# -----------------------------------------------------------------------------
# yacc_inf.py
#
# Infinite recursion
import sys
sys.tracebacklimit = 0
sys.path.insert(0,"..")
import ply.yacc as yacc
from calclex import tokens
# Parsing rules
precedence = (
('left','PLUS','MINUS'),
('left','TIMES','DIVIDE'),
('right','UMINUS'),
)
# dictionary of names
names = { }
def p_statement_assign(t):
'statement : NAME EQUALS expression'
names[t[1]] = t[3]
def p_statement_expr(t):
'statement : expression'
print t[1]
def p_expression_binop(t):
'''expression : expression PLUS expression
| expression MINUS expression
| expression TIMES expression
| expression DIVIDE expression'''
if t[2] == '+' : t[0] = t[1] + t[3]
elif t[2] == '-': t[0] = t[1] - t[3]
elif t[2] == '*': t[0] = t[1] * t[3]
elif t[3] == '/': t[0] = t[1] / t[3]
def p_expression_uminus(t):
'expression : MINUS expression %prec UMINUS'
t[0] = -t[2]
def p_expression_group(t):
'expression : LPAREN expression RPAREN'
t[0] = t[2]
def p_error(t):
print "Syntax error at '%s'" % t.value
yacc.yacc()
