Class: Canon::DiffFormatter::ByLine::XmlFormatter

Inherits:
BaseFormatter
  • Object
show all
Defined in:
lib/canon/diff_formatter/by_line/xml_formatter.rb

Overview

XML formatter with DOM-guided diffing Uses DOM parsing and element matching for intelligent XML diffs

Instance Attribute Summary

Attributes inherited from BaseFormatter

#context_lines, #diff_grouping_lines, #diff_mode, #legacy_terminal, #show_diffs, #use_color, #visualization_map

Instance Method Summary collapse

Methods inherited from BaseFormatter

#apply_bg, #apply_color, #apply_theme_style, #changed_content_styles, #compute_line_num_width, #content_style, #display_mode, for_format, #initialize, #marker_style, #normalize_color_for_rainbow, #structure_color, #structure_styles, #styled_marker, #theme, #theme_color, #theme_style, #unchanged_content_style, #visualization_chars

Constructor Details

This class inherits a constructor from Canon::DiffFormatter::ByLine::BaseFormatter

Instance Method Details

#append_unlocated_context(report) ⇒ Object

Trailing context for DiffNodes with no located char ranges (multiline reflowed text, relocated content): one removed DiffLine per serialized_before line, one added per serialized_after line. Nil positions render as blank line numbers.



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 88

def append_unlocated_context(report)
  unlocated = @differences.select do |dn|
    dn.char_ranges.nil? || dn.char_ranges.empty?
  end
  return if unlocated.empty?

  unlocated = unlocated.reject do |dn|
    (@show_diffs == :normative && !dn.normative?) ||
      (@show_diffs == :informative && !dn.informative?)
  end
  return if unlocated.empty?

  # Place each unlocated node's context after the report
  # context containing its nearest preceding LOCATED node
  # (@differences is comparator-walk order = document order),
  # so the change reads in position instead of trailing.
  unlocated.each do |dn|
    context = Canon::Diff::DiffContext.new(
      lines: unlocated_lines(dn),
    )
    anchor_index = context_index_after(report, preceding_located(dn))
    report.contexts.insert(anchor_index, context)
  end
end

#context_index_after(report, anchor_node) ⇒ Object

Index into report.contexts for inserting an unlocated context: after the context holding the anchor node's lines, or at the front when the anchor is nil (nothing precedes).



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 203

def context_index_after(report, anchor_node)
  return 0 if anchor_node.nil?

  report.contexts.each_with_index do |context, idx|
    has_anchor = context.lines.any? do |dl|
      dl.diff_node&.equal?(anchor_node)
    end
    return idx + 1 if has_anchor
  end
  report.contexts.length
end

#format(doc1, doc2) ⇒ String

Format DOM-guided XML diff

Parameters:

  • doc1 (String) —

    First XML document

  • doc2 (String) —

    Second XML document

Returns:

  • (String) —

    Formatted diff



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 17

def format(doc1, doc2)
  compute_line_num_width(doc1, doc2)

  # If we have DiffNodes from comparison, check if there are normative diffs
  # based on show_diffs setting
  if @differences&.any?(Canon::Diff::DiffNode)
    # Check if we should skip based on show_diffs setting
    if should_skip_diff_display?
      return ""
    end

    # Use new pipeline when DiffNodes available
    return format_with_pipeline(doc1, doc2)
  end

  # LEGACY: Fall back to old behavior for backward compatibility
  # This handles formatting-only differences (0 DiffNodes) and legacy Hash entries
  format_legacy(doc1, doc2)
end

#format_context_from_lines(context, lines1, _lines2) ⇒ Object

Format a context using its DiffLines



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 246

def format_context_from_lines(context, lines1, _lines2)
  output = []

  context.lines.each do |diff_line|
    case diff_line.type
    when :unchanged
      old_num = diff_line.line_number&.+(1)
      new_num = (diff_line.new_position || diff_line.line_number)&.+(1)
      output << format_unified_line(old_num, new_num, " ",
                                    diff_line.content)
    when :location_header
      output << format_location_header(diff_line.content)

    when :removed
      line_num = diff_line.line_number&.+(1)
      formatting = diff_line.formatting?
      informative = diff_line.informative?

      output << if formatting
                  # Formatting-only removal: use theme formatting style
                  format_unified_line(line_num, nil, "[",
                                      diff_line.content,
                                      theme_color(:formatting, :content),
                                      formatting: true)
                elsif informative
                  # Informative removal: use theme informative style
                  format_unified_line(line_num, nil, "<",
                                      diff_line.content,
                                      theme_color(:informative, :content),
                                      informative: true)
                elsif diff_line.has_char_ranges?
                  # Use character-level highlighting when char_ranges available.
                  highlighted = render_line_from_char_ranges(
                    diff_line.content, diff_line.char_ranges, :old
                  )
                  old_str = "%#{@line_num_width}d" % line_num
                  blank = " " * @line_num_width
                  if @use_color
                    yellow_old = colorize(old_str,
                                          structure_color(:line_number) || :yellow)
                    yellow_pipe1 = colorize("|",
                                            structure_color(:pipe) || :yellow)
                    yellow_pipe2 = colorize("|",
                                            structure_color(:pipe) || :yellow)
                    red_marker = styled_marker("-", :removed)
                    "#{yellow_old}#{yellow_pipe1}#{blank}#{red_marker} #{yellow_pipe2} #{highlighted}"
                  else
                    "#{old_str}|#{blank}- | #{highlighted}"
                  end
                else
                  # Normative removal: use theme removed style
                  format_unified_line(line_num, nil, "-",
                                      diff_line.content,
                                      theme_color(:removed, :content))
                end
    when :added
      line_num = (diff_line.new_position || diff_line.line_number)&.+(1)
      formatting = diff_line.formatting?
      informative = diff_line.informative?

      output << if formatting
                  # Formatting-only addition: use theme formatting style
                  format_unified_line(nil, line_num, "]",
                                      diff_line.content,
                                      theme_color(:formatting, :content),
                                      formatting: true)
                elsif informative
                  # Informative addition: use theme informative style
                  format_unified_line(nil, line_num, ">",
                                      diff_line.content,
                                      theme_color(:informative, :content),
                                      informative: true)
                else
                  # Normative addition: use theme added style
                  format_unified_line(nil, line_num, "+",
                                      diff_line.content,
                                      theme_color(:added, :content))
                end
    when :changed
      output << format_changed_line(diff_line, lines1)
    when :reflow_summary
      # Reflow summary: show collapsed formatting-only reflow
      output << format_reflow_summary(diff_line)
    end
  end

  output.join("\n")
end

#format_legacy(doc1, doc2) ⇒ Object

Legacy format method (for backward compatibility)



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 336

def format_legacy(doc1, doc2)
  # Check if we should show any diffs based on differences array
  if should_skip_diff_display?
    return ""
  end

  # If documents are equivalent (no normative diffs), do NOT run legacy formatter.
  # The legacy formatter shows ALL differences it finds via LCS on lines,
  # which can be misleading when the comparison found no normative differences.
  # Only run legacy formatter when we have actual DiffNode data to display.
  if @equivalent == true && (@differences.nil? || @differences.empty? ||
     @differences.none?(Canon::Diff::DiffNode))
    return ""
  end

  output = []

  begin
    # Parse to DOM
    root1 = Canon::Xml::DataModel.from_xml(doc1)
    root2 = Canon::Xml::DataModel.from_xml(doc2)

    # Match elements semantically
    matcher = Canon::Xml::ElementMatcher.new
    matches = matcher.match_trees(root1, root2)

    # Build line range maps using ORIGINAL documents
    mapper1 = Canon::Xml::LineRangeMapper.new(indent: 2)
    mapper2 = Canon::Xml::LineRangeMapper.new(indent: 2)
    map1 = mapper1.build_map(root1, doc1)
    map2 = mapper2.build_map(root2, doc2)

    # Use ORIGINAL document lines for display
    lines1 = doc1.split("\n")
    lines2 = doc2.split("\n")

    # Display diffs based on element matches
    output << format_element_matches(matches, map1, map2, lines1,
                                     lines2)
  rescue StandardError => e
    # Fall back to simple diff on error
    output << colorize("Warning: DOM parsing failed, using simple diff",
                       :yellow)
    output << colorize("Error: #{e.class}: #{e.message}", :red)

    # Include relevant backtrace lines
    relevant_trace = e.backtrace.select do |line|
      line.include?("canon")
    end.take(3)
    unless relevant_trace.empty?
      output << colorize("Backtrace:", :yellow)
      relevant_trace.each do |line|
        output << colorize("  #{line}", :yellow)
      end
    end

    output << ""
    simple = SimpleFormatter.new(
      use_color: @use_color,
      context_lines: @context_lines,
      diff_grouping_lines: @diff_grouping_lines,
      visualization_map: @visualization_map,
    )
    output << simple.format(doc1, doc2)
  end

  output.join("\n")
end

#format_report(report, doc1, doc2) ⇒ Object

Format a DiffReport for display



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 216

def format_report(report, doc1, doc2)
  return "" if report.contexts.empty?

  lines1 = @pipeline_lines1 || doc1.split("\n")
  lines2 = @pipeline_lines2 || doc2.split("\n")

  output = []

  # Detect non-ASCII characters — scan the source strings
  # directly; joining the split lines back into one document
  # per render was pure garbage.
  non_ascii = Legend.detect_non_ascii(doc1, @visualization_map)
  non_ascii.merge!(Legend.detect_non_ascii(doc2, @visualization_map))

  # Add Unicode legend if needed
  unless non_ascii.empty?
    output << Legend.build_legend(non_ascii, use_color: @use_color)
    output << ""
  end

  # Format each context
  report.contexts.each_with_index do |context, idx|
    output << "" if idx.positive?
    output << format_context_from_lines(context, lines1, lines2)
  end

  output.join("\n")
end

#format_with_pipeline(doc1, doc2) ⇒ Object

Format using new DiffReportBuilder pipeline



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 38

def format_with_pipeline(doc1, doc2)
  # Check if we should show any diffs
  if should_skip_diff_display?
    return ""
  end

  # Compute line number width BEFORE formatting
  compute_line_num_width(doc1, doc2)

  # The pipeline splits both documents once here; every stage
  # downstream reuses the arrays (three redundant full-doc
  # splits per render before).
  @pipeline_lines1 = doc1.split("\n")
  @pipeline_lines2 = doc2.split("\n")

  # Phase 1: Enrich DiffNodes with character positions
  Canon::Diff::DiffNodeEnricher.build(@differences, doc1, doc2,
                                      lines1: @pipeline_lines1,
                                      lines2: @pipeline_lines2)

  # Phase 2: Assemble DiffLines from enriched DiffNodes
  diff_lines = Canon::Diff::DiffLineBuilder.build(@differences, doc1,
                                                  doc2,
                                                  lines1: @pipeline_lines1,
                                                  lines2: @pipeline_lines2)

  # Layers 3-5: Build report through pipeline
  report = Canon::Diff::DiffReportBuilder.build(
    diff_lines,
    show_diffs: @show_diffs,
    context_lines: @context_lines,
    grouping_lines: @diff_grouping_lines,
  )

  # #85/#86: DiffNodes the enricher could not locate were
  # previously dropped silently — the absorption mechanism.
  # Their serialized content renders as a trailing context so
  # the change is always visible, without perturbing the
  # located walk's line accounting.
  append_unlocated_context(report)

  # Layer 6: Format the report
  format_report(report, doc1, doc2)
end

#parent_chain(path) ⇒ Object

Display chain of a DiffNode's ancestor elements, e.g. "bibitem > formattedref" — gives the blank-numbered unlocated lines a readable home (#86).



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 169

def parent_chain(path)
  return nil if path.nil?

  segments = path.split("/").reject(&:empty?)
  return nil if segments.length < 2

  chain = segments[0...-1].filter_map do |seg|
    seg[/\A(?:\{[^}]+\})?([a-zA-Z0-9_:-]+)/, 1]
  end
  # Comparator paths repeat the element name before the node
  # segment ("formattedref/formattedref/text()") — collapse
  # consecutive repeats for display.
  collapsed = chain.each_with_object([]) do |name, acc|
    acc << name unless acc.last == name
  end
  collapsed.join(" > ")
end

#preceding_located(diff_node) ⇒ Object

The nearest preceding node (in @differences walk order) that the enricher DID locate.



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 189

def preceding_located(diff_node)
  index = @differences.index(diff_node)
  return nil unless index

  (index - 1).downto(0) do |i|
    dn = @differences[i]
    return dn if dn.char_ranges && !dn.char_ranges.empty?
  end
  nil
end

#unlocated_lines(diff_node) ⇒ Object

Mini-diff of one unlocated node's serialized sides: shared lines render as :unchanged context instead of remove-all + add-all. Blank line numbers throughout — no located position.



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# File 'lib/canon/diff_formatter/by_line/xml_formatter.rb', line 116

def unlocated_lines(diff_node)
  before = diff_node.serialized_before&.split("\n") || []
  after = diff_node.serialized_after&.split("\n") || []
  fmt = diff_node.formatting?
  lines = []
  header = parent_chain(diff_node.path)
  if header
    lines << Canon::Diff::DiffLine.new(
      line_number: nil, new_position: nil,
      content: header, type: :location_header
    )
  end
  require "diff/lcs" unless defined?(::Diff::LCS)

  ::Diff::LCS.sdiff(before, after).each do |change|
    case change.action
    when "="
      lines << Canon::Diff::DiffLine.new(
        line_number: nil, new_position: nil,
        content: change.old_element, type: :unchanged,
        diff_node: diff_node
      )
    when "-"
      lines << Canon::Diff::DiffLine.new(
        line_number: nil, new_position: nil,
        content: change.old_element, type: :removed,
        diff_node: diff_node, formatting: fmt
      )
    when "+"
      lines << Canon::Diff::DiffLine.new(
        line_number: nil, new_position: nil,
        content: change.new_element, type: :added,
        diff_node: diff_node, formatting: fmt
      )
    when "!"
      lines << Canon::Diff::DiffLine.new(
        line_number: nil, new_position: nil,
        content: change.old_element, type: :removed,
        diff_node: diff_node, formatting: fmt
      )
      lines << Canon::Diff::DiffLine.new(
        line_number: nil, new_position: nil,
        content: change.new_element, type: :added,
        diff_node: diff_node, formatting: fmt
      )
    end
  end
  lines
end