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// 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 java.util.Arrays;
import java.util.List;
/**
* Interface for parsing options from a single options specification class.
*
* The {@link Options#parse(Class, String...)} method in this class has no clear
* use case. Instead, use the {@link OptionsParser} class directly, as in this
* code snippet:
*
* <pre>
* OptionsParser parser = OptionsParser.newOptionsParser(FooOptions.class);
* try {
* parser.parse(FooOptions.class, args);
* } catch (OptionsParsingException e) {
* System.err.print("Error parsing options: " + e.getMessage());
* System.err.print(options.getUsage());
* System.exit(1);
* }
* FooOptions foo = parser.getOptions(FooOptions.class);
* List<String> otherArguments = parser.getResidue();
* </pre>
*
* Using this class in this case actually results in more code.
*
* @see OptionsParser for parsing options from multiple options specification classes.
*/
public class Options<O extends OptionsBase> {
/**
* Parse the options provided in args, given the specification in
* optionsClass.
*/
public static <O extends OptionsBase> Options<O> parse(Class<O> optionsClass, String... args)
throws OptionsParsingException {
OptionsParser parser = OptionsParser.newOptionsParser(optionsClass);
parser.parse(OptionPriority.COMMAND_LINE, null, Arrays.asList(args));
List<String> remainingArgs = parser.getResidue();
return new Options<O>(parser.getOptions(optionsClass),
remainingArgs.toArray(new String[0]));
}
/**
* Returns an options object at its default values. The returned object may
* be freely modified by the caller, by assigning its fields.
*/
public static <O extends OptionsBase> O getDefaults(Class<O> optionsClass) {
try {
return parse(optionsClass, new String[0]).getOptions();
} catch (OptionsParsingException e) {
String message = "Error while parsing defaults: " + e.getMessage();
throw new AssertionError(message);
}
}
/**
* Returns a usage string (renders the help information, the defaults, and
* of course the option names).
*/
public static String getUsage(Class<? extends OptionsBase> optionsClass) {
StringBuilder usage = new StringBuilder();
OptionsUsage.getUsage(optionsClass, usage);
return usage.toString();
}
private O options;
private String[] remainingArgs;
private Options(O options, String[] remainingArgs) {
this.options = options;
this.remainingArgs = remainingArgs;
}
/**
* Returns an instance of options class O.
*/
public O getOptions() {
return options;
}
/**
* Returns the arguments that we didn't parse.
*/
public String[] getRemainingArgs() {
return remainingArgs;
}
}
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