从Ruby块中提取AST [英] Extract the AST from a Ruby block

问题描述

是否可以从Ruby本身获取块的AST？

Is it possible to grab the AST of a block from Ruby itself?

我看过ParseTree和ruby_parser，但它们似乎都具有对Ruby 1.9.2的粗略支持（根据我的阅读）。我需要与1.9.2兼容的东西。

I've had a look at both ParseTree and ruby_parser, but they both seem to have sketchy support (from what I've read) for Ruby 1.9.2. I need something that works well with 1.9.2.

推荐答案

开膛手包含在MRI 1.9中。

Ripper is included in MRI 1.9 out of the box.

ruby-1.9.2-p180 :004 > require 'ripper'
 => true
ruby-1.9.2-p180 :005 > Ripper.sexp("def a; end")
 => [:program, [[:def, [:@ident, "a", [1, 4]], [:params, nil, nil, nil, nil, nil], [:bodystmt, [[:void_stmt]], nil, nil, nil]]]] 

在1.8中，Ruby通过遍历AST执行代码，因此可以获取给定方法/块的AST。在1.9中并非如此；该代码首先被解析，然后转换为YARV字节码，然后执行。在翻译步骤之后，不会保留源，也不会保留AST，并且后者不可逆；因此您无法在1.9版中获得AST。

In 1.8, Ruby executes the code by traversing the AST, so it is possible to get the AST for a given method/block. In 1.9 it is not so; the code is first parsed, then converted to YARV bytecode, and then executed. Not the source, nor AST is kept after the translating step, and the latter is not reversible; hence you cannot get the AST for a block in 1.9.

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