class CodeTools::AST::SingleBlockArg

Handles Rubinius.single_block_arg

Given the following code:

m { |x| ... }

In Ruby 1.8, this has the following semantics:

* x == nil if no values are yielded
* x == val if one value is yielded
* x == [p, q, r, ...] if more than one value is yielded
* x == [a, b, c, ...] if one Array is yielded

In Ruby 1.9, this has the following semantics:

* x == nil if no values are yielded
* x == val if one value is yielded
* x == p if yield(p, q, r, ...)
* x == [a, b, c, ...] if one Array is yielded

However, in Ruby 1.9, the Enumerator code manually implements the 1.8 block argument semantics. This transform exposes the VM instruction we use in 1.8 mode (cast_for_single_block_arg) so we can use it in 1.9 mode for Enumerator.

Public Class Methods

match?(line, receiver, name, arguments, privately) click to toggle source
# File lib/rubinius/code/ast/transforms.rb, line 178
def self.match?(line, receiver, name, arguments, privately)
  match_send? receiver, :Rubinius, name, :single_block_arg
end

Public Instance Methods

bytecode(g) click to toggle source
# File lib/rubinius/code/ast/transforms.rb, line 182
def bytecode(g)
  if @arguments.splat?
    raise CompileError, "splat argument passed to single_block_arg"
  elsif @block
    raise CompileError, "block passed to single_block_arg"
  end

  pos(g)
  g.cast_for_single_block_arg
end