"""Implements a Jinja / Python combination lexer. The ``Lexer`` class
is used to do some preprocessing. It filters out invalid operators like
the bitshift operators we don't allow in templates. It separates
template code and python code in expressions.
"""
import re
import typing as t
from ast import literal_eval
from collections import deque
from sys import intern
from ._identifier import pattern as name_re
from .exceptions import TemplateSyntaxError
from .utils import LRUCache
if t.TYPE_CHECKING:
import typing_extensions as te
from .environment import Environment
# cache for the lexers. Exists in order to be able to have multiple
# environments with the same lexer
_lexer_cache: t.MutableMapping[t.Tuple, "Lexer"] = LRUCache(50) # type: ignore
# static regular expressions
whitespace_re = re.compile(r"\s+")
newline_re = re.compile(r"(\r\n|\r|\n)")
string_re = re.compile(
r"('([^'\\]*(?:\\.[^'\\]*)*)'" r'|"([^"\\]*(?:\\.[^"\\]*)*)")', re.S
)
integer_re = re.compile(
r"""
(
0b(_?[0-1])+ # binary
|
0o(_?[0-7])+ # octal
|
0x(_?[\da-f])+ # hex
|
[1-9](_?\d)* # decimal
|
0(_?0)* # decimal zero
)
""",
re.IGNORECASE | re.VERBOSE,
)
float_re = re.compile(
r"""
(?<!\.) # doesn't start with a .
(\d+_)*\d+ # digits, possibly _ separated
(
(\.(\d+_)*\d+)? # optional fractional part
e[+\-]?(\d+_)*\d+ # exponent part
|
\.(\d+_)*\d+ # required fractional part
)
""",
re.IGNORECASE | re.VERBOSE,
)
# 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 = {v: k for k, v in operators.items()}
assert len(operators) == len(reverse_operators), "operators dropped"
operator_re = re.compile(
f"({'|'.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: str) -> str:
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: "Token") -> str:
"""Returns a description of the token."""
if token.type == TOKEN_NAME:
return token.value
return _describe_token_type(token.type)
def describe_token_expr(expr: str) -> str:
"""Like `describe_token` but for token expressions."""
if ":" in expr:
type, value = expr.split(":", 1)
if type == TOKEN_NAME:
return value
else:
type = expr
return _describe_token_type(type)
def count_newlines(value: str) -> int:
"""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: "Environment") -> t.List[t.Tuple[str, str]]:
"""Compiles all the rules from the environment into a list of rules."""
e = re.escape
rules = [
(
len(environment.comment_start_string),
TOKEN_COMMENT_BEGIN,
e(environment.comment_start_string),
),
(
len(environment.block_start_string),
TOKEN_BLOCK_BEGIN,
e(environment.block_start_string),
),
(
len(environment.variable_start_string),
TOKEN_VARIABLE_BEGIN,
e(environment.variable_start_string),
),
]
if environment.line_statement_prefix is not None:
rules.append(
(
len(environment.line_statement_prefix),
TOKEN_LINESTATEMENT_BEGIN,
r"^[ \t\v]*" + e(environment.line_statement_prefix),
)
)
if environment.line_comment_prefix is not None:
rules.append(
(
len(environment.line_comment_prefix),
TOKEN_LINECOMMENT_BEGIN,
r"(?:^|(?<=\S))[^\S\r\n]*" + e(environment.line_comment_prefix),
)
)
return [x[1:] for x in sorted(rules, reverse=True)]
class Failure:
"""Class that raises a `TemplateSyntaxError` if called.
Used by the `Lexer` to specify known errors.
"""
def __init__(
self, message: str, cls: t.Type[TemplateSyntaxError] = TemplateSyntaxError
) -> None:
self.message = message
self.error_class = cls
def __call__(self, lineno: int, filename: str) -> "te.NoReturn":
raise self.error_class(self.message, lineno, filename)
class Token(t.NamedTuple):
lineno: int
type: str
value: str
def __str__(self) -> str:
return describe_token(self)
def test(self, expr: str) -> bool:
"""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
if ":" in expr:
return expr.split(":", 1) == [self.type, self.value]
return False
def test_any(self, *iterable: str) -> bool:
"""Test against multiple token expressions."""
return any(self.test(expr) for expr in iterable)
class TokenStreamIterator:
"""The iterator for tokenstreams. Iterate over the stream
until the eof token is reached.
"""
def __init__(self, stream: "TokenStream") -> None:
self.stream = stream
def __iter__(self) -> "TokenStreamIterator":
return self
def __next__(self) -> Token:
token = self.stream.current
if token.type is TOKEN_EOF:
self.stream.close()
raise StopIteration
next(self.stream)
return token
class TokenStream:
"""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: t.Iterable[Token],
name: t.Optional[str],
filename: t.Optional[str],
):
self._iter = iter(generator)
self._pushed: "te.Deque[Token]" = deque()
self.name = name
self.filename = filename
self.closed = False
self.current = Token(1, TOKEN_INITIAL, "")
next(self)
def __iter__(self) -> TokenStreamIterator:
return TokenStreamIterator(self)
def __bool__(self) -> bool:
return bool(self._pushed) or self.current.type is not TOKEN_EOF
@property
def eos(self) -> bool:
"""Are we at the end of the stream?"""
return not self
def push(self, token: Token) -> None:
"""Push a token back to the stream."""
self._pushed.append(token)
def look(self) -> Token:
"""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: int = 1) -> None:
"""Got n tokens ahead."""
for _ in range(n):
next(self)
def next_if(self, expr: str) -> t.Optional[Token]:
"""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)
return None
def skip_if(self, expr: str) -> bool:
"""Like :meth:`next_if` but only returns `True` or `False`."""
return self.next_if(expr) is not None
def __next__(self) -> Token:
"""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) -> None:
"""Close the stream."""
self.current = Token(self.current.lineno, TOKEN_EOF, "")
self._iter = iter(())
self.closed = True
def expect(self, expr: str) -> Token:
"""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(
f"unexpected end of template, expected {expr!r}.",
self.current.lineno,
self.name,
self.filename,
)
raise TemplateSyntaxError(
f"expected token {expr!r}, got {describe_token(self.current)!r}",
self.current.lineno,
self.name,
self.filename,
)
return next(self)
def get_lexer(environment: "Environment") -> "Lexer":
"""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_cache[key] = lexer = Lexer(environment)
return lexer
class OptionalLStrip(tuple):
"""A special tuple for marking a point in the state that can have
lstrip applied.
"""
__slots__ = ()
# Even though it looks like a no-op, creating instances fails
# without this.
def __new__(cls, *members, **kwargs): # type: ignore
return super().__new__(cls, members)
class _Rule(t.NamedTuple):
pattern: t.Pattern[str]
tokens: t.Union[str, t.Tuple[str, ...], t.Tuple[Failure]]
command: t.Optional[str]
class Lexer:
"""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: "Environment") -> None:
# shortcuts
e = re.escape
def c(x: str) -> t.Pattern[str]:
return re.compile(x, re.M | re.S)
# lexing rules for tags
tag_rules: t.List[_Rule] = [
_Rule(whitespace_re, TOKEN_WHITESPACE, None),
_Rule(float_re, TOKEN_FLOAT, None),
_Rule(integer_re, TOKEN_INTEGER, None),
_Rule(name_re, TOKEN_NAME, None),
_Rule(string_re, TOKEN_STRING, None),
_Rule(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_start_re = e(environment.block_start_string)
block_end_re = e(environment.block_end_string)
comment_end_re = e(environment.comment_end_string)
variable_end_re = e(environment.variable_end_string)
# block suffix if trimming is enabled
block_suffix_re = "\\n?" if environment.trim_blocks else ""
self.lstrip_blocks = environment.lstrip_blocks
self.newline_sequence = environment.newline_sequence
self.keep_trailing_newline = environment.keep_trailing_newline
root_raw_re = (
rf"(?P<raw_begin>{block_start_re}(\-|\+|)\s*raw\s*"
rf"(?:\-{block_end_re}\s*|{block_end_re}))"
)
root_parts_re = "|".join(
[root_raw_re] + [rf"(?P<{n}>{r}(\-|\+|))" for n, r in root_tag_rules]
)
# global lexing rules
self.rules: t.Dict[str, t.List[_Rule]] = {
"root": [
# directives
_Rule(
c(rf"(.*?)(?:{root_parts_re})"),
OptionalLStrip(TOKEN_DATA, "#bygroup"), # type: ignore
"#bygroup",
),
# data
_Rule(c(".+"), TOKEN_DATA, None),
],
# comments
TOKEN_COMMENT_BEGIN: [
_Rule(
c(
rf"(.*?)((?:\+{comment_end_re}|\-{comment_end_re}\s*"
rf"|{comment_end_re}{block_suffix_re}))"
),
(TOKEN_COMMENT, TOKEN_COMMENT_END),
"#pop",
),
_Rule(c(r"(.)"), (Failure("Missing end of comment tag"),), None),
],
# blocks
TOKEN_BLOCK_BEGIN: [
_Rule(
c(
rf"(?:\+{block_end_re}|\-{block_end_re}\s*"
rf"|{block_end_re}{block_suffix_re})"
),
TOKEN_BLOCK_END,
"#pop",
),
]
+ tag_rules,
# variables
TOKEN_VARIABLE_BEGIN: [
_Rule(
c(rf"\-{variable_end_re}\s*|{variable_end_re}"),
TOKEN_VARIABLE_END,
"#pop",
)
]
+ tag_rules,
# raw block
TOKEN_RAW_BEGIN: [
_Rule(
c(
rf"(.*?)((?:{block_start_re}(\-|\+|))\s*endraw\s*"
rf"(?:\+{block_end_re}|\-{block_end_re}\s*"
rf"|{block_end_re}{block_suffix_re}))"
),
OptionalLStrip(TOKEN_DATA, TOKEN_RAW_END), # type: ignore
"#pop",
),
_Rule(c(r"(.)"), (Failure("Missing end of raw directive"),), None),
],
# line statements
TOKEN_LINESTATEMENT_BEGIN: [
_Rule(c(r"\s*(\n|$)"), TOKEN_LINESTATEMENT_END, "#pop")
]
+ tag_rules,
# line comments
TOKEN_LINECOMMENT_BEGIN: [
_Rule(
c(r"(.*?)()(?=\n|$)"),
(TOKEN_LINECOMMENT, TOKEN_LINECOMMENT_END),
"#pop",
)
],
}
def _normalize_newlines(self, value: str) -> str:
"""Replace all newlines with the configured sequence in strings
and template data.
"""
return newline_re.sub(self.newline_sequence, value)
def tokenize(
self,
source: str,
name: t.Optional[str] = None,
filename: t.Optional[str] = None,
state: t.Optional[str] = None,
) -> TokenStream:
"""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: t.Iterable[t.Tuple[int, str, str]],
name: t.Optional[str] = None,
filename: t.Optional[str] = None,
) -> t.Iterator[Token]:
"""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_str in stream:
if token in ignored_tokens:
continue
value: t.Any = value_str
if token == TOKEN_LINESTATEMENT_BEGIN:
token = TOKEN_BLOCK_BEGIN
elif token == TOKEN_LINESTATEMENT_END:
token = TOKEN_BLOCK_END
# we are not interested in those tokens in the parser
elif token in (TOKEN_RAW_BEGIN, TOKEN_RAW_END):
continue
elif token == TOKEN_DATA:
value = self._normalize_newlines(value_str)
elif token == "keyword":
token = value_str
elif token == TOKEN_NAME:
value = value_str
if not value.isidentifier():
raise TemplateSyntaxError(
"Invalid character in identifier", lineno, name, filename
)
elif token == TOKEN_STRING:
# try to unescape string
try:
value = (
self._normalize_newlines(value_str[1:-1])
.encode("ascii", "backslashreplace")
.decode("unicode-escape")
)
except Exception as e:
msg = str(e).split(":")[-1].strip()
raise TemplateSyntaxError(msg, lineno, name, filename) from e
elif token == TOKEN_INTEGER:
value = int(value_str.replace("_", ""), 0)
elif token == TOKEN_FLOAT:
# remove all "_" first to support more Python versions
value = literal_eval(value_str.replace("_", ""))
elif token == TOKEN_OPERATOR:
token = operators[value_str]
yield Token(lineno, token, value)
def tokeniter(
self,
source: str,
name: t.Optional[str],
filename: t.Optional[str] = None,
state: t.Optional[str] = None,
) -> t.Iterator[t.Tuple[int, str, str]]:
"""This method tokenizes the text and returns the tokens in a
generator. Use this method if you just want to tokenize a template.
.. versionchanged:: 3.0
Only ``\\n``, ``\\r\\n`` and ``\\r`` are treated as line
breaks.
"""
lines = newline_re.split(source)[::2]
if not self.keep_trailing_newline and lines[-1] == "":
del lines[-1]
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")
statetokens = self.rules[stack[-1]]
source_length = len(source)
balancing_stack: t.List[str] = []
newlines_stripped = 0
line_starting = True
while True:
# 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 (
TOKEN_VARIABLE_END,
TOKEN_BLOCK_END,
TOKEN_LINESTATEMENT_END,
):
continue
# tuples support more options
if isinstance(tokens, tuple):
groups: t.Sequence[str] = m.groups()
if isinstance(tokens, OptionalLStrip):
# Rule supports lstrip. Match will look like
# text, block type, whitespace control, type, control, ...
text = groups[0]
# Skipping the text and first type, every other group is the
# whitespace control for each type. One of the groups will be
# -, +, or empty string instead of None.
strip_sign = next(g for g in groups[2::2] if g is not None)
if strip_sign == "-":
# Strip all whitespace between the text and the tag.
stripped = text.rstrip()
newlines_stripped = text[len(stripped) :].count("\n")
groups = [stripped, *groups[1:]]
elif (
# Not marked for preserving whitespace.
strip_sign != "+"
# lstrip is enabled.
and self.lstrip_blocks
# Not a variable expression.
and not m.groupdict().get(TOKEN_VARIABLE_BEGIN)
):
# The start of text between the last newline and the tag.
l_pos = text.rfind("\n") + 1
if l_pos > 0 or line_starting:
# If there's only whitespace between the newline and the
# tag, strip it.
if whitespace_re.fullmatch(text, l_pos):
groups = [text[:l_pos], *groups[1:]]
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 m.groupdict().items():
if value is not None:
yield lineno, key, value
lineno += value.count("\n")
break
else:
raise RuntimeError(
f"{regex!r} wanted to resolve the token dynamically"
" but no group matched"
)
# normal group
else:
data = groups[idx]
if data or token not in ignore_if_empty:
yield lineno, token, data
lineno += data.count("\n") + newlines_stripped
newlines_stripped = 0
# strings as token just are yielded as it.
else:
data = m.group()
# update brace/parentheses balance
if tokens == TOKEN_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(
f"unexpected '{data}'", lineno, name, filename
)
expected_op = balancing_stack.pop()
if expected_op != data:
raise TemplateSyntaxError(
f"unexpected '{data}', expected '{expected_op}'",
lineno,
name,
filename,
)
# yield items
if data or tokens not in ignore_if_empty:
yield lineno, tokens, data
lineno += data.count("\n")
line_starting = m.group()[-1:] == "\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 m.groupdict().items():
if value is not None:
stack.append(key)
break
else:
raise RuntimeError(
f"{regex!r} wanted to resolve the new state dynamically"
f" but no group matched"
)
# 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(
f"{regex!r} yielded empty string without stack change"
)
# 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(
f"unexpected char {source[pos]!r} at {pos}", lineno, name, filename
)
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