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django/templatetags/i18n.py

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from django.conf import settings
from django.template import Library, Node, TemplateSyntaxError, Variable
from django.template.base import TokenType, render_value_in_context
from django.template.defaulttags import token_kwargs
from django.utils import translation
from django.utils.safestring import SafeData, mark_safe

register = Library()


class GetAvailableLanguagesNode(Node):
    def __init__(self, variable):
        self.variable = variable

    def render(self, context):
        context[self.variable] = [(k, translation.gettext(v)) for k, v in settings.LANGUAGES]
        return ''


class GetLanguageInfoNode(Node):
    def __init__(self, lang_code, variable):
        self.lang_code = lang_code
        self.variable = variable

    def render(self, context):
        lang_code = self.lang_code.resolve(context)
        context[self.variable] = translation.get_language_info(lang_code)
        return ''


class GetLanguageInfoListNode(Node):
    def __init__(self, languages, variable):
        self.languages = languages
        self.variable = variable

    def get_language_info(self, language):
        # ``language`` is either a language code string or a sequence
        # with the language code as its first item
        if len(language[0]) > 1:
            return translation.get_language_info(language[0])
        else:
            return translation.get_language_info(str(language))

    def render(self, context):
        langs = self.languages.resolve(context)
        context[self.variable] = [self.get_language_info(lang) for lang in langs]
        return ''


class GetCurrentLanguageNode(Node):
    def __init__(self, variable):
        self.variable = variable

    def render(self, context):
        context[self.variable] = translation.get_language()
        return ''


class GetCurrentLanguageBidiNode(Node):
    def __init__(self, variable):
        self.variable = variable

    def render(self, context):
        context[self.variable] = translation.get_language_bidi()
        return ''


class TranslateNode(Node):
    def __init__(self, filter_expression, noop, asvar=None,
                 message_context=None):
        self.noop = noop
        self.asvar = asvar
        self.message_context = message_context
        self.filter_expression = filter_expression
        if isinstance(self.filter_expression.var, str):
            self.filter_expression.var = Variable("'%s'" %
                                                  self.filter_expression.var)

    def render(self, context):
        self.filter_expression.var.translate = not self.noop
        if self.message_context:
            self.filter_expression.var.message_context = (
                self.message_context.resolve(context))
        output = self.filter_expression.resolve(context)
        value = render_value_in_context(output, context)
        # Restore percent signs. Percent signs in template text are doubled
        # so they are not interpreted as string format flags.
        is_safe = isinstance(value, SafeData)
        value = value.replace('%%', '%')
        value = mark_safe(value) if is_safe else value
        if self.asvar:
            context[self.asvar] = value
            return ''
        else:
            return value


class BlockTranslateNode(Node):

    def __init__(self, extra_context, singular, plural=None, countervar=None,
                 counter=None, message_context=None, trimmed=False, asvar=None):
        self.extra_context = extra_context
        self.singular = singular
        self.plural = plural
        self.countervar = countervar
        self.counter = counter
        self.message_context = message_context
        self.trimmed = trimmed
        self.asvar = asvar

    def render_token_list(self, tokens):
        result = []
        vars = []
        for token in tokens:
            if token.token_type == TokenType.TEXT:
                result.append(token.contents.replace('%', '%%'))
            elif token.token_type == TokenType.VAR:
                result.append('%%(%s)s' % token.contents)
                vars.append(token.contents)
        msg = ''.join(result)
        if self.trimmed:
            msg = translation.trim_whitespace(msg)
        return msg, vars

    def render(self, context, nested=False):
        if self.message_context:
            message_context = self.message_context.resolve(context)
        else:
            message_context = None
        # Update() works like a push(), so corresponding context.pop() is at
        # the end of function
        context.update({var: val.resolve(context) for var, val in self.extra_context.items()})
        singular, vars = self.render_token_list(self.singular)
        if self.plural and self.countervar and self.counter:
            count = self.counter.resolve(context)
            context[self.countervar] = count
            plural, plural_vars = self.render_token_list(self.plural)
            if message_context:
                result = translation.npgettext(message_context, singular,
                                               plural, count)
            else:
                result = translation.ngettext(singular, plural, count)
            vars.extend(plural_vars)
        else:
            if message_context:
                result = translation.pgettext(message_context, singular)
            else:
                result = translation.gettext(singular)
        default_value = context.template.engine.string_if_invalid

        def render_value(key):
            if key in context:
                val = context[key]
            else:
                val = default_value % key if '%s' in default_value else default_value
            return render_value_in_context(val, context)

        data = {v: render_value(v) for v in vars}
        context.pop()
        try:
            result = result % data
        except (KeyError, ValueError):
            if nested:
                # Either string is malformed, or it's a bug
                raise TemplateSyntaxError(
                    "'blocktrans' is unable to format string returned by gettext: %r using %r"
                    % (result, data)
                )
            with translation.override(None):
                result = self.render(context, nested=True)
        if self.asvar:
            context[self.asvar] = result
            return ''
        else:
            return result


class LanguageNode(Node):
    def __init__(self, nodelist, language):
        self.nodelist = nodelist
        self.language = language

    def render(self, context):
        with translation.override(self.language.resolve(context)):
            output = self.nodelist.render(context)
        return output


@register.tag("get_available_languages")
def do_get_available_languages(parser, token):
    """
    Store a list of available languages in the context.

    Usage::

        {% get_available_languages as languages %}
        {% for language in languages %}
        ...
        {% endfor %}

    This puts settings.LANGUAGES into the named variable.
    """
    # token.split_contents() isn't useful here because this tag doesn't accept variable as arguments
    args = token.contents.split()
    if len(args) != 3 or args[1] != 'as':
        raise TemplateSyntaxError("'get_available_languages' requires 'as variable' (got %r)" % args)
    return GetAvailableLanguagesNode(args[2])


@register.tag("get_language_info")
def do_get_language_info(parser, token):
    """
    Store the language information dictionary for the given language code in a
    context variable.

    Usage::

        {% get_language_info for LANGUAGE_CODE as l %}
        {{ l.code }}
        {{ l.name }}
        {{ l.name_translated }}
        {{ l.name_local }}
        {{ l.bidi|yesno:"bi-directional,uni-directional" }}
    """
    args = token.split_contents()
    if len(args) != 5 or args[1] != 'for' or args[3] != 'as':
        raise TemplateSyntaxError("'%s' requires 'for string as variable' (got %r)" % (args[0], args[1:]))
    return GetLanguageInfoNode(parser.compile_filter(args[2]), args[4])


@register.tag("get_language_info_list")
def do_get_language_info_list(parser, token):
    """
    Store a list of language information dictionaries for the given language
    codes in a context variable. The language codes can be specified either as
    a list of strings or a settings.LANGUAGES style list (or any sequence of
    sequences whose first items are language codes).

    Usage::

        {% get_language_info_list for LANGUAGES as langs %}
        {% for l in langs %}
          {{ l.code }}
          {{ l.name }}
          {{ l.name_translated }}
          {{ l.name_local }}
          {{ l.bidi|yesno:"bi-directional,uni-directional" }}
        {% endfor %}
    """
    args = token.split_contents()
    if len(args) != 5 or args[1] != 'for' or args[3] != 'as':
        raise TemplateSyntaxError("'%s' requires 'for sequence as variable' (got %r)" % (args[0], args[1:]))
    return GetLanguageInfoListNode(parser.compile_filter(args[2]), args[4])


@register.filter
def language_name(lang_code):
    return translation.get_language_info(lang_code)['name']


@register.filter
def language_name_translated(lang_code):
    english_name = translation.get_language_info(lang_code)['name']
    return translation.gettext(english_name)


@register.filter
def language_name_local(lang_code):
    return translation.get_language_info(lang_code)['name_local']


@register.filter
def language_bidi(lang_code):
    return translation.get_language_info(lang_code)['bidi']


@register.tag("get_current_language")
def do_get_current_language(parser, token):
    """
    Store the current language in the context.

    Usage::

        {% get_current_language as language %}

    This fetches the currently active language and puts its value into the
    ``language`` context variable.
    """
    # token.split_contents() isn't useful here because this tag doesn't accept variable as arguments
    args = token.contents.split()
    if len(args) != 3 or args[1] != 'as':
        raise TemplateSyntaxError("'get_current_language' requires 'as variable' (got %r)" % args)
    return GetCurrentLanguageNode(args[2])


@register.tag("get_current_language_bidi")
def do_get_current_language_bidi(parser, token):
    """
    Store the current language layout in the context.

    Usage::

        {% get_current_language_bidi as bidi %}

    This fetches the currently active language's layout and puts its value into
    the ``bidi`` context variable. True indicates right-to-left layout,
    otherwise left-to-right.
    """
    # token.split_contents() isn't useful here because this tag doesn't accept variable as arguments
    args = token.contents.split()
    if len(args) != 3 or args[1] != 'as':
        raise TemplateSyntaxError("'get_current_language_bidi' requires 'as variable' (got %r)" % args)
    return GetCurrentLanguageBidiNode(args[2])


@register.tag("trans")
def do_translate(parser, token):
    """
    Mark a string for translation and translate the string for the current
    language.

    Usage::

        {% trans "this is a test" %}

    This marks the string for translation so it will be pulled out by
    makemessages into the .po files and runs the string through the translation
    engine.

    There is a second form::

        {% trans "this is a test" noop %}

    This marks the string for translation, but returns the string unchanged.
    Use it when you need to store values into forms that should be translated
    later on.

    You can use variables instead of constant strings
    to translate stuff you marked somewhere else::

        {% trans variable %}

    This tries to translate the contents of the variable ``variable``. Make
    sure that the string in there is something that is in the .po file.

    It is possible to store the translated string into a variable::

        {% trans "this is a test" as var %}
        {{ var }}

    Contextual translations are also supported::

        {% trans "this is a test" context "greeting" %}

    This is equivalent to calling pgettext instead of (u)gettext.
    """
    bits = token.split_contents()
    if len(bits) < 2:
        raise TemplateSyntaxError("'%s' takes at least one argument" % bits[0])
    message_string = parser.compile_filter(bits[1])
    remaining = bits[2:]

    noop = False
    asvar = None
    message_context = None
    seen = set()
    invalid_context = {'as', 'noop'}

    while remaining:
        option = remaining.pop(0)
        if option in seen:
            raise TemplateSyntaxError(
                "The '%s' option was specified more than once." % option,
            )
        elif option == 'noop':
            noop = True
        elif option == 'context':
            try:
                value = remaining.pop(0)
            except IndexError:
                raise TemplateSyntaxError(
                    "No argument provided to the '%s' tag for the context option." % bits[0]
                )
            if value in invalid_context:
                raise TemplateSyntaxError(
                    "Invalid argument '%s' provided to the '%s' tag for the context option" % (value, bits[0]),
                )
            message_context = parser.compile_filter(value)
        elif option == 'as':
            try:
                value = remaining.pop(0)
            except IndexError:
                raise TemplateSyntaxError(
                    "No argument provided to the '%s' tag for the as option." % bits[0]
                )
            asvar = value
        else:
            raise TemplateSyntaxError(
                "Unknown argument for '%s' tag: '%s'. The only options "
                "available are 'noop', 'context' \"xxx\", and 'as VAR'." % (
                    bits[0], option,
                )
            )
        seen.add(option)

    return TranslateNode(message_string, noop, asvar, message_context)


@register.tag("blocktrans")
def do_block_translate(parser, token):
    """
    Translate a block of text with parameters.

    Usage::

        {% blocktrans with bar=foo|filter boo=baz|filter %}
        This is {{ bar }} and {{ boo }}.
        {% endblocktrans %}

    Additionally, this supports pluralization::

        {% blocktrans count count=var|length %}
        There is {{ count }} object.
        {% plural %}
        There are {{ count }} objects.
        {% endblocktrans %}

    This is much like ngettext, only in template syntax.

    The "var as value" legacy format is still supported::

        {% blocktrans with foo|filter as bar and baz|filter as boo %}
        {% blocktrans count var|length as count %}

    The translated string can be stored in a variable using `asvar`::

        {% blocktrans with bar=foo|filter boo=baz|filter asvar var %}
        This is {{ bar }} and {{ boo }}.
        {% endblocktrans %}
        {{ var }}

    Contextual translations are supported::

        {% blocktrans with bar=foo|filter context "greeting" %}
            This is {{ bar }}.
        {% endblocktrans %}

    This is equivalent to calling pgettext/npgettext instead of
    (u)gettext/(u)ngettext.
    """
    bits = token.split_contents()

    options = {}
    remaining_bits = bits[1:]
    asvar = None
    while remaining_bits:
        option = remaining_bits.pop(0)
        if option in options:
            raise TemplateSyntaxError('The %r option was specified more '
                                      'than once.' % option)
        if option == 'with':
            value = token_kwargs(remaining_bits, parser, support_legacy=True)
            if not value:
                raise TemplateSyntaxError('"with" in %r tag needs at least '
                                          'one keyword argument.' % bits[0])
        elif option == 'count':
            value = token_kwargs(remaining_bits, parser, support_legacy=True)
            if len(value) != 1:
                raise TemplateSyntaxError('"count" in %r tag expected exactly '
                                          'one keyword argument.' % bits[0])
        elif option == "context":
            try:
                value = remaining_bits.pop(0)
                value = parser.compile_filter(value)
            except Exception:
                raise TemplateSyntaxError(
                    '"context" in %r tag expected exactly one argument.' % bits[0]
                )
        elif option == "trimmed":
            value = True
        elif option == "asvar":
            try:
                value = remaining_bits.pop(0)
            except IndexError:
                raise TemplateSyntaxError(
                    "No argument provided to the '%s' tag for the asvar option." % bits[0]
                )
            asvar = value
        else:
            raise TemplateSyntaxError('Unknown argument for %r tag: %r.' %
                                      (bits[0], option))
        options[option] = value

    if 'count' in options:
        countervar, counter = next(iter(options['count'].items()))
    else:
        countervar, counter = None, None
    if 'context' in options:
        message_context = options['context']
    else:
        message_context = None
    extra_context = options.get('with', {})

    trimmed = options.get("trimmed", False)

    singular = []
    plural = []
    while parser.tokens:
        token = parser.next_token()
        if token.token_type in (TokenType.VAR, TokenType.TEXT):
            singular.append(token)
        else:
            break
    if countervar and counter:
        if token.contents.strip() != 'plural':
            raise TemplateSyntaxError("'blocktrans' doesn't allow other block tags inside it")
        while parser.tokens:
            token = parser.next_token()
            if token.token_type in (TokenType.VAR, TokenType.TEXT):
                plural.append(token)
            else:
                break
    if token.contents.strip() != 'endblocktrans':
        raise TemplateSyntaxError("'blocktrans' doesn't allow other block tags (seen %r) inside it" % token.contents)

    return BlockTranslateNode(extra_context, singular, plural, countervar,
                              counter, message_context, trimmed=trimmed,
                              asvar=asvar)


@register.tag
def language(parser, token):
    """
    Enable the given language just for this block.

    Usage::

        {% language "de" %}
            This is {{ bar }} and {{ boo }}.
        {% endlanguage %}
    """
    bits = token.split_contents()
    if len(bits) != 2:
        raise TemplateSyntaxError("'%s' takes one argument (language)" % bits[0])
    language = parser.compile_filter(bits[1])
    nodelist = parser.parse(('endlanguage',))
    parser.delete_first_token()
    return LanguageNode(nodelist, language)