Edit File: lexer.py
# -*- 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) 2010 by the Jinja Team. :license: BSD, see LICENSE for more details. """ import re from operator import itemgetter from collections import deque from jinja2.exceptions import TemplateSyntaxError from jinja2.utils import LRUCache from jinja2._compat import next, iteritems, implements_iterator, text_type, \ intern # 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+') # we use the unicode identifier rule if this python version is able # to handle unicode identifiers, otherwise the standard ASCII one. try: compile('föö', '<unknown>', 'eval') except SyntaxError: name_re = re.compile(r'\b[a-zA-Z_][a-zA-Z0-9_]*\b') else: from jinja2 import _stringdefs name_re = re.compile(r'[%s][%s]*' % (_stringdefs.xid_start, _stringdefs.xid_continue)) 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_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""" 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('(?:\-%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('\-%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('(.*?)((?:\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) 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) # if we can express it as bytestring (ascii only) # we do that for support of semi broken APIs # as datetime.datetime.strftime. On python 3 this # call becomes a noop thanks to 2to3 try: value = str(value) except UnicodeError: pass 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)