aboutsummaryrefslogtreecommitdiffstats
path: root/actionview/lib/action_view/template.rb
blob: 6e3af1536af29a03b0acd0929125494b8f637cad (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
# frozen_string_literal: true

require "active_support/core_ext/object/try"
require "active_support/core_ext/kernel/singleton_class"
require "active_support/deprecation"
require "thread"
require "delegate"

module ActionView
  # = Action View Template
  class Template
    extend ActiveSupport::Autoload

    def self.finalize_compiled_template_methods
      ActiveSupport::Deprecation.warn "ActionView::Template.finalize_compiled_template_methods is deprecated and has no effect"
    end

    def self.finalize_compiled_template_methods=(_)
      ActiveSupport::Deprecation.warn "ActionView::Template.finalize_compiled_template_methods= is deprecated and has no effect"
    end

    # === Encodings in ActionView::Template
    #
    # ActionView::Template is one of a few sources of potential
    # encoding issues in Rails. This is because the source for
    # templates are usually read from disk, and Ruby (like most
    # encoding-aware programming languages) assumes that the
    # String retrieved through File IO is encoded in the
    # <tt>default_external</tt> encoding. In Rails, the default
    # <tt>default_external</tt> encoding is UTF-8.
    #
    # As a result, if a user saves their template as ISO-8859-1
    # (for instance, using a non-Unicode-aware text editor),
    # and uses characters outside of the ASCII range, their
    # users will see diamonds with question marks in them in
    # the browser.
    #
    # For the rest of this documentation, when we say "UTF-8",
    # we mean "UTF-8 or whatever the default_internal encoding
    # is set to". By default, it will be UTF-8.
    #
    # To mitigate this problem, we use a few strategies:
    # 1. If the source is not valid UTF-8, we raise an exception
    #    when the template is compiled to alert the user
    #    to the problem.
    # 2. The user can specify the encoding using Ruby-style
    #    encoding comments in any template engine. If such
    #    a comment is supplied, Rails will apply that encoding
    #    to the resulting compiled source returned by the
    #    template handler.
    # 3. In all cases, we transcode the resulting String to
    #    the UTF-8.
    #
    # This means that other parts of Rails can always assume
    # that templates are encoded in UTF-8, even if the original
    # source of the template was not UTF-8.
    #
    # From a user's perspective, the easiest thing to do is
    # to save your templates as UTF-8. If you do this, you
    # do not need to do anything else for things to "just work".
    #
    # === Instructions for template handlers
    #
    # The easiest thing for you to do is to simply ignore
    # encodings. Rails will hand you the template source
    # as the default_internal (generally UTF-8), raising
    # an exception for the user before sending the template
    # to you if it could not determine the original encoding.
    #
    # For the greatest simplicity, you can support only
    # UTF-8 as the <tt>default_internal</tt>. This means
    # that from the perspective of your handler, the
    # entire pipeline is just UTF-8.
    #
    # === Advanced: Handlers with alternate metadata sources
    #
    # If you want to provide an alternate mechanism for
    # specifying encodings (like ERB does via <%# encoding: ... %>),
    # you may indicate that you will handle encodings yourself
    # by implementing <tt>handles_encoding?</tt> on your handler.
    #
    # If you do, Rails will not try to encode the String
    # into the default_internal, passing you the unaltered
    # bytes tagged with the assumed encoding (from
    # default_external).
    #
    # In this case, make sure you return a String from
    # your handler encoded in the default_internal. Since
    # you are handling out-of-band metadata, you are
    # also responsible for alerting the user to any
    # problems with converting the user's data to
    # the <tt>default_internal</tt>.
    #
    # To do so, simply raise +WrongEncodingError+ as follows:
    #
    #     raise WrongEncodingError.new(
    #       problematic_string,
    #       expected_encoding
    #     )

    ##
    # :method: local_assigns
    #
    # Returns a hash with the defined local variables.
    #
    # Given this sub template rendering:
    #
    #   <%= render "shared/header", { headline: "Welcome", person: person } %>
    #
    # You can use +local_assigns+ in the sub templates to access the local variables:
    #
    #   local_assigns[:headline] # => "Welcome"

    eager_autoload do
      autoload :Error
      autoload :Handlers
      autoload :HTML
      autoload :Inline
      autoload :Text
      autoload :Types
    end

    extend Template::Handlers

    attr_reader :source, :identifier, :handler, :original_encoding, :updated_at
    attr_reader :variable, :format, :variant, :locals, :virtual_path

    def initialize(source, identifier, handler, format: nil, variant: nil, locals: nil, virtual_path: nil, updated_at: nil)
      unless locals
        ActiveSupport::Deprecation.warn "ActionView::Template#initialize requires a locals parameter"
        locals = []
      end

      @source            = source
      @identifier        = identifier
      @handler           = handler
      @compiled          = false
      @locals            = locals
      @virtual_path      = virtual_path

      @variable = if @virtual_path
        base = @virtual_path[-1] == "/" ? "" : File.basename(@virtual_path)
        base =~ /\A_?(.*?)(?:\.\w+)*\z/
        $1.to_sym
      end

      if updated_at
        ActiveSupport::Deprecation.warn "ActionView::Template#updated_at is deprecated"
        @updated_at        = updated_at
      else
        @updated_at        = Time.now
      end
      @format            = format
      @variant           = variant
      @compile_mutex     = Mutex.new
    end

    deprecate :original_encoding
    deprecate :updated_at
    deprecate def virtual_path=(_); end
    deprecate def locals=(_); end
    deprecate def formats=(_); end
    deprecate def formats; Array(format); end
    deprecate def variants=(_); end
    deprecate def variants; [variant]; end

    # Returns whether the underlying handler supports streaming. If so,
    # a streaming buffer *may* be passed when it starts rendering.
    def supports_streaming?
      handler.respond_to?(:supports_streaming?) && handler.supports_streaming?
    end

    # Render a template. If the template was not compiled yet, it is done
    # exactly before rendering.
    #
    # This method is instrumented as "!render_template.action_view". Notice that
    # we use a bang in this instrumentation because you don't want to
    # consume this in production. This is only slow if it's being listened to.
    def render(view, locals, buffer = ActionView::OutputBuffer.new, &block)
      instrument_render_template do
        compile!(view)
        view._run(method_name, self, locals, buffer, &block)
      end
    rescue => e
      handle_render_error(view, e)
    end

    def type
      @type ||= Types[format]
    end

    # Receives a view object and return a template similar to self by using @virtual_path.
    #
    # This method is useful if you have a template object but it does not contain its source
    # anymore since it was already compiled. In such cases, all you need to do is to call
    # refresh passing in the view object.
    #
    # Notice this method raises an error if the template to be refreshed does not have a
    # virtual path set (true just for inline templates).
    def refresh(view)
      raise "A template needs to have a virtual path in order to be refreshed" unless @virtual_path
      lookup  = view.lookup_context
      pieces  = @virtual_path.split("/")
      name    = pieces.pop
      partial = !!name.sub!(/^_/, "")
      lookup.disable_cache do
        lookup.find_template(name, [ pieces.join("/") ], partial, @locals)
      end
    end

    def short_identifier
      @short_identifier ||= defined?(Rails.root) ? identifier.sub("#{Rails.root}/", "") : identifier
    end

    def inspect
      "#<#{self.class.name} #{short_identifier} locals=#{@locals.inspect}>"
    end

    # This method is responsible for properly setting the encoding of the
    # source. Until this point, we assume that the source is BINARY data.
    # If no additional information is supplied, we assume the encoding is
    # the same as <tt>Encoding.default_external</tt>.
    #
    # The user can also specify the encoding via a comment on the first
    # line of the template (# encoding: NAME-OF-ENCODING). This will work
    # with any template engine, as we process out the encoding comment
    # before passing the source on to the template engine, leaving a
    # blank line in its stead.
    def encode!
      source = self.source

      return source unless source.encoding == Encoding::BINARY

      # Look for # encoding: *. If we find one, we'll encode the
      # String in that encoding, otherwise, we'll use the
      # default external encoding.
      if source.sub!(/\A#{ENCODING_FLAG}/, "")
        encoding = magic_encoding = $1
      else
        encoding = Encoding.default_external
      end

      # Tag the source with the default external encoding
      # or the encoding specified in the file
      source.force_encoding(encoding)

      # If the user didn't specify an encoding, and the handler
      # handles encodings, we simply pass the String as is to
      # the handler (with the default_external tag)
      if !magic_encoding && @handler.respond_to?(:handles_encoding?) && @handler.handles_encoding?
        source
      # Otherwise, if the String is valid in the encoding,
      # encode immediately to default_internal. This means
      # that if a handler doesn't handle encodings, it will
      # always get Strings in the default_internal
      elsif source.valid_encoding?
        source.encode!
      # Otherwise, since the String is invalid in the encoding
      # specified, raise an exception
      else
        raise WrongEncodingError.new(source, encoding)
      end
    end


    # Exceptions are marshalled when using the parallel test runner with DRb, so we need
    # to ensure that references to the template object can be marshalled as well. This means forgoing
    # the marshalling of the compiler mutex and instantiating that again on unmarshalling.
    def marshal_dump # :nodoc:
      [ @source, @identifier, @handler, @compiled, @locals, @virtual_path, @updated_at, @format, @variant ]
    end

    def marshal_load(array) # :nodoc:
      @source, @identifier, @handler, @compiled, @locals, @virtual_path, @updated_at, @format, @variant = *array
      @compile_mutex = Mutex.new
    end

    private

      # Compile a template. This method ensures a template is compiled
      # just once and removes the source after it is compiled.
      def compile!(view)
        return if @compiled

        # Templates can be used concurrently in threaded environments
        # so compilation and any instance variable modification must
        # be synchronized
        @compile_mutex.synchronize do
          # Any thread holding this lock will be compiling the template needed
          # by the threads waiting. So re-check the @compiled flag to avoid
          # re-compilation
          return if @compiled

          mod = view.compiled_method_container

          instrument("!compile_template") do
            compile(mod)
          end

          # Just discard the source if we have a virtual path. This
          # means we can get the template back.
          @source = nil if @virtual_path
          @compiled = true
        end
      end

      class LegacyTemplate < DelegateClass(Template) # :nodoc:
        attr_reader :source

        def initialize(template, source)
          super(template)
          @source = source
        end
      end

      # Among other things, this method is responsible for properly setting
      # the encoding of the compiled template.
      #
      # If the template engine handles encodings, we send the encoded
      # String to the engine without further processing. This allows
      # the template engine to support additional mechanisms for
      # specifying the encoding. For instance, ERB supports <%# encoding: %>
      #
      # Otherwise, after we figure out the correct encoding, we then
      # encode the source into <tt>Encoding.default_internal</tt>.
      # In general, this means that templates will be UTF-8 inside of Rails,
      # regardless of the original source encoding.
      def compile(mod)
        source = encode!
        code = @handler.call(self, source)

        # Make sure that the resulting String to be eval'd is in the
        # encoding of the code
        source = +<<-end_src
          def #{method_name}(local_assigns, output_buffer)
            @virtual_path = #{@virtual_path.inspect};#{locals_code};#{code}
          end
        end_src

        # Make sure the source is in the encoding of the returned code
        source.force_encoding(code.encoding)

        # In case we get back a String from a handler that is not in
        # BINARY or the default_internal, encode it to the default_internal
        source.encode!

        # Now, validate that the source we got back from the template
        # handler is valid in the default_internal. This is for handlers
        # that handle encoding but screw up
        unless source.valid_encoding?
          raise WrongEncodingError.new(source, Encoding.default_internal)
        end

        mod.module_eval(source, identifier, 0)
      end

      def handle_render_error(view, e)
        if e.is_a?(Template::Error)
          e.sub_template_of(self)
          raise e
        else
          template = self
          unless template.source
            template = refresh(view)
            template.encode!
          end
          raise Template::Error.new(template)
        end
      end

      def locals_code
        # Only locals with valid variable names get set directly. Others will
        # still be available in local_assigns.
        locals = @locals - Module::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 method_name
        @method_name ||= begin
          m = +"_#{identifier_method_name}__#{@identifier.hash}_#{__id__}"
          m.tr!("-", "_")
          m
        end
      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