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#!/usr/bin/env python3
#
# Copyright (c) 2016 Intel Corporation.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import sys
import os
import copy
import threading
import re
try:
import ply.lex as lex
import ply.yacc as yacc
except ImportError:
print("PLY library for Python 3 not installed.")
print("Please install the python3-ply package using your workstation's")
print("package manager or the 'pip' tool.")
sys.exit(1)
reserved = {
'and' : 'AND',
'or' : 'OR',
'not' : 'NOT',
'in' : 'IN',
}
tokens = [
"HEX",
"STR",
"INTEGER",
"EQUALS",
"NOTEQUALS",
"LT",
"GT",
"LTEQ",
"GTEQ",
"OPAREN",
"CPAREN",
"OBRACKET",
"CBRACKET",
"COMMA",
"SYMBOL",
"COLON",
] + list(reserved.values())
def t_HEX(t):
r"0x[0-9a-fA-F]+"
t.value = str(int(t.value, 16))
return t
def t_INTEGER(t):
r"\d+"
t.value = str(int(t.value))
return t
def t_STR(t):
r'\"([^\\\n]|(\\.))*?\"|\'([^\\\n]|(\\.))*?\''
# nip off the quotation marks
t.value = t.value[1:-1]
return t
t_EQUALS = r"=="
t_NOTEQUALS = r"!="
t_LT = r"<"
t_GT = r">"
t_LTEQ = r"<="
t_GTEQ = r">="
t_OPAREN = r"[(]"
t_CPAREN = r"[)]"
t_OBRACKET = r"\["
t_CBRACKET = r"\]"
t_COMMA = r","
t_COLON = ":"
def t_SYMBOL(t):
r"[A-Za-z_][0-9A-Za-z_]*"
t.type = reserved.get(t.value, "SYMBOL")
return t
t_ignore = " \t\n"
def t_error(t):
raise SyntaxError("Unexpected token '%s'" % t.value)
lex.lex()
precedence = (
('left', 'OR'),
('left', 'AND'),
('right', 'NOT'),
('nonassoc' , 'EQUALS', 'NOTEQUALS', 'GT', 'LT', 'GTEQ', 'LTEQ', 'IN'),
)
def p_expr_or(p):
'expr : expr OR expr'
p[0] = ("or", p[1], p[3])
def p_expr_and(p):
'expr : expr AND expr'
p[0] = ("and", p[1], p[3])
def p_expr_not(p):
'expr : NOT expr'
p[0] = ("not", p[2])
def p_expr_parens(p):
'expr : OPAREN expr CPAREN'
p[0] = p[2]
def p_expr_eval(p):
"""expr : SYMBOL EQUALS const
| SYMBOL NOTEQUALS const
| SYMBOL GT number
| SYMBOL LT number
| SYMBOL GTEQ number
| SYMBOL LTEQ number
| SYMBOL IN list
| SYMBOL COLON STR"""
p[0] = (p[2], p[1], p[3])
def p_expr_single(p):
"""expr : SYMBOL"""
p[0] = ("exists", p[1])
def p_list(p):
"""list : OBRACKET list_intr CBRACKET"""
p[0] = p[2]
def p_list_intr_single(p):
"""list_intr : const"""
p[0] = [p[1]]
def p_list_intr_mult(p):
"""list_intr : list_intr COMMA const"""
p[0] = copy.copy(p[1])
p[0].append(p[3])
def p_const(p):
"""const : STR
| number"""
p[0] = p[1]
def p_number(p):
"""number : INTEGER
| HEX"""
p[0] = p[1]
def p_error(p):
if p:
raise SyntaxError("Unexpected token '%s'" % p.value)
else:
raise SyntaxError("Unexpected end of expression")
parser = yacc.yacc()
def ast_sym(ast, env):
if ast in env:
return str(env[ast])
return ""
def ast_sym_int(ast, env):
if ast in env:
return int(env[ast])
return 0
def ast_expr(ast, env):
if ast[0] == "not":
return not ast_expr(ast[1], env)
elif ast[0] == "or":
return ast_expr(ast[1], env) or ast_expr(ast[2], env)
elif ast[0] == "and":
return ast_expr(ast[1], env) and ast_expr(ast[2], env)
elif ast[0] == "==":
return ast_sym(ast[1], env) == ast[2]
elif ast[0] == "!=":
return ast_sym(ast[1], env) != ast[2]
elif ast[0] == ">":
return ast_sym_int(ast[1], env) > int(ast[2])
elif ast[0] == "<":
return ast_sym_int(ast[1], env) < int(ast[2])
elif ast[0] == ">=":
return ast_sym_int(ast[1], env) >= int(ast[2])
elif ast[0] == "<=":
return ast_sym_int(ast[1], env) <= int(ast[2])
elif ast[0] == "in":
return ast_sym(ast[1], env) in ast[2]
elif ast[0] == "exists":
return True if ast_sym(ast[1], env) else False
elif ast[0] == ":":
return True if re.compile(ast[2]).match(ast_sym(ast[1], env)) else False
mutex = threading.Lock()
def parse(expr_text, env):
"""Given a text representation of an expression in our language,
use the provided environment to determine whether the expression
is true or false"""
# Like it's C counterpart, state machine is not thread-safe
mutex.acquire()
try:
ast = parser.parse(expr_text)
finally:
mutex.release()
return ast_expr(ast, env)
# Just some test code
if __name__ == "__main__":
local_env = {
"A" : "1",
"C" : "foo",
"D" : "20",
"E" : 0x100,
"F" : "baz"
}
for line in open(sys.argv[1]).readlines():
lex.input(line)
for tok in iter(lex.token, None):
print(tok.type, tok.value)
parser = yacc.yacc()
print(parser.parse(line))
print(parse(line, local_env))
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