Class: Instruction

Inherits:
Object
  • Object
show all
Defined in:
lib/rpeg/parsing_machine.rb

Overview

Instances are generated during program generation in Pattern and consumed in the ParsingMachine

  • op_code: the instruction op

  • offset: the address offset used in jumps, calls, etc.

  • aux: extra information used by instructions like capture

    • in LPEG this is used to carefully pack data by bit-twiddling, etc., but we can use anything, such as structs, etc., as needed

  • data: this is called “key” in LPEG and is used to store pointers to Lua-based objects, etc.

    • we will just store Ruby objects here.

    • it contains things like the set of characters for Charset instructions, etc.

  • dec: “decorations” for other things like labels that might be useful later in debugging, etc.

    • it is ignored by the VM

Constant Summary collapse

OP_CODES = 
%i[
  char charset any jump choice call return commit back_commit
  partial_commit span op_end fail fail_twice
  open_capture close_capture close_run_time full_capture behind
  test_char test_charset test_any
].each do |op|
  const_set op.upcase, op
end
OP_WIDTH = 
OP_CODES.map(&:length).max
DECORATION_WIDTH = 
15

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(op_code, offset: nil, data: nil, aux: nil, dec: nil) ⇒ Instruction

Returns a new instance of Instruction.



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# File 'lib/rpeg/parsing_machine.rb', line 30

def initialize(op_code, offset: nil, data: nil, aux: nil, dec: nil)
  raise "Bad instruction op_code #{op_code}" unless OP_CODES.include?(op_code)

  @op_code = op_code
  @offset = offset
  @data = data
  @aux = aux
  @dec = dec
end

Instance Attribute Details

#aux ⇒ Object (readonly)

Returns the value of attribute aux.



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# File 'lib/rpeg/parsing_machine.rb', line 27

def aux
  @aux
end

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/rpeg/parsing_machine.rb', line 27

def data
  @data
end

#dec ⇒ Object

Returns the value of attribute dec.



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# File 'lib/rpeg/parsing_machine.rb', line 28

def dec
  @dec
end

#offset ⇒ Object

Returns the value of attribute offset.



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# File 'lib/rpeg/parsing_machine.rb', line 28

def offset
  @offset
end

#op_code ⇒ Object (readonly)

Returns the value of attribute op_code.



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# File 'lib/rpeg/parsing_machine.rb', line 27

def op_code
  @op_code
end

Instance Method Details

#to_s ⇒ Object 



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# File 'lib/rpeg/parsing_machine.rb', line 40

def to_s
  return @to_s if @to_s

  str = (dec || "").to_s.rjust(DECORATION_WIDTH) + " :"
  str << op_code.to_s.upcase.rjust(OP_WIDTH + 1)

  str << " offset: #{offset}" if [TEST_CHAR, TEST_ANY, TEST_CHARSET].include?(op_code)

  case op_code
  when CHAR, TEST_CHAR
    str << "  #{data.dump}"
  when BEHIND
    str << "  #{aux}"
  when CHARSET, SPAN, TEST_CHARSET
    str << "  #{charset_rep(data)}"
  when JUMP, CHOICE, CALL, COMMIT, BACK_COMMIT, PARTIAL_COMMIT
    str << "  #{offset}"
  when RETURN, OP_END, FAIL, FAIL_TWICE, ANY, TEST_ANY
  # no-op
  when OPEN_CAPTURE, CLOSE_CAPTURE, FULL_CAPTURE, CLOSE_RUN_TIME
    str << "  data:#{data}, aux:#{aux}"
  else
    raise "Unhandled op_code #{op_code} in Instruction#to_s"
  end
  @to_s = str
end