Class: SyntaxTree::YARV::Disassembler

Inherits:
Object
  • Object
show all
Defined in:
lib/syntax_tree/yarv/disassembler.rb

Defined Under Namespace

Classes: Squished

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(current_iseq = nil) ⇒ Disassembler

Returns a new instance of Disassembler.



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 46

def initialize(current_iseq = nil)
  @output = StringIO.new
  @queue = []

  @current_prefix = ""
  @current_iseq = current_iseq
end

Instance Attribute Details

#current_iseq ⇒ Object

Returns the value of attribute current_iseq.



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 44

def current_iseq
  @current_iseq
end

#current_prefix ⇒ Object (readonly)

Returns the value of attribute current_prefix.



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 43

def current_prefix
  @current_prefix
end

#output ⇒ Object (readonly)

Returns the value of attribute output.



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 41

def output
  @output
end

#queue ⇒ Object (readonly)

Returns the value of attribute queue.



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 41

def queue
  @queue
end

Instance Method Details

#calldata(value) ⇒ Object

Helpers for various instructions



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 58

def calldata(value)
  value.inspect
end

#enqueue(iseq) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 62

def enqueue(iseq)
  queue << iseq
end

#event(name) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 66

def event(name)
  case name
  when :RUBY_EVENT_B_CALL
    "Bc"
  when :RUBY_EVENT_B_RETURN
    "Br"
  when :RUBY_EVENT_CALL
    "Ca"
  when :RUBY_EVENT_CLASS
    "Cl"
  when :RUBY_EVENT_END
    "En"
  when :RUBY_EVENT_LINE
    "Li"
  when :RUBY_EVENT_RETURN
    "Re"
  else
    raise "Unknown event: #{name}"
  end
end

#format! ⇒ Object

Entrypoints



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 116

def format!
  while (@current_iseq = queue.shift)
    output << "\n" if output.pos > 0
    format_iseq(@current_iseq)
  end
end

#format_insns!(insns, length = 0) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 123

def format_insns!(insns, length = 0)
  events = []
  lines = []

  insns.each do |insn|
    case insn
    when Integer
      lines << insn
    when Symbol
      events << event(insn)
    when InstructionSequence::Label
      # skip
    else
      output << "#{current_prefix}%04d " % length

      disasm = insn.disasm(self)
      output << disasm

      if lines.any?
        output << " " * (65 - disasm.length) if disasm.length < 65
      elsif events.any?
        output << " " * (39 - disasm.length) if disasm.length < 39
      end

      if lines.any?
        output << "(%4d)" % lines.last
        lines.clear
      end

      if events.any?
        output << "[#{events.join}]"
        events.clear
      end

      # A hook here to allow for custom formatting of instructions after
      # the main body has been processed.
      yield insn, length if block_given?

      output << "\n"
      length += insn.length
    end
  end
end

#inline_storage(cache) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 87

def inline_storage(cache)
  "<is:#{cache}>"
end

#instruction(name, operands = []) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 91

def instruction(name, operands = [])
  operands.empty? ? name : "%-38s %s" % [name, operands.join(", ")]
end

#label(value) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 95

def label(value)
  value.name["label_".length..]
end

#local(index, explicit: nil, implicit: nil) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 99

def local(index, explicit: nil, implicit: nil)
  current = current_iseq
  (explicit || implicit).times { current = current.parent_iseq }

  value = "#{current.local_table.name_at(index)}@#{index}"
  value << ", #{explicit}" if explicit
  value
end

#object(value) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 108

def object(value)
  value.inspect
end

#print(string) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 167

def print(string)
  output.print(string)
end

#puts(string) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 171

def puts(string)
  output.puts(string)
end

#string ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 175

def string
  output.string
end

#with_prefix(value) ⇒ Object 



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# File 'lib/syntax_tree/yarv/disassembler.rb', line 179

def with_prefix(value)
  previous = @current_prefix

  begin
    @current_prefix = value
    yield value
  ensure
    @current_prefix = previous
  end
end