Mini Shell
# -*- coding: utf-8 -*-
"""
jinja2.lexer
~~~~~~~~~~~~
This module implements a Jinja / Python combination lexer. The
`Lexer` class provided by this module is used to do some preprocessing
for Jinja.
On the one hand it filters out invalid operators like the bitshift
operators we don't allow in templates. On the other hand it separates
template code and python code in expressions.
:copyright: (c) 2017 by the Jinja Team.
:license: BSD, see LICENSE for more details.
"""
import re
from collections import deque
from operator import itemgetter
from jinja2._compat import implements_iterator, intern, iteritems, text_type
from jinja2.exceptions import TemplateSyntaxError
from jinja2.utils import LRUCache
# cache for the lexers. Exists in order to be able to have multiple
# environments with the same lexer
_lexer_cache = LRUCache(50)
# static regular expressions
whitespace_re = re.compile(r'\s+', re.U)
string_re = re.compile(r"('([^'\\]*(?:\\.[^'\\]*)*)'"
r'|"([^"\\]*(?:\\.[^"\\]*)*)")', re.S)
integer_re = re.compile(r'\d+')
try:
# check if this Python supports Unicode identifiers
compile('föö', '<unknown>', 'eval')
except SyntaxError:
# no Unicode support, use ASCII identifiers
name_re = re.compile(r'[a-zA-Z_][a-zA-Z0-9_]*')
check_ident = False
else:
# Unicode support, build a pattern to match valid characters, and set flag
# to use str.isidentifier to validate during lexing
from jinja2 import _identifier
name_re = re.compile(r'[\w{0}]+'.format(_identifier.pattern))
check_ident = True
# remove the pattern from memory after building the regex
import sys
del sys.modules['jinja2._identifier']
import jinja2
del jinja2._identifier
del _identifier
float_re = re.compile(r'(?<!\.)\d+\.\d+')
newline_re = re.compile(r'(\r\n|\r|\n)')
# internal the tokens and keep references to them
TOKEN_ADD = intern('add')
TOKEN_ASSIGN = intern('assign')
TOKEN_COLON = intern('colon')
TOKEN_COMMA = intern('comma')
TOKEN_DIV = intern('div')
TOKEN_DOT = intern('dot')
TOKEN_EQ = intern('eq')
TOKEN_FLOORDIV = intern('floordiv')
TOKEN_GT = intern('gt')
TOKEN_GTEQ = intern('gteq')
TOKEN_LBRACE = intern('lbrace')
TOKEN_LBRACKET = intern('lbracket')
TOKEN_LPAREN = intern('lparen')
TOKEN_LT = intern('lt')
TOKEN_LTEQ = intern('lteq')
TOKEN_MOD = intern('mod')
TOKEN_MUL = intern('mul')
TOKEN_NE = intern('ne')
TOKEN_PIPE = intern('pipe')
TOKEN_POW = intern('pow')
TOKEN_RBRACE = intern('rbrace')
TOKEN_RBRACKET = intern('rbracket')
TOKEN_RPAREN = intern('rparen')
TOKEN_SEMICOLON = intern('semicolon')
TOKEN_SUB = intern('sub')
TOKEN_TILDE = intern('tilde')
TOKEN_WHITESPACE = intern('whitespace')
TOKEN_FLOAT = intern('float')
TOKEN_INTEGER = intern('integer')
TOKEN_NAME = intern('name')
TOKEN_STRING = intern('string')
TOKEN_OPERATOR = intern('operator')
TOKEN_BLOCK_BEGIN = intern('block_begin')
TOKEN_BLOCK_END = intern('block_end')
TOKEN_VARIABLE_BEGIN = intern('variable_begin')
TOKEN_VARIABLE_END = intern('variable_end')
TOKEN_RAW_BEGIN = intern('raw_begin')
TOKEN_RAW_END = intern('raw_end')
TOKEN_COMMENT_BEGIN = intern('comment_begin')
TOKEN_COMMENT_END = intern('comment_end')
TOKEN_COMMENT = intern('comment')
TOKEN_LINESTATEMENT_BEGIN = intern('linestatement_begin')
TOKEN_LINESTATEMENT_END = intern('linestatement_end')
TOKEN_LINECOMMENT_BEGIN = intern('linecomment_begin')
TOKEN_LINECOMMENT_END = intern('linecomment_end')
TOKEN_LINECOMMENT = intern('linecomment')
TOKEN_DATA = intern('data')
TOKEN_INITIAL = intern('initial')
TOKEN_EOF = intern('eof')
# bind operators to token types
operators = {
'+': TOKEN_ADD,
'-': TOKEN_SUB,
'/': TOKEN_DIV,
'//': TOKEN_FLOORDIV,
'*': TOKEN_MUL,
'%': TOKEN_MOD,
'**': TOKEN_POW,
'~': TOKEN_TILDE,
'[': TOKEN_LBRACKET,
']': TOKEN_RBRACKET,
'(': TOKEN_LPAREN,
')': TOKEN_RPAREN,
'{': TOKEN_LBRACE,
'}': TOKEN_RBRACE,
'==': TOKEN_EQ,
'!=': TOKEN_NE,
'>': TOKEN_GT,
'>=': TOKEN_GTEQ,
'<': TOKEN_LT,
'<=': TOKEN_LTEQ,
'=': TOKEN_ASSIGN,
'.': TOKEN_DOT,
':': TOKEN_COLON,
'|': TOKEN_PIPE,
',': TOKEN_COMMA,
';': TOKEN_SEMICOLON
}
reverse_operators = dict([(v, k) for k, v in iteritems(operators)])
assert len(operators) == len(reverse_operators), 'operators dropped'
operator_re = re.compile('(%s)' % '|'.join(re.escape(x) for x in
sorted(operators, key=lambda x: -len(x))))
ignored_tokens = frozenset([TOKEN_COMMENT_BEGIN, TOKEN_COMMENT,
TOKEN_COMMENT_END, TOKEN_WHITESPACE,
TOKEN_LINECOMMENT_BEGIN, TOKEN_LINECOMMENT_END,
TOKEN_LINECOMMENT])
ignore_if_empty = frozenset([TOKEN_WHITESPACE, TOKEN_DATA,
TOKEN_COMMENT, TOKEN_LINECOMMENT])
def _describe_token_type(token_type):
if token_type in reverse_operators:
return reverse_operators[token_type]
return {
TOKEN_COMMENT_BEGIN: 'begin of comment',
TOKEN_COMMENT_END: 'end of comment',
TOKEN_COMMENT: 'comment',
TOKEN_LINECOMMENT: 'comment',
TOKEN_BLOCK_BEGIN: 'begin of statement block',
TOKEN_BLOCK_END: 'end of statement block',
TOKEN_VARIABLE_BEGIN: 'begin of print statement',
TOKEN_VARIABLE_END: 'end of print statement',
TOKEN_LINESTATEMENT_BEGIN: 'begin of line statement',
TOKEN_LINESTATEMENT_END: 'end of line statement',
TOKEN_DATA: 'template data / text',
TOKEN_EOF: 'end of template'
}.get(token_type, token_type)
def describe_token(token):
"""Returns a description of the token."""
if token.type == 'name':
return token.value
return _describe_token_type(token.type)
def describe_token_expr(expr):
"""Like `describe_token` but for token expressions."""
if ':' in expr:
type, value = expr.split(':', 1)
if type == 'name':
return value
else:
type = expr
return _describe_token_type(type)
def count_newlines(value):
"""Count the number of newline characters in the string. This is
useful for extensions that filter a stream.
"""
return len(newline_re.findall(value))
def compile_rules(environment):
"""Compiles all the rules from the environment into a list of rules."""
e = re.escape
rules = [
(len(environment.comment_start_string), 'comment',
e(environment.comment_start_string)),
(len(environment.block_start_string), 'block',
e(environment.block_start_string)),
(len(environment.variable_start_string), 'variable',
e(environment.variable_start_string))
]
if environment.line_statement_prefix is not None:
rules.append((len(environment.line_statement_prefix), 'linestatement',
r'^[ \t\v]*' + e(environment.line_statement_prefix)))
if environment.line_comment_prefix is not None:
rules.append((len(environment.line_comment_prefix), 'linecomment',
r'(?:^|(?<=\S))[^\S\r\n]*' +
e(environment.line_comment_prefix)))
return [x[1:] for x in sorted(rules, reverse=True)]
class Failure(object):
"""Class that raises a `TemplateSyntaxError` if called.
Used by the `Lexer` to specify known errors.
"""
def __init__(self, message, cls=TemplateSyntaxError):
self.message = message
self.error_class = cls
def __call__(self, lineno, filename):
raise self.error_class(self.message, lineno, filename)
class Token(tuple):
"""Token class."""
__slots__ = ()
lineno, type, value = (property(itemgetter(x)) for x in range(3))
def __new__(cls, lineno, type, value):
return tuple.__new__(cls, (lineno, intern(str(type)), value))
def __str__(self):
if self.type in reverse_operators:
return reverse_operators[self.type]
elif self.type == 'name':
return self.value
return self.type
def test(self, expr):
"""Test a token against a token expression. This can either be a
token type or ``'token_type:token_value'``. This can only test
against string values and types.
"""
# here we do a regular string equality check as test_any is usually
# passed an iterable of not interned strings.
if self.type == expr:
return True
elif ':' in expr:
return expr.split(':', 1) == [self.type, self.value]
return False
def test_any(self, *iterable):
"""Test against multiple token expressions."""
for expr in iterable:
if self.test(expr):
return True
return False
def __repr__(self):
return 'Token(%r, %r, %r)' % (
self.lineno,
self.type,
self.value
)
@implements_iterator
class TokenStreamIterator(object):
"""The iterator for tokenstreams. Iterate over the stream
until the eof token is reached.
"""
def __init__(self, stream):
self.stream = stream
def __iter__(self):
return self
def __next__(self):
token = self.stream.current
if token.type is TOKEN_EOF:
self.stream.close()
raise StopIteration()
next(self.stream)
return token
@implements_iterator
class TokenStream(object):
"""A token stream is an iterable that yields :class:`Token`\\s. The
parser however does not iterate over it but calls :meth:`next` to go
one token ahead. The current active token is stored as :attr:`current`.
"""
def __init__(self, generator, name, filename):
self._iter = iter(generator)
self._pushed = deque()
self.name = name
self.filename = filename
self.closed = False
self.current = Token(1, TOKEN_INITIAL, '')
next(self)
def __iter__(self):
return TokenStreamIterator(self)
def __bool__(self):
return bool(self._pushed) or self.current.type is not TOKEN_EOF
__nonzero__ = __bool__ # py2
eos = property(lambda x: not x, doc="Are we at the end of the stream?")
def push(self, token):
"""Push a token back to the stream."""
self._pushed.append(token)
def look(self):
"""Look at the next token."""
old_token = next(self)
result = self.current
self.push(result)
self.current = old_token
return result
def skip(self, n=1):
"""Got n tokens ahead."""
for x in range(n):
next(self)
def next_if(self, expr):
"""Perform the token test and return the token if it matched.
Otherwise the return value is `None`.
"""
if self.current.test(expr):
return next(self)
def skip_if(self, expr):
"""Like :meth:`next_if` but only returns `True` or `False`."""
return self.next_if(expr) is not None
def __next__(self):
"""Go one token ahead and return the old one.
Use the built-in :func:`next` instead of calling this directly.
"""
rv = self.current
if self._pushed:
self.current = self._pushed.popleft()
elif self.current.type is not TOKEN_EOF:
try:
self.current = next(self._iter)
except StopIteration:
self.close()
return rv
def close(self):
"""Close the stream."""
self.current = Token(self.current.lineno, TOKEN_EOF, '')
self._iter = None
self.closed = True
def expect(self, expr):
"""Expect a given token type and return it. This accepts the same
argument as :meth:`jinja2.lexer.Token.test`.
"""
if not self.current.test(expr):
expr = describe_token_expr(expr)
if self.current.type is TOKEN_EOF:
raise TemplateSyntaxError('unexpected end of template, '
'expected %r.' % expr,
self.current.lineno,
self.name, self.filename)
raise TemplateSyntaxError("expected token %r, got %r" %
(expr, describe_token(self.current)),
self.current.lineno,
self.name, self.filename)
try:
return self.current
finally:
next(self)
def get_lexer(environment):
"""Return a lexer which is probably cached."""
key = (environment.block_start_string,
environment.block_end_string,
environment.variable_start_string,
environment.variable_end_string,
environment.comment_start_string,
environment.comment_end_string,
environment.line_statement_prefix,
environment.line_comment_prefix,
environment.trim_blocks,
environment.lstrip_blocks,
environment.newline_sequence,
environment.keep_trailing_newline)
lexer = _lexer_cache.get(key)
if lexer is None:
lexer = Lexer(environment)
_lexer_cache[key] = lexer
return lexer
class Lexer(object):
"""Class that implements a lexer for a given environment. Automatically
created by the environment class, usually you don't have to do that.
Note that the lexer is not automatically bound to an environment.
Multiple environments can share the same lexer.
"""
def __init__(self, environment):
# shortcuts
c = lambda x: re.compile(x, re.M | re.S)
e = re.escape
# lexing rules for tags
tag_rules = [
(whitespace_re, TOKEN_WHITESPACE, None),
(float_re, TOKEN_FLOAT, None),
(integer_re, TOKEN_INTEGER, None),
(name_re, TOKEN_NAME, None),
(string_re, TOKEN_STRING, None),
(operator_re, TOKEN_OPERATOR, None)
]
# assemble the root lexing rule. because "|" is ungreedy
# we have to sort by length so that the lexer continues working
# as expected when we have parsing rules like <% for block and
# <%= for variables. (if someone wants asp like syntax)
# variables are just part of the rules if variable processing
# is required.
root_tag_rules = compile_rules(environment)
# block suffix if trimming is enabled
block_suffix_re = environment.trim_blocks and '\\n?' or ''
# strip leading spaces if lstrip_blocks is enabled
prefix_re = {}
if environment.lstrip_blocks:
# use '{%+' to manually disable lstrip_blocks behavior
no_lstrip_re = e('+')
# detect overlap between block and variable or comment strings
block_diff = c(r'^%s(.*)' % e(environment.block_start_string))
# make sure we don't mistake a block for a variable or a comment
m = block_diff.match(environment.comment_start_string)
no_lstrip_re += m and r'|%s' % e(m.group(1)) or ''
m = block_diff.match(environment.variable_start_string)
no_lstrip_re += m and r'|%s' % e(m.group(1)) or ''
# detect overlap between comment and variable strings
comment_diff = c(r'^%s(.*)' % e(environment.comment_start_string))
m = comment_diff.match(environment.variable_start_string)
no_variable_re = m and r'(?!%s)' % e(m.group(1)) or ''
lstrip_re = r'^[ \t]*'
block_prefix_re = r'%s%s(?!%s)|%s\+?' % (
lstrip_re,
e(environment.block_start_string),
no_lstrip_re,
e(environment.block_start_string),
)
comment_prefix_re = r'%s%s%s|%s\+?' % (
lstrip_re,
e(environment.comment_start_string),
no_variable_re,
e(environment.comment_start_string),
)
prefix_re['block'] = block_prefix_re
prefix_re['comment'] = comment_prefix_re
else:
block_prefix_re = '%s' % e(environment.block_start_string)
self.newline_sequence = environment.newline_sequence
self.keep_trailing_newline = environment.keep_trailing_newline
# global lexing rules
self.rules = {
'root': [
# directives
(c('(.*?)(?:%s)' % '|'.join(
[r'(?P<raw_begin>(?:\s*%s\-|%s)\s*raw\s*(?:\-%s\s*|%s))' % (
e(environment.block_start_string),
block_prefix_re,
e(environment.block_end_string),
e(environment.block_end_string)
)] + [
r'(?P<%s_begin>\s*%s\-|%s)' % (n, r, prefix_re.get(n,r))
for n, r in root_tag_rules
])), (TOKEN_DATA, '#bygroup'), '#bygroup'),
# data
(c('.+'), TOKEN_DATA, None)
],
# comments
TOKEN_COMMENT_BEGIN: [
(c(r'(.*?)((?:\-%s\s*|%s)%s)' % (
e(environment.comment_end_string),
e(environment.comment_end_string),
block_suffix_re
)), (TOKEN_COMMENT, TOKEN_COMMENT_END), '#pop'),
(c('(.)'), (Failure('Missing end of comment tag'),), None)
],
# blocks
TOKEN_BLOCK_BEGIN: [
(c(r'(?:\-%s\s*|%s)%s' % (
e(environment.block_end_string),
e(environment.block_end_string),
block_suffix_re
)), TOKEN_BLOCK_END, '#pop'),
] + tag_rules,
# variables
TOKEN_VARIABLE_BEGIN: [
(c(r'\-%s\s*|%s' % (
e(environment.variable_end_string),
e(environment.variable_end_string)
)), TOKEN_VARIABLE_END, '#pop')
] + tag_rules,
# raw block
TOKEN_RAW_BEGIN: [
(c(r'(.*?)((?:\s*%s\-|%s)\s*endraw\s*(?:\-%s\s*|%s%s))' % (
e(environment.block_start_string),
block_prefix_re,
e(environment.block_end_string),
e(environment.block_end_string),
block_suffix_re
)), (TOKEN_DATA, TOKEN_RAW_END), '#pop'),
(c('(.)'), (Failure('Missing end of raw directive'),), None)
],
# line statements
TOKEN_LINESTATEMENT_BEGIN: [
(c(r'\s*(\n|$)'), TOKEN_LINESTATEMENT_END, '#pop')
] + tag_rules,
# line comments
TOKEN_LINECOMMENT_BEGIN: [
(c(r'(.*?)()(?=\n|$)'), (TOKEN_LINECOMMENT,
TOKEN_LINECOMMENT_END), '#pop')
]
}
def _normalize_newlines(self, value):
"""Called for strings and template data to normalize it to unicode."""
return newline_re.sub(self.newline_sequence, value)
def tokenize(self, source, name=None, filename=None, state=None):
"""Calls tokeniter + tokenize and wraps it in a token stream.
"""
stream = self.tokeniter(source, name, filename, state)
return TokenStream(self.wrap(stream, name, filename), name, filename)
def wrap(self, stream, name=None, filename=None):
"""This is called with the stream as returned by `tokenize` and wraps
every token in a :class:`Token` and converts the value.
"""
for lineno, token, value in stream:
if token in ignored_tokens:
continue
elif token == 'linestatement_begin':
token = 'block_begin'
elif token == 'linestatement_end':
token = 'block_end'
# we are not interested in those tokens in the parser
elif token in ('raw_begin', 'raw_end'):
continue
elif token == 'data':
value = self._normalize_newlines(value)
elif token == 'keyword':
token = value
elif token == 'name':
value = str(value)
if check_ident and not value.isidentifier():
raise TemplateSyntaxError(
'Invalid character in identifier',
lineno, name, filename)
elif token == 'string':
# try to unescape string
try:
value = self._normalize_newlines(value[1:-1]) \
.encode('ascii', 'backslashreplace') \
.decode('unicode-escape')
except Exception as e:
msg = str(e).split(':')[-1].strip()
raise TemplateSyntaxError(msg, lineno, name, filename)
elif token == 'integer':
value = int(value)
elif token == 'float':
value = float(value)
elif token == 'operator':
token = operators[value]
yield Token(lineno, token, value)
def tokeniter(self, source, name, filename=None, state=None):
"""This method tokenizes the text and returns the tokens in a
generator. Use this method if you just want to tokenize a template.
"""
source = text_type(source)
lines = source.splitlines()
if self.keep_trailing_newline and source:
for newline in ('\r\n', '\r', '\n'):
if source.endswith(newline):
lines.append('')
break
source = '\n'.join(lines)
pos = 0
lineno = 1
stack = ['root']
if state is not None and state != 'root':
assert state in ('variable', 'block'), 'invalid state'
stack.append(state + '_begin')
else:
state = 'root'
statetokens = self.rules[stack[-1]]
source_length = len(source)
balancing_stack = []
while 1:
# tokenizer loop
for regex, tokens, new_state in statetokens:
m = regex.match(source, pos)
# if no match we try again with the next rule
if m is None:
continue
# we only match blocks and variables if braces / parentheses
# are balanced. continue parsing with the lower rule which
# is the operator rule. do this only if the end tags look
# like operators
if balancing_stack and \
tokens in ('variable_end', 'block_end',
'linestatement_end'):
continue
# tuples support more options
if isinstance(tokens, tuple):
for idx, token in enumerate(tokens):
# failure group
if token.__class__ is Failure:
raise token(lineno, filename)
# bygroup is a bit more complex, in that case we
# yield for the current token the first named
# group that matched
elif token == '#bygroup':
for key, value in iteritems(m.groupdict()):
if value is not None:
yield lineno, key, value
lineno += value.count('\n')
break
else:
raise RuntimeError('%r wanted to resolve '
'the token dynamically'
' but no group matched'
% regex)
# normal group
else:
data = m.group(idx + 1)
if data or token not in ignore_if_empty:
yield lineno, token, data
lineno += data.count('\n')
# strings as token just are yielded as it.
else:
data = m.group()
# update brace/parentheses balance
if tokens == 'operator':
if data == '{':
balancing_stack.append('}')
elif data == '(':
balancing_stack.append(')')
elif data == '[':
balancing_stack.append(']')
elif data in ('}', ')', ']'):
if not balancing_stack:
raise TemplateSyntaxError('unexpected \'%s\'' %
data, lineno, name,
filename)
expected_op = balancing_stack.pop()
if expected_op != data:
raise TemplateSyntaxError('unexpected \'%s\', '
'expected \'%s\'' %
(data, expected_op),
lineno, name,
filename)
# yield items
if data or tokens not in ignore_if_empty:
yield lineno, tokens, data
lineno += data.count('\n')
# fetch new position into new variable so that we can check
# if there is a internal parsing error which would result
# in an infinite loop
pos2 = m.end()
# handle state changes
if new_state is not None:
# remove the uppermost state
if new_state == '#pop':
stack.pop()
# resolve the new state by group checking
elif new_state == '#bygroup':
for key, value in iteritems(m.groupdict()):
if value is not None:
stack.append(key)
break
else:
raise RuntimeError('%r wanted to resolve the '
'new state dynamically but'
' no group matched' %
regex)
# direct state name given
else:
stack.append(new_state)
statetokens = self.rules[stack[-1]]
# we are still at the same position and no stack change.
# this means a loop without break condition, avoid that and
# raise error
elif pos2 == pos:
raise RuntimeError('%r yielded empty string without '
'stack change' % regex)
# publish new function and start again
pos = pos2
break
# if loop terminated without break we haven't found a single match
# either we are at the end of the file or we have a problem
else:
# end of text
if pos >= source_length:
return
# something went wrong
raise TemplateSyntaxError('unexpected char %r at %d' %
(source[pos], pos), lineno,
name, filename)
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