10 files changed, 206 insertions, 131 deletions

diff --git a/actionview/lib/action_view/template/error.rb b/actionview/lib/action_view/template/error.rb
index 4e3c02e05e..d0ea03e228 100644
--- a/actionview/lib/action_view/template/error.rb
+++ b/actionview/lib/action_view/template/error.rb
@@ -109,7 +109,7 @@ module ActionView
           end
       end
 
-      def annoted_source_code
+      def annotated_source_code
         source_extract(4)
       end
 
@@ -138,4 +138,24 @@ module ActionView
   end
 
   TemplateError = Template::Error
+
+  class SyntaxErrorInTemplate < TemplateError #:nodoc
+    def initialize(template, offending_code_string)
+      @offending_code_string = offending_code_string
+      super(template)
+    end
+
+    def message
+      <<~MESSAGE
+        Encountered a syntax error while rendering template: check #{@offending_code_string}
+      MESSAGE
+    end
+
+    def annotated_source_code
+      @offending_code_string.split("\n").map.with_index(1) { |line, index|
+        indentation = " " * 4
+        "#{index}:#{indentation}#{line}"
+      }
+    end
+  end
 end
diff --git a/actionview/lib/action_view/template/handlers.rb b/actionview/lib/action_view/template/handlers.rb
index ddaac7a100..6450513003 100644
--- a/actionview/lib/action_view/template/handlers.rb
+++ b/actionview/lib/action_view/template/handlers.rb
@@ -45,12 +45,12 @@ module ActionView #:nodoc:
 
         unless params.find_all { |type, _| type == :req || type == :opt }.length >= 2
           ActiveSupport::Deprecation.warn <<~eowarn
-          Single arity template handlers are deprecated.  Template handlers must
+          Single arity template handlers are deprecated. Template handlers must
           now accept two parameters, the view object and the source for the view object.
           Change:
-            >> #{handler.class}#call(#{params.map(&:last).join(", ")})
+            >> #{handler}.call(#{params.map(&:last).join(", ")})
           To:
-            >> #{handler.class}#call(#{params.map(&:last).join(", ")}, source)
+            >> #{handler}.call(#{params.map(&:last).join(", ")}, source)
           eowarn
           handler = LegacyHandlerWrapper.new(handler)
         end
diff --git a/actionview/lib/action_view/template/handlers/erb/erubi.rb b/actionview/lib/action_view/template/handlers/erb/erubi.rb
index 15ca202024..e602aa117a 100644
--- a/actionview/lib/action_view/template/handlers/erb/erubi.rb
+++ b/actionview/lib/action_view/template/handlers/erb/erubi.rb
@@ -25,9 +25,9 @@ module ActionView
             src = @src
             view = Class.new(ActionView::Base) {
               include action_view_erb_handler_context._routes.url_helpers
-              class_eval("define_method(:_template) { |local_assigns, output_buffer| #{src} }", @filename || "(erubi)", 0)
-            }.with_context(action_view_erb_handler_context)
-            view.run(:_template, {}, ActionView::OutputBuffer.new)
+              class_eval("define_method(:_template) { |local_assigns, output_buffer| #{src} }", defined?(@filename) ? @filename : "(erubi)", 0)
+            }.empty
+            view._run(:_template, nil, {}, ActionView::OutputBuffer.new)
           end
 
         private
diff --git a/actionview/lib/action_view/template/html.rb b/actionview/lib/action_view/template/html.rb
index a262c6d9ad..ecd1c31e79 100644
--- a/actionview/lib/action_view/template/html.rb
+++ b/actionview/lib/action_view/template/html.rb
@@ -1,15 +1,21 @@
 # frozen_string_literal: true
 
+require "active_support/deprecation"
+
 module ActionView #:nodoc:
   # = Action View HTML Template
   class Template #:nodoc:
     class HTML #:nodoc:
-      attr_accessor :type
+      attr_reader :type
 
       def initialize(string, type = nil)
+        unless type
+          ActiveSupport::Deprecation.warn "ActionView::Template::HTML#initialize requires a type parameter"
+          type = :html
+        end
+
         @string = string.to_s
-        @type   = Types[type] || type if type
-        @type ||= Types[:html]
+        @type   = type
       end
 
       def identifier
@@ -26,9 +32,12 @@ module ActionView #:nodoc:
         to_str
       end
 
-      def formats
-        [@type.respond_to?(:ref) ? @type.ref : @type.to_s]
+      def format
+        @type
       end
+
+      def formats; Array(format); end
+      deprecate :formats
     end
   end
 end
diff --git a/actionview/lib/action_view/template/inline.rb b/actionview/lib/action_view/template/inline.rb
new file mode 100644
index 0000000000..44658487ea
--- /dev/null
+++ b/actionview/lib/action_view/template/inline.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module ActionView #:nodoc:
+  class Template #:nodoc:
+    class Inline < Template #:nodoc:
+      # This finalizer is needed (and exactly with a proc inside another proc)
+      # otherwise templates leak in development.
+      Finalizer = proc do |method_name, mod| # :nodoc:
+        proc do
+          mod.module_eval do
+            remove_possible_method method_name
+          end
+        end
+      end
+
+      def compile(mod)
+        super
+        ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
+      end
+    end
+  end
+end
diff --git a/actionview/lib/action_view/template/raw_file.rb b/actionview/lib/action_view/template/raw_file.rb
new file mode 100644
index 0000000000..623351305f
--- /dev/null
+++ b/actionview/lib/action_view/template/raw_file.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module ActionView #:nodoc:
+  # = Action View RawFile Template
+  class Template #:nodoc:
+    class RawFile #:nodoc:
+      attr_accessor :type, :format
+
+      def initialize(filename)
+        @filename = filename.to_s
+        extname = ::File.extname(filename).delete(".")
+        @type = Template::Types[extname] || Template::Types[:text]
+        @format = @type.symbol
+      end
+
+      def identifier
+        @filename
+      end
+
+      def render(*args)
+        ::File.read(@filename)
+      end
+
+      def formats; Array(format); end
+      deprecate :formats
+    end
+  end
+end
diff --git a/actionview/lib/action_view/template/resolver.rb b/actionview/lib/action_view/template/resolver.rb
index 3b4594942b..ce53eb046d 100644
--- a/actionview/lib/action_view/template/resolver.rb
+++ b/actionview/lib/action_view/template/resolver.rb
@@ -63,26 +63,11 @@ module ActionView
 
       # Cache the templates returned by the block
       def cache(key, name, prefix, partial, locals)
-        if Resolver.caching?
-          @data[key][name][prefix][partial][locals] ||= canonical_no_templates(yield)
-        else
-          fresh_templates  = yield
-          cached_templates = @data[key][name][prefix][partial][locals]
-
-          if templates_have_changed?(cached_templates, fresh_templates)
-            @data[key][name][prefix][partial][locals] = canonical_no_templates(fresh_templates)
-          else
-            cached_templates || NO_TEMPLATES
-          end
-        end
+        @data[key][name][prefix][partial][locals] ||= canonical_no_templates(yield)
       end
 
       def cache_query(query) # :nodoc:
-        if Resolver.caching?
-          @query_cache[query] ||= canonical_no_templates(yield)
-        else
-          yield
-        end
+        @query_cache[query] ||= canonical_no_templates(yield)
       end
 
       def clear
@@ -112,19 +97,6 @@ module ActionView
         def canonical_no_templates(templates)
           templates.empty? ? NO_TEMPLATES : templates
         end
-
-        def templates_have_changed?(cached_templates, fresh_templates)
-          # if either the old or new template list is empty, we don't need to (and can't)
-          # compare modification times, and instead just check whether the lists are different
-          if cached_templates.blank? || fresh_templates.blank?
-            return fresh_templates.blank? != cached_templates.blank?
-          end
-
-          cached_templates_max_updated_at = cached_templates.map(&:updated_at).max
-
-          # if a template has changed, it will be now be newer than all the cached templates
-          fresh_templates.any? { |t| t.updated_at > cached_templates_max_updated_at }
-        end
     end
 
     cattr_accessor :caching, default: true
@@ -143,35 +115,33 @@ module ActionView
 
     # Normalizes the arguments and passes it on to find_templates.
     def find_all(name, prefix = nil, partial = false, details = {}, key = nil, locals = [])
-      cached(key, [name, prefix, partial], details, locals) do
-        find_templates(name, prefix, partial, details)
-      end
-    end
+      locals = locals.map(&:to_s).sort!.freeze
 
-    def find_all_anywhere(name, prefix, partial = false, details = {}, key = nil, locals = [])
       cached(key, [name, prefix, partial], details, locals) do
-        find_templates(name, prefix, partial, details, true)
+        _find_all(name, prefix, partial, details, key, locals)
       end
     end
 
+    alias :find_all_anywhere :find_all
+    deprecate :find_all_anywhere
+
     def find_all_with_query(query) # :nodoc:
       @cache.cache_query(query) { find_template_paths(File.join(@path, query)) }
     end
 
   private
 
+    def _find_all(name, prefix, partial, details, key, locals)
+      find_templates(name, prefix, partial, details, locals)
+    end
+
     delegate :caching?, to: :class
 
     # This is what child classes implement. No defaults are needed
     # because Resolver guarantees that the arguments are present and
     # normalized.
-    def find_templates(name, prefix, partial, details, outside_app_allowed = false)
-      raise NotImplementedError, "Subclasses must implement a find_templates(name, prefix, partial, details, outside_app_allowed = false) method"
-    end
-
-    # Helpers that builds a path. Useful for building virtual paths.
-    def build_path(name, prefix, partial)
-      Path.build(name, prefix, partial)
+    def find_templates(name, prefix, partial, details, locals = [])
+      raise NotImplementedError, "Subclasses must implement a find_templates(name, prefix, partial, details, locals = []) method"
     end
 
     # Handles templates caching. If a key is given and caching is on
@@ -180,25 +150,13 @@ module ActionView
     # resolver is fresher before returning it.
     def cached(key, path_info, details, locals)
       name, prefix, partial = path_info
-      locals = locals.map(&:to_s).sort!
 
       if key
         @cache.cache(key, name, prefix, partial, locals) do
-          decorate(yield, path_info, details, locals)
+          yield
         end
       else
-        decorate(yield, path_info, details, locals)
-      end
-    end
-
-    # Ensures all the resolver information is set in the template.
-    def decorate(templates, path_info, details, locals)
-      cached = nil
-      templates.each do |t|
-        t.locals         = locals
-        t.formats        = details[:formats]  || [:html] if t.formats.empty?
-        t.variants       = details[:variants] || []      if t.variants.empty?
-        t.virtual_path ||= (cached ||= build_path(*path_info))
+        yield
       end
     end
   end
@@ -209,33 +167,60 @@ module ActionView
     DEFAULT_PATTERN = ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}"
 
     def initialize(pattern = nil)
-      @pattern = pattern || DEFAULT_PATTERN
+      if pattern
+        ActiveSupport::Deprecation.warn "Specifying a custom path for #{self.class} is deprecated. Implement a custom Resolver subclass instead."
+        @pattern = pattern
+      else
+        @pattern = DEFAULT_PATTERN
+      end
+      @unbound_templates = Concurrent::Map.new
+      super()
+    end
+
+    def clear_cache
+      @unbound_templates.clear
       super()
     end
 
     private
 
-      def find_templates(name, prefix, partial, details, outside_app_allowed = false)
+      def _find_all(name, prefix, partial, details, key, locals)
         path = Path.build(name, prefix, partial)
-        query(path, details, details[:formats], outside_app_allowed)
+        query(path, details, details[:formats], locals, cache: !!key)
       end
 
-      def query(path, details, formats, outside_app_allowed)
+      def query(path, details, formats, locals, cache:)
         template_paths = find_template_paths_from_details(path, details)
-        template_paths = reject_files_external_to_app(template_paths) unless outside_app_allowed
+        template_paths = reject_files_external_to_app(template_paths)
 
         template_paths.map do |template|
-          handler, format, variant = extract_handler_and_format_and_variant(template)
-
-          FileTemplate.new(File.expand_path(template), handler,
-            virtual_path: path.virtual,
-            format: format,
-            variant: variant,
-            updated_at: mtime(template)
-          )
+          unbound_template =
+            if cache
+              @unbound_templates.compute_if_absent([template, path.virtual]) do
+                build_unbound_template(template, path.virtual)
+              end
+            else
+              build_unbound_template(template, path.virtual)
+            end
+
+          unbound_template.bind_locals(locals)
         end
       end
 
+      def build_unbound_template(template, virtual_path)
+        handler, format, variant = extract_handler_and_format_and_variant(template)
+        source = Template::Sources::File.new(template)
+
+        UnboundTemplate.new(
+          source,
+          template,
+          handler,
+          virtual_path: virtual_path,
+          format: format,
+          variant: variant,
+        )
+      end
+
       def reject_files_external_to_app(files)
         files.reject { |filename| !inside_path?(@path, filename) }
       end
@@ -284,11 +269,6 @@ module ActionView
         entry.gsub(/[*?{}\[\]]/, '\\\\\\&')
       end
 
-      # Returns the file mtime from the filesystem.
-      def mtime(p)
-        File.mtime(p)
-      end
-
       # Extract handler, formats and variant from path. If a format cannot be found neither
       # from the path, or the handler, we should return the array of formats given
       # to the resolver.
@@ -300,51 +280,25 @@ module ActionView
 
         handler = Template.handler_for_extension(extension)
         format, variant = pieces.last.split(EXTENSIONS[:variants], 2) if pieces.last
-        format &&= Template::Types[format]
+        format = if format
+          Template::Types[format]&.ref
+        else
+          if handler.respond_to?(:default_format) # default_format can return nil
+            handler.default_format
+          else
+            nil
+          end
+        end
 
+        # Template::Types[format] and handler.default_format can return nil
         [handler, format, variant]
       end
   end
 
-  # A resolver that loads files from the filesystem. It allows setting your own
-  # resolving pattern. Such pattern can be a glob string supported by some variables.
-  #
-  # ==== Examples
-  #
-  # Default pattern, loads views the same way as previous versions of rails, eg. when you're
-  # looking for <tt>users/new</tt> it will produce query glob: <tt>users/new{.{en},}{.{html,js},}{.{erb,haml},}</tt>
-  #
-  #   FileSystemResolver.new("/path/to/views", ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}")
-  #
-  # This one allows you to keep files with different formats in separate subdirectories,
-  # eg. <tt>users/new.html</tt> will be loaded from <tt>users/html/new.erb</tt> or <tt>users/new.html.erb</tt>,
-  # <tt>users/new.js</tt> from <tt>users/js/new.erb</tt> or <tt>users/new.js.erb</tt>, etc.
-  #
-  #   FileSystemResolver.new("/path/to/views", ":prefix/{:formats/,}:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}")
-  #
-  # If you don't specify a pattern then the default will be used.
-  #
-  # In order to use any of the customized resolvers above in a Rails application, you just need
-  # to configure ActionController::Base.view_paths in an initializer, for example:
-  #
-  #   ActionController::Base.view_paths = FileSystemResolver.new(
-  #     Rails.root.join("app/views"),
-  #     ":prefix/:action{.:locale,}{.:formats,}{+:variants,}{.:handlers,}",
-  #   )
-  #
-  # ==== Pattern format and variables
-  #
-  # Pattern has to be a valid glob string, and it allows you to use the
-  # following variables:
-  #
-  # * <tt>:prefix</tt> - usually the controller path
-  # * <tt>:action</tt> - name of the action
-  # * <tt>:locale</tt> - possible locale versions
-  # * <tt>:formats</tt> - possible request formats (for example html, json, xml...)
-  # * <tt>:variants</tt> - possible request variants (for example phone, tablet...)
-  # * <tt>:handlers</tt> - possible handlers (for example erb, haml, builder...)
-  #
+  # A resolver that loads files from the filesystem.
   class FileSystemResolver < PathResolver
+    attr_reader :path
+
     def initialize(path, pattern = nil)
       raise ArgumentError, "path already is a Resolver class" if path.is_a?(Resolver)
       super(pattern)
@@ -364,6 +318,10 @@ module ActionView
 
   # An Optimized resolver for Rails' most common case.
   class OptimizedFileSystemResolver < FileSystemResolver #:nodoc:
+    def initialize(path)
+      super(path)
+    end
+
     private
 
       def find_template_paths_from_details(path, details)
@@ -419,12 +377,18 @@ module ActionView
   # The same as FileSystemResolver but does not allow templates to store
   # a virtual path since it is invalid for such resolvers.
   class FallbackFileSystemResolver < FileSystemResolver #:nodoc:
+    private_class_method :new
+
     def self.instances
       [new(""), new("/")]
     end
 
-    def decorate(*)
-      super.each { |t| t.virtual_path = nil }
+    def build_unbound_template(template, _)
+      super(template, nil)
+    end
+
+    def reject_files_external_to_app(files)
+      files
     end
   end
 end
diff --git a/actionview/lib/action_view/template/sources.rb b/actionview/lib/action_view/template/sources.rb
new file mode 100644
index 0000000000..8b89535741
--- /dev/null
+++ b/actionview/lib/action_view/template/sources.rb
@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module ActionView
+  class Template
+    module Sources
+      extend ActiveSupport::Autoload
+
+      eager_autoload do
+        autoload :File
+      end
+    end
+  end
+end
diff --git a/actionview/lib/action_view/template/sources/file.rb b/actionview/lib/action_view/template/sources/file.rb
new file mode 100644
index 0000000000..2d3a7dec7f
--- /dev/null
+++ b/actionview/lib/action_view/template/sources/file.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module ActionView
+  class Template
+    module Sources
+      class File
+        def initialize(filename)
+          @filename = filename
+        end
+
+        def to_s
+          ::File.binread @filename
+        end
+      end
+    end
+  end
+end
diff --git a/actionview/lib/action_view/template/text.rb b/actionview/lib/action_view/template/text.rb
index f8d6c2811f..c5fd55f1b3 100644
--- a/actionview/lib/action_view/template/text.rb
+++ b/actionview/lib/action_view/template/text.rb
@@ -8,7 +8,6 @@ module ActionView #:nodoc:
 
       def initialize(string)
         @string = string.to_s
-        @type = Types[:text]
       end
 
       def identifier
@@ -25,9 +24,12 @@ module ActionView #:nodoc:
         to_str
       end
 
-      def formats
-        [@type.ref]
+      def format
+        :text
       end
+
+      def formats; Array(format); end
+      deprecate :formats
     end
   end
 end