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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
class Type:
def __init__(self, name, pattern=None):
self.name = name
self.pattern = pattern
def __repr__(self):
return self.name
class Lexicon:
def __init__(self):
self.types = []
self._eof = None
def define(self, name, pattern):
t = Type(name, pattern)
self.types.append(t)
return t
def eof(self, name):
t = Type(name)
self._eof = t
return t
def compile(self):
types = self.types[:]
joined = "|".join(["(%s)" % t.pattern for t in types])
rexp = re.compile(joined)
return Lexer(types, self._eof, rexp)
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(%s)" % (self.type, self.value)
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
class Lexer:
def __init__(self, types, eof, rexp):
self.types = types
self.eof = eof
self.rexp = rexp
self.byname = {}
for t in self.types + [eof]:
self.byname[t.name] = t
def type(self, name):
return self.byname[name]
def lex(self, st):
pos = 0
while pos < len(st):
m = self.rexp.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(self.types[idx - 1], m.group(idx), st, pos)
yield t
pos = m.end()
yield Token(self.eof, None, st, pos)
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