Class: Canon::Diff::DiffNodeMapper

Inherits:
Object
  • Object
show all
Defined in:
lib/canon/diff/diff_node_mapper.rb

Overview

Maps semantic DiffNodes to textual DiffLines This is Layer 2 of the diff pipeline, bridging semantic differences (from comparators) to textual representation (for formatters)

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(diff_nodes, text1, text2, options = {}) ⇒ DiffNodeMapper

Returns a new instance of DiffNodeMapper.



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# File 'lib/canon/diff/diff_node_mapper.rb', line 24

def initialize(diff_nodes, text1, text2, options = {})
  @diff_nodes = diff_nodes
  @text1 = text1
  @text2 = text2
  @line_map1 = options[:line_map1]
  @line_map2 = options[:line_map2]
end

Class Method Details

.map(diff_nodes, text1, text2, options = {}) ⇒ Array<DiffLine>

Map diff nodes to diff lines

Parameters:

  • diff_nodes (Array<DiffNode>) —

    The semantic differences

  • text1 (String) —

    The first text being compared

  • text2 (String) —

    The second text being compared

  • options (Hash) (defaults to: {}) —

    Mapping options

Options Hash (options):

  • :line_map1 (Hash) —

    Pre-built line range map for text1

  • :line_map2 (Hash) —

    Pre-built line range map for text2

Returns:

  • (Array<DiffLine>) —

    Diff lines with semantic linkage



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# File 'lib/canon/diff/diff_node_mapper.rb', line 20

def self.map(diff_nodes, text1, text2, options = {})
  new(diff_nodes, text1, text2, options).map
end

Instance Method Details

#map ⇒ Object 



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# File 'lib/canon/diff/diff_node_mapper.rb', line 32

def map
  lines1 = @text1.split("\n")
  lines2 = @text2.split("\n")

  # Use LCS to get structural diff
  require "diff/lcs"
  lcs_diffs = ::Diff::LCS.sdiff(lines1, lines2)

  # Check if ALL DiffNodes are informative
  all_informative = @diff_nodes && !@diff_nodes.empty? &&
    @diff_nodes.all?(&:informative?)

  # Convert LCS diffs to DiffLines
  # If all DiffNodes are informative, we create a single shared informative DiffNode
  # for all changed lines (this avoids complex linking)
  shared_informative_node = if all_informative
                              @diff_nodes.first # Use any informative node
                            end

  diff_lines = []
  line_num = 0

  lcs_diffs.each do |change|
    diff_line = case change.action
                when "="
                  DiffLine.new(
                    line_number: line_num,
                    content: change.old_element,
                    type: :unchanged,
                    diff_node: nil,
                  )
                when "-"
                  # Find the diff node for this line
                  node = shared_informative_node || find_diff_node_for_line(
                    line_num, lines1, :removed
                  )

                  # Check if this is formatting-only:
                  # 1. First check if the DiffNode itself is marked as formatting-only
                  # 2. Otherwise, check line-level formatting
                  formatting = if node.respond_to?(:formatting?) && node.formatting?
                                 true
                               else
                                 formatting_only_line?(
                                   change.old_element, ""
                                 )
                               end

                  DiffLine.new(
                    line_number: line_num,
                    content: change.old_element,
                    type: :removed,
                    diff_node: node,
                    formatting: formatting,
                  )
                when "+"
                  # Find the diff node for this line
                  node = shared_informative_node || find_diff_node_for_line(
                    line_num, lines2, :added
                  )

                  # Check if this is formatting-only:
                  # 1. First check if the DiffNode itself is marked as formatting-only
                  # 2. Otherwise, check line-level formatting
                  formatting = if node.respond_to?(:formatting?) && node.formatting?
                                 true
                               else
                                 formatting_only_line?("",
                                                       change.new_element)
                               end

                  DiffLine.new(
                    line_number: line_num,
                    content: change.new_element,
                    type: :added,
                    diff_node: node,
                    formatting: formatting,
                  )
                when "!"
                  # Find the diff node for this line
                  node = shared_informative_node || find_diff_node_for_line(
                    line_num, lines2, :changed
                  )

                  # Check if this is formatting-only:
                  # 1. First check if the DiffNode itself is marked as formatting-only
                  # 2. Otherwise, check line-level formatting
                  formatting = if node.respond_to?(:formatting?) && node.formatting?
                                 true
                               else
                                 formatting_only_line?(
                                   change.old_element, change.new_element
                                 )
                               end

                  DiffLine.new(
                    line_number: line_num,
                    content: change.new_element,
                    type: :changed,
                    diff_node: node,
                    formatting: formatting,
                  )
                end

    diff_lines << diff_line
    line_num += 1
  end

  diff_lines
end