Class: KPeg::StringEscape

Inherits:
Object
  • Object
show all
Defined in:
lib/kpeg/string_escape.rb

Defined Under Namespace

Classes: MemoEntry, ParseError, RuleInfo

Constant Summary collapse

Rules = 
{}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str, debug = false) ⇒ StringEscape

This is distinct from setup_parser so that a standalone parser can redefine #initialize and still have access to the proper parser setup code.



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# File 'lib/kpeg/string_escape.rb', line 7

def initialize(str, debug=false)
  setup_parser(str, debug)
end

Instance Attribute Details

#failed_rule ⇒ Object (readonly)

Returns the value of attribute failed_rule.



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# File 'lib/kpeg/string_escape.rb', line 148

def failed_rule
  @failed_rule
end

#failing_rule_offset ⇒ Object (readonly)

Returns the value of attribute failing_rule_offset.



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# File 'lib/kpeg/string_escape.rb', line 27

def failing_rule_offset
  @failing_rule_offset
end

#pos ⇒ Object

Returns the value of attribute pos.



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# File 'lib/kpeg/string_escape.rb', line 28

def pos
  @pos
end

#result ⇒ Object

Returns the value of attribute result.



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# File 'lib/kpeg/string_escape.rb', line 28

def result
  @result
end

#string ⇒ Object (readonly)

Returns the value of attribute string.



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# File 'lib/kpeg/string_escape.rb', line 26

def string
  @string
end

#text ⇒ Object (readonly)

Returns the value of attribute text.



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# File 'lib/kpeg/string_escape.rb', line 356

def text
  @text
end

Class Method Details

.rule_info(name, rendered) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 348

def self.rule_info(name, rendered)
  RuleInfo.new(name, rendered)
end

Instance Method Details

#_embed ⇒ Object

embed = embed_seg*:s { @text = s.join }



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# File 'lib/kpeg/string_escape.rb', line 572

def _embed

  _save = self.pos
  while true # sequence
    _ary = []
    while true
      _tmp = apply(:_embed_seg)
      _ary << @result if _tmp
      break unless _tmp
    end
    _tmp = true
    @result = _ary
    s = @result
    unless _tmp
      self.pos = _save
      break
    end
    @result = begin;  @text = s.join ; end
    _tmp = true
    unless _tmp
      self.pos = _save
    end
    break
  end # end sequence

  set_failed_rule :_embed unless _tmp
  return _tmp
end

#_embed_seg ⇒ Object

embed_seg = (“#” { “\#” } | segment)



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# File 'lib/kpeg/string_escape.rb', line 539

def _embed_seg

  _save = self.pos
  while true # choice

    _save1 = self.pos
    while true # sequence
      _tmp = match_string("#")
      unless _tmp
        self.pos = _save1
        break
      end
      @result = begin;  "\\#" ; end
      _tmp = true
      unless _tmp
        self.pos = _save1
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save
    _tmp = apply(:_segment)
    break if _tmp
    self.pos = _save
    break
  end # end choice

  set_failed_rule :_embed_seg unless _tmp
  return _tmp
end

#_root ⇒ Object

root = segment*:s { @text = s.join }



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# File 'lib/kpeg/string_escape.rb', line 509

def _root

  _save = self.pos
  while true # sequence
    _ary = []
    while true
      _tmp = apply(:_segment)
      _ary << @result if _tmp
      break unless _tmp
    end
    _tmp = true
    @result = _ary
    s = @result
    unless _tmp
      self.pos = _save
      break
    end
    @result = begin;  @text = s.join ; end
    _tmp = true
    unless _tmp
      self.pos = _save
    end
    break
  end # end sequence

  set_failed_rule :_root unless _tmp
  return _tmp
end

#_segment ⇒ Object

segment = (< /[w ]+/ > { text } | “\” { “\\” } | “n” { “\n” } | “t” { “\t” } | “b” { “\b” } | “"” { “\"” } | < . > { text })



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# File 'lib/kpeg/string_escape.rb', line 363

def _segment

  _save = self.pos
  while true # choice

    _save1 = self.pos
    while true # sequence
      _text_start = self.pos
      _tmp = scan(/\A(?-mix:[\w ]+)/)
      if _tmp
        text = get_text(_text_start)
      end
      unless _tmp
        self.pos = _save1
        break
      end
      @result = begin;  text ; end
      _tmp = true
      unless _tmp
        self.pos = _save1
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save

    _save2 = self.pos
    while true # sequence
      _tmp = match_string("\\")
      unless _tmp
        self.pos = _save2
        break
      end
      @result = begin;  "\\\\" ; end
      _tmp = true
      unless _tmp
        self.pos = _save2
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save

    _save3 = self.pos
    while true # sequence
      _tmp = match_string("\n")
      unless _tmp
        self.pos = _save3
        break
      end
      @result = begin;  "\\n" ; end
      _tmp = true
      unless _tmp
        self.pos = _save3
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save

    _save4 = self.pos
    while true # sequence
      _tmp = match_string("\t")
      unless _tmp
        self.pos = _save4
        break
      end
      @result = begin;  "\\t" ; end
      _tmp = true
      unless _tmp
        self.pos = _save4
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save

    _save5 = self.pos
    while true # sequence
      _tmp = match_string("\b")
      unless _tmp
        self.pos = _save5
        break
      end
      @result = begin;  "\\b" ; end
      _tmp = true
      unless _tmp
        self.pos = _save5
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save

    _save6 = self.pos
    while true # sequence
      _tmp = match_string("\"")
      unless _tmp
        self.pos = _save6
        break
      end
      @result = begin;  "\\\"" ; end
      _tmp = true
      unless _tmp
        self.pos = _save6
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save

    _save7 = self.pos
    while true # sequence
      _text_start = self.pos
      _tmp = get_byte
      if _tmp
        text = get_text(_text_start)
      end
      unless _tmp
        self.pos = _save7
        break
      end
      @result = begin;  text ; end
      _tmp = true
      unless _tmp
        self.pos = _save7
      end
      break
    end # end sequence

    break if _tmp
    self.pos = _save
    break
  end # end choice

  set_failed_rule :_segment unless _tmp
  return _tmp
end

#apply(rule) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 283

def apply(rule)
  if m = @memoizations[rule][@pos]
    @pos = m.pos
    if !m.set
      m.left_rec = true
      return nil
    end

    @result = m.result

    return m.ans
  else
    m = MemoEntry.new(nil, @pos)
    @memoizations[rule][@pos] = m
    start_pos = @pos

    ans = __send__ rule

    lr = m.left_rec

    m.move! ans, @pos, @result

    # Don't bother trying to grow the left recursion
    # if it's failing straight away (thus there is no seed)
    if ans and lr
      return grow_lr(rule, nil, start_pos, m)
    else
      return ans
    end

    return ans
  end
end

#apply_with_args(rule, *args) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 248

def apply_with_args(rule, *args)
  memo_key = [rule, args]
  if m = @memoizations[memo_key][@pos]
    @pos = m.pos
    if !m.set
      m.left_rec = true
      return nil
    end

    @result = m.result

    return m.ans
  else
    m = MemoEntry.new(nil, @pos)
    @memoizations[memo_key][@pos] = m
    start_pos = @pos

    ans = __send__ rule, *args

    lr = m.left_rec

    m.move! ans, @pos, @result

    # Don't bother trying to grow the left recursion
    # if it's failing straight away (thus there is no seed)
    if ans and lr
      return grow_lr(rule, args, start_pos, m)
    else
      return ans
    end

    return ans
  end
end

#current_column(target = pos) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 31

def current_column(target=pos)
  if c = string.rindex("\n", target-1)
    return target - c - 1
  end

  target + 1
end

#current_line(target = pos) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 39

def current_line(target=pos)
  cur_offset = 0
  cur_line = 0

  string.each_line do |line|
    cur_line += 1
    cur_offset += line.size
    return cur_line if cur_offset >= target
  end

  -1
end

#external_invoke(other, rule, *args) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 227

def external_invoke(other, rule, *args)
  old_pos = @pos
  old_string = @string

  @pos = other.pos
  @string = other.string

  begin
    if val = __send__(rule, *args)
      other.pos = @pos
      other.result = @result
    else
      other.set_failed_rule "#{self.class}##{rule}"
    end
    val
  ensure
    @pos = old_pos
    @string = old_string
  end
end

#failure_caret ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 85

def failure_caret
  l = current_line @failing_rule_offset
  c = current_column @failing_rule_offset

  line = lines[l-1]
  "#{line}\n#{' ' * (c - 1)}^"
end

#failure_character ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 93

def failure_character
  l = current_line @failing_rule_offset
  c = current_column @failing_rule_offset
  lines[l-1][c-1, 1]
end

#failure_info ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 73

def failure_info
  l = current_line @failing_rule_offset
  c = current_column @failing_rule_offset

  if @failed_rule.kind_of? Symbol
    info = self.class::Rules[@failed_rule]
    "line #{l}, column #{c}: failed rule '#{info.name}' = '#{info.rendered}'"
  else
    "line #{l}, column #{c}: failed rule '#{@failed_rule}'"
  end
end

#failure_oneline ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 99

def failure_oneline
  l = current_line @failing_rule_offset
  c = current_column @failing_rule_offset

  char = lines[l-1][c-1, 1]

  if @failed_rule.kind_of? Symbol
    info = self.class::Rules[@failed_rule]
    "@#{l}:#{c} failed rule '#{info.name}', got '#{char}'"
  else
    "@#{l}:#{c} failed rule '#{@failed_rule}', got '#{char}'"
  end
end

#get_byte ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 171

def get_byte
  if @pos >= @string.size
    return nil
  end

  s = @string.getbyte @pos
  @pos += 1
  s
end

#get_text(start) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 60

def get_text(start)
  @string[start..@pos-1]
end

#grow_lr(rule, args, start_pos, m) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 317

def grow_lr(rule, args, start_pos, m)
  while true
    @pos = start_pos
    @result = m.result

    if args
      ans = __send__ rule, *args
    else
      ans = __send__ rule
    end
    return nil unless ans

    break if @pos <= m.pos

    m.move! ans, @pos, @result
  end

  @result = m.result
  @pos = m.pos
  return m.ans
end

#lines ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 52

def lines
  lines = []
  string.each_line { |l| lines << l }
  lines
end

#match_string(str) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 150

def match_string(str)
  len = str.size
  if @string[pos,len] == str
    @pos += len
    return str
  end

  return nil
end

#parse(rule = nil) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 192

def parse(rule=nil)
  # We invoke the rules indirectly via apply
  # instead of by just calling them as methods because
  # if the rules use left recursion, apply needs to
  # manage that.

  if !rule
    apply(:_root)
  else
    method = rule.gsub("-","_hyphen_")
    apply :"_#{method}"
  end
end

#raise_error ⇒ Object

Raises:



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# File 'lib/kpeg/string_escape.rb', line 116

def raise_error
  raise ParseError, failure_oneline
end

#scan(reg) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 160

def scan(reg)
  if m = reg.match(@string[@pos..-1])
    width = m.end(0)
    @pos += width
    return true
  end

  return nil
end

#set_failed_rule(name) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 141

def set_failed_rule(name)
  if @pos > @failing_rule_offset
    @failed_rule = name
    @failing_rule_offset = @pos
  end
end

#setup_foreign_grammar ⇒ Object

:stopdoc:



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# File 'lib/kpeg/string_escape.rb', line 360

def setup_foreign_grammar; end

#setup_parser(str, debug = false) ⇒ Object

Prepares for parsing str. If you define a custom initialize you must call this method before #parse



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# File 'lib/kpeg/string_escape.rb', line 15

def setup_parser(str, debug=false)
  @string = str
  @pos = 0
  @memoizations = Hash.new { |h,k| h[k] = {} }
  @result = nil
  @failed_rule = nil
  @failing_rule_offset = -1

  setup_foreign_grammar
end

#show_error(io = STDOUT) ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 120

def show_error(io=STDOUT)
  error_pos = @failing_rule_offset
  line_no = current_line(error_pos)
  col_no = current_column(error_pos)

  io.puts "On line #{line_no}, column #{col_no}:"

  if @failed_rule.kind_of? Symbol
    info = self.class::Rules[@failed_rule]
    io.puts "Failed to match '#{info.rendered}' (rule '#{info.name}')"
  else
    io.puts "Failed to match rule '#{@failed_rule}'"
  end

  io.puts "Got: #{string[error_pos,1].inspect}"
  line = lines[line_no-1]
  io.puts "=> #{line}"
  io.print(" " * (col_no + 3))
  io.puts "^"
end

#show_pos ⇒ Object 



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# File 'lib/kpeg/string_escape.rb', line 64

def show_pos
  width = 10
  if @pos < width
    "#{@pos} (\"#{@string[0,@pos]}\" @ \"#{@string[@pos,width]}\")"
  else
    "#{@pos} (\"... #{@string[@pos - width, width]}\" @ \"#{@string[@pos,width]}\")"
  end
end