#activate activate}, etc) is in {Middleman::CoreExtensions::Extensions} in
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# `middleman-core/core_extensions/extensions.rb`.
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module Extensions
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@registered = {}
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class << self
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# A hash of all registered extensions. Registered extensions are not necessarily active - this
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# is the set of all extensions that are known to Middleman.
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# @return [Hash{Symbol => Class<Middleman::Extension>, Proc}] A directory of known extensions indexed by the name they were registered under. The value may be a Proc, which can be lazily called to return an extension class.
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attr_reader :registered
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# Register a new extension. Choose a name which will be
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# used to activate the extension in `config.rb`, like this:
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#
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# activate :my_extension
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#
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# Provide your extension class either as the second parameter:
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#
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# Middleman::Extensions.register(:my_extension, MyExtension)
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#
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# Or better, return it from a block, which allows you to lazily require the implementation:
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#
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# Middleman::Extensions.register :my_extension do
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# require 'my_extension'
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# MyExtension
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# end
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#
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# @param [Symbol] name The name of the extension
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# @param [Class<Middleman::Extension>] extension_class The extension class (Must inherit from {Middleman::Extension})
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# @yield Instead of passing a module in namespace, you can provide
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# a block which returns your extension class. This gives
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# you the ability to require other files only when the
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# extension is first activated.
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# @return [void]
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def register(name, extension_class=nil, &block)
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raise 'Extension name must be a symbol' unless name.is_a?(Symbol)
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# If we've already got an extension registered under this name, bail out
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raise "There is already an extension registered with the name '#{name}'" if registered.key?(name)
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registered[name] = if block_given?
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block
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elsif extension_class && extension_class.ancestors.include?(::Middleman::Extension)
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extension_class
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else
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raise 'You must provide a Middleman::Extension or a block that returns a Middleman::Extension'
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end
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end
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# @api private
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# Load an extension by name, lazily evaluating the block provided to {#register} if necessary.
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# @param [Symbol] name The name of the extension
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# @return [Class<Middleman::Extension>] A {Middleman::Extension} class implementing the extension
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#
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def load(name)
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raise 'Extension name must be a symbol' unless name.is_a?(Symbol)
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unless registered.key?(name)
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raise "Unknown Extension: #{name}. Check the name and make sure you have referenced the extension's gem in your Gemfile."
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end
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extension_class = registered[name]
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if extension_class.is_a?(Proc)
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extension_class = extension_class.call
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registered[name] = extension_class
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end
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unless extension_class.ancestors.include?(::Middleman::Extension)
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raise "Tried to activate old-style extension: #{name}. They are no longer supported."
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end
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# Set the extension's name to whatever it was registered as.
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extension_class.ext_name = name
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extension_class
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end
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end
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end
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end
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