本文介绍了使用PyParsing解析函数调用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试解析一种简单的语言.问题来自于解析函数调用.我试图告诉它，函数调用是一个表达式，后跟左括号，参数列表和右括号.我有这样的东西:
I'm trying to parse a simple language. The trouble comes with parsing function calls. I'm trying to tell it that a function call is an expression followed by left parenthesis, argument list, and right parenthesis. I have something like this:
expr = Forward()
iden = Word(alphas+'_', alphanums+'_')
integer = Word(nums)
binop = operatorPrecedence(expr, ...) # irrevelant
call = expr + Literal('(') + delimitedList(expr) + Literal(')')
expr << call | integer | iden
问题很明显:expr是左递归的.但是，我无法解决该问题.我对右递归样式语法(也称为PLY，Yacc等)很有经验，但仍在尝试找出左递归语法.
The problem is obvious: expr is left-recursive. However, I can't figure what to do to solve this. I'm experienced with right-recursive-style grammars(a.k.a. PLY, Yacc, etc.) but am still trying to figure out left-recursive grammars.
推荐答案
Functionname = Word(alphanums + '_')
functionbody = Forward()
functionbody <<= Functionname + (Literal("(") +
Optional( delimitedList ( functionbody | Word(alphanums + '_') | "''"),'')
+ Literal(")"))
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