path: root/contrib/python/Jinja2/py2/jinja2/ext.py

# -*- coding: utf-8 -*- 
"""Extension API for adding custom tags and behavior."""
import pprint
import re 
from sys import version_info
 
from markupsafe import Markup
 
from . import nodes
from ._compat import iteritems
from ._compat import string_types
from ._compat import with_metaclass
from .defaults import BLOCK_END_STRING
from .defaults import BLOCK_START_STRING
from .defaults import COMMENT_END_STRING
from .defaults import COMMENT_START_STRING
from .defaults import KEEP_TRAILING_NEWLINE
from .defaults import LINE_COMMENT_PREFIX
from .defaults import LINE_STATEMENT_PREFIX
from .defaults import LSTRIP_BLOCKS
from .defaults import NEWLINE_SEQUENCE
from .defaults import TRIM_BLOCKS
from .defaults import VARIABLE_END_STRING
from .defaults import VARIABLE_START_STRING
from .environment import Environment
from .exceptions import TemplateAssertionError
from .exceptions import TemplateSyntaxError
from .nodes import ContextReference
from .runtime import concat
from .utils import contextfunction
from .utils import import_string
 
# the only real useful gettext functions for a Jinja template.  Note 
# that ugettext must be assigned to gettext as Jinja doesn't support 
# non unicode strings. 
GETTEXT_FUNCTIONS = ("_", "gettext", "ngettext")
 
_ws_re = re.compile(r"\s*\n\s*")
 

class ExtensionRegistry(type): 
    """Gives the extension an unique identifier.""" 
 
    def __new__(mcs, name, bases, d):
        rv = type.__new__(mcs, name, bases, d)
        rv.identifier = rv.__module__ + "." + rv.__name__
        return rv 
 
 
class Extension(with_metaclass(ExtensionRegistry, object)): 
    """Extensions can be used to add extra functionality to the Jinja template 
    system at the parser level.  Custom extensions are bound to an environment 
    but may not store environment specific data on `self`.  The reason for 
    this is that an extension can be bound to another environment (for 
    overlays) by creating a copy and reassigning the `environment` attribute. 
 
    As extensions are created by the environment they cannot accept any 
    arguments for configuration.  One may want to work around that by using 
    a factory function, but that is not possible as extensions are identified 
    by their import name.  The correct way to configure the extension is 
    storing the configuration values on the environment.  Because this way the 
    environment ends up acting as central configuration storage the 
    attributes may clash which is why extensions have to ensure that the names 
    they choose for configuration are not too generic.  ``prefix`` for example 
    is a terrible name, ``fragment_cache_prefix`` on the other hand is a good 
    name as includes the name of the extension (fragment cache). 
    """ 
 
    #: if this extension parses this is the list of tags it's listening to. 
    tags = set() 
 
    #: the priority of that extension.  This is especially useful for 
    #: extensions that preprocess values.  A lower value means higher 
    #: priority. 
    #: 
    #: .. versionadded:: 2.4 
    priority = 100 
 
    def __init__(self, environment): 
        self.environment = environment 
 
    def bind(self, environment): 
        """Create a copy of this extension bound to another environment.""" 
        rv = object.__new__(self.__class__) 
        rv.__dict__.update(self.__dict__) 
        rv.environment = environment 
        return rv 
 
    def preprocess(self, source, name, filename=None): 
        """This method is called before the actual lexing and can be used to 
        preprocess the source.  The `filename` is optional.  The return value 
        must be the preprocessed source. 
        """ 
        return source 
 
    def filter_stream(self, stream): 
        """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used 
        to filter tokens returned.  This method has to return an iterable of 
        :class:`~jinja2.lexer.Token`\\s, but it doesn't have to return a 
        :class:`~jinja2.lexer.TokenStream`. 
        """ 
        return stream 
 
    def parse(self, parser): 
        """If any of the :attr:`tags` matched this method is called with the 
        parser as first argument.  The token the parser stream is pointing at 
        is the name token that matched.  This method has to return one or a 
        list of multiple nodes. 
        """ 
        raise NotImplementedError() 
 
    def attr(self, name, lineno=None): 
        """Return an attribute node for the current extension.  This is useful 
        to pass constants on extensions to generated template code. 
 
        :: 
 
            self.attr('_my_attribute', lineno=lineno) 
        """ 
        return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno) 
 
    def call_method(
        self, name, args=None, kwargs=None, dyn_args=None, dyn_kwargs=None, lineno=None
    ):
        """Call a method of the extension.  This is a shortcut for 
        :meth:`attr` + :class:`jinja2.nodes.Call`. 
        """ 
        if args is None: 
            args = [] 
        if kwargs is None: 
            kwargs = [] 
        return nodes.Call(
            self.attr(name, lineno=lineno),
            args,
            kwargs,
            dyn_args,
            dyn_kwargs,
            lineno=lineno,
        )
 
 
@contextfunction 
def _gettext_alias(__context, *args, **kwargs): 
    return __context.call(__context.resolve("gettext"), *args, **kwargs)
 
 
def _make_new_gettext(func): 
    @contextfunction 
    def gettext(__context, __string, **variables): 
        rv = __context.call(func, __string) 
        if __context.eval_ctx.autoescape: 
            rv = Markup(rv) 
        # Always treat as a format string, even if there are no
        # variables. This makes translation strings more consistent
        # and predictable. This requires escaping
        return rv % variables 

    return gettext 
 
 
def _make_new_ngettext(func): 
    @contextfunction 
    def ngettext(__context, __singular, __plural, __num, **variables): 
        variables.setdefault("num", __num)
        rv = __context.call(func, __singular, __plural, __num) 
        if __context.eval_ctx.autoescape: 
            rv = Markup(rv) 
        # Always treat as a format string, see gettext comment above.
        return rv % variables 

    return ngettext 
 
 
class InternationalizationExtension(Extension): 
    """This extension adds gettext support to Jinja."""
 
    tags = {"trans"}

    # TODO: the i18n extension is currently reevaluating values in a few 
    # situations.  Take this example: 
    #   {% trans count=something() %}{{ count }} foo{% pluralize 
    #     %}{{ count }} fooss{% endtrans %} 
    # something is called twice here.  One time for the gettext value and 
    # the other time for the n-parameter of the ngettext function. 
 
    def __init__(self, environment): 
        Extension.__init__(self, environment) 
        environment.globals["_"] = _gettext_alias
        environment.extend( 
            install_gettext_translations=self._install, 
            install_null_translations=self._install_null, 
            install_gettext_callables=self._install_callables, 
            uninstall_gettext_translations=self._uninstall, 
            extract_translations=self._extract, 
            newstyle_gettext=False,
        ) 
 
    def _install(self, translations, newstyle=None): 
        gettext = getattr(translations, "ugettext", None)
        if gettext is None: 
            gettext = translations.gettext 
        ngettext = getattr(translations, "ungettext", None)
        if ngettext is None: 
            ngettext = translations.ngettext 
        self._install_callables(gettext, ngettext, newstyle) 
 
    def _install_null(self, newstyle=None): 
        self._install_callables( 
            lambda x: x, lambda s, p, n: (n != 1 and (p,) or (s,))[0], newstyle
        ) 
 
    def _install_callables(self, gettext, ngettext, newstyle=None): 
        if newstyle is not None: 
            self.environment.newstyle_gettext = newstyle 
        if self.environment.newstyle_gettext: 
            gettext = _make_new_gettext(gettext) 
            ngettext = _make_new_ngettext(ngettext) 
        self.environment.globals.update(gettext=gettext, ngettext=ngettext)
 
    def _uninstall(self, translations): 
        for key in "gettext", "ngettext":
            self.environment.globals.pop(key, None) 
 
    def _extract(self, source, gettext_functions=GETTEXT_FUNCTIONS): 
        if isinstance(source, string_types): 
            source = self.environment.parse(source) 
        return extract_from_ast(source, gettext_functions) 
 
    def parse(self, parser): 
        """Parse a translatable tag.""" 
        lineno = next(parser.stream).lineno 
        num_called_num = False 
 
        # find all the variables referenced.  Additionally a variable can be 
        # defined in the body of the trans block too, but this is checked at 
        # a later state. 
        plural_expr = None 
        plural_expr_assignment = None 
        variables = {} 
        trimmed = None 
        while parser.stream.current.type != "block_end":
            if variables: 
                parser.stream.expect("comma")
 
            # skip colon for python compatibility 
            if parser.stream.skip_if("colon"):
                break 
 
            name = parser.stream.expect("name")
            if name.value in variables: 
                parser.fail(
                    "translatable variable %r defined twice." % name.value,
                    name.lineno,
                    exc=TemplateAssertionError,
                )
 
            # expressions 
            if parser.stream.current.type == "assign":
                next(parser.stream) 
                variables[name.value] = var = parser.parse_expression() 
            elif trimmed is None and name.value in ("trimmed", "notrimmed"):
                trimmed = name.value == "trimmed"
                continue 
            else: 
                variables[name.value] = var = nodes.Name(name.value, "load")
 
            if plural_expr is None: 
                if isinstance(var, nodes.Call): 
                    plural_expr = nodes.Name("_trans", "load")
                    variables[name.value] = plural_expr 
                    plural_expr_assignment = nodes.Assign( 
                        nodes.Name("_trans", "store"), var
                    )
                else: 
                    plural_expr = var 
                num_called_num = name.value == "num"
 
        parser.stream.expect("block_end")
 
        plural = None 
        have_plural = False 
        referenced = set() 
 
        # now parse until endtrans or pluralize 
        singular_names, singular = self._parse_block(parser, True) 
        if singular_names: 
            referenced.update(singular_names) 
            if plural_expr is None: 
                plural_expr = nodes.Name(singular_names[0], "load")
                num_called_num = singular_names[0] == "num"
 
        # if we have a pluralize block, we parse that too 
        if parser.stream.current.test("name:pluralize"):
            have_plural = True 
            next(parser.stream) 
            if parser.stream.current.type != "block_end":
                name = parser.stream.expect("name")
                if name.value not in variables: 
                    parser.fail(
                        "unknown variable %r for pluralization" % name.value,
                        name.lineno,
                        exc=TemplateAssertionError,
                    )
                plural_expr = variables[name.value] 
                num_called_num = name.value == "num"
            parser.stream.expect("block_end")
            plural_names, plural = self._parse_block(parser, False) 
            next(parser.stream) 
            referenced.update(plural_names) 
        else: 
            next(parser.stream) 
 
        # register free names as simple name expressions 
        for var in referenced: 
            if var not in variables: 
                variables[var] = nodes.Name(var, "load")
 
        if not have_plural: 
            plural_expr = None 
        elif plural_expr is None: 
            parser.fail("pluralize without variables", lineno)
 
        if trimmed is None: 
            trimmed = self.environment.policies["ext.i18n.trimmed"]
        if trimmed: 
            singular = self._trim_whitespace(singular) 
            if plural: 
                plural = self._trim_whitespace(plural) 
 
        node = self._make_node(
            singular,
            plural,
            variables,
            plural_expr,
            bool(referenced),
            num_called_num and have_plural,
        )
        node.set_lineno(lineno) 
        if plural_expr_assignment is not None: 
            return [plural_expr_assignment, node] 
        else: 
            return node 
 
    def _trim_whitespace(self, string, _ws_re=_ws_re):
        return _ws_re.sub(" ", string.strip())
 
    def _parse_block(self, parser, allow_pluralize): 
        """Parse until the next block tag with a given name.""" 
        referenced = [] 
        buf = [] 
        while 1: 
            if parser.stream.current.type == "data":
                buf.append(parser.stream.current.value.replace("%", "%%"))
                next(parser.stream) 
            elif parser.stream.current.type == "variable_begin":
                next(parser.stream) 
                name = parser.stream.expect("name").value
                referenced.append(name) 
                buf.append("%%(%s)s" % name)
                parser.stream.expect("variable_end")
            elif parser.stream.current.type == "block_begin":
                next(parser.stream) 
                if parser.stream.current.test("name:endtrans"):
                    break 
                elif parser.stream.current.test("name:pluralize"):
                    if allow_pluralize: 
                        break 
                    parser.fail(
                        "a translatable section can have only one pluralize section"
                    )
                parser.fail(
                    "control structures in translatable sections are not allowed"
                )
            elif parser.stream.eos: 
                parser.fail("unclosed translation block")
            else: 
                raise RuntimeError("internal parser error")
 
        return referenced, concat(buf) 
 
    def _make_node(
        self, singular, plural, variables, plural_expr, vars_referenced, num_called_num
    ):
        """Generates a useful node from the data provided.""" 
        # no variables referenced?  no need to escape for old style 
        # gettext invocations only if there are vars. 
        if not vars_referenced and not self.environment.newstyle_gettext: 
            singular = singular.replace("%%", "%")
            if plural: 
                plural = plural.replace("%%", "%")
 
        # singular only: 
        if plural_expr is None: 
            gettext = nodes.Name("gettext", "load")
            node = nodes.Call(gettext, [nodes.Const(singular)], [], None, None)
 
        # singular and plural 
        else: 
            ngettext = nodes.Name("ngettext", "load")
            node = nodes.Call(
                ngettext,
                [nodes.Const(singular), nodes.Const(plural), plural_expr],
                [],
                None,
                None,
            )
 
        # in case newstyle gettext is used, the method is powerful 
        # enough to handle the variable expansion and autoescape 
        # handling itself 
        if self.environment.newstyle_gettext: 
            for key, value in iteritems(variables): 
                # the function adds that later anyways in case num was 
                # called num, so just skip it. 
                if num_called_num and key == "num":
                    continue 
                node.kwargs.append(nodes.Keyword(key, value)) 
 
        # otherwise do that here 
        else: 
            # mark the return value as safe if we are in an 
            # environment with autoescaping turned on 
            node = nodes.MarkSafeIfAutoescape(node) 
            if variables: 
                node = nodes.Mod(
                    node,
                    nodes.Dict(
                        [
                            nodes.Pair(nodes.Const(key), value)
                            for key, value in variables.items()
                        ]
                    ),
                )
        return nodes.Output([node]) 
 
 
class ExprStmtExtension(Extension): 
    """Adds a `do` tag to Jinja that works like the print statement just
    that it doesn't print the return value. 
    """ 
 
    tags = set(["do"])

    def parse(self, parser): 
        node = nodes.ExprStmt(lineno=next(parser.stream).lineno) 
        node.node = parser.parse_tuple() 
        return node 
 
 
class LoopControlExtension(Extension): 
    """Adds break and continue to the template engine.""" 
 
    tags = set(["break", "continue"])

    def parse(self, parser): 
        token = next(parser.stream) 
        if token.value == "break":
            return nodes.Break(lineno=token.lineno) 
        return nodes.Continue(lineno=token.lineno) 
 
 
class WithExtension(Extension): 
    pass 
 
 
class AutoEscapeExtension(Extension): 
    pass 
 
 
class DebugExtension(Extension):
    """A ``{% debug %}`` tag that dumps the available variables,
    filters, and tests.

    .. code-block:: html+jinja

        <pre>{% debug %}</pre>

    .. code-block:: text

        {'context': {'cycler': <class 'jinja2.utils.Cycler'>,
                     ...,
                     'namespace': <class 'jinja2.utils.Namespace'>},
         'filters': ['abs', 'attr', 'batch', 'capitalize', 'center', 'count', 'd',
                     ..., 'urlencode', 'urlize', 'wordcount', 'wordwrap', 'xmlattr'],
         'tests': ['!=', '<', '<=', '==', '>', '>=', 'callable', 'defined',
                   ..., 'odd', 'sameas', 'sequence', 'string', 'undefined', 'upper']}

    .. versionadded:: 2.11.0
    """

    tags = {"debug"}

    def parse(self, parser):
        lineno = parser.stream.expect("name:debug").lineno
        context = ContextReference()
        result = self.call_method("_render", [context], lineno=lineno)
        return nodes.Output([result], lineno=lineno)

    def _render(self, context):
        result = {
            "context": context.get_all(),
            "filters": sorted(self.environment.filters.keys()),
            "tests": sorted(self.environment.tests.keys()),
        }

        # Set the depth since the intent is to show the top few names.
        if version_info[:2] >= (3, 4):
            return pprint.pformat(result, depth=3, compact=True)
        else:
            return pprint.pformat(result, depth=3)


def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS, babel_style=True):
    """Extract localizable strings from the given template node.  Per 
    default this function returns matches in babel style that means non string 
    parameters as well as keyword arguments are returned as `None`.  This 
    allows Babel to figure out what you really meant if you are using 
    gettext functions that allow keyword arguments for placeholder expansion. 
    If you don't want that behavior set the `babel_style` parameter to `False` 
    which causes only strings to be returned and parameters are always stored 
    in tuples.  As a consequence invalid gettext calls (calls without a single 
    string parameter or string parameters after non-string parameters) are 
    skipped. 
 
    This example explains the behavior: 
 
    >>> from jinja2 import Environment 
    >>> env = Environment() 
    >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}') 
    >>> list(extract_from_ast(node)) 
    [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))] 
    >>> list(extract_from_ast(node, babel_style=False)) 
    [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))] 
 
    For every string found this function yields a ``(lineno, function, 
    message)`` tuple, where: 
 
    * ``lineno`` is the number of the line on which the string was found, 
    * ``function`` is the name of the ``gettext`` function used (if the 
      string was extracted from embedded Python code), and 
    *  ``message`` is the string itself (a ``unicode`` object, or a tuple 
       of ``unicode`` objects for functions with multiple string arguments). 
 
    This extraction function operates on the AST and is because of that unable 
    to extract any comments.  For comment support you have to use the babel 
    extraction interface or extract comments yourself. 
    """ 
    for node in node.find_all(nodes.Call): 
        if (
            not isinstance(node.node, nodes.Name)
            or node.node.name not in gettext_functions
        ):
            continue 
 
        strings = [] 
        for arg in node.args: 
            if isinstance(arg, nodes.Const) and isinstance(arg.value, string_types):
                strings.append(arg.value) 
            else: 
                strings.append(None) 
 
        for _ in node.kwargs:
            strings.append(None) 
        if node.dyn_args is not None: 
            strings.append(None) 
        if node.dyn_kwargs is not None: 
            strings.append(None) 
 
        if not babel_style: 
            strings = tuple(x for x in strings if x is not None) 
            if not strings: 
                continue 
        else: 
            if len(strings) == 1: 
                strings = strings[0] 
            else: 
                strings = tuple(strings) 
        yield node.lineno, node.node.name, strings 
 
 
class _CommentFinder(object): 
    """Helper class to find comments in a token stream.  Can only 
    find comments for gettext calls forwards.  Once the comment 
    from line 4 is found, a comment for line 1 will not return a 
    usable value. 
    """ 
 
    def __init__(self, tokens, comment_tags): 
        self.tokens = tokens 
        self.comment_tags = comment_tags 
        self.offset = 0 
        self.last_lineno = 0 
 
    def find_backwards(self, offset): 
        try: 
            for _, token_type, token_value in reversed(
                self.tokens[self.offset : offset]
            ):
                if token_type in ("comment", "linecomment"):
                    try: 
                        prefix, comment = token_value.split(None, 1) 
                    except ValueError: 
                        continue 
                    if prefix in self.comment_tags: 
                        return [comment.rstrip()] 
            return [] 
        finally: 
            self.offset = offset 
 
    def find_comments(self, lineno): 
        if not self.comment_tags or self.last_lineno > lineno: 
            return [] 
        for idx, (token_lineno, _, _) in enumerate(self.tokens[self.offset :]):
            if token_lineno > lineno: 
                return self.find_backwards(self.offset + idx) 
        return self.find_backwards(len(self.tokens)) 
 
 
def babel_extract(fileobj, keywords, comment_tags, options): 
    """Babel extraction method for Jinja templates. 
 
    .. versionchanged:: 2.3 
       Basic support for translation comments was added.  If `comment_tags` 
       is now set to a list of keywords for extraction, the extractor will 
       try to find the best preceding comment that begins with one of the
       keywords.  For best results, make sure to not have more than one 
       gettext call in one line of code and the matching comment in the 
       same line or the line before. 
 
    .. versionchanged:: 2.5.1 
       The `newstyle_gettext` flag can be set to `True` to enable newstyle 
       gettext calls. 
 
    .. versionchanged:: 2.7 
       A `silent` option can now be provided.  If set to `False` template 
       syntax errors are propagated instead of being ignored. 
 
    :param fileobj: the file-like object the messages should be extracted from 
    :param keywords: a list of keywords (i.e. function names) that should be 
                     recognized as translation functions 
    :param comment_tags: a list of translator tags to search for and include 
                         in the results. 
    :param options: a dictionary of additional options (optional) 
    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples. 
             (comments will be empty currently) 
    """ 
    extensions = set() 
    for extension in options.get("extensions", "").split(","):
        extension = extension.strip() 
        if not extension: 
            continue 
        extensions.add(import_string(extension)) 
    if InternationalizationExtension not in extensions: 
        extensions.add(InternationalizationExtension) 
 
    def getbool(options, key, default=False): 
        return options.get(key, str(default)).lower() in ("1", "on", "yes", "true")
 
    silent = getbool(options, "silent", True)
    environment = Environment( 
        options.get("block_start_string", BLOCK_START_STRING),
        options.get("block_end_string", BLOCK_END_STRING),
        options.get("variable_start_string", VARIABLE_START_STRING),
        options.get("variable_end_string", VARIABLE_END_STRING),
        options.get("comment_start_string", COMMENT_START_STRING),
        options.get("comment_end_string", COMMENT_END_STRING),
        options.get("line_statement_prefix") or LINE_STATEMENT_PREFIX,
        options.get("line_comment_prefix") or LINE_COMMENT_PREFIX,
        getbool(options, "trim_blocks", TRIM_BLOCKS),
        getbool(options, "lstrip_blocks", LSTRIP_BLOCKS),
        NEWLINE_SEQUENCE, 
        getbool(options, "keep_trailing_newline", KEEP_TRAILING_NEWLINE),
        frozenset(extensions), 
        cache_size=0, 
        auto_reload=False,
    ) 
 
    if getbool(options, "trimmed"):
        environment.policies["ext.i18n.trimmed"] = True
    if getbool(options, "newstyle_gettext"):
        environment.newstyle_gettext = True 
 
    source = fileobj.read().decode(options.get("encoding", "utf-8"))
    try: 
        node = environment.parse(source) 
        tokens = list(environment.lex(environment.preprocess(source))) 
    except TemplateSyntaxError:
        if not silent: 
            raise 
        # skip templates with syntax errors 
        return 
 
    finder = _CommentFinder(tokens, comment_tags) 
    for lineno, func, message in extract_from_ast(node, keywords): 
        yield lineno, func, message, finder.find_comments(lineno) 
 
 
#: nicer import names 
i18n = InternationalizationExtension 
do = ExprStmtExtension 
loopcontrols = LoopControlExtension 
with_ = WithExtension 
autoescape = AutoEscapeExtension 
debug = DebugExtension