Class: Rng::RncToRngConverter

Inherits:
Object
  • Object
show all
Defined in:
lib/rng/rnc_to_rng_converter.rb

Overview

RncToRngConverter converts RNC parse trees to RNG XML format.

This class takes the parse tree output from the Parslet RNC parser and converts it to RNG XML using Nokogiri’s XML builder. The resulting XML can then be deserialized into Grammar objects using Lutaml::Model.

Examples:

Convert a parse tree to RNG XML

tree = parser.parse(rnc_content)
converter = Rng::RncToRngConverter.new
rng_xml = converter.convert(tree)
grammar = Rng::Grammar.from_xml(rng_xml)

Constant Summary collapse

RNG_NAMESPACE = 
'http://relaxng.org/ns/structure/1.0'

Instance Method Summary collapse

Instance Method Details

#convert(tree) ⇒ String

Convert a parse tree to RNG XML

Parameters:

  • tree (Hash) —

    The parse tree from RncParser

Returns:

  • (String) —

    RNG XML string



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# File 'lib/rng/rnc_to_rng_converter.rb', line 25

def convert(tree)
  # Track defined names for augmentation support
  defined_names = Set.new

  # Check if we need the annotations namespace
  @has_documentation = has_documentation_comments?(tree)

  # Collect prefixed namespace declarations from preamble
  @namespace_prefixes = {}
  collect_namespace_prefixes(tree[:preamble_items])

  # Validate that element notations in preamble annotations are only used with element/attribute patterns
  validate_preamble_element_notation_usage(tree[:preamble_items], tree[:definitions])

  builder = Nokogiri::XML::Builder.new(encoding: 'UTF-8') do |xml|
    grammar_attrs = { xmlns: 'http://relaxng.org/ns/structure/1.0' }
    if @has_documentation
      grammar_attrs[:'xmlns:a'] =
        'http://relaxng.org/ns/compatibility/annotations/1.0'
    end

    xml.grammar(grammar_attrs) do
      # Add namespace if present
      if tree[:namespace]
        xml.parent[:ns] =
          process_string_literal(tree[:namespace][:namespace_uri])
      end

      # Add datatype library if present
      if tree[:datatype_library]
        xml.parent[:datatypeLibrary] =
          process_string_literal(tree[:datatype_library][:uri])
      elsif tree[:datatype_map] && !tree[:datatype_map].empty?
        # From ParseTreeProcessor - datatype_map is {prefix => uri}
        # Use the first (typically only) datatype library
        xml.parent[:datatypeLibrary] = tree[:datatype_map].values.first
      end

      # If no explicit start but we have top-level elements, wrap them in start
      has_explicit_start = tree[:start] && tree[:start][:start_pattern]
      has_top_elements = tree[:definitions]&.any? do |d|
        d.key?(:top_element)
      end
      has_top_choice = tree[:definitions]&.any? do |d|
        d.key?(:top_choice)
      end

      if has_explicit_start
        # Process explicit start pattern
        xml.start do
          add_documentation(xml, tree[:start]) if tree[:start][:docs]
          process_pattern_list(xml, tree[:start][:start_pattern])
        end
      elsif has_top_choice
        # No explicit start, but has top-level choice - wrap in start with choice
        first_choice = tree[:definitions].find { |d| d.key?(:top_choice) }
        xml.start do
          xml.choice do
            process_content_item(xml, first_choice[:top_choice][:first])
            first_choice[:top_choice][:choice_items]&.each do |item|
              process_content_item(xml, item)
            end
          end
        end
      elsif has_top_elements
        # No explicit start, but has top-level elements - wrap first one in start
        xml.start do
          first_element = tree[:definitions].find do |d|
            d.key?(:top_element)
          end
          process_content_item(xml, first_element[:top_element])
        end
      end

      # Process named patterns and remaining top-level elements
      tree[:definitions]&.each_with_index do |def_item, idx|
        if def_item.key?(:href)
          # Include directive
          href = process_string_literal(def_item[:href])

          if def_item[:override]
            # Include with override block - override is properly scoped
            override = def_item[:override]

            # Check if override has any content
            has_content = (override[:start] && override[:start][:start_pattern]) ||
                          (override[:patterns] && !override[:patterns].empty?)

            if has_content
              xml.include(href: href) do
                # Process override start if present
                if override[:start] && override[:start][:start_pattern]
                  xml.start do
                    process_pattern_list(xml,
                                         override[:start][:start_pattern])
                  end
                end

                # Process override patterns (named patterns, div blocks, and top-level elements)
                override[:patterns]&.each do |pattern_item|
                  if pattern_item.key?(:name)
                    # Named pattern in override
                    name = process_identifier(pattern_item[:name])
                    operator = pattern_item[:operator] ? extract_string(pattern_item[:operator]) : '='

                    if operator == '='
                      xml.define(name: name) do
                        if pattern_item[:docs]
                          add_documentation(xml,
                                            pattern_item)
                        end
                        process_pattern_list(xml, pattern_item[:pattern])
                      end
                    else
                      combine_type = operator == '|=' ? 'choice' : 'interleave'
                      xml.define(name: name, combine: combine_type) do
                        if pattern_item[:docs]
                          add_documentation(xml,
                                            pattern_item)
                        end
                        process_pattern_list(xml, pattern_item[:pattern])
                      end
                    end
                  elsif pattern_item.key?(:top_element)
                    # Top-level element in override
                    process_content_item(xml, pattern_item[:top_element])
                  elsif pattern_item.key?(:div)
                    # Div block in override
                    process_div_block(xml, pattern_item[:div])
                  end
                end
              end
            else
              # Empty override block
              xml.include(href: href)
            end
          else
            # Include without override block
            xml.include(href: href)
          end
        elsif def_item.key?(:name)
          # Named pattern - handle augmentation operators
          name = process_identifier(def_item[:name])
          operator = def_item[:operator] ? extract_string(def_item[:operator]) : '='

          if operator == '=' || !defined_names.include?(name)
            # First definition or normal definition
            xml.define(name: name) do
              add_documentation(xml, def_item) if def_item[:docs]
              process_pattern_list(xml, def_item[:pattern])
            end
            defined_names.add(name)
          else
            # Augmentation - use combine attribute
            combine_type = operator == '|=' ? 'choice' : 'interleave'
            xml.define(name: name, combine: combine_type) do
              add_documentation(xml, def_item) if def_item[:docs]
              process_pattern_list(xml, def_item[:pattern])
            end
          end
        elsif def_item.key?(:top_element) && has_explicit_start
          # Top-level element (only add if we already have explicit start)
          process_content_item(xml, def_item[:top_element])
        elsif def_item.key?(:top_element) && !has_explicit_start && idx.positive?
          # Additional top-level elements after the first (which is in start)
          process_content_item(xml, def_item[:top_element])
        elsif def_item.key?(:top_choice) && !has_explicit_start
          # Top-level choice already handled in start generation above, skip
        elsif def_item.key?(:div)
          # Div block for documentation and grouping
          process_div_block(xml, def_item[:div])
        elsif def_item.key?(:standalone)
          # Standalone pattern (bare wildcard, etc.)
          process_standalone_pattern(xml, def_item[:standalone])
        elsif def_item.key?(:foreign_name)
          # Foreign element annotation - emit as foreign element in RNG XML
          process_foreign_element(xml, def_item)
        end
      end
    end
  end

  builder.to_xml
end