com.google.devtools.common.options.OptionsBase Maven / Gradle / Ivy
// 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.common.options;
import com.google.common.collect.Maps;
import com.google.common.escape.CharEscaperBuilder;
import com.google.common.escape.Escaper;
import java.util.List;
import java.util.Map;
import java.util.Objects;
/**
* Base class for all options classes. Extend this class, adding public instance fields annotated
* with {@link Option}. Then you can create instances either programmatically:
*
*
* X x = Options.getDefaults(X.class);
* x.host = "localhost";
* x.port = 80;
*
*
* or from an array of command-line arguments:
*
*
* OptionsParser parser = OptionsParser.builder()
* .optionsClasses(X.class)
* .build();
* parser.parse("--host", "localhost", "--port", "80");
* X x = parser.getOptions(X.class);
*
*
* Subclasses of {@code OptionsBase} must be constructed reflectively, i.e. using not
* {@code new MyOptions()}, but one of the above methods instead. (Direct construction creates an
* empty instance, not containing default values. This leads to surprising behavior and often {@code
* NullPointerExceptions}, etc.)
*/
public abstract class OptionsBase {
private static final Escaper ESCAPER = new CharEscaperBuilder()
.addEscape('\\', "\\\\").addEscape('"', "\\\"").toEscaper();
/**
* Subclasses must provide a default (no argument) constructor.
*/
protected OptionsBase() {
// There used to be a sanity check here that checks the stack trace of this constructor
// invocation; unfortunately, that makes the options construction about 10x slower. So be
// careful with how you construct options classes.
}
/**
* Returns a mapping from option names to values, for each option on this object, including
* inherited ones. The mapping is a copy, so subsequent mutations to it or to this object are
* independent. Entries are sorted alphabetically.
*/
public final Map asMap() {
List definitions = OptionsData.getAllOptionDefinitionsForClass(getClass());
Map map = Maps.newLinkedHashMapWithExpectedSize(definitions.size());
for (OptionDefinition definition : definitions) {
map.put(definition.getOptionName(), getValueFromDefinition(definition));
}
return map;
}
/** Returns the value of the option described by {@code definition}. */
public final Object getValueFromDefinition(OptionDefinition definition) {
try {
return definition.getField().get(this);
} catch (IllegalAccessException e) {
throw new IllegalStateException("All options fields of options classes should be public", e);
}
}
@Override
public final String toString() {
return getClass().getName() + asMap();
}
/**
* Returns a string that uniquely identifies the options. This value is
* intended for analysis caching.
*/
public final String cacheKey() {
StringBuilder result = new StringBuilder(getClass().getName()).append("{");
result.append(mapToCacheKey(asMap()));
return result.append("}").toString();
}
public static String mapToCacheKey(Map optionsMap) {
StringBuilder result = new StringBuilder();
for (Map.Entry entry : optionsMap.entrySet()) {
result.append(entry.getKey()).append("=");
Object value = entry.getValue();
// This special case is needed because List.toString() prints the same
// ("[]") for an empty list and for a list with a single empty string.
if (value instanceof List && ((List) value).isEmpty()) {
result.append("EMPTY");
} else if (value == null) {
result.append("NULL");
} else {
result
.append('"')
.append(ESCAPER.escape(value.toString()))
.append('"');
}
result.append(", ");
}
return result.toString();
}
@Override
@SuppressWarnings("EqualsGetClass") // Options can only be equal if they are of the same type.
public final boolean equals(Object that) {
if (this == that) {
return true;
}
if (that == null || !getClass().equals(that.getClass())) {
return false;
}
OptionsBase other = (OptionsBase) that;
for (OptionDefinition def : OptionsParser.getOptionDefinitions(getClass())) {
if (!Objects.equals(getValueFromDefinition(def), other.getValueFromDefinition(def))) {
return false;
}
}
return true;
}
@Override
public final int hashCode() {
return this.getClass().hashCode() + asMap().hashCode();
}
}