Class: Markbridge::Renderers::Discourse::Renderer

Inherits:
Object
  • Object
show all
Defined in:
lib/markbridge/renderers/discourse/renderer.rb

Overview

Renders AST to Discourse-flavored Markdown in-memory.

Instance Method Summary collapse

Constructor Details

#initialize(tag_library: nil, escaper: nil, html_escaper: nil) ⇒ Renderer

Returns a new instance of Renderer.



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# File 'lib/markbridge/renderers/discourse/renderer.rb', line 8

def initialize(tag_library: nil, escaper: nil, html_escaper: nil)
  @tag_library = tag_library || TagLibrary.default
  @escaper = escaper || MarkdownEscaper.new
  @html_escaper = html_escaper || HtmlEscaper
  # @interface_cache is lazily initialized in #render's top-level
  # call and reset to nil after the call completes. No init
  # needed here — unset ivar returns nil under `.nil?` check.
end

Instance Method Details

#render(node, context: RenderContext.new) ⇒ String

Render a node to Markdown

Parameters:

  • node (AST::Node)
  • context (RenderContext) (defaults to: RenderContext.new) —

    rendering context with parent chain

Returns:

  • (String) 


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# File 'lib/markbridge/renderers/discourse/renderer.rb', line 21

def render(node, context: RenderContext.new)
  root_call = @interface_cache.nil?
  @interface_cache ||= {}

  tag = @tag_library[node.class]
  if tag
    interface = interface_for(context)
    return tag.render(node, interface)
  end

  case node
  when AST::Element # Document is an Element subclass
    render_children(node, context:)
  when AST::MarkdownText
    render_markdown_text(node, context)
  when AST::Text
    render_text(node, context)
  else
    ""
  end
ensure
  @interface_cache = nil if root_call
end

#render_children(node, context:) ⇒ String

Render all children of a node

Parameters:

Returns:

  • (String) 


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# File 'lib/markbridge/renderers/discourse/renderer.rb', line 49

def render_children(node, context:)
  result = +""
  node.children.each do |child|
    part = render(child, context:)
    next if part.empty?

    # Integer-byte check avoids allocating substrings for the
    # per-child adjacency probe. EMPHASIS_DELIMITER_BYTES.include?
    # over a 4-element Set is O(1).
    if !result.empty? && (last_byte = result.getbyte(-1)) == part.getbyte(0) &&
         EMPHASIS_DELIMITER_BYTES.include?(last_byte)
      result << EMPHASIS_BOUNDARY
    end
    result << part
  end
  result
end