tools/cpp/crosstool_utils.bzl

# pylint: disable=g-bad-file-header
# Copyright 2018 The Bazel Authors. All rights reserved.
#
# 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.
"""Utility functions for writing crosstool files in Skylark"""

# All possible C++ compile actions
COMPILE_ACTIONS = [
    "c-compile",
    "c++-compile",
    "c++-header-parsing",
    "c++-module-compile",
    "c++-module-codegen",
    "assemble",
    "preprocess-assemble",
    "clif-match",
    "linkstamp-compile",
    "cc-flags-make-variable",
]

# All possible C++ link actions
LINK_ACTIONS = [
    "c++-link-executable",
    "c++-link-dynamic-library",
    "c++-link-nodeps-dynamic-library",
]

# All possible C++ archive actions
ARCHIVE_ACTIONS = [
    "c++-link-static-library",
]

# All remaining actions used by C++ rules that are configured in the CROSSTOOL
OTHER_ACTIONS = [
    "strip",
]

def action_config(action_name, tool_path):
    """Emit action_config message.

    Examples:
      action_config("c-compile", "/usr/bin/gcc") ->
        action_config {
          config_name: 'c-compile'
          action_name: 'c-compile'
          tool {
            tool_path: '/usr/bin/gcc'
          }
        }

    Args:
      action_name: name of the action
      tool_path: absolute or CROSSTOOL-relative path to the tool

    Returns:
      a string to be placed into the CROSSTOOL
    """
    if action_name == None or action_name == "":
        fail("action_name must be present")
    if tool_path == None or tool_path == "":
        fail("tool_path must be present")
    return """
  action_config {{
    config_name: '{action_name}'
    action_name: '{action_name}'
    tool {{
      tool_path: '{tool_path}'
    }}
  }}""".format(action_name = action_name, tool_path = tool_path)

def feature(name, flag_sets, enabled = True, provides = None):
    """Emit feature message.

    Examples:
      feature("fully_static_link", flag_sets, enabled = False) ->
        feature {
          name: 'fully_static_link'
          enabled = false
          <flags_sets>
        }

    Args:
      name: name of the feature
      flag_sets: a collection of flag_set messages
      enabled: whether this feature is turned on by default
      provides: a symbol this feature provides, used to implement mutually incompatible features

    Returns:
      a string to be placed into the CROSSTOOL
    """
    if name == None or name == "":
        fail("feature name must be present")
    return """
  feature {{
    name: '{name}'
    enabled: {enabled}{provides}{flag_sets}
  }}""".format(
        provides = ("\n      provides: '%s'" % provides if provides != None else ""),
        name = name,
        enabled = _to_proto_value(enabled),
        flag_sets = "".join(flag_sets),
    )

def simple_feature(
        name,
        actions,
        flags,
        enabled = True,
        provides = None,
        expand_if_all_available = [],
        iterate_over = None):
    """Sugar for emitting simple feature message.

    Examples:
      simple_feature("foo", ['c-compile'], flags("-foo")) ->
        feature {
          name: 'foo'
          flag_set {
            action: 'c-compile'
            flag_group {
              flag: '-foo'
            }
          }
        }

    Args:
      name: name of the feature
      actions: for which actions should flags be emitted
      flags: a collection of flag messages
      enabled: whether this feature is turned on by default
      provides: a symbol this feature provides, used to implement mutually incompatible features
      expand_if_all_available: specify which build variables need to be present
        for this group to be expanded
      iterate_over: expand this flag_group for every item in the build variable

    Returns:
      a string to be placed into the CROSSTOOL
    """
    if len(flags) == 0:
        return feature(name, [])
    else:
        return feature(
            name,
            [flag_set(
                actions,
                [flag_group(
                    [flag(f) for f in flags],
                    iterate_over = iterate_over,
                    expand_if_all_available = expand_if_all_available,
                )],
            )],
            enabled = enabled,
            provides = provides,
        )

def flag_set(actions, flag_groups):
    """Emit flag_set message.

    Examples:
      flag_set(['c-compile'], flag_groups) ->
        flag_set {
          action: 'c-compile'
          <flag_groups>
        }

    Args:
      actions: for which actions should flags be emitted
      flag_groups: a collection of flag_group messages

    Returns:
      a string to be placed into the CROSSTOOL
    """
    if actions == None or len(actions) == 0:
        fail("empty actions list is not allowed for flag_set")
    if flag_groups == None or len(flag_groups) == 0:
        fail("empty flag_groups list is not allowed for flag_set")
    actions_string = ""
    for action in actions:
        actions_string += "\n      action: '%s'" % action

    return """
    flag_set {{{actions}{flag_groups}
    }}""".format(actions = actions_string, flag_groups = "".join(flag_groups))

def flag_group(
        content,
        expand_if_all_available = [],
        expand_if_none_available = [],
        expand_if_true = [],
        expand_if_false = [],
        expand_if_equal = [],
        iterate_over = None):
    """Emit flag_group message.

    Examples:
      flag_group(flags("-foo %{output_file}"), expand_if_all_available="output_file") ->
        flag_group { expand_if_all_available: "output_file"
          flag: "-foo %{output_file}"
        }

    Args:
      content: a collection of flag messages or a collection of flag_group messages
      expand_if_all_available: specify which build variables need to be present
        for this group to be expanded
      expand_if_none_available: specify which build variables need to be missing
        for this group to be expanded
      expand_if_true: specify which build variables need to be truthy for this group
        to be expanded
      expand_if_false: specify which build variables need to be falsey for this group
        to be expanded
      expand_if_equal: [[var1, value1], [var2, value2]...] specify what values
        should specific build variables have for this group to be expanded
      iterate_over: expand this flag_group for every item in the build variable

    Returns:
      a string to be placed into the CROSSTOOL
    """
    if content == None or len(content) == 0:
        fail("flag_group without flags is not allowed")
    conditions = ""
    for var in expand_if_all_available:
        conditions += "\n        expand_if_all_available: '%s'" % var
    for var in expand_if_none_available:
        conditions += "\n        expand_if_none_available: '%s'" % var
    for var in expand_if_true:
        conditions += "\n        expand_if_true: '%s'" % var
    for var in expand_if_false:
        conditions += "\n        expand_if_false: '%s'" % var
    for var in expand_if_equal:
        conditions += "\n        expand_if_equal { variable: '%s' value: '%s' }" % (var[0], var[1])
    return """
      flag_group {{{conditions}{iterate_over}{content}
      }}""".format(
        content = "".join(content),
        iterate_over = ("\n        iterate_over: '%s'" % iterate_over if iterate_over != None else ""),
        conditions = conditions,
    )

def flag(flag):
    """Emit flag field.

    Examples:
      flag("-foo") -> flag: '-foo'

    Args:
      flag: value to be emitted to the command line

    Returns:
      a string to be placed into the CROSSTOOL
    """
    return "\n        flag: '%s'" % flag

def flags(*flags):
    """Sugar for emitting sequence of flag fields.

    Examples:
      flags("-foo", "-bar") ->
        flag: '-foo'
        flag: '-bar'

    Args:
      *flags: values to be emitted to the command line

    Returns:
      a string to be placed into the CROSSTOOL
    """
    return [flag(f) for f in flags]

def _to_proto_value(boolean):
    if boolean:
        return "true"
    else:
        return "false"