| // Copyright 2014 Google Inc. 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.base.Joiner; |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.ImmutableCollection; |
| import com.google.common.collect.ImmutableMap; |
| import com.google.common.collect.Ordering; |
| import com.google.common.collect.Sets; |
| import com.google.common.collect.Sets.SetView; |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable; |
| import com.google.devtools.build.lib.events.Location; |
| |
| import java.io.Serializable; |
| import java.util.Map; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * An interface for objects behaving like Skylark structs. |
| */ |
| // TODO(bazel-team): type checks |
| public interface ClassObject { |
| |
| /** |
| * Returns the value associated with the name field in this struct, |
| * or null if the field does not exist. |
| */ |
| @Nullable |
| Object getValue(String name); |
| |
| /** |
| * Returns the fields of this struct. |
| */ |
| ImmutableCollection<String> getKeys(); |
| |
| /** |
| * Returns a customized error message to print if the name is not a valid struct field |
| * of this struct, or returns null to use the default error message. |
| */ |
| @Nullable String errorMessage(String name); |
| |
| /** |
| * An implementation class of ClassObject for structs created in Skylark code. |
| */ |
| // TODO(bazel-team): maybe move the SkylarkModule annotation to the ClassObject interface? |
| @Immutable |
| @SkylarkModule(name = "struct", |
| doc = "A special language element to support structs (i.e. simple value objects). " |
| + "See the global <a href=\"globals.html#struct\">struct</a> function " |
| + "for more details.") |
| public class SkylarkClassObject implements ClassObject, Serializable { |
| /** Error message to use when errorMessage argument is null. */ |
| private static final String DEFAULT_ERROR_MESSAGE = "'struct' object has no attribute '%s'"; |
| |
| private final ImmutableMap<String, Object> values; |
| private final Location creationLoc; |
| private final String errorMessage; |
| |
| /** |
| * Creates a built-in struct (i.e. without creation loc). The errorMessage has to have |
| * exactly one '%s' parameter to substitute the struct field name. |
| */ |
| public SkylarkClassObject(Map<String, Object> values, String errorMessage) { |
| this.values = ImmutableMap.copyOf(values); |
| this.creationLoc = null; |
| this.errorMessage = Preconditions.checkNotNull(errorMessage); |
| } |
| |
| public SkylarkClassObject(Map<String, Object> values, Location creationLoc) { |
| this.values = ImmutableMap.copyOf(values); |
| this.creationLoc = Preconditions.checkNotNull(creationLoc); |
| this.errorMessage = DEFAULT_ERROR_MESSAGE; |
| } |
| |
| @Override |
| public Object getValue(String name) { |
| return values.get(name); |
| } |
| |
| @Override |
| public ImmutableCollection<String> getKeys() { |
| return values.keySet(); |
| } |
| |
| public Location getCreationLoc() { |
| return Preconditions.checkNotNull(creationLoc, |
| "This struct was not created in a Skylark code"); |
| } |
| |
| static SkylarkClassObject concat( |
| SkylarkClassObject lval, SkylarkClassObject rval, Location loc) throws EvalException { |
| SetView<String> commonFields = Sets.intersection(lval.values.keySet(), rval.values.keySet()); |
| if (!commonFields.isEmpty()) { |
| throw new EvalException(loc, "Cannot concat structs with common field(s): " |
| + Joiner.on(",").join(commonFields)); |
| } |
| return new SkylarkClassObject(ImmutableMap.<String, Object>builder() |
| .putAll(lval.values).putAll(rval.values).build(), loc); |
| } |
| |
| @Override |
| public String errorMessage(String name) { |
| String suffix = |
| "Available attributes: " |
| + Joiner.on(", ").join(Ordering.natural().sortedCopy(values.keySet())); |
| return String.format(errorMessage, name) + "\n" + suffix; |
| } |
| |
| /** |
| * Convert the object to string using Skylark syntax. The output tries to be |
| * reversible (but there is no guarantee, it depends on the actual values). |
| */ |
| @Override |
| public String toString() { |
| StringBuilder builder = new StringBuilder(); |
| boolean first = true; |
| builder.append("struct("); |
| // Sort by key to ensure deterministic output. |
| for (String key : Ordering.natural().sortedCopy(values.keySet())) { |
| if (!first) { |
| builder.append(", "); |
| } |
| first = false; |
| builder.append(key); |
| builder.append(" = "); |
| Printer.write(builder, values.get(key)); |
| } |
| builder.append(")"); |
| return builder.toString(); |
| } |
| } |
| } |