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#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you 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 re
TYPES = []
class Type:
def __init__(self, name, pattern=None):
self.name = name
self.pattern = pattern
if self.pattern:
TYPES.append(self)
def __repr__(self):
return self.name
LBRACE = Type("LBRACE", r"\{")
RBRACE = Type("RBRACE", r"\}")
COLON = Type("COLON", r":")
SEMI = Type("SEMI", r";")
SLASH = Type("SLASH", r"/")
COMMA = Type("COMMA", r",")
NUMBER = Type("NUMBER", r'[+-]?[0-9]*\.?[0-9]+')
ID = Type("ID", r'[a-zA-Z_](?:[a-zA-Z0-9_-]*[a-zA-Z0-9_])?')
STRING = Type("STRING", r""""(?:[^\\"]|\\.)*"|'(?:[^\\']|\\.)*'""")
ESC = Type("ESC", r"\\[^ux]|\\x[0-9a-fA-F][0-9a-fA-F]|\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]")
SYM = Type("SYM", r"[.#*%@$^!+-]")
WSPACE = Type("WSPACE", r"[ \n\r\t]+")
EOF = Type("EOF")
class Token:
def __init__(self, type, value, input, position):
self.type = type
self.value = value
self.input = input
self.position = position
def line_info(self):
return line_info(self.input, self.position)
def __repr__(self):
if self.value is None:
return repr(self.type)
else:
return "%s(%r)" % (self.type, self.value)
joined = "|".join(["(%s)" % t.pattern for t in TYPES])
LEXER = re.compile(joined)
class LexError(Exception):
pass
def line_info(st, pos):
idx = 0
lineno = 1
column = 0
line_pos = 0
while idx < pos:
if st[idx] == "\n":
lineno += 1
column = 0
line_pos = idx
column += 1
idx += 1
end = st.find("\n", line_pos)
if end < 0:
end = len(st)
line = st[line_pos:end]
return line, lineno, column
def lex(st):
pos = 0
while pos < len(st):
m = LEXER.match(st, pos)
if m is None:
line, ln, col = line_info(st, pos)
raise LexError("unrecognized characters line:%s,%s: %s" % (ln, col, line))
else:
idx = m.lastindex
t = Token(TYPES[idx - 1], m.group(idx), st, pos)
yield t
pos = m.end()
yield Token(EOF, None, st, pos)
def tok2str(tok):
if tok.type is STRING:
return eval(tok.value)
elif tok.type is ESC:
if tok.value[1] == "x":
return eval('"%s"' % tok.value)
elif tok.value[1] == "u":
return eval('u"%s"' % tok.value)
else:
return tok.value[1]
else:
return tok.value
def tok2obj(tok):
if tok.type in (STRING, NUMBER):
return eval(tok.value)
else:
return tok.value
def toks2str(toks):
if toks:
return "".join(map(tok2str, toks))
else:
return None
class ParseError(Exception):
def __init__(self, token, *expected):
line, ln, col = token.line_info()
exp = ", ".join(map(str, expected))
if len(expected) > 1:
exp = "(%s)" % exp
if expected:
msg = "expecting %s, got %s line:%s,%s:%s" % (exp, token, ln, col, line)
else:
msg = "unexpected token %s line:%s,%s:%s" % (token, ln, col, line)
Exception.__init__(self, msg)
self.token = token
self.expected = expected
class Parser:
def __init__(self, tokens):
self.tokens = [t for t in tokens if t.type is not WSPACE]
self.idx = 0
def next(self):
return self.tokens[self.idx]
def matches(self, *types):
return self.next().type in types
def eat(self, *types):
if types and not self.matches(*types):
raise ParseError(self.next(), *types)
else:
t = self.next()
self.idx += 1
return t
def eat_until(self, *types):
result = []
while not self.matches(*types):
result.append(self.eat())
return result
def parse(self):
result = self.address()
self.eat(EOF)
return result
def address(self):
name = toks2str(self.eat_until(SLASH, SEMI, EOF))
if name is None:
raise ParseError(self.next())
if self.matches(SLASH):
self.eat(SLASH)
subject = toks2str(self.eat_until(SEMI, EOF))
else:
subject = None
if self.matches(SEMI):
self.eat(SEMI)
options = self.map()
else:
options = None
return name, subject, options
def map(self):
self.eat(LBRACE)
result = {}
while True:
if self.matches(ID):
n, v = self.nameval()
result[n] = v
if self.matches(COMMA):
self.eat(COMMA)
elif self.matches(RBRACE):
break
else:
raise ParseError(self.next(), COMMA, RBRACE)
elif self.matches(RBRACE):
break
else:
raise ParseError(self.next(), ID, RBRACE)
self.eat(RBRACE)
return result
def nameval(self):
name = self.eat(ID).value
self.eat(COLON)
val = self.value()
return (name, val)
def value(self):
if self.matches(NUMBER, STRING, ID):
return tok2obj(self.eat())
elif self.matches(LBRACE):
return self.map()
else:
raise ParseError(self.next(), NUMBER, STRING, ID, LBRACE)
def parse(addr):
return Parser(lex(addr)).parse()
__all__ = ["parse", "ParseError"]
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