I am using Python with PLY to parse LISP-like S-Expressions and when parsing a function call there can be zero or more arguments. How can I put this into the yacc code. This is my function s开发者_开发技巧o far:
def p_EXPR(p):
'''EXPR : NUMBER
| STRING
| LPAREN funcname [EXPR] RPAREN'''
if len(p) == 2:
p[0] = p[1]
else:
p[0] = ("Call", p[2], p[3:-1])
I need to replace "[EXPR]" with something that allows zero or more EXPR's. How can I do this?
How about this:
EXPR : NUMBER
| STRING
| LPAREN funcname EXPR_REPEAT RPAREN
EXPR_REPEAT: /*nothing*/
| EXPR EXPR_REPEAT
Are you sure you want a Context Free Grammar and not a Parsing Expression Grammar? Also, in my experience the design of PLY couples the grammar and parsing and post-processing very badly so I would recommend an implementation with more modular design.
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