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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":")
COMMA = Type("COMMA", r",")
SLASH = Type("SLASH", r"/")
ID = Type("ID", r'[a-zA-Z_][a-zA-Z0-9_.#*-]*')
NUMBER = Type("NUMBER", r'[+-]?[0-9]*\.?[0-9]+')
STRING = Type("STRING", r""""(?:[^\\"]|\\.)*"|'(?:[^\\']|\\.)*'""")
WSPACE = Type("WSPACE", r"[ \n\r\t]+")
EOF = Type("EOF")
class Token:
def __init__(self, type, value):
self.type = type
self.value = value
def __repr__(self):
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 character in <string>:%s,%s: %s" % (ln, col, line))
else:
idx = m.lastindex
t = Token(TYPES[idx - 1], m.group(idx))
yield t
pos = m.end()
yield Token(EOF, None)
class ParseError(Exception): pass
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("expecting %s -- got %s" % (", ".join(map(str, types)), self.next()))
else:
t = self.next()
self.idx += 1
return t
def parse(self):
result = self.address()
self.eat(EOF)
return result
def address(self):
name = self.eat(ID).value
subject = None
options = None
if self.matches(SLASH):
self.eat(SLASH)
if self.matches(ID):
subject = self.eat(ID).value
else:
subject = ""
elif self.matches(LBRACE):
options = self.map()
return name, subject, options
def map(self):
self.eat(LBRACE)
result = {}
while True:
if self.matches(RBRACE):
self.eat(RBRACE)
break
else:
if self.matches(ID):
n, v = self.nameval()
result[n] = v
elif self.matches(COMMA):
self.eat(COMMA)
else:
raise ParseError("expecting (ID, COMMA), got %s" % self.next())
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):
return eval(self.eat().value)
elif self.matches(ID):
return self.eat().value
elif self.matches(LBRACE):
return self.map()
else:
raise ParseError("expecting (NUMBER, STRING, LBRACE) got %s" % self.next())
def parse(addr):
return Parser(lex(addr)).parse()
__all__ = ["parse"]
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