| // Copyright 2015 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.syntax; |
| |
| import com.google.common.collect.ImmutableList; |
| import com.google.devtools.build.lib.events.Location; |
| import com.google.devtools.build.lib.skylarkinterface.SkylarkModule; |
| import com.google.devtools.build.lib.skylarkinterface.SkylarkValue; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * An attribute value consisting of a concatenation of native types and selects, e.g: |
| * |
| * <pre> |
| * rule( |
| * name = 'myrule', |
| * deps = |
| * [':defaultdep'] |
| * + select({ |
| * 'a': [':adep'], |
| * 'b': [':bdep'],}) |
| * + select({ |
| * 'c': [':cdep'], |
| * 'd': [':ddep'],}) |
| * ) |
| * </pre> |
| */ |
| @SkylarkModule(name = "select", |
| doc = "A selector between configuration-dependent entities.", |
| documented = false) |
| public final class SelectorList implements SkylarkValue { |
| // TODO(build-team): Selectors are currently split between .packages and .syntax . They should |
| // really all be in .packages, but then we'd need to figure out a way how to extend binary |
| // operators, which is a non-trivial problem. |
| private final Class<?> type; |
| private final List<Object> elements; |
| |
| private SelectorList(Class<?> type, List<Object> elements) { |
| this.type = type; |
| this.elements = elements; |
| } |
| |
| /** |
| * Returns an ordered list of the elements in this expression. Each element may be a |
| * native type or a select. |
| */ |
| public List<Object> getElements() { |
| return elements; |
| } |
| |
| /** |
| * Returns the native type contained by this expression. |
| */ |
| public Class<?> getType() { |
| return type; |
| } |
| |
| /** |
| * Creates a "wrapper" list that consists of a single select. |
| */ |
| public static SelectorList of(SelectorValue selector) { |
| return new SelectorList(selector.getType(), ImmutableList.<Object>of(selector)); |
| } |
| |
| /** |
| * Creates a list that concatenates two values, where each value may be either a native |
| * type or a select over that type. |
| * |
| * @throws EvalException if the values don't have the same underlying type |
| */ |
| public static SelectorList concat(Location location, Object value1, Object value2) |
| throws EvalException { |
| ImmutableList.Builder<Object> builder = ImmutableList.builder(); |
| Class<?> type1 = addValue(value1, builder); |
| Class<?> type2 = addValue(value2, builder); |
| if (!canConcatenate(type1, type2)) { |
| throw new EvalException( |
| location, |
| String.format( |
| "'+' operator applied to incompatible types (%s, %s)", |
| EvalUtils.getDataTypeName(value1, true), |
| EvalUtils.getDataTypeName(value2, true))); |
| } |
| return new SelectorList(type1, builder.build()); |
| } |
| |
| // TODO(bazel-team): match on the List interface, not the actual implementation. For now, |
| // we verify this is the right class through test coverage. |
| private static final Class<?> NATIVE_LIST_TYPE = ArrayList.class; |
| |
| private static Class<?> addValue(Object value, ImmutableList.Builder<Object> builder) { |
| if (value instanceof SelectorList) { |
| SelectorList selectorList = (SelectorList) value; |
| builder.addAll(selectorList.getElements()); |
| return selectorList.getType(); |
| } else if (value instanceof SelectorValue) { |
| builder.add(value); |
| return ((SelectorValue) value).getType(); |
| } else { |
| builder.add(value); |
| return value.getClass(); |
| } |
| } |
| |
| private static boolean isListType(Class<?> type) { |
| return type == NATIVE_LIST_TYPE |
| || type.getSuperclass() == SkylarkList.class |
| || type == GlobList.class; |
| } |
| |
| private static boolean canConcatenate(Class<?> type1, Class<?> type2) { |
| if (type1 == type2) { |
| return true; |
| } else if (isListType(type1) && isListType(type2)) { |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return Printer.repr(this); |
| } |
| |
| @Override |
| public void write(Appendable buffer, char quotationMark) { |
| Printer.printList(buffer, elements, "", " + ", "", null, quotationMark); |
| } |
| |
| @Override |
| public boolean isImmutable() { |
| return false; |
| } |
| } |