calculate-utils-4-lib/calculate/templates/template_engine.py

# vim: fileencoding=utf-8
#
from jinja2.ext import Extension
from jinja2 import Environment, FileSystemLoader, TemplateSyntaxError, nodes
from jinja2.utils import missing
from jinja2.runtime import Context, Undefined
from collections.abc import MutableMapping


class Variables(MutableMapping):
    '''Класс заглушка вместо модуля переменных.'''
    def __init__(self, *args, **kwargs):
        self.__attrs = dict(*args, **kwargs)

    def __next__(self):
        iterator = iter(self.__attrs)
        return next(iterator)

    def __getattribute__(self, name):
        if name == '_Variables__attrs':
            return super().__getattribute__(name)
        try:
            return self.__attrs[name]
        except KeyError:
            raise AttributeError(name)

    def __getitem__(self, name):
        return self.__attrs[name]

    def __setitem__(self, name, value):
        self.__attrs[name] = value

    def __delitem__(self, name):
        del self.__attrs[name]

    def __iter__(self):
        return iter(self.__attrs)

    def __len__(self):
        return len(self.__attrs)

    def __repr__(self):
        return '<Variables {}>'.format(self.__attrs)


def resolve_or_missing(context, key, missing=missing, env={}):
    datavars = context.parent['__datavars__']
    if key in context.vars:
        return context.vars[key]
    if key in context.parent:
        return context.parent[key]
    if key in datavars:
        return datavars[key]
    for name in env:
        if name in datavars and key in datavars[name]:
            return datavars[name][key]
    return missing


class CalculateContext(Context):
    _env_set = set()

    def resolve(self, key):
        if self._legacy_resolve_mode:
            rv = resolve_or_missing(self, key,
                                    env=self._env_set)
        else:
            rv = self.resolve_or_missing(key)
        if rv is missing:
            return self.environment.undefined(name=key)
        return rv

    def resolve_or_missing(self, key):
        if self._legacy_resolve_mode:
            rv = self.resolve(key)
            if isinstance(rv, Undefined):
                rv = missing
                return rv
        return resolve_or_missing(self, key,
                                  env=self._env_set)


class Parameters(MutableMapping):
    '''Класс для хранения параметров и условий, взятых из шаблона, и передачи
    их шаблонизатору.'''
    def __init__(self, parameters_dictionary={}, condition=True):
        self.__parameters = parameters_dictionary
        self.__condition = condition

    def set_parameters(self, *args, **kwargs):
        parameters = dict(*args, **kwargs)
        self.__parameters.update(parameters)

    def set_condition(self, condition):
        self.__condition = self.__condition and condition

    def __getitem__(self, name):
        return self.__parameters[name]

    def __setitem__(self, name, value):
        self.__parameters[name] = value

    def __delitem__(self, name):
        del self.__parameters[name]

    def __iter__(self):
        return iter(self.__parameters)

    def __len__(self):
        return len(self.__parameters)

    def __repr__(self):
        return '<Parameters: {0}, condition={1}>'.format(self.__parameters,
                                                         self.__condition)

    @property
    def condition(self):
        return self.__condition

    @property
    def parameters(self):
        return self.__parameters


class CalculateExtension(Extension):
    _parameters_set = set()

    def __init__(self, environment):
        self.tags = {'calculate', 'save', 'set_var'}
        self.CONDITION_TOKENS_TYPES = {'eq', 'ne', 'lt', 'gt', 'lteq', 'gteq'}
        self.LITERAL_TOKENS_TYPES = {'string', 'integer', 'float'}
        self.TARGET_FILES_SET = {'grp', 'system', 'etc', 'local', 'remote'}

        self.parse_methods = {'calculate': self.parse_calculate,
                              'save': self.parse_save}

    def parse(self, parser):
        self.parser = parser
        self.stream = parser.stream
        tag_token = self.stream.current.value
        return [self.parse_methods[tag_token]()]

    def parse_save(self):
        lineno = next(self.stream).lineno
        target_file = nodes.Const('', lineno=lineno)

        if self.stream.skip_if('dot'):
            target_file_name = self.stream.expect('name').value
            if target_file_name in self.TARGET_FILES_SET:
                target_file = nodes.Const(target_file_name)
            else:
                TemplateSyntaxError("Unknown target file '{}'".
                                    format(target_file_name),
                                    lineno=lineno)

        # получаем список из имени переменной.
        module_name = self.stream.expect('name').value
        variable_name = [nodes.Const(module_name, lineno=lineno)]
        while self.stream.skip_if('dot'):
            name = self.stream.expect('name').value
            variable_name.append(nodes.Const(name, lineno=lineno))
        variable_name = nodes.List(variable_name, lineno=lineno)

        if self.stream.skip_if('assign'):
            right_value = self.parser.parse_expression(with_condexpr=True)
            save_variable_node = self.call_method('save_variable',
                                                  [variable_name,
                                                   right_value,
                                                   target_file,
                                                   nodes.ContextReference()],
                                                  lineno=lineno)
            return nodes.Output([save_variable_node], lineno=lineno)
        else:
            TemplateSyntaxError("'=' is expected in 'save' tag.",
                                lineno=lineno)

    def parse_calculate(self):
        pairs_list = []
        expect_comma_flag = False
        conditions = nodes.Const(True)

        lineno = next(self.stream).lineno

        while self.stream.current.type != 'block_end':
            if expect_comma_flag:
                self.stream.expect('comma')

            if self.stream.current.type == 'name':
                if (self.stream.current.value in self._parameters_set and
                   self.stream.look().type != 'dot'):
                    pairs_list.append(self.get_parameter_node())
                else:
                    conditions = nodes.And(
                                       self.parser.parse_expression(
                                                            with_condexpr=True
                                                                   ),
                                       conditions
                                          )
            else:
                raise TemplateSyntaxError('Name is expected in calculate tag.',
                                          lineno=self.stream.current.lineno)
            expect_comma_flag = True
        dictionary_node = nodes.Dict(pairs_list)
        save_node = self.call_method('save_parameters',
                                     [dictionary_node,
                                      conditions,
                                      nodes.ContextReference()],
                                     lineno=lineno)
        return nodes.Output([save_node], lineno=lineno)

    def save_variable(self, variable_name, right_value, target_file, context):
        '''Временный метод для сохранения значений переменных.'''
        datavars = context.parent['__datavars__']
        module_name = variable_name[0]
        namespaces = variable_name[1:-1]
        variable_name = variable_name[-1]

        if module_name in datavars:
            variables_module = datavars[module_name]
            for namespace in namespaces:
                if namespace not in variables_module:
                    variables_module[namespace] = Variables()
                variables_module = variables_module[namespace]
            variables_module[variable_name] = right_value
        else:
            AttributeError("Unknown variables module '{}'".
                           format(module_name))
        return ''

    def get_parameter_node(self):
        lineno = self.stream.current.lineno
        parameter_name = self.stream.expect('name').value
        parameter_name_node = nodes.Const(parameter_name, lineno=lineno)
        if self.stream.skip_if('assign'):
            parameter_value = self.stream.current.value
            parameter_rvalue = self.parser.parse_expression(with_condexpr=True)
            if parameter_name == 'env':
                env_names = parameter_value.split(',')
                for name in env_names:
                    CalculateContext._env_set.add(name.strip())
        else:
            parameter_rvalue = nodes.Const(True, lineno=lineno)
        return nodes.Pair(parameter_name_node, parameter_rvalue)

    def save_parameters(cls, parameters_dictionary, compare_result, context):
        context.parent['__parameters__'].set_parameters(parameters_dictionary)
        context.parent['__parameters__'].set_condition(compare_result)
        return ''


class TemplateEngine():
    def __init__(self, directory_path='/',
                 parameters_set=set(),
                 env_set=set(),
                 datavars_module=Variables()):
        CalculateExtension._parameters_set = parameters_set

        self._datavars_module = datavars_module
        self._parameters_object = Parameters()
        self._template_text = ''

        self.environment = Environment(loader=FileSystemLoader(directory_path),
                                       extensions=[CalculateExtension])
        self.environment.context_class = CalculateContext

    def change_directory(self, directory_path):
        self.environment.loader = FileSystemLoader(directory_path)

    def process_template(self, template_path, env=set()):
        CalculateContext._env_set = env
        template = self.environment.get_template(template_path)
        self._parameters_object = Parameters(parameters_dictionary={},
                                             condition=True)
        self._template_text = template.render(
                                         __datavars__=self._datavars_module,
                                         __parameters__=self._parameters_object
                                             )

    def process_template_from_string(self, string, env=set()):
        CalculateContext._env_set = env
        template = self.environment.from_string(string)
        self._parameters_object = Parameters(parameters_dictionary={},
                                             condition=True)
        self._template_text = template.render(
                                         __datavars__=self._datavars_module,
                                         __parameters__=self._parameters_object
                                             )

    @property
    def condition(self):
        return self._parameters_object.condition

    @property
    def parameters(self):
        return self._parameters_object.parameters

    @property
    def template_text(self):
        text, self._template_text = self._template_text, ''
        return text