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Work in progress. Changes to parser production API

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This commit is contained in:
David Beazley
2016-09-08 15:05:03 -05:00
parent 9a1899fa69
commit 05a709aaea
4 changed files with 1869 additions and 182 deletions
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33
example/calc/calc.py
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@@ -44,46 +44,45 @@ class CalcParser(Parser):
@_('NAME "=" expression')
def statement(self, p):
self.names[p[1]] = p[3]
self.names[p.NAME] = p.expression
@_('expression')
def statement(self, p):
print(p[1])
print(p.expression)
@_('expression "+" expression',
'expression "-" expression',
'expression "*" expression',
'expression "/" expression')
def expression(self, p):
if p[2] == '+':
p[0] = p[1] + p[3]
elif p[2] == '-':
p[0] = p[1] - p[3]
elif p[2] == '*':
p[0] = p[1] * p[3]
elif p[2] == '/':
p[0] = p[1] / p[3]
if p[1] == '+':
return p.expression0 + p.expression1
elif p[1] == '-':
return p.expression0 - p.expression1
elif p[1] == '*':
return p.expression0 * p.expression1
elif p[1] == '/':
return p.expression0 / p.expression1
@_('"-" expression %prec UMINUS')
def expression(self, p):
p[0] = -p[2]
return -p.expression
@_('"(" expression ")"')
def expression(self, p):
p[0] = p[2]
return p.expression
@_('NUMBER')
def expression(self, p):
p[0] = p[1]
return p.NUMBER
@_('NAME')
def expression(self, p):
try:
p[0] = self.names[p[1]]
return self.names[p.NAME]
except LookupError:
print("Undefined name '%s'" % p[1])
p[0] = 0
print("Undefined name '%s'" % p.NAME)
return 0
if __name__ == '__main__':
lexer = CalcLexer()