Module: SourceMap::Parser

Included in:
SourceMap
Defined in:
lib/source_map/parser.rb

Instance Method Summary collapse

Instance Method Details

#parse_mapping(segment, line_num) ⇒ Object

Parse an individual mapping.

This is a list of variable-length-quanitity, with 1, 4 or 5 items. See the spec docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit for more details.



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# File 'lib/source_map/parser.rb', line 62

def parse_mapping(segment, line_num)
  item = VLQ.decode_array(segment)

  unless [1, 4, 5].include?(item.size)
    raise ParserError, "In map for #{file}:#{line_num}: unparseable item: #{segment}"
  end

  map = {
    :generated_line => line_num,
    :generated_col => undiff(item[0], :generated_col),
  }

  if item.size >= 4
    map[:source] = sources[undiff(item[1], :source_id)]
    map[:source_line] = undiff(item[2], :source_line) + 1 # line numbers are stored starting from 0
    map[:source_col] = undiff(item[3], :source_col)
    map[:name] = names[undiff(item[4], :name_id)] if item[4]
  end

  if map[:generated_col] < 0
    raise ParserError, "In map for #{file}:#{line_num}: unexpected generated_col: #{map[:generated_col]}"

  elsif map.key?(:source) && (map[:source].nil? || @previous[:source_id] < 0)
    raise ParserError, "In map for #{file}:#{line_num}: unknown source id: #{@previous[:source_id]}"

  elsif map.key?(:source_line) && map[:source_line] < 1
    raise ParserError, "In map for #{file}:#{line_num}: unexpected source_line: #{map[:source_line]}"

  elsif map.key?(:source_col) && map[:source_col] < 0
    raise ParserError, "In map for #{file}:#{line_num}: unexpected source_col: #{map[:source_col]}"

  elsif map.key?(:name) && (map[:name].nil? || @previous[:name_id] < 0)
    raise ParserError, "In map for #{file}:#{line_num}: unknown name id: #{@previous[:name_id]}"

  else
    map

  end
end

#parse_mappings(string) ⇒ Object

Parse the mapping string from a SourceMap.

The mappings string contains one comma-separated list of segments per line in the output file, these lists are joined by semi-colons.



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# File 'lib/source_map/parser.rb', line 36

def parse_mappings(string)
  @previous = Hash.new{ 0 }

  string.split(";").each_with_index do |line, line_idx|
    # The generated_col resets to 0 at the start of every line, though
    # all the other differences are maintained.
    @previous[:generated_col] = 0
    line.split(",").each do |segment|
      mappings << parse_mapping(segment, line_idx + 1)
    end
  end

  self.mappings = self.mappings.sort_by{ |x| [x[:generated_line], x[:generated_col]] }
end

#undiff(int, type) ⇒ Object

All the numbers in SourceMaps are stored as differences from each other, so we need to remove the difference every time we read a number.



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# File 'lib/source_map/parser.rb', line 53

def undiff(int, type)
  @previous[type] += int
end