Class: Parser::Source::Buffer

Inherits:
Object
  • Object
show all
Defined in:
lib/parser/source/buffer.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, first_line = 1) ⇒ Buffer

Returns a new instance of Buffer.



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# File 'lib/parser/source/buffer.rb', line 52

def initialize(name, first_line = 1)
  @name        = name
  @source      = nil
  @first_line  = first_line

  @lines       = nil
  @line_begins = nil
end

Instance Attribute Details

#first_line ⇒ Object (readonly)

Returns the value of attribute first_line.



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# File 'lib/parser/source/buffer.rb', line 7

def first_line
  @first_line
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/parser/source/buffer.rb', line 7

def name
  @name
end

Class Method Details

.recognize_encoding(string) ⇒ Object 



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# File 'lib/parser/source/buffer.rb', line 9

def self.recognize_encoding(string)
  if string.empty?
    return Encoding::BINARY
  end

  # TODO: Make this more efficient.
  first_line, second_line = string.lines.first(2)

  [first_line, second_line].each do |line|
    line.force_encoding(Encoding::ASCII_8BIT) if line
  end

  if first_line =~ /\A\xef\xbb\xbf/ # BOM
    return Encoding::UTF_8
  elsif first_line[0, 2] == '#!'
    encoding_line = second_line
  else
    encoding_line = first_line
  end

  if encoding_line =~ /^#.*coding[:=]\s*([a-z0-9_-]+)/
    Encoding.find($1)
  else
    string.encoding
  end
end

.reencode_string(string) ⇒ Object

Lexer expects UTF-8 input. This method processes the input in an arbitrary valid Ruby encoding and returns an UTF-8 encoded string.



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# File 'lib/parser/source/buffer.rb', line 40

def self.reencode_string(string)
  encoding = recognize_encoding(string)

  unless encoding.ascii_compatible?
    raise RuntimeError, "Encoding #{encoding} is not ASCII-compatible"
  end

  string.
    force_encoding(encoding).
    encode(Encoding::UTF_8)
end

Instance Method Details

#decompose_position(position) ⇒ Object 



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# File 'lib/parser/source/buffer.rb', line 90

def decompose_position(position)
  line_no, line_begin = line_for(position)

  [ @first_line + line_no, position - line_begin ]
end

#line_begins ⇒ Object (private) 



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# File 'lib/parser/source/buffer.rb', line 114

def line_begins
  unless @line_begins
    @line_begins, index = [ [ 0, 0 ] ], 1

    @source.each_char do |char|
      if char == "\n"
        @line_begins << [ @line_begins.length, index ]
      end

      index += 1
    end

    @line_begins = @line_begins.reverse
  end

  @line_begins
end

#line_for(position) ⇒ Object (private) 



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# File 'lib/parser/source/buffer.rb', line 132

def line_for(position)
  if line_begins.respond_to? :bsearch
    line_begins.bsearch do |line, line_begin|
      line_begin <= position
    end
  else
    # Slower variant for <= Ruby 2.0.
    line_begins.find do |line, line_begin|
      line_begin <= position
    end
  end
end

#read ⇒ Object 



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# File 'lib/parser/source/buffer.rb', line 61

def read
  File.open(@name, 'rb') do |io|
    self.source = io.read
  end

  self
end

#source ⇒ Object 



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# File 'lib/parser/source/buffer.rb', line 69

def source
  if @source.nil?
    raise RuntimeError, 'Cannot extract source from uninitialized Source::Buffer'
  end

  @source
end

#source=(source) ⇒ Object 



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# File 'lib/parser/source/buffer.rb', line 77

def source=(source)
  if @source
    raise ArgumentError, "Source::Buffer is immutable"
  end

  if source.respond_to? :encoding
    source = source.dup if source.frozen?
    source = self.class.reencode_string(source)
  end

  @source = source.freeze
end

#source_line(line) ⇒ Object 



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# File 'lib/parser/source/buffer.rb', line 96

def source_line(line)
  unless @lines
    @lines = @source.lines.map do |source_line|
      # Line endings will be commonly present for all lines
      # except the last one. It does not make sense to keep them.
      if source_line.end_with? "\n"
        source_line.chomp
      else
        source_line
      end
    end
  end

  @lines[line - @first_line].dup
end