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# -*- coding: utf-8 -*-
# Copyright © 2009/2021 Andrey Vlasovskikh
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of this
# software and associated documentation files (the "Software"), to deal in the Software
# without restriction, including without limitation the rights to use, copy, modify,
# merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be included in all copies
# or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
# INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
# PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
# OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
from __future__ import unicode_literals
__all__ = ["make_tokenizer", "TokenSpec", "Token", "LexerError"]
import re
class LexerError(Exception):
def __init__(self, place, msg):
self.place = place
self.msg = msg
def __str__(self):
s = "cannot tokenize data"
line, pos = self.place
return '%s: %d,%d: "%s"' % (s, line, pos, self.msg)
class TokenSpec(object):
"""A token specification for generating a lexer via `make_tokenizer()`."""
def __init__(self, type, pattern, flags=0):
"""Initialize a `TokenSpec` object.
Parameters:
type (str): User-defined type of the token (e.g. `"name"`, `"number"`,
`"operator"`)
pattern (str): Regexp for matching this token type
flags (int, optional): Regexp flags, the second argument of `re.compile()`
"""
self.type = type
self.pattern = pattern
self.flags = flags
def __repr__(self):
return "TokenSpec(%r, %r, %r)" % (self.type, self.pattern, self.flags)
class Token(object):
"""A token object that represents a substring of certain type in your text.
You can compare tokens for equality using the `==` operator. Tokens also define
custom `repr()` and `str()`.
Attributes:
type (str): User-defined type of the token (e.g. `"name"`, `"number"`,
`"operator"`)
value (str): Text value of the token
start (Optional[Tuple[int, int]]): Start position (_line_, _column_)
end (Optional[Tuple[int, int]]): End position (_line_, _column_)
"""
def __init__(self, type, value, start=None, end=None):
"""Initialize a `Token` object."""
self.type = type
self.value = value
self.start = start
self.end = end
def __repr__(self):
return "Token(%r, %r)" % (self.type, self.value)
def __eq__(self, other):
# FIXME: Case sensitivity is assumed here
if other is None:
return False
else:
return self.type == other.type and self.value == other.value
def _pos_str(self):
if self.start is None or self.end is None:
return ""
else:
sl, sp = self.start
el, ep = self.end
return "%d,%d-%d,%d:" % (sl, sp, el, ep)
def __str__(self):
s = "%s %s '%s'" % (self._pos_str(), self.type, self.value)
return s.strip()
@property
def name(self):
return self.value
def pformat(self):
return "%s %s '%s'" % (
self._pos_str().ljust(20), # noqa
self.type.ljust(14),
self.value,
)
def make_tokenizer(specs):
# noinspection GrazieInspection
"""Make a function that tokenizes text based on the regexp specs.
Type: `(Sequence[TokenSpec | Tuple]) -> Callable[[str], Iterable[Token]]`
A token spec is `TokenSpec` instance.
!!! Note
For legacy reasons, a token spec may also be a tuple of (_type_, _args_), where
_type_ sets the value of `Token.type` for the token, and _args_ are the
positional arguments for `re.compile()`: either just (_pattern_,) or
(_pattern_, _flags_).
It returns a tokenizer function that takes a string and returns an iterable of
`Token` objects, or raises `LexerError` if it cannot tokenize the string according
to its token specs.
Examples:
```pycon
>>> tokenize = make_tokenizer([
... TokenSpec("space", r"\\s+"),
... TokenSpec("id", r"\\w+"),
... TokenSpec("op", r"[,!]"),
... ])
>>> text = "Hello, World!"
>>> [t for t in tokenize(text) if t.type != "space"] # noqa
[Token('id', 'Hello'), Token('op', ','), Token('id', 'World'), Token('op', '!')]
>>> text = "Bye?"
>>> list(tokenize(text))
Traceback (most recent call last):
...
lexer.LexerError: cannot tokenize data: 1,4: "Bye?"
```
"""
compiled = []
for spec in specs:
if isinstance(spec, TokenSpec):
c = spec.type, re.compile(spec.pattern, spec.flags)
else:
name, args = spec
c = name, re.compile(*args)
compiled.append(c)
def match_specs(s, i, position):
line, pos = position
for type, regexp in compiled:
m = regexp.match(s, i)
if m is not None:
value = m.group()
nls = value.count("\n")
n_line = line + nls
if nls == 0:
n_pos = pos + len(value)
else:
n_pos = len(value) - value.rfind("\n") - 1
return Token(type, value, (line, pos + 1), (n_line, n_pos))
else:
err_line = s.splitlines()[line - 1]
raise LexerError((line, pos + 1), err_line)
def f(s):
length = len(s)
line, pos = 1, 0
i = 0
while i < length:
t = match_specs(s, i, (line, pos))
yield t
line, pos = t.end
i += len(t.value)
return f
# This is an example of token specs. See also [this article][1] for a
# discussion of searching for multiline comments using regexps (including `*?`).
#
# [1]: http://ostermiller.org/findcomment.html
_example_token_specs = [
TokenSpec("COMMENT", r"\(\*(.|[\r\n])*?\*\)", re.MULTILINE),
TokenSpec("COMMENT", r"\{(.|[\r\n])*?\}", re.MULTILINE),
TokenSpec("COMMENT", r"//.*"),
TokenSpec("NL", r"[\r\n]+"),
TokenSpec("SPACE", r"[ \t\r\n]+"),
TokenSpec("NAME", r"[A-Za-z_][A-Za-z_0-9]*"),
TokenSpec("REAL", r"[0-9]+\.[0-9]*([Ee][+\-]?[0-9]+)*"),
TokenSpec("INT", r"[0-9]+"),
TokenSpec("INT", r"\$[0-9A-Fa-f]+"),
TokenSpec("OP", r"(\.\.)|(<>)|(<=)|(>=)|(:=)|[;,=\(\):\[\]\.+\-<>\*/@\^]"),
TokenSpec("STRING", r"'([^']|(''))*'"),
TokenSpec("CHAR", r"#[0-9]+"),
TokenSpec("CHAR", r"#\$[0-9A-Fa-f]+"),
]
# tokenize = make_tokenizer(_example_token_specs)
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