codeql/python/extractor/lark/lexer.py at codeql-cli/v2.26.3 · github/codeql · GitHub

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## Lexer Implementation

import re

from .utils import Str, classify

from .common import PatternStr, PatternRE, TokenDef

from .exceptions import UnexpectedCharacters, LexError

###{standalone

class Token(Str):

__slots__ = ('type', 'pos_in_stream', 'value', 'line', 'column', 'end_line', 'end_column')

def __new__(cls, type_, value, pos_in_stream=None, line=None, column=None):

self = super(Token, cls).__new__(cls, value)

self.type = type_

self.pos_in_stream = pos_in_stream

self.value = value

self.line = line

self.column = column

self.end_line = None

self.end_column = None

return self

@classmethod

def new_borrow_pos(cls, type_, value, borrow_t):

return cls(type_, value, borrow_t.pos_in_stream, line=borrow_t.line, column=borrow_t.column)

def __reduce__(self):

return (self.__class__, (self.type, self.value, self.pos_in_stream, self.line, self.column, ))

def __repr__(self):

return 'Token(%s, %r)' % (self.type, self.value)

def __deepcopy__(self, memo):

return Token(self.type, self.value, self.pos_in_stream, self.line, self.column)

def __eq__(self, other):

if isinstance(other, Token) and self.type != other.type:

return False

return Str.__eq__(self, other)

__hash__ = Str.__hash__

class LineCounter:

def __init__(self):

self.newline_char = '\n'

self.char_pos = 0

self.line = 1

self.column = 1

self.line_start_pos = 0

def feed(self, token, test_newline=True):

"""Consume a token and calculate the new line & column.

As an optional optimization, set test_newline=False is token doesn't contain a newline.

"""

if test_newline:

newlines = token.count(self.newline_char)

if newlines:

self.line += newlines

self.line_start_pos = self.char_pos + token.rindex(self.newline_char) + 1

self.char_pos += len(token)

self.column = self.char_pos - self.line_start_pos + 1

class _Lex:

"Built to serve both Lexer and ContextualLexer"

def __init__(self, lexer, state=None):

self.lexer = lexer

self.state = state

def lex(self, stream, newline_types, ignore_types):

newline_types = list(newline_types)

ignore_types = list(ignore_types)

line_ctr = LineCounter()

t = None

while True:

lexer = self.lexer

for mre, type_from_index in lexer.mres:

m = mre.match(stream, line_ctr.char_pos)

if m:

value = m.group(0)

type_ = type_from_index[m.lastindex]

if type_ not in ignore_types:

t = Token(type_, value, line_ctr.char_pos, line_ctr.line, line_ctr.column)

if t.type in lexer.callback:

t = lexer.callback[t.type](t)

yield t

else:

if type_ in lexer.callback:

t = Token(type_, value, line_ctr.char_pos, line_ctr.line, line_ctr.column)

lexer.callback[type_](t)

line_ctr.feed(value, type_ in newline_types)

if t:

t.end_line = line_ctr.line

t.end_column = line_ctr.column

break

else:

if line_ctr.char_pos < len(stream):

raise UnexpectedCharacters(stream, line_ctr.char_pos, line_ctr.line, line_ctr.column, state=self.state)

break

class UnlessCallback:

def __init__(self, mres):

self.mres = mres

def __call__(self, t):

for mre, type_from_index in self.mres:

m = mre.match(t.value)

if m:

t.type = type_from_index[m.lastindex]

break

return t

###}

def _create_unless(tokens):

tokens_by_type = classify(tokens, lambda t: type(t.pattern))

assert len(tokens_by_type) <= 2, tokens_by_type.keys()

embedded_strs = set()

callback = {}

for retok in tokens_by_type.get(PatternRE, []):

unless = [] # {}

for strtok in tokens_by_type.get(PatternStr, []):

if strtok.priority > retok.priority:

continue

s = strtok.pattern.value

m = re.match(retok.pattern.to_regexp(), s)

if m and m.group(0) == s:

unless.append(strtok)

if strtok.pattern.flags <= retok.pattern.flags:

embedded_strs.add(strtok)

if unless:

callback[retok.name] = UnlessCallback(build_mres(unless, match_whole=True))

tokens = [t for t in tokens if t not in embedded_strs]

return tokens, callback

def _build_mres(tokens, max_size, match_whole):

# Python sets an unreasonable group limit (currently 100) in its re module

# Worse, the only way to know we reached it is by catching an AssertionError!

# This function recursively tries less and less groups until it's successful.

postfix = '$' if match_whole else ''

mres = []

while tokens:

try:

mre = re.compile(u'|'.join(u'(?P<%s>%s)'%(t.name, t.pattern.to_regexp()+postfix) for t in tokens[:max_size]))

except AssertionError: # Yes, this is what Python provides us.. :/

return _build_mres(tokens, max_size//2, match_whole)

mres.append((mre, {i:n for n,i in mre.groupindex.items()} ))

tokens = tokens[max_size:]

return mres

def build_mres(tokens, match_whole=False):

return _build_mres(tokens, len(tokens), match_whole)

def _regexp_has_newline(r):

return '\n' in r or '\\n' in r or ('(?s' in r and '.' in r)

class Lexer:

"""Lexer interface

Method Signatures:

lex(self, stream) -> Iterator[Token]

set_parser_state(self, state) # Optional

"""

set_parser_state = NotImplemented

lex = NotImplemented

class TraditionalLexer(Lexer):

def __init__(self, tokens, ignore=(), user_callbacks={}):

assert all(isinstance(t, TokenDef) for t in tokens), tokens

tokens = list(tokens)

# Sanitization

for t in tokens:

try:

re.compile(t.pattern.to_regexp())

except:

raise LexError("Cannot compile token %s: %s" % (t.name, t.pattern))

if t.pattern.min_width == 0:

raise LexError("Lexer does not allow zero-width tokens. (%s: %s)" % (t.name, t.pattern))

assert set(ignore) <= {t.name for t in tokens}

# Init

self.newline_types = [t.name for t in tokens if _regexp_has_newline(t.pattern.to_regexp())]

self.ignore_types = list(ignore)

tokens.sort(key=lambda x:(-x.priority, -x.pattern.max_width, -len(x.pattern.value), x.name))

tokens, self.callback = _create_unless(tokens)

assert all(self.callback.values())

for type_, f in user_callbacks.items():

assert type_ not in self.callback

self.callback[type_] = f

self.tokens = tokens

self.mres = build_mres(tokens)

def lex(self, stream):

return _Lex(self).lex(stream, self.newline_types, self.ignore_types)

class ContextualLexer(Lexer):

def __init__(self, tokens, states, ignore=(), always_accept=(), user_callbacks={}):

tokens_by_name = {}

for t in tokens:

assert t.name not in tokens_by_name, t

tokens_by_name[t.name] = t

lexer_by_tokens = {}

self.lexers = {}

for state, accepts in states.items():

key = frozenset(accepts)

try:

lexer = lexer_by_tokens[key]

except KeyError:

accepts = set(accepts) | set(ignore) | set(always_accept)

state_tokens = [tokens_by_name[n] for n in accepts if n and n in tokens_by_name]

lexer = TraditionalLexer(state_tokens, ignore=ignore, user_callbacks=user_callbacks)

lexer_by_tokens[key] = lexer

self.lexers[state] = lexer

self.root_lexer = TraditionalLexer(tokens, ignore=ignore, user_callbacks=user_callbacks)

self.set_parser_state(None) # Needs to be set on the outside

def set_parser_state(self, state):

self.parser_state = state

def lex(self, stream):

l = _Lex(self.lexers[self.parser_state], self.parser_state)

for x in l.lex(stream, self.root_lexer.newline_types, self.root_lexer.ignore_types):

yield x

l.lexer = self.lexers[self.parser_state]

l.state = self.parser_state

codeql/python/extractor/lark/lexer.py at codeql-cli/v2.26.3 · github/codeql · GitHub

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