Let Convert/Node filters to use context at calltime

Author: gjtorikian

README.md

@@ -60,9 +60,15 @@ results tothe next filter. A pipeline has several kinds of filters available to
 
 You can assemble each sequence into a single pipeline, or choose to call each filter individually.
 
-As an example, suppose we want to transform Commonmark source text into Markdown HTML. With the content, we also want to:
+As an example, suppose we want to transform Commonmark source text into Markdown HTML:
 
-- change every instance of `$NAME` to "`Johnny"
+```
+Hey there, @gjtorikian
+```
+
+With the content, we also want to:
+
+- change every instance of `Hey` to `Hello`
 - strip undesired HTML
 - linkify @mention
 
@@ -73,7 +79,7 @@ require 'html_pipeline'
 
 class HelloJohnnyFilter < HTMLPipelineFilter
   def call
-    text.gsub("$NAME", "Johnny")
+    text.gsub("Hey", "Hello")
   end
 end
 
@@ -104,11 +110,21 @@ used to pass around arguments and metadata between filters in a pipeline. For
 example, if you want to disable footnotes in the `MarkdownFilter`, you can pass an option in the context hash:
 
 ```ruby
-context =  { markdown: { extensions: { footnotes: false } } }
+context = { markdown: { extensions: { footnotes: false } } }
 filter = HTMLPipeline::ConvertFilter::MarkdownFilter.new(context: context)
 filter.call("Hi **world**!")
 ```
 
+Alternatively, you can construct a pipeline, and pass in a context during the call:
+
+```ruby
+pipeline = HTMLPipeline.new(
+  convert_filter: HTMLPipeline::ConvertFilter::MarkdownFilter.new,
+  node_filters: [HTMLPipeline::NodeFilter::MentionFilter.new]
+)
+pipeline.call(user_supplied_text, context: { markdown: { extensions: { footnotes: false } } })
+```
+
 Please refer to the documentation for each filter to understand what configuration options are available.
 
 ### More Examples

lib/html_pipeline.rb

@@ -171,12 +171,13 @@ def call(text, context: {}, result: {})
       text
     else
       instrument("call_convert_filter.html_pipeline", payload) do
-        html = @convert_filter.call(text)
+        html = @convert_filter.call(text, context: context)
       end
     end
 
     unless @node_filters.empty?
       instrument("call_node_filters.html_pipeline", payload) do
+        @node_filters.each { |filter| filter.context = (filter.context || {}).merge(context) }
         result[:output] = Selma::Rewriter.new(sanitizer: @sanitization_config, handlers: @node_filters).rewrite(html)
         html = result[:output]
         payload = default_payload({

lib/html_pipeline/convert_filter/markdown_filter.rb

@@ -16,8 +16,8 @@ def initialize(context: {}, result: {})
       end
 
       # Convert Commonmark to HTML using the best available implementation.
-      def call(text)
-        options = @context.fetch(:markdown, {})
+      def call(text, context: @context)
+        options = context.fetch(:markdown, {})
         plugins = options.fetch(:plugins, {})
         Commonmarker.to_html(text, options: options, plugins: plugins).rstrip!
       end

lib/html_pipeline/node_filter.rb

@@ -4,6 +4,8 @@
 
 class HTMLPipeline
   class NodeFilter < Filter
+    attr_accessor :context
+
     def initialize(context: {}, result: {})
       super(context: context, result: {})
       send(:after_initialize) if respond_to?(:after_initialize)

test/html_pipeline_test.rb

@@ -116,4 +116,34 @@ def test_kitchen_sink
 
     assert_equal("<p>!&gt;eeuqram/eeuqram&lt; ees ot evoL .yllib@ ,ereht <strong>yeH</strong></p>", result)
   end
+
+  def test_context_is_carried_over_in_call
+    text = "yeH! I _think_ <marquee>@gjtorikian is ~great~</marquee>!"
+
+    pipeline = HTMLPipeline.new(
+      text_filters: [YehBolderFilter.new],
+      convert_filter: HTMLPipeline::ConvertFilter::MarkdownFilter.new,
+      node_filters: [HTMLPipeline::NodeFilter::MentionFilter.new],
+    )
+    result = pipeline.call(text)[:output]
+
+    # note:
+    # - yeH is bolded
+    # - strikethroughs are rendered
+    # - mentions are not linked
+    assert_equal("<p><strong>yeH</strong>! I <em>think</em> <a href=\"/gjtorikian\">@gjtorikian</a> is <del>great</del>!</p>", result)
+
+    context = {
+      no_bolding: false,
+      markdown: { extension: { strikethrough: false } },
+      base_url: "http://your-domain.com",
+    }
+    result_with_context = pipeline.call(text, context: context)[:output]
+
+    # note:
+    # - yeH is not bolded
+    # - strikethroughs are not rendered
+    # - mentions are linked
+    assert_equal("<p>yeH! I <em>think</em> <a href=\"http://your-domain.com/gjtorikian\">@gjtorikian</a> is ~great~!</p>", result_with_context)
+  end
 end

test/sanitization_filter_test.rb

@@ -263,5 +263,31 @@ def test_sanitization_pipeline_can_be_removed
 
       assert_equal(result[:output].to_s, expected.chomp)
     end
+
+    def test_sanitization_pipeline_does_not_need_node_filters
+      config = {
+        elements: ["p", "pre", "code"],
+      }
+
+      pipeline = HTMLPipeline.new(
+        convert_filter:
+          HTMLPipeline::ConvertFilter::MarkdownFilter.new,
+        sanitization_config: config,
+      )
+
+      result = pipeline.call(<<~CODE)
+        This is *great*, @birdcar:
+
+            some_code(:first)
+      CODE
+
+      expected = <<~HTML
+        <p>This is great, @birdcar:</p>
+        <pre><code>some_code(:first)
+        </code></pre>
+      HTML
+
+      assert_equal(result[:output].to_s, expected.chomp)
+    end
   end
 end

test/test_helper.rb

@@ -25,6 +25,6 @@ def call(input, context: {}, result: {})
 # bolds any instance of the word yeH
 class YehBolderFilter < HTMLPipeline::TextFilter
   def call(input, context: {}, result: {})
-    input.gsub("yeH", "**yeH**")
+    input.gsub("yeH", "**yeH**") unless context[:no_bolding] == false
   end
 end