/
tokrules.py
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/
tokrules.py
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# ***************************************************************************
# * Copyright (c) 2020 Werner Mayer <wmayer[at]users.sourceforge.net> *
# * *
# * This file is part of the FreeCAD CAx development system. *
# * *
# * This program is free software; you can redistribute it and/or modify *
# * it under the terms of the GNU Lesser General Public License (LGPL) *
# * as published by the Free Software Foundation; either version 2 of *
# * the License, or (at your option) any later version. *
# * for detail see the LICENCE text file. *
# * *
# * This program is distributed in the hope that it will be useful, *
# * but WITHOUT ANY WARRANTY; without even the implied warranty of *
# * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
# * GNU Library General Public License for more details. *
# * *
# * You should have received a copy of the GNU Library General Public *
# * License along with this program; if not, write to the Free Software *
# * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 *
# * USA *
# * *
# ***************************************************************************
__title__ = "FEM Utilities"
__author__ = "Werner Mayer"
__url__ = "https://www.freecadweb.org"
tokens = (
'NAME',
'FLOAT',
'INT',
'PLUS',
'MINUS',
'TIMES',
'DIVIDE',
'EQUALS',
'LPAREN',
'RPAREN',
'POWER'
)
# Tokens
t_PLUS = r'\+'
t_MINUS = r'-'
t_TIMES = r'\*'
t_DIVIDE = r'/'
t_EQUALS = r'='
t_LPAREN = r'\('
t_RPAREN = r'\)'
t_POWER = r'\^'
t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'
def t_FLOAT(t):
r'\d+\.(\d+)?([eE][-+]?\d+)?'
t.value = float(t.value)
return t
def t_INT(t):
r'\d+'
t.value = int(t.value)
return t
# Ignored characters
t_ignore = " \t"
def t_COMMENT(t):
r'\#.*'
pass
def t_newline(t):
r'\n+'
t.lexer.lineno += t.value.count("\n")
def t_error(t):
print("Illegal character '%s'" % t.value[0])
t.lexer.skip(1)
# Build the lexer
import ply.lex as lex
lex.lex()
# Precedence rules for the arithmetic operators
precedence = (
('left', 'PLUS', 'MINUS'),
('left', 'TIMES', 'DIVIDE'),
('left', 'POWER'),
('right', 'UMINUS')
)
# dictionary of names (for storing variables)
names = {}
def p_statement_assign(p):
'statement : NAME EQUALS expression'
names[p[1]] = p[3]
def p_statement_expr(p):
'statement : expression'
print(p[1])
def p_expression_binop(p):
'''expression : expression PLUS expression
| expression MINUS expression
| expression TIMES expression
| expression DIVIDE expression
| expression POWER expression'''
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(p):
'expression : MINUS expression %prec UMINUS'
p[0] = -p[2]
def p_expression_group(p):
'expression : LPAREN expression RPAREN'
p[0] = p[2]
def p_expression_float(p):
'expression : FLOAT'
p[0] = p[1]
def p_expression_int(p):
'expression : INT'
p[0] = p[1]
def p_expression_name(p):
'expression : NAME'
try:
p[0] = names[p[1]]
except LookupError:
print("Undefined name '%s'" % p[1])
p[0] = 0
def p_error(p):
print("Syntax error at '%s'" % p.value)
import ply.yacc as yacc
yacc.yacc(debug=False, write_tables=False)