Class: Canon::DiffFormatter

Inherits:
Object
  • Object
show all
Defined in:
lib/canon/diff_formatter.rb,
lib/canon/diff_formatter/theme.rb,
lib/canon/diff_formatter/legend.rb,
lib/canon/diff_formatter/debug_output.rb,
lib/canon/diff_formatter/by_line_formatter.rb,
lib/canon/diff_formatter/by_object_formatter.rb,
lib/canon/diff_formatter/by_line/xml_formatter.rb,
lib/canon/diff_formatter/diff_detail_formatter.rb,
lib/canon/diff_formatter/pretty_diff_formatter.rb,
lib/canon/diff_formatter/by_line/base_formatter.rb,
lib/canon/diff_formatter/by_line/html_formatter.rb,
lib/canon/diff_formatter/by_line/json_formatter.rb,
lib/canon/diff_formatter/by_line/yaml_formatter.rb,
lib/canon/diff_formatter/by_object/xml_formatter.rb,
lib/canon/diff_formatter/by_line/simple_formatter.rb,
lib/canon/diff_formatter/by_object/base_formatter.rb,
lib/canon/diff_formatter/by_object/json_formatter.rb,
lib/canon/diff_formatter/by_object/yaml_formatter.rb,
lib/canon/diff_formatter/diff_detail_formatter/node_utils.rb,
lib/canon/diff_formatter/diff_detail_formatter/text_utils.rb,
lib/canon/diff_formatter/diff_detail_formatter/color_helper.rb,
lib/canon/diff_formatter/diff_detail_formatter/location_extractor.rb,
lib/canon/diff_formatter/diff_detail_formatter/dimension_formatter.rb

Overview

Formatter for displaying semantic differences with color support

This is a pure orchestrator class that delegates formatting to mode-specific and format-specific formatters. It provides a unified interface for generating both by-line and by-object diffs across multiple formats (XML, HTML, JSON, YAML).

Architecture

DiffFormatter follows the orchestrator pattern with MECE (Mutually Exclusive, Collectively Exhaustive) delegation:

  1. **Mode Selection**: Chooses by-line or by-object visualization

  2. **Format Delegation**: Dispatches to format-specific formatter

  3. Customization: Applies color, context, and visualization options

Diff Modes

**By-Object Mode** (default for XML/JSON/YAML):

  • Tree-based semantic diff

  • Shows only what changed in the structure

  • Visual tree with box-drawing characters

  • Best for configuration files and structured data

**By-Line Mode** (default for HTML):

  • Traditional line-by-line diff

  • Shows changes in document order with context

  • Syntax-aware token highlighting

  • Best for markup and when line context matters

Visualization Features

  • **Color support**: Red (deletions), green (additions), yellow (structure), cyan (informative)

  • **Whitespace visualization**: Makes invisible characters visible

  • **Context lines**: Shows unchanged lines around changes

  • **Diff grouping**: Groups nearby changes into blocks

  • **Character map customization**: CJK-safe Unicode symbols

Usage

# Basic usage
formatter = Canon::DiffFormatter.new(use_color: true, mode: :by_object)
output = formatter.format(differences, :xml, doc1: xml1, doc2: xml2)

# With options
formatter = Canon::DiffFormatter.new(
  use_color: true,
  mode: :by_line,
  context_lines: 5,
  diff_grouping_lines: 10,
  show_diffs: :normative
)

Defined Under Namespace

Modules: ByLine, ByObject, DebugOutput, DiffDetailFormatter, DiffDetailFormatterHelpers, Legend, Theme Classes: ByLineFormatter, ByObjectFormatter, PrettyDiffFormatter

Constant Summary collapse

DEFAULT_VISUALIZATION_MAP =

Default character visualization map (loaded from YAML)

character_map_data[:visualization_map].freeze
CHARACTER_CATEGORY_MAP =

Character category map (loaded from YAML)

character_map_data[:category_map].freeze
CHARACTER_CATEGORY_NAMES =

Category display names (loaded from YAML)

character_map_data[:category_names].freeze
CHARACTER_METADATA =

Character metadata including names (loaded from YAML)

character_map_data[:character_metadata].freeze
DIFF_DESCRIPTIONS =

Map difference codes to human-readable descriptions

{
  Comparison::EQUIVALENT => "Equivalent",
  Comparison::MISSING_ATTRIBUTE => "Missing attribute",
  Comparison::MISSING_NODE => "Missing node",
  Comparison::UNEQUAL_ATTRIBUTES => "Unequal attributes",
  Comparison::UNEQUAL_COMMENTS => "Unequal comments",
  Comparison::UNEQUAL_DOCUMENTS => "Unequal documents",
  Comparison::UNEQUAL_ELEMENTS => "Unequal elements",
  Comparison::UNEQUAL_NODES_TYPES => "Unequal node types",
  Comparison::UNEQUAL_TEXT_CONTENTS => "Unequal text contents",
  Comparison::MISSING_HASH_KEY => "Missing hash key",
  Comparison::UNEQUAL_HASH_VALUES => "Unequal hash values",
  Comparison::UNEQUAL_ARRAY_LENGTHS => "Unequal array lengths",
  Comparison::UNEQUAL_ARRAY_ELEMENTS => "Unequal array elements",
  Comparison::UNEQUAL_TYPES => "Unequal types",
  Comparison::UNEQUAL_PRIMITIVES => "Unequal primitive values",
}.freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(use_color: true, mode: :by_object, context_lines: 3, diff_grouping_lines: nil, visualization_map: nil, character_map_file: nil, character_definitions: nil, show_diffs: :all, verbose_diff: false, show_raw_inputs: false, show_raw_expected: false, show_raw_received: false, show_preprocessed_inputs: false, show_preprocessed_expected: false, show_preprocessed_received: false, show_prettyprint_inputs: false, show_prettyprint_expected: false, show_prettyprint_received: false, show_line_numbered_inputs: false, character_visualization: true, display_preprocessing: :none, pretty_printer_indent: 2, pretty_printer_indent_type: :space, preserve_whitespace_elements: [], collapse_whitespace_elements: [], strip_whitespace_elements: [], pretty_printed_expected: false, pretty_printed_received: false, pretty_printer_sort_attributes: false, compact_semantic_report: false, expand_difference: false, diff_mode: :separate, legacy_terminal: false) ⇒ DiffFormatter

rubocop:disable Metrics/ParameterLists



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

def initialize(use_color: true, mode: :by_object, context_lines: 3,
               diff_grouping_lines: nil, visualization_map: nil,
               character_map_file: nil, character_definitions: nil,
               show_diffs: :all, verbose_diff: false,
               show_raw_inputs: false, show_raw_expected: false,
               show_raw_received: false,
               show_preprocessed_inputs: false,
               show_preprocessed_expected: false,
               show_preprocessed_received: false,
               show_prettyprint_inputs: false,
               show_prettyprint_expected: false,
               show_prettyprint_received: false,
               show_line_numbered_inputs: false,
               character_visualization: true,
               display_preprocessing: :none,
               pretty_printer_indent: 2,
               pretty_printer_indent_type: :space,
               preserve_whitespace_elements: [],
               collapse_whitespace_elements: [],
               strip_whitespace_elements: [],
               pretty_printed_expected: false,
               pretty_printed_received: false,
               pretty_printer_sort_attributes: false,
               compact_semantic_report: false,
               expand_difference: false,
               diff_mode: :separate, legacy_terminal: false)
  # rubocop:enable Metrics/ParameterLists
  @use_color = use_color
  @mode = mode
  @context_lines = context_lines
  @diff_grouping_lines = diff_grouping_lines
  @show_diffs = show_diffs
  @verbose_diff = verbose_diff
  @show_raw_inputs = show_raw_inputs
  @show_raw_expected = show_raw_expected
  @show_raw_received = show_raw_received
  @show_preprocessed_inputs = show_preprocessed_inputs
  @show_preprocessed_expected = show_preprocessed_expected
  @show_preprocessed_received = show_preprocessed_received
  @show_prettyprint_inputs = show_prettyprint_inputs
  @show_prettyprint_expected = show_prettyprint_expected
  @show_prettyprint_received = show_prettyprint_received
  @show_line_numbered_inputs = show_line_numbered_inputs
  @character_visualization = character_visualization
  @display_preprocessing = display_preprocessing
  @pretty_printer_indent = pretty_printer_indent
  @pretty_printer_indent_type = pretty_printer_indent_type
  @preserve_whitespace_elements = Array(preserve_whitespace_elements).map(&:to_s)
  @collapse_whitespace_elements = Array(collapse_whitespace_elements).map(&:to_s)
  @strip_whitespace_elements = Array(strip_whitespace_elements).map(&:to_s)
  @pretty_printed_expected = pretty_printed_expected
  @pretty_printed_received = pretty_printed_received
  @pretty_printer_sort_attributes = pretty_printer_sort_attributes
  @compact_semantic_report = compact_semantic_report
  @expand_difference = expand_difference
  @diff_mode = legacy_terminal ? :separate : diff_mode
  @legacy_terminal = legacy_terminal
  @visualization_map = build_visualization_map(
    character_visualization: character_visualization,
    visualization_map: visualization_map,
    character_map_file: character_map_file,
    character_definitions: character_definitions,
  )
end

Class Method Details

.build_character_definition(definition) ⇒ Hash

Build character definition from hash

Parameters:

  • definition (Hash) —

    Character definition with keys (matching YAML format):

    • :character or :unicode (required)

    • :visualization (required)

    • :category (required)

    • :name (required)

Returns:

  • (Hash) —

    Single-entry visualization map



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# File 'lib/canon/diff_formatter.rb', line 272

def self.build_character_definition(definition)
  # Validate required fields
  char = if definition[:unicode]
           [definition[:unicode].to_i(16)].pack("U")
         elsif definition[:character]
           definition[:character]
         else
           raise ArgumentError,
                 "Character definition must include :character or :unicode"
         end

  unless definition[:visualization]
    raise ArgumentError, "Character definition must include :visualization"
  end

  unless definition[:category]
    raise ArgumentError, "Character definition must include :category"
  end

  unless definition[:name]
    raise ArgumentError, "Character definition must include :name"
  end

  { char => definition[:visualization] }
end

.character_map_data ⇒ Object

Lazily load and cache character map data



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# File 'lib/canon/diff_formatter.rb', line 133

def self.character_map_data
  @character_map_data ||= load_character_map
end

.load_character_map ⇒ Hash

Load character map from YAML file

Returns:

  • (Hash) —

    Hash with :visualization_map, :category_map, :category_names



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

def self.load_character_map
  yaml_path = File.join(__dir__, "diff_formatter", "character_map.yml")
  data = YAML.load_file(yaml_path)

  visualization_map = {}
  category_map = {}
  character_metadata = {}

  data["characters"].each do |char_data|
    # Get character from either unicode code point or character field
    char = if char_data["unicode"]
             # Convert hex string to character
             [char_data["unicode"].to_i(16)].pack("U")
           else
             # Use character field directly (handles \n, \r, \t, etc.)
             char_data["character"]
           end

    vis = char_data["visualization"]
    category = char_data["category"].to_sym
    name = char_data["name"]

    visualization_map[char] = vis
    category_map[char] = category
    character_metadata[char] = {
      visualization: vis,
      category: category,
      name: name,
    }
  end

  category_names = {}
  data["category_names"].each do |key, value|
    category_names[key.to_sym] = value
  end

  {
    visualization_map: visualization_map,
    category_map: category_map,
    category_names: category_names,
    character_metadata: character_metadata,
  }
end

.load_custom_character_map(file_path) ⇒ Hash

Load character map from custom YAML file

Parameters:

  • file_path (String) —

    Path to YAML file with character definitions

Returns:

  • (Hash) —

    Character visualization map



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

def self.load_custom_character_map(file_path)
  data = YAML.load_file(file_path)
  visualization_map = {}

  data["characters"].each do |char_data|
    # Get character from either unicode code point or character field
    char = if char_data["unicode"]
             [char_data["unicode"].to_i(16)].pack("U")
           else
             char_data["character"]
           end

    visualization_map[char] = char_data["visualization"]
  end

  visualization_map
end

.merge_visualization_map(custom_map) ⇒ Hash

Merge custom character visualization map with defaults

Parameters:

  • custom_map (Hash, nil) —

    Custom character mappings

Returns:

  • (Hash) —

    Merged character visualization map



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# File 'lib/canon/diff_formatter.rb', line 238

def self.merge_visualization_map(custom_map)
  DEFAULT_VISUALIZATION_MAP.merge(custom_map || {})
end

Instance Method Details

#format(differences, format, doc1: nil, doc2: nil, html_version: nil) ⇒ String

Format differences array for display

Parameters:

  • differences (Array) —

    Array of difference hashes

  • format (Symbol) —

    Format type (:xml, :html, :json, :yaml)

  • doc1 (String, nil) (defaults to: nil) —

    First document content (for by-line mode)

  • doc2 (String, nil) (defaults to: nil) —

    Second document content (for by-line mode)

  • html_version (Symbol, nil) (defaults to: nil) —

    HTML version (:html4 or :html5)

Returns:

  • (String) —

    Formatted output



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# File 'lib/canon/diff_formatter.rb', line 306

def format(differences, format, doc1: nil, doc2: nil, html_version: nil)
  # In by-line mode with both docs present, always use by-line diff
  if @mode == :by_line && doc1 && doc2
    doc1, doc2 = apply_display_preprocessing(doc1, doc2, format)
    # rubocop:disable Layout/HashAlignment
    return by_line_formatter.format(doc1, doc2, format: format,
                                              html_version: html_version,
                                              differences: differences)
    # rubocop:enable Layout/HashAlignment
  end

  # In pretty_diff mode, always use text-LCS diff (bypasses DiffNodeMapper).
  if @mode == :pretty_diff
    d1, d2 = if doc1 && doc2
               apply_display_preprocessing(doc1, doc2,
                                           format)
             else
               [doc1,
                doc2]
             end
    return pretty_diff_formatter.format(d1, d2, format: format)
  end

  no_diffs = if differences.respond_to?(:equivalent?)
               differences.equivalent?
             else
               differences.empty?
             end
  return success_message if no_diffs

  case @mode
  when :by_line
    if doc1 && doc2
      doc1, doc2 = apply_display_preprocessing(doc1, doc2,
                                               format)
    end
    # rubocop:disable Layout/HashAlignment
    by_line_formatter.format(doc1, doc2, format: format,
                                           html_version: html_version,
                                           differences: differences)
    # rubocop:enable Layout/HashAlignment
  when :pretty_diff
    d1, d2 = if doc1 && doc2
               apply_display_preprocessing(doc1, doc2,
                                           format)
             else
               [doc1,
                doc2]
             end
    pretty_diff_formatter.format(d1, d2, format: format)
  else
    by_object_formatter.format(differences, format)
  end
end

#format_comparison_result(comparison_result, expected, actual) ⇒ String

Format comparison result from Canon::Comparison.equivalent? This is the single entry point for generating diffs from comparison results

Parameters:

  • comparison_result (ComparisonResult, Hash, Array, Boolean) —

    Result from Canon::Comparison.equivalent?

  • expected (Object) —

    Expected value

  • actual (Object) —

    Actual value

Returns:

  • (String) —

    Formatted diff output



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# File 'lib/canon/diff_formatter.rb', line 368

def format_comparison_result(comparison_result, expected, actual)
  # Detect format from expected content
  format = Canon::Comparison::FormatDetector.detect(expected)

  formatter_options = {
    use_color: @use_color,
    mode: @mode,
    context_lines: @context_lines,
    diff_grouping_lines: @diff_grouping_lines,
    show_diffs: @show_diffs,
    verbose_diff: @verbose_diff,
  }

  output = []

  # Display the algorithm being used
  if comparison_result.is_a?(Canon::Comparison::ComparisonResult)
    algorithm_name = case comparison_result.algorithm
                     when :semantic
                       "SEMANTIC TREE DIFF"
                     else
                       "DOM DIFF"
                     end
    output << colorize("Algorithm: #{algorithm_name}", :cyan, :bold)
    output << "" # Blank line for spacing
  end

  # 1. CANON VERBOSE tables (ONLY if CANON_VERBOSE=1)
  verbose_tables = DebugOutput.verbose_tables_only(
    comparison_result,
    formatter_options,
  )
  output << verbose_tables unless verbose_tables.empty?

  # 2. Semantic Diff Report (ALWAYS if diffs exist)
  if comparison_result.is_a?(Canon::Comparison::ComparisonResult) &&
      comparison_result.differences.any?
    require_relative "diff_formatter/diff_detail_formatter"
    output << DiffDetailFormatter.format_report(
      comparison_result.differences,
      use_color: @use_color,
      show_diffs: @show_diffs,
      compact_semantic_report: @compact_semantic_report,
      expand_difference: @expand_difference,
    )
  end

  # verbose_diff / show_raw_inputs shows both sides as a convenience shorthand.
  # show_raw_expected / show_raw_received give per-side control.
  combined_raw = @verbose_diff || @show_raw_inputs
  show_raw_exp = combined_raw || @show_raw_expected
  show_raw_rec = combined_raw || @show_raw_received
  verbose      = show_raw_exp || show_raw_rec
  # verbose_diff / show_preprocessed_inputs shows both sides as a shorthand.
  # show_preprocessed_expected / show_preprocessed_received give per-side control.
  combined_prep = @verbose_diff || @show_preprocessed_inputs
  show_prep_exp = combined_prep || @show_preprocessed_expected
  show_prep_rec = combined_prep || @show_preprocessed_received
  show_prep = show_prep_exp || show_prep_rec
  show_line = @verbose_diff || @show_line_numbered_inputs

  # 3. Raw/Original Input Display (when show_raw_inputs/show_raw_expected/show_raw_received enabled)
  if verbose && comparison_result.is_a?(Canon::Comparison::ComparisonResult)
    original1, original2 = comparison_result.original_strings
    if original1 && original2
      output << format_raw_inputs(original1, original2,
                                  show_expected: show_raw_exp,
                                  show_received: show_raw_rec)
    end
  end

  # 4. Preprocessed Input Display (when show_preprocessed_inputs/expected/received enabled)
  if show_prep && comparison_result.is_a?(Canon::Comparison::ComparisonResult)
    preprocessed1, preprocessed2 = comparison_result.preprocessed_strings
    if preprocessed1 && preprocessed2
      preprocessing_info = comparison_result.match_options&.dig(:match,
                                                                :preprocessing)
      output << format_preprocessed_inputs(preprocessed1, preprocessed2,
                                           preprocessing_info,
                                           show_expected: show_prep_exp,
                                           show_received: show_prep_rec)
    end
  end

  # 4.5. Pretty-printed Input Display (when show_prettyprint_inputs/expected/received enabled)
  # Pretty-prints the ORIGINAL strings (not preprocessed) through PrettyPrinter::Xml/Html
  # with NO character visualization — output is plain ASCII suitable for copy-pasting
  # into RSpec fixture heredocs.  verbose_diff does NOT enable these options.
  show_pp_inp = @show_prettyprint_inputs
  show_pp_exp = show_pp_inp || @show_prettyprint_expected
  show_pp_rec = show_pp_inp || @show_prettyprint_received
  show_pp = show_pp_exp || show_pp_rec

  if show_pp && comparison_result.is_a?(Canon::Comparison::ComparisonResult)
    orig1, orig2 = comparison_result.original_strings
    if orig1 && orig2
      pp1, pp2 = prettyprint_for_display(orig1, orig2, format)
      output << format_prettyprint_inputs(pp1, pp2,
                                          show_expected: show_pp_exp,
                                          show_received: show_pp_rec)
    end
  end

  # 5. Line-Numbered Input Display (when show_line_numbered_inputs is enabled)
  if show_line && comparison_result.is_a?(Canon::Comparison::ComparisonResult)
    original1, original2 = comparison_result.original_strings
    if original1 && original2
      output << format_line_numbered_inputs(original1, original2)
    end
  end

  # 6. Main diff output (by-line or by-object) - ALWAYS

  # Check if comparison result is a ComparisonResult object
  if comparison_result.is_a?(Canon::Comparison::ComparisonResult)
    # Use original strings for line diff to show actual formatting/namespace differences
    # Use preprocessed strings for semantic comparison only
    doc1, doc2 = comparison_result.original_strings
    differences = comparison_result.differences
    html_version = comparison_result.html_version
  elsif comparison_result.is_a?(Hash) && comparison_result[:preprocessed]
    # Legacy Hash format - Use preprocessed strings from comparison
    doc1, doc2 = comparison_result[:preprocessed]
    differences = comparison_result[:differences]
    html_version = comparison_result[:html_version]
  else
    # Legacy path: normalize content for display
    doc1, doc2 = normalize_content_for_display(expected, actual, format)
    # comparison_result is an array of differences when verbose: true
    differences = comparison_result.is_a?(Array) ? comparison_result : []
    html_version = nil
  end

  # Generate diff using existing format method
  output << format(differences, format, doc1: doc1, doc2: doc2,
                                        html_version: html_version)

  output.compact.join("\n")
end