Java tutorial
// Copyright 2016 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.packages; import com.google.common.base.Joiner; import com.google.common.base.Objects; 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.devtools.build.lib.events.Location; import com.google.devtools.build.lib.skylarkinterface.SkylarkModule; import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory; import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter; import com.google.devtools.build.lib.skylarkinterface.SkylarkValue; import com.google.devtools.build.lib.syntax.ClassObject; import com.google.devtools.build.lib.syntax.EvalException; import com.google.devtools.build.lib.syntax.Printer; import com.google.devtools.build.lib.syntax.SkylarkType; import java.io.Serializable; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.Map; import javax.annotation.Nullable; /** Represents information provided by a {@link Provider}. */ @SkylarkModule(name = "struct", category = SkylarkModuleCategory.BUILTIN, 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 abstract class Info implements ClassObject, SkylarkValue, Serializable { private final Provider provider; private final Location creationLoc; private final String errorMessage; /** Creates an empty struct with a given location. */ public Info(Provider provider, Location location) { this.provider = provider; this.creationLoc = location; this.errorMessage = provider.getErrorMessageFormatForInstances(); } /** Creates a built-in struct (i.e. without creation loc). */ public Info(Provider provider) { this.provider = provider; this.creationLoc = null; this.errorMessage = provider.getErrorMessageFormatForInstances(); } /** * Creates a built-in struct (i.e. without creation loc). * * <p>Allows to supply a specific error message. Only used in * {@link com.google.devtools.build.lib.packages.NativeProvider.StructConstructor#create(Map, * String)} If you need to override an error message, preferred way is to create a specific {@link * NativeProvider}. */ Info(Provider provider, Map<String, Object> values, String errorMessage) { this.provider = provider; this.creationLoc = null; this.errorMessage = Preconditions.checkNotNull(errorMessage); } // Ensure that values are all acceptable to Skylark before to stuff them in a ClassObject protected static ImmutableMap<String, Object> copyValues(Map<String, Object> values) { ImmutableMap.Builder<String, Object> builder = ImmutableMap.builder(); for (Map.Entry<String, Object> e : values.entrySet()) { builder.put(Attribute.getSkylarkName(e.getKey()), SkylarkType.convertToSkylark(e.getValue(), null)); } return builder.build(); } public abstract boolean hasKey(String name); /** Returns a value and try to cast it into specified type */ public <TYPE> TYPE getValue(String key, Class<TYPE> type) throws EvalException { Object obj = getValue(key); if (obj == null) { return null; } SkylarkType.checkType(obj, type, key); return type.cast(obj); } public Location getCreationLoc() { return Preconditions.checkNotNull(creationLoc, "This struct was not created in a Skylark code"); } public Provider getProvider() { return provider; } @Nullable public Location getCreationLocOrNull() { return creationLoc; } /** * Returns the fields of this struct. * * Overrides {@link ClassObject#getKeys()}, but does not allow {@link EvalException} to * be thrown. */ @Override public abstract ImmutableCollection<String> getKeys(); /** * Returns the value associated with the name field in this struct, * or null if the field does not exist. * * Overrides {@link ClassObject#getValue(String)}, but does not allow {@link EvalException} to * be thrown. */ @Nullable @Override public abstract Object getValue(String name); @Override public String errorMessage(String name) { String suffix = "Available attributes: " + Joiner.on(", ").join(Ordering.natural().sortedCopy(getKeys())); return String.format(errorMessage, name) + "\n" + suffix; } @Override public boolean equals(Object otherObject) { if (!(otherObject instanceof Info)) { return false; } Info other = (Info) otherObject; if (this == other) { return true; } if (!this.provider.equals(other.provider)) { return false; } // Compare objects' keys and values if (!this.getKeys().equals(other.getKeys())) { return false; } for (String key : getKeys()) { if (!this.getValue(key).equals(other.getValue(key))) { return false; } } return true; } @Override public int hashCode() { List<String> keys = new ArrayList<>(getKeys()); Collections.sort(keys); List<Object> objectsToHash = new ArrayList<>(); objectsToHash.add(provider); for (String key : keys) { objectsToHash.add(key); objectsToHash.add(getValue(key)); } return Objects.hashCode(objectsToHash.toArray()); } /** * 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 void repr(SkylarkPrinter printer) { boolean first = true; printer.append("struct("); // Sort by key to ensure deterministic output. for (String key : Ordering.natural().sortedCopy(getKeys())) { if (!first) { printer.append(", "); } first = false; printer.append(key); printer.append(" = "); printer.repr(getValue(key)); } printer.append(")"); } @Override public String toString() { return Printer.repr(this); } }