6cf883a136
Ref: https://bugs.ruby-lang.org/issues/15554 Ruby 3.4 now warns when passing a block to a method that never expects one. In the case of rendered template, a block is always passed for some engines that do expect one, but some never expect it. We can silence that warning by declaring an anonymous block.
581 lines
20 KiB
Ruby
581 lines
20 KiB
Ruby
# frozen_string_literal: true
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require "thread"
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require "delegate"
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module ActionView
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# = Action View \Template
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class Template
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extend ActiveSupport::Autoload
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STRICT_LOCALS_REGEX = /\#\s+locals:\s+\((.*)\)/
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# === Encodings in ActionView::Template
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#
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# ActionView::Template is one of a few sources of potential
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# encoding issues in \Rails. This is because the source for
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# templates are usually read from disk, and Ruby (like most
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# encoding-aware programming languages) assumes that the
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# String retrieved through File IO is encoded in the
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# <tt>default_external</tt> encoding. In \Rails, the default
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# <tt>default_external</tt> encoding is UTF-8.
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#
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# As a result, if a user saves their template as ISO-8859-1
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# (for instance, using a non-Unicode-aware text editor),
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# and uses characters outside of the ASCII range, their
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# users will see diamonds with question marks in them in
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# the browser.
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#
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# For the rest of this documentation, when we say "UTF-8",
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# we mean "UTF-8 or whatever the default_internal encoding
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# is set to". By default, it will be UTF-8.
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#
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# To mitigate this problem, we use a few strategies:
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# 1. If the source is not valid UTF-8, we raise an exception
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# when the template is compiled to alert the user
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# to the problem.
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# 2. The user can specify the encoding using Ruby-style
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# encoding comments in any template engine. If such
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# a comment is supplied, \Rails will apply that encoding
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# to the resulting compiled source returned by the
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# template handler.
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# 3. In all cases, we transcode the resulting String to
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# the UTF-8.
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#
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# This means that other parts of \Rails can always assume
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# that templates are encoded in UTF-8, even if the original
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# source of the template was not UTF-8.
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#
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# From a user's perspective, the easiest thing to do is
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# to save your templates as UTF-8. If you do this, you
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# do not need to do anything else for things to "just work".
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#
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# === Instructions for template handlers
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#
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# The easiest thing for you to do is to simply ignore
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# encodings. \Rails will hand you the template source
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# as the default_internal (generally UTF-8), raising
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# an exception for the user before sending the template
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# to you if it could not determine the original encoding.
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#
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# For the greatest simplicity, you can support only
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# UTF-8 as the <tt>default_internal</tt>. This means
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# that from the perspective of your handler, the
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# entire pipeline is just UTF-8.
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#
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# === Advanced: Handlers with alternate metadata sources
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#
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# If you want to provide an alternate mechanism for
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# specifying encodings (like ERB does via <%# encoding: ... %>),
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# you may indicate that you will handle encodings yourself
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# by implementing <tt>handles_encoding?</tt> on your handler.
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#
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# If you do, \Rails will not try to encode the String
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# into the default_internal, passing you the unaltered
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# bytes tagged with the assumed encoding (from
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# default_external).
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#
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# In this case, make sure you return a String from
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# your handler encoded in the default_internal. Since
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# you are handling out-of-band metadata, you are
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# also responsible for alerting the user to any
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# problems with converting the user's data to
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# the <tt>default_internal</tt>.
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#
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# To do so, simply raise +WrongEncodingError+ as follows:
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#
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# raise WrongEncodingError.new(
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# problematic_string,
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# expected_encoding
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# )
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##
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# :method: local_assigns
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#
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# Returns a hash with the defined local variables.
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#
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# Given this sub template rendering:
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#
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# <%= render "application/header", { headline: "Welcome", person: person } %>
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#
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# You can use +local_assigns+ in the sub templates to access the local variables:
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#
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# local_assigns[:headline] # => "Welcome"
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#
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# Each key in +local_assigns+ is available as a partial-local variable:
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#
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# local_assigns[:headline] # => "Welcome"
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# headline # => "Welcome"
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#
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# Since +local_assigns+ is a +Hash+, it's compatible with Ruby 3.1's pattern
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# matching assignment operator:
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#
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# local_assigns => { headline:, **options }
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# headline # => "Welcome"
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# options # => {}
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#
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# Pattern matching assignment also supports variable renaming:
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#
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# local_assigns => { headline: title }
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# title # => "Welcome"
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#
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# If a template refers to a variable that isn't passed into the view as part
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# of the <tt>locals: { ... }</tt> Hash, the template will raise an
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# +ActionView::Template::Error+:
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#
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# <%# => raises ActionView::Template::Error %>
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# <% alerts.each do |alert| %>
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# <p><%= alert %></p>
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# <% end %>
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#
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# Since +local_assigns+ returns a +Hash+ instance, you can conditionally
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# read a variable, then fall back to a default value when
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# the key isn't part of the <tt>locals: { ... }</tt> options:
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#
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# <% local_assigns.fetch(:alerts, []).each do |alert| %>
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# <p><%= alert %></p>
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# <% end %>
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#
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# Combining Ruby 3.1's pattern matching assignment with calls to
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# +Hash#with_defaults+ enables compact partial-local variable
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# assignments:
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#
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# <% local_assigns.with_defaults(alerts: []) => { headline:, alerts: } %>
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#
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# <h1><%= headline %></h1>
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#
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# <% alerts.each do |alert| %>
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# <p><%= alert %></p>
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# <% end %>
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#
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# By default, templates will accept any <tt>locals</tt> as keyword arguments
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# and make them available to <tt>local_assigns</tt>. To restrict what
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# <tt>local_assigns</tt> a template will accept, add a <tt>locals:</tt> magic comment:
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#
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# <%# locals: (headline:, alerts: []) %>
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#
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# <h1><%= headline %></h1>
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#
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# <% alerts.each do |alert| %>
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# <p><%= alert %></p>
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# <% end %>
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#
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# Read more about strict locals in {Action View Overview}[https://guides.rubyonrails.org/action_view_overview.html#strict-locals]
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# in the guides.
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eager_autoload do
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autoload :Error
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autoload :RawFile
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autoload :Renderable
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autoload :Handlers
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autoload :HTML
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autoload :Inline
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autoload :Types
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autoload :Sources
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autoload :Text
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autoload :Types
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end
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extend Template::Handlers
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singleton_class.attr_accessor :frozen_string_literal
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@frozen_string_literal = false
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class << self # :nodoc:
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def mime_types_implementation=(implementation)
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# This method isn't thread-safe, but it's not supposed
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# to be called after initialization
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if self::Types != implementation
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remove_const(:Types)
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const_set(:Types, implementation)
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end
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end
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end
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attr_reader :identifier, :handler
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attr_reader :variable, :format, :variant, :virtual_path
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NONE = Object.new
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def initialize(source, identifier, handler, locals:, format: nil, variant: nil, virtual_path: nil)
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@source = source.dup
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@identifier = identifier
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@handler = handler
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@compiled = false
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@locals = locals
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@virtual_path = virtual_path
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@variable = if @virtual_path
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base = @virtual_path.end_with?("/") ? "" : ::File.basename(@virtual_path)
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base =~ /\A_?(.*?)(?:\.\w+)*\z/
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$1.to_sym
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end
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@format = format
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@variant = variant
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@compile_mutex = Mutex.new
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@strict_locals = NONE
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@strict_local_keys = nil
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@type = nil
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end
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# The locals this template has been or will be compiled for, or nil if this
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# is a strict locals template.
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def locals
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if strict_locals?
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nil
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else
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@locals
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end
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end
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def spot(location) # :nodoc:
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ast = RubyVM::AbstractSyntaxTree.parse(compiled_source, keep_script_lines: true)
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node_id = RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(location)
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node = find_node_by_id(ast, node_id)
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ErrorHighlight.spot(node)
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end
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# Translate an error location returned by ErrorHighlight to the correct
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# source location inside the template.
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def translate_location(backtrace_location, spot)
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if handler.respond_to?(:translate_location)
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handler.translate_location(spot, backtrace_location, encode!) || spot
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else
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spot
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end
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end
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# Returns whether the underlying handler supports streaming. If so,
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# a streaming buffer *may* be passed when it starts rendering.
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def supports_streaming?
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handler.respond_to?(:supports_streaming?) && handler.supports_streaming?
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end
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# Render a template. If the template was not compiled yet, it is done
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# exactly before rendering.
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#
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# This method is instrumented as "!render_template.action_view". Notice that
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# we use a bang in this instrumentation because you don't want to
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# consume this in production. This is only slow if it's being listened to.
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def render(view, locals, buffer = nil, implicit_locals: [], add_to_stack: true, &block)
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instrument_render_template do
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compile!(view)
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if strict_locals? && @strict_local_keys && !implicit_locals.empty?
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locals_to_ignore = implicit_locals - @strict_local_keys
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locals.except!(*locals_to_ignore)
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end
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if buffer
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view._run(method_name, self, locals, buffer, add_to_stack: add_to_stack, has_strict_locals: strict_locals?, &block)
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nil
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else
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result = view._run(method_name, self, locals, OutputBuffer.new, add_to_stack: add_to_stack, has_strict_locals: strict_locals?, &block)
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result.is_a?(OutputBuffer) ? result.to_s : result
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end
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end
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rescue => e
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handle_render_error(view, e)
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end
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def type
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@type ||= Types[format]
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end
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def short_identifier
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@short_identifier ||= defined?(Rails.root) ? identifier.delete_prefix("#{Rails.root}/") : identifier
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end
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def inspect
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"#<#{self.class.name} #{short_identifier} locals=#{locals.inspect}>"
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end
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def source
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@source.to_s
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end
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LEADING_ENCODING_REGEXP = /\A#{ENCODING_FLAG}/
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private_constant :LEADING_ENCODING_REGEXP
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# This method is responsible for properly setting the encoding of the
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# source. Until this point, we assume that the source is BINARY data.
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# If no additional information is supplied, we assume the encoding is
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# the same as <tt>Encoding.default_external</tt>.
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#
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# The user can also specify the encoding via a comment on the first
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# line of the template (<tt># encoding: NAME-OF-ENCODING</tt>). This will work
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# with any template engine, as we process out the encoding comment
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# before passing the source on to the template engine, leaving a
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# blank line in its stead.
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def encode!
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source = self.source
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return source unless source.encoding == Encoding::BINARY
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# Look for # encoding: *. If we find one, we'll encode the
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# String in that encoding, otherwise, we'll use the
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# default external encoding.
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if source.sub!(LEADING_ENCODING_REGEXP, "")
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encoding = magic_encoding = $1
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else
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encoding = Encoding.default_external
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end
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# Tag the source with the default external encoding
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# or the encoding specified in the file
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source.force_encoding(encoding)
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# If the user didn't specify an encoding, and the handler
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# handles encodings, we simply pass the String as is to
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# the handler (with the default_external tag)
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if !magic_encoding && @handler.respond_to?(:handles_encoding?) && @handler.handles_encoding?
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source
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# Otherwise, if the String is valid in the encoding,
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# encode immediately to default_internal. This means
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# that if a handler doesn't handle encodings, it will
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# always get Strings in the default_internal
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elsif source.valid_encoding?
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source.encode!
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# Otherwise, since the String is invalid in the encoding
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# specified, raise an exception
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else
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raise WrongEncodingError.new(source, encoding)
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end
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end
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# This method is responsible for marking a template as having strict locals
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# which means the template can only accept the locals defined in a magic
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# comment. For example, if your template acceps the locals +title+ and
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# +comment_count+, add the following to your template file:
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#
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# <%# locals: (title: "Default title", comment_count: 0) %>
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#
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# Strict locals are useful for validating template arguments and for
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# specifying defaults.
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def strict_locals!
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if @strict_locals == NONE
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self.source.sub!(STRICT_LOCALS_REGEX, "")
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@strict_locals = $1
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return if @strict_locals.nil? # Magic comment not found
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@strict_locals = "**nil" if @strict_locals.blank?
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end
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@strict_locals
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end
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# Returns whether a template is using strict locals.
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def strict_locals?
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strict_locals!
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end
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# Exceptions are marshalled when using the parallel test runner with DRb, so we need
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# to ensure that references to the template object can be marshalled as well. This means forgoing
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# the marshalling of the compiler mutex and instantiating that again on unmarshalling.
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def marshal_dump # :nodoc:
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[ @source, @identifier, @handler, @compiled, @locals, @virtual_path, @format, @variant ]
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end
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def marshal_load(array) # :nodoc:
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@source, @identifier, @handler, @compiled, @locals, @virtual_path, @format, @variant = *array
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@compile_mutex = Mutex.new
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end
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def method_name # :nodoc:
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@method_name ||= begin
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m = +"_#{identifier_method_name}__#{@identifier.hash}_#{__id__}"
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m.tr!("-", "_")
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m
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end
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end
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private
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def find_node_by_id(node, node_id)
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return node if node.node_id == node_id
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node.children.grep(node.class).each do |child|
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found = find_node_by_id(child, node_id)
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return found if found
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end
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false
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end
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# Compile a template. This method ensures a template is compiled
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# just once and removes the source after it is compiled.
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def compile!(view)
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return if @compiled
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# Templates can be used concurrently in threaded environments
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# so compilation and any instance variable modification must
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# be synchronized
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@compile_mutex.synchronize do
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# Any thread holding this lock will be compiling the template needed
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# by the threads waiting. So re-check the @compiled flag to avoid
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# re-compilation
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return if @compiled
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mod = view.compiled_method_container
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instrument("!compile_template") do
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compile(mod)
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end
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@compiled = true
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end
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end
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# This method compiles the source of the template. The compilation of templates
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# involves setting strict_locals! if applicable, encoding the template, and setting
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# frozen string literal.
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def compiled_source
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set_strict_locals = strict_locals!
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source = encode!
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code = @handler.call(self, source)
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method_arguments =
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if set_strict_locals
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if set_strict_locals.include?("&")
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"output_buffer, #{set_strict_locals}"
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else
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"output_buffer, #{set_strict_locals}, &_"
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end
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else
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"local_assigns, output_buffer, &_"
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end
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# Make sure that the resulting String to be eval'd is in the
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# encoding of the code
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source = +<<-end_src
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def #{method_name}(#{method_arguments})
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@virtual_path = #{@virtual_path.inspect};#{locals_code};#{code}
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end
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end_src
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# Make sure the source is in the encoding of the returned code
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source.force_encoding(code.encoding)
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# In case we get back a String from a handler that is not in
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# BINARY or the default_internal, encode it to the default_internal
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source.encode!
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# Now, validate that the source we got back from the template
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# handler is valid in the default_internal. This is for handlers
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# that handle encoding but screw up
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unless source.valid_encoding?
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raise WrongEncodingError.new(source, Encoding.default_internal)
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end
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if Template.frozen_string_literal
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"# frozen_string_literal: true\n#{source}"
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else
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source
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end
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end
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# Among other things, this method is responsible for properly setting
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# the encoding of the compiled template.
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#
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# If the template engine handles encodings, we send the encoded
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# String to the engine without further processing. This allows
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# the template engine to support additional mechanisms for
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# specifying the encoding. For instance, ERB supports <%# encoding: %>
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#
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# Otherwise, after we figure out the correct encoding, we then
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# encode the source into <tt>Encoding.default_internal</tt>.
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# In general, this means that templates will be UTF-8 inside of Rails,
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# regardless of the original source encoding.
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def compile(mod)
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begin
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mod.module_eval(compiled_source, identifier, offset)
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rescue SyntaxError
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# Account for when code in the template is not syntactically valid; e.g. if we're using
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# ERB and the user writes <%= foo( %>, attempting to call a helper `foo` and interpolate
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# the result into the template, but missing an end parenthesis.
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raise SyntaxErrorInTemplate.new(self, encode!)
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end
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return unless strict_locals?
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parameters = mod.instance_method(method_name).parameters - [[:req, :output_buffer]]
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# Check compiled method parameters to ensure that only kwargs
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# were provided as strict locals, preventing `locals: (foo, *foo)` etc
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|
# and allowing `locals: (foo:)`.
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non_kwarg_parameters = parameters.select do |parameter|
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|
![:keyreq, :key, :keyrest, :nokey].include?(parameter[0])
|
|
end
|
|
|
|
non_kwarg_parameters.pop if non_kwarg_parameters.last == %i(block _)
|
|
|
|
unless non_kwarg_parameters.empty?
|
|
mod.undef_method(method_name)
|
|
|
|
raise ArgumentError.new(
|
|
"#{non_kwarg_parameters.map { |_, name| "`#{name}`" }.to_sentence} set as non-keyword " \
|
|
"#{'argument'.pluralize(non_kwarg_parameters.length)} for #{short_identifier}. " \
|
|
"Locals can only be set as keyword arguments."
|
|
)
|
|
end
|
|
|
|
unless parameters.any? { |type, _| type == :keyrest }
|
|
parameters.map!(&:last)
|
|
parameters.sort!
|
|
@strict_local_keys = parameters.freeze
|
|
end
|
|
end
|
|
|
|
def offset
|
|
if Template.frozen_string_literal
|
|
-1
|
|
else
|
|
0
|
|
end
|
|
end
|
|
|
|
def handle_render_error(view, e)
|
|
if e.is_a?(Template::Error)
|
|
e.sub_template_of(self)
|
|
raise e
|
|
else
|
|
raise Template::Error.new(self)
|
|
end
|
|
end
|
|
|
|
RUBY_RESERVED_KEYWORDS = ::ActiveSupport::Delegation::RUBY_RESERVED_KEYWORDS
|
|
private_constant :RUBY_RESERVED_KEYWORDS
|
|
|
|
def locals_code
|
|
return "" if strict_locals?
|
|
|
|
# Only locals with valid variable names get set directly. Others will
|
|
# still be available in local_assigns.
|
|
locals = @locals - RUBY_RESERVED_KEYWORDS
|
|
|
|
locals = locals.grep(/\A(?![A-Z0-9])(?:[[:alnum:]_]|[^\0-\177])+\z/)
|
|
|
|
# Assign for the same variable is to suppress unused variable warning
|
|
locals.each_with_object(+"") { |key, code| code << "#{key} = local_assigns[:#{key}]; #{key} = #{key};" }
|
|
end
|
|
|
|
def identifier_method_name
|
|
short_identifier.tr("^a-z_", "_")
|
|
end
|
|
|
|
def instrument(action, &block) # :doc:
|
|
ActiveSupport::Notifications.instrument("#{action}.action_view", instrument_payload, &block)
|
|
end
|
|
|
|
def instrument_render_template(&block)
|
|
ActiveSupport::Notifications.instrument("!render_template.action_view", instrument_payload, &block)
|
|
end
|
|
|
|
def instrument_payload
|
|
{ virtual_path: @virtual_path, identifier: @identifier }
|
|
end
|
|
end
|
|
end
|