Python ast 模块，GeneratorExp() 实例源码

def _get_offsets(func_ast):
        for arg in func_ast.args:
            start_line, start_col = arg.lineno - 2, arg.col_offset - 1

            # horrible hack for http://bugs.python.org/issue31241
            if isinstance(arg, (ast.ListComp, ast.GeneratorExp)):
                start_col -= 1
            yield start_line, start_col
        for kw in func_ast.keywords:
            yield kw.value.lineno - 2, kw.value.col_offset - len(kw.arg) - 2

def visit_Call(self, node):
        if (
                isinstance(node.func, ast.Name) and
                node.func.id == 'dict' and
                len(node.args) == 1 and
                not _has_kwargs(node) and
                isinstance(node.args[0], (ast.ListComp, ast.GeneratorExp)) and
                isinstance(node.args[0].elt, (ast.Tuple, ast.List)) and
                len(node.args[0].elt.elts) == 2
        ):
            arg, = node.args
            key = Offset(node.func.lineno, node.func.col_offset)
            self.dicts[key] = arg
        self.generic_visit(node)

def visit_GeneratorExp(self, node):
        # type: (ast.GeneratorExp) -> None
        # Generator expressions are an interesting case.
        # They create a new sub scope, but they're not
        # explicitly named.  Python just creates a table
        # with the name "genexpr".
        self._handle_comprehension(node, 'genexpr')

def visit_Call(self, node):
        argnodes = node.args + node.keywords
        py2_starargs = getattr(node, 'starargs', None)
        if py2_starargs:  # pragma: no cover (<PY35)
            argnodes.append(py2_starargs)
        py2_kwargs = getattr(node, 'kwargs', None)
        if py2_kwargs:  # pragma: no cover (<PY35)
            argnodes.append(py2_kwargs)

        arg_offsets = set()
        has_starargs = bool(py2_starargs or py2_kwargs)
        for argnode in argnodes:
            if (
                    _is_star_arg(argnode) or
                    _is_star_star_kwarg(argnode)
            ):  # pragma: no cover (PY35+)
                has_starargs = True

            offset = _to_offset(argnode)
            # multiline strings have invalid position, ignore them
            if offset.utf8_byte_offset != -1:  # pragma: no branch (cpy bug)
                arg_offsets.add(offset)

        # If the sole argument is a generator, don't add a trailing comma as
        # this breaks lib2to3 based tools
        only_a_generator = (
            len(argnodes) == 1 and isinstance(argnodes[0], ast.GeneratorExp)
        )

        if arg_offsets and not only_a_generator:
            key = Offset(node.lineno, node.col_offset)
            self.calls[key].append(Call(node, has_starargs, arg_offsets))

        self.generic_visit(node)

def test_generatorexp(self):
        self._simple_comp(ast.GeneratorExp)

def test_generatorexp(self):
        self._simple_comp(ast.GeneratorExp)

def test_generatorexp(self):
        self._simple_comp(ast.GeneratorExp)

def checkCompare(self, compare, modelName = None, script = None):
        """Check an AST Compare node - iterate for Attribute nodes and match
           against modelName argument. Recurse for script's model defs."""

        if modelName is None and script is None:
            return

        if modelName is not None:
            valueCallArgs = []
            generatorExps = []
            for node in ast.walk(compare):
                if isinstance(node, ast.Attribute):
                    if isinstance(node.value, ast.Name):
                        if node.value.id == modelName:
                            wrapped = self.checkWrapped(node, valueCallArgs, generatorExps)
                            if not wrapped:
                                self.problem("Comparison on attribute {0}.{1} not wrapped in value()".format(modelName, node.attr), lineno=compare.lineno)
                elif isinstance(node, ast.Call):
                    if isinstance(node.func, ast.Name):
                        if node.func.id == 'value':
                            valueCallArgs.append(node.args)
                elif isinstance(node, ast.GeneratorExp):
                    generatorExps.append(node)

        if script is not None:
            for name in script.modelVars:
                self.checkCompare(compare, modelName = name)

def node_defines_name(node, name):
    """
    Check if the specified statement node defines symbol *name*.

    :param node: The node to check.
    :param name: The symbol name to check.
    :return: Whether or not the node defines the symbole specified.
    :rtype: bool
    """
    if isinstance(name, ast.Name):
        name = name.id

    if isinstance(node, ast.Assign):
        if node_targets_name(node, name):
            return True
        if isinstance(node.value, (ast.DictComp, ast.ListComp, ast.SetComp)):
            return node_defines_name(node.value, name)
    elif isinstance(node, ast.ClassDef):
        return node.name == name
    # these ones all assume the iterable will be executed at least once
    elif isinstance(node, (ast.DictComp, ast.GeneratorExp, ast.ListComp, ast.SetComp)):
        for generator in node.generators:
            target = generator.target
            if isinstance(target, ast.Name):
                if target.id == name:
                    return True
                continue
            for child_node in iter_child_expr_nodes(target):
                if isinstance(child_node, ast.Name) and child_node.id == name:
                    return True
        return False
    elif isinstance(node, ast.ExceptHandler):
        if isinstance(node.name, ast.Name):
            return node.name.id == name
        elif isinstance(node.name, str):
            return node.name == name
    elif isinstance(node, ast.Expr):
        if isinstance(node.value, (ast.DictComp, ast.GeneratorExp, ast.ListComp, ast.SetComp)):
            return node_defines_name(node.value, name)
    elif isinstance(node, ast.For):
        return isinstance(node.target, ast.Name) and node.target.id == name
    elif isinstance(node, ast.FunctionDef):
        return node.name == name
    elif isinstance(node, (ast.Import, ast.ImportFrom)):
        return next((alias for alias in node.names if (alias.asname or alias.name) == name), None) is not None
    return False

def peval_comprehension(state, node, ctx):

    accum_cls = {
        ast.ListComp: ListAccumulator,
        ast.GeneratorExp: GeneratorExpAccumulator,
        ast.SetComp: SetAccumulator,
        ast.DictComp: DictAccumulator,
    }

    # variables from generators temporary mask bindings
    target_names = set()
    for generator in node.generators:
        if type(generator.target) == ast.Name:
            target_names.add(generator.target.id)
        else:
            target_names.update([elt.id for elt in generator.target.elts])

    # pre-evaluate the expression
    elt_bindings = dict(ctx.bindings)
    for name in target_names:
        if name in elt_bindings:
            del elt_bindings[name]
    elt_ctx = ctx.update(bindings=elt_bindings)

    if type(node) == ast.DictComp:
        elt = ast.Tuple(elts=[node.key, node.value])
    else:
        elt = node.elt
    state, new_elt = _peval_expression(state, elt, elt_ctx)

    try:
        state, container = _peval_comprehension(
            state, accum_cls[type(node)], new_elt, node.generators, ctx)
        evaluated = True
    except CannotEvaluateComprehension:
        evaluated = False

    if evaluated:
        return state, KnownValue(value=container)
    else:
        state, new_elt = map_reify(state, new_elt)
        state, new_generators = _peval_comprehension_generators(state, node.generators, ctx)
        if type(node) == ast.DictComp:
            key, value = new_elt.elts
            return state, replace_fields(node, key=key, value=value, generators=new_generators)
        else:
            return state, replace_fields(node, elt=new_elt, generators=new_generators)