75 lines
2.5 KiB
Java
75 lines
2.5 KiB
Java
// Copyright 2014 The Bazel Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.devtools.common.options;
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import java.util.Arrays;
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/**
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* A converter superclass for converters that parse enums.
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*
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* <p>Just subclass this class, creating a zero argument constructor that
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* calls {@link #EnumConverter(Class, String)}.
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*
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* <p>This class compares the input string to the string returned by the toString()
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* method of each enum member in a case-insensitive way. Usually, this is the
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* name of the symbol, but beware if you override toString()!
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*/
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public abstract class EnumConverter<T extends Enum<T>>
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implements Converter<T> {
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private final Class<T> enumType;
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private final String typeName;
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/**
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* Creates a new enum converter. You *must* implement a zero-argument
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* constructor that delegates to this constructor, passing in the appropriate
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* parameters.
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*
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* @param enumType The type of your enumeration; usually a class literal
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* like MyEnum.class
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* @param typeName The intuitive name of your enumeration, for example, the
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* type name for CompilationMode might be "compilation mode".
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*/
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protected EnumConverter(Class<T> enumType, String typeName) {
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this.enumType = enumType;
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this.typeName = typeName;
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}
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/**
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* Implements {@link #convert(String)}.
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*/
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@Override
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public T convert(String input) throws OptionsParsingException {
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for (T value : enumType.getEnumConstants()) {
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if (value.toString().equalsIgnoreCase(input)) {
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return value;
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}
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}
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throw new OptionsParsingException("Not a valid " + typeName + ": '"
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+ input + "' (should be "
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+ getTypeDescription() + ")");
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}
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/**
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* Implements {@link #getTypeDescription()}.
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*/
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@Override
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public final String getTypeDescription() {
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return Converters.joinEnglishList(
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Arrays.asList(enumType.getEnumConstants())).toLowerCase();
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}
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}
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