使用Ruby解析Tcl DSL [英] Use Ruby to parse a Tcl DSL

问题描述

我希望能够解析一些参数不被字符串包围的Tcl代码.

I would like to be able to parse some Tcl code where arguments are not surrounded by strings.

考虑以下tcl代码:

proc foo {name} {
  puts "Foo --> $name"
}    

foo bar

对于那些不熟悉Tcl的人，foo是方法名称，而bar是参数(在Tcl中引号是可选的).

For those unfamiliar with Tcl, foo is the method name and bar is the argument (quotes are optional in Tcl).

先前的代码将输出:

Foo --> bar

是否可以使用ruby准确解析 相同的输入(bar保持未引用)?

Is it possible to parse exactly the same input using ruby (bar remains unquoted)?

等效的红宝石代码为:

def foo(name)
  puts "Foo --> #{name}"
end

tcl = <<-TCL.gsub(/^\s+/, "").chop
  foo bar
TCL
instance_eval(tcl)

当然，它到达bar时失败，因为期望它被引用.

Of course that fails when it reaches bar since it's expected it to be quoted.

我尝试过修改method_missing

def method_missing(meth, *args)
    puts meth.to_s + " --> args.to_s
end

但是它以相反的顺序解析:

but it parses in reverse order:

to_hash --> []
bar --> []
foo --> [nil]

有人对这种类型的问题有一个明确的解决方案吗?我想避免标记字符串，因为与词法分析相比，通过调用方法读取数据所需的工作最少.但是，如果我试图做一些不可能的事情，我想知道.谢谢.

Does anyone have a clean solution to this type of problem. I'd like to avoid tokenizing the strings since reading the data in by calling a method requires minimal work compared to lexical analysis. But if I'm trying to do something that's not possible, I'd like to know. Thanks.

推荐答案

它对您不起作用，因为.puts方法返回nil而不是字符串:

It's doesn't work for you because .puts method returns nil instead of string:

irb(main):003:0> puts "42"
42
=> nil

我真的不知道为什么to_hash出现在此method_missing中，但是它可以工作:

I really don't know why to_hash appears in this method_missing but it works:

def foo(name)
  puts "Foo --> #{name}"
end

def method_missing(meth, *args)
     meth.to_s unless meth.to_s  == "to_hash"
end

tcl = <<-TCL.gsub(/^\s+/, "").chop
  foo bar
TCL

instance_eval(tcl)

=> Foo --> bar

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