Class: CRewriter

Inherits:
SexpProcessor
  • Object
show all
Defined in:
lib/crewriter.rb

Overview

CRewriter (should probably move this out to its own file) does rewritings that are language specific to C.

Constant Summary collapse

REWRITES =

REWRITES maps a function signature to a proc responsible for generating the appropriate sexp for that rewriting.

{
  [Type.str, :+, Type.str] => proc { |l,n,r|
    t(:call, nil, :strcat, r.unshift(r.shift, l), Type.str)
  },
  [Type.file, :puts, Type.str] => proc { |l,n,r|
    t(:call, nil, :fputs, r.push(l))
  },
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ CRewriter

:nodoc:



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# File 'lib/crewriter.rb', line 30

def initialize # :nodoc:
  super
  self.auto_shift_type = true
  self.expected = TypedSexp
  @env = ::R2CEnvironment.new
  @extra_methods = []
end

Instance Attribute Details

#env ⇒ Object (readonly)

Returns the value of attribute env.



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# File 'lib/crewriter.rb', line 27

def env
  @env
end

#extra_methods ⇒ Object (readonly)

Returns the value of attribute extra_methods.



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# File 'lib/crewriter.rb', line 28

def extra_methods
  @extra_methods
end

Instance Method Details

#free ⇒ Object

REFACTOR: this is a violation of responsibility, should be in Env



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# File 'lib/crewriter.rb', line 38

def free # REFACTOR: this is a violation of responsibility, should be in Env
  parent = @env.env[0..-2]
  bound_in_parent = parent.map { |h| h.keys }.flatten

  env = @env.all

  free = env.select { |k, (t, v)| bound_in_parent.include? k or not v }
  vars = free.map { |k, (t, v)| [k, t] }
  return vars
end

#process_call(exp) ⇒ Object

Rewrites function calls by looking them up in the REWRITES map. If a match exists, it invokes the block passing in the lhs, rhs, and function name. If one does not exist, it simply repacks the sexp and sends it along.



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# File 'lib/crewriter.rb', line 55

def process_call(exp)
  lhs = process exp.shift
  name = exp.shift
  rhs = process exp.shift

  lhs_type = lhs.sexp_type rescue nil
  type_signature = [lhs_type, name]
  type_signature += rhs[1..-1].map { |sexp| sexp.sexp_type } unless rhs.nil?

  result = if REWRITES.has_key? type_signature then
             REWRITES[type_signature].call(lhs, name, rhs)
           else
             t(:call, lhs, name, rhs, exp.sexp_type)
           end

  return result
end

#process_class(exp) ⇒ Object 



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# File 'lib/crewriter.rb', line 73

def process_class(exp)
  klassname = exp.shift
  superklassname = exp.shift

  methods = []

  until exp.empty? do
    methods << process(exp.shift)
  end

  @extra_methods.reverse_each do |defx| methods.unshift defx end
  @extra_methods.clear

  result = t(:class, klassname, superklassname, Type.zclass)
  result.push(*methods)

  return result
end

#process_iter(exp) ⇒ Object

TODO register statics



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# File 'lib/crewriter.rb', line 95

def process_iter(exp)
  iter_method_name = Unique.next

  value_var_name = Unique.next
  value_var_type = Type.unknown

  memo_var_name = Unique.next

  call = process exp.shift
  vars = process exp.shift
  body = nil

  free_vars = @env.scope do
    body = process exp.shift
    self.free.map { |name, type| [name, :"static_#{Unique.next}", type] }
  end

  var_names = var_names_in vars

  frees = t(:array, Type.void)
  statics = t(:array, Type.void)
  defx_body_block = t(:block)

  # set statics first so block vars can update statics
  free_vars.each do |name, static_name, type| # free vars go on both sides
    frees << t(:lvar, name, type)
    statics << t(:lvar, static_name, type)
    defx_body_block << t(:lasgn, name,
                         t(:lvar, static_name, type),
                         type)
  end

  if var_names.length == 1 then # expand block args to lasgn
    value_var_type = var_names.first.last

    defx_body_block << t(:lasgn, var_names.first.first,
                         t(:lvar, value_var_name, var_names.first.last),
                         var_names.first.last)

  else # expand block args to masgn
    value_var_type = Type.value
    dyn_vars = t(:array)

    var_names.each do |name, type|
      dyn_vars << t(:lasgn, name, nil, type)
    end

    defx_body_block << t(:masgn,
                         dyn_vars,
                         t(:to_ary, t(:lvar, value_var_name, Type.value)))
  end

  defx_body_block << body

  free_vars.each do |name, static_name, type|
    defx_body_block << t(:lasgn, static_name, t(:lvar, name, type), type)
    @extra_methods << t(:static, "static VALUE #{static_name};", Type.fucked)
  end

  defx_body_block << t(:return, t(:nil, Type.value))

  defx = t(:defx,
           iter_method_name,
           t(:args,
             t(value_var_name, value_var_type),
             t(memo_var_name, Type.value)),
           t(:scope, defx_body_block),
           Type.void)

  @extra_methods << defx

  args = t(:args, frees, statics, Type.void)

  return t(:iter, call, args, iter_method_name)
end

#process_lasgn(exp) ⇒ Object 



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# File 'lib/crewriter.rb', line 171

def process_lasgn(exp)
  name = exp.shift
  value = process(exp.shift)

  @env.add name, exp.sexp_type
  @env.set_val name, true

  return t(:lasgn, name, value, exp.sexp_type)
end

#process_lvar(exp) ⇒ Object 



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# File 'lib/crewriter.rb', line 181

def process_lvar(exp)
  name = exp.shift

  @env.add name, Type.value
  @env.lookup name rescue @env.set_val name, false

  return t(:lvar, name, exp.sexp_type)
end

#var_names_in(exp) ⇒ Object 



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# File 'lib/crewriter.rb', line 190

def var_names_in(exp)
  return [[exp.last, exp.sexp_type]] if exp.length == 2 and not Sexp === exp.last

  var_names = []
  exp.each_of_type :dasgn_curr do |sexp|
    var_names << [sexp.sexp_body.first, sexp.sexp_type]
  end
  return var_names
end