gem5/ext/ply/example/newclasscalc/calc.py
Jason Lowe-Power 87b9f0b87b misc: Update #!env calls for python to explicit version
In some newer Linux distributions, env python default to Python 3.0. This
patch explicitly uses "python2" instead of just "python" for all scripts
that use #!

Reported-by: Sanchayan Maity <maitysanchayan@gmail.com>
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
2017-02-10 10:00:18 -05:00

160 lines
4 KiB
Python
Executable file

#!/usr/bin/env python2
# -----------------------------------------------------------------------------
# calc.py
#
# A simple calculator with variables. This is from O'Reilly's
# "Lex and Yacc", p. 63.
#
# Class-based example contributed to PLY by David McNab.
#
# Modified to use new-style classes. Test case.
# -----------------------------------------------------------------------------
import sys
sys.path.insert(0,"../..")
if sys.version_info[0] >= 3:
raw_input = input
import ply.lex as lex
import ply.yacc as yacc
import os
class Parser(object):
"""
Base class for a lexer/parser that has the rules defined as methods
"""
tokens = ()
precedence = ()
def __init__(self, **kw):
self.debug = kw.get('debug', 0)
self.names = { }
try:
modname = os.path.split(os.path.splitext(__file__)[0])[1] + "_" + self.__class__.__name__
except:
modname = "parser"+"_"+self.__class__.__name__
self.debugfile = modname + ".dbg"
self.tabmodule = modname + "_" + "parsetab"
#print self.debugfile, self.tabmodule
# Build the lexer and parser
lex.lex(module=self, debug=self.debug)
yacc.yacc(module=self,
debug=self.debug,
debugfile=self.debugfile,
tabmodule=self.tabmodule)
def run(self):
while 1:
try:
s = raw_input('calc > ')
except EOFError:
break
if not s: continue
yacc.parse(s)
class Calc(Parser):
tokens = (
'NAME','NUMBER',
'PLUS','MINUS','EXP', 'TIMES','DIVIDE','EQUALS',
'LPAREN','RPAREN',
)
# Tokens
t_PLUS = r'\+'
t_MINUS = r'-'
t_EXP = r'\*\*'
t_TIMES = r'\*'
t_DIVIDE = r'/'
t_EQUALS = r'='
t_LPAREN = r'\('
t_RPAREN = r'\)'
t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'
def t_NUMBER(self, t):
r'\d+'
try:
t.value = int(t.value)
except ValueError:
print("Integer value too large %s" % t.value)
t.value = 0
#print "parsed number %s" % repr(t.value)
return t
t_ignore = " \t"
def t_newline(self, t):
r'\n+'
t.lexer.lineno += t.value.count("\n")
def t_error(self, t):
print("Illegal character '%s'" % t.value[0])
t.lexer.skip(1)
# Parsing rules
precedence = (
('left','PLUS','MINUS'),
('left','TIMES','DIVIDE'),
('left', 'EXP'),
('right','UMINUS'),
)
def p_statement_assign(self, p):
'statement : NAME EQUALS expression'
self.names[p[1]] = p[3]
def p_statement_expr(self, p):
'statement : expression'
print(p[1])
def p_expression_binop(self, p):
"""
expression : expression PLUS expression
| expression MINUS expression
| expression TIMES expression
| expression DIVIDE expression
| expression EXP expression
"""
#print [repr(p[i]) for i in range(0,4)]
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]
elif p[2] == '**': p[0] = p[1] ** p[3]
def p_expression_uminus(self, p):
'expression : MINUS expression %prec UMINUS'
p[0] = -p[2]
def p_expression_group(self, p):
'expression : LPAREN expression RPAREN'
p[0] = p[2]
def p_expression_number(self, p):
'expression : NUMBER'
p[0] = p[1]
def p_expression_name(self, p):
'expression : NAME'
try:
p[0] = self.names[p[1]]
except LookupError:
print("Undefined name '%s'" % p[1])
p[0] = 0
def p_error(self, p):
if p:
print("Syntax error at '%s'" % p.value)
else:
print("Syntax error at EOF")
if __name__ == '__main__':
calc = Calc()
calc.run()