| // Copyright 2014 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. |
| package com.google.devtools.build.lib.rules.python; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.devtools.build.lib.packages.Attribute.AllowedValueSet; |
| import com.google.devtools.build.lib.packages.AttributeMap; |
| import com.google.devtools.build.lib.packages.RawAttributeMapper; |
| import com.google.devtools.build.lib.packages.RuleTransitionFactory; |
| import com.google.devtools.build.lib.syntax.Type; |
| import com.google.devtools.build.lib.util.FileType; |
| |
| /** Rule definitions for Python rules. */ |
| public class PyRuleClasses { |
| |
| public static final FileType PYTHON_SOURCE = FileType.of(".py", ".py3"); |
| |
| /** |
| * A value set of the target and sentinel values that doesn't mention the sentinel in error |
| * messages. |
| */ |
| public static final AllowedValueSet TARGET_PYTHON_ATTR_VALUE_SET = |
| new AllowedValueSet(PythonVersion.TARGET_AND_SENTINEL_STRINGS) { |
| @Override |
| public String getErrorReason(Object value) { |
| return String.format("has to be one of 'PY2' or 'PY3' instead of '%s'", value); |
| } |
| }; |
| |
| /** |
| * Returns a rule transition factory for Python binary rules and other rules that may change the |
| * Python version. |
| * |
| * <p>The factory reads the version specified by the target's {@code python_version} attribute if |
| * given, falling back on the {@code default_python_version} attribute otherwise. Both attributes |
| * must exist on the rule class. If a value was read successfully, the factory returns a |
| * transition that sets the version to that value. Otherwise if neither attribute was set, the |
| * factory returns {@code defaultTransition} instead. |
| * |
| * <p>If either attribute has an unparsable value on the target, then the factory returns {@code |
| * defaultTransition} and it is up to the rule's analysis phase ({@link |
| * PyCommon#validateTargetPythonVersionAttr}) to report an attribute error to the user. This case |
| * should be prevented by attribute validation if the rule class is defined correctly. |
| */ |
| public static RuleTransitionFactory makeVersionTransition( |
| PythonVersionTransition defaultTransition) { |
| return (rule) -> { |
| AttributeMap attrs = RawAttributeMapper.of(rule); |
| // Fail fast if we're used on an ill-defined rule class. |
| Preconditions.checkArgument( |
| attrs.has(PyCommon.PYTHON_VERSION_ATTRIBUTE, Type.STRING) |
| && attrs.has(PyCommon.DEFAULT_PYTHON_VERSION_ATTRIBUTE, Type.STRING), |
| "python version transitions require that the RuleClass define both " |
| + "'default_python_version' and 'python_version'"); |
| // Attribute validation should enforce that the attribute string value is either a target |
| // value ("PY2" or "PY3") or the sentinel value ("_INTERNAL_SENTINEL"). But just in case, |
| // we'll, treat an invalid value as the default value rather than propagate an unchecked |
| // exception in this context. That way the user can at least get a clean error message |
| // instead of a crash. |
| PythonVersionTransition transition; |
| try { |
| PythonVersion versionFromAttributes = PyCommon.readPythonVersionFromAttributes(attrs); |
| if (versionFromAttributes == null) { |
| transition = defaultTransition; |
| } else { |
| transition = PythonVersionTransition.toConstant(versionFromAttributes); |
| } |
| } catch (IllegalArgumentException ex) { |
| transition = defaultTransition; |
| } |
| return transition; |
| }; |
| } |
| |
| /** |
| * A Python version transition that sets the version as specified by the target's attributes, with |
| * a default determined by {@link PythonOptions#getDefaultPythonVersion}. |
| */ |
| public static final RuleTransitionFactory VERSION_TRANSITION = |
| makeVersionTransition(PythonVersionTransition.toDefault()); |
| } |