#     Copyright 2019, Kay Hayen, mailto:kay.hayen@gmail.com
#
#     Part of "Nuitka", an optimizing Python compiler that is compatible and
#     integrates with CPython, but also works on its own.
#
#     Licensed under the Apache License, Version 2.0 (the "License");
#     you may not use this file except in compliance with the License.
#     You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
#     Unless required by applicable law or agreed to in writing, software
#     distributed under the License is distributed on an "AS IS" BASIS,
#     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#     See the License for the specific language governing permissions and
#     limitations under the License.
#
""" Reformulation of "yield" and "yield from" expressions.

Consult the developer manual for information. TODO: Add ability to sync
source code comments with developer manual sections.

"""

import ast

from nuitka.nodes.ConstantRefNodes import ExpressionConstantNoneRef
from nuitka.nodes.YieldNodes import ExpressionYield, ExpressionYieldFrom
from nuitka.PythonVersions import python_version

from .SyntaxErrors import raiseSyntaxError
from .TreeHelpers import buildNode


def _checkInsideGenerator(provider, node, source_ref):
    if provider.isCompiledPythonModule():
        raiseSyntaxError(
            "'yield' outside function", source_ref.atColumnNumber(node.col_offset)
        )

    # This yield is forbidden in 3.5, but allowed in 3.6, but yield_from
    # is neither.
    if provider.isExpressionAsyncgenObjectBody() and (
        node.__class__ is not ast.Yield or python_version < 360
    ):
        raiseSyntaxError(
            "'%s' inside async function"
            % ("yield" if node.__class__ is ast.Yield else "yield from",),
            source_ref.atColumnNumber(node.col_offset),
        )

    assert (
        provider.isExpressionGeneratorObjectBody()
        or provider.isExpressionAsyncgenObjectBody()
    ), provider


def buildYieldNode(provider, node, source_ref):
    _checkInsideGenerator(provider, node, source_ref)

    if node.value is not None:
        return ExpressionYield(
            expression=buildNode(provider, node.value, source_ref),
            source_ref=source_ref,
        )
    else:
        return ExpressionYield(
            expression=ExpressionConstantNoneRef(
                source_ref=source_ref, user_provided=True
            ),
            source_ref=source_ref,
        )


def buildYieldFromNode(provider, node, source_ref):
    assert python_version >= 300

    _checkInsideGenerator(provider, node, source_ref)

    return ExpressionYieldFrom(
        expression=buildNode(provider, node.value, source_ref), source_ref=source_ref
    )
