com.google.errorprone.ErrorProneFlags.java Source code

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Here is the source code for com.google.errorprone.ErrorProneFlags.java

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/*
 * Copyright 2017 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.errorprone;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import javax.annotation.CheckReturnValue;

/**
 * Represents an immutable map of Error Prone flags to their set values.
 *
 * <p>All get* methods return an {@code Optional<*>} containing the value for the given key, or
 * empty if the flag is unset.
 *
 * <p>To access ErrorProneFlags from a BugChecker class, add a constructor to the class that takes
 * one parameter of type ErrorProneFlags.
 *
 * <p>See <a href=http://errorprone.info/docs/flags>documentation</a> for full syntax description.
 */
public final class ErrorProneFlags implements Serializable {
    public static final String PREFIX = "-XepOpt:";

    private final ImmutableMap<String, String> flagsMap;

    public static ErrorProneFlags empty() {
        return new ErrorProneFlags(ImmutableMap.of());
    }

    public static ErrorProneFlags fromMap(Map<String, String> flagsMap) {
        return new ErrorProneFlags(ImmutableMap.copyOf(flagsMap));
    }

    private ErrorProneFlags(ImmutableMap<String, String> flagsMap) {
        this.flagsMap = flagsMap;
    }

    public ImmutableMap<String, String> getFlagsMap() {
        return ImmutableMap.copyOf(flagsMap);
    }

    /**
     * Gets flag value for the given key as a String, wrapped in an {@link Optional}, which is empty
     * if the flag is unset.
     */
    public Optional<String> get(String key) {
        return Optional.ofNullable(flagsMap.get(key));
    }

    /**
     * Gets the flag value for the given key as a Boolean, wrapped in an {@link Optional}, which is
     * empty if the flag is unset.
     *
     * <p>The value within the {@link Optional} will be {@code true} if the flag's value is "true",
     * {@code false} for "false", both case insensitive. If the value is neither "true" nor "false",
     * throws an {@link IllegalArgumentException}.
     *
     * <p>Note that any flag set without a value, e.g. {@code -XepOpt:FlagValue}, will be "true".
     */
    public Optional<Boolean> getBoolean(String key) {
        return this.get(key).map(ErrorProneFlags::parseBoolean);
    }

    private static boolean parseBoolean(String value) {
        if ("true".equalsIgnoreCase(value)) {
            return true;
        }
        if ("false".equalsIgnoreCase(value)) {
            return false;
        }
        throw new IllegalArgumentException(
                String.format("Error Prone flag value %s could not be parsed as a boolean.", value));
    }

    /**
     * Gets the flag value for the given key as an Integer, wrapped in an {@link Optional}, which is
     * empty if the flag is unset.
     *
     * <p>If the flag's value cannot be interpreted as an Integer, throws a {@link
     * NumberFormatException} (note: float values will *not* be interpreted as integers and will throw
     * an exception!)
     */
    public Optional<Integer> getInteger(String key) {
        return this.get(key).map(Integer::valueOf);
    }

    /**
     * Gets the flag value for the given key as a comma-separated {@link ImmutableList} of Strings,
     * wrapped in an {@link Optional}, which is empty if the flag is unset.
     *
     * <p>(note: empty strings included, e.g. {@code "-XepOpt:List=,1,,2," => ["","1","","2",""]})
     */
    public Optional<ImmutableList<String>> getList(String key) {
        return this.get(key).map(v -> ImmutableList.copyOf(Splitter.on(',').split(v)));
    }

    /** Whether this Flags object is empty, i.e. no flags have been set. */
    public boolean isEmpty() {
        return this.flagsMap.isEmpty();
    }

    /**
     * Returns a new ErrorProneFlags object with the values of two ErrorProneFlags objects added
     * together. For flags that appear in both instances, the values in {@code other} override {@code
     * this}.
     */
    @CheckReturnValue
    public ErrorProneFlags plus(ErrorProneFlags other) {
        Map<String, String> combinedMaps = new HashMap<>(this.getFlagsMap());
        combinedMaps.putAll(other.getFlagsMap());
        return ErrorProneFlags.fromMap(combinedMaps);
    }

    /** Builder for Error Prone command-line flags object. Parses flags from strings. */
    public static class Builder {

        private final HashMap<String, String> flagsMap = new HashMap<>();

        private Builder() {
        }

        /**
         * Given a String custom flag in the format {@code "-XepOpt:FlagName=Value"}, places the flag in
         * this builder's dictionary, e.g. {@code flagsMap["FlagName"] = "Value"}
         */
        @CanIgnoreReturnValue
        public Builder parseFlag(String flag) {
            checkArgument(flag.startsWith(PREFIX));

            // Strip prefix
            String remaining = flag.substring(PREFIX.length());

            // Get key and value by splitting on first equals sign.
            String[] parts = remaining.split("=", 2);
            String key = parts[0];
            String value = parts.length < 2 ? "true" : parts[1];

            this.putFlag(key, value);
            return this;
        }

        /** Puts a key-value pair directly in this builder's dictionary. Mostly exists for testing. */
        @CanIgnoreReturnValue
        public Builder putFlag(String key, String value) {
            flagsMap.put(key, value);
            return this;
        }

        public ErrorProneFlags build() {
            return fromMap(flagsMap);
        }
    }

    public static Builder builder() {
        return new Builder();
    }
}