com.google.javascript.jscomp.GwtProperties.java Source code

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Here is the source code for com.google.javascript.jscomp.GwtProperties.java

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/*
 * Copyright 2016 The Closure Compiler Authors.
 *
 * 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.javascript.jscomp;

import com.google.common.collect.ImmutableMap;
import java.util.Collection;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * GWT-compatible helper for dealing with Java .properties files. The format is probably not
 * fully parsed by this code, but is suitable for simple use-cases inside Closure.
 */
public class GwtProperties {
    // Matches the first part of a property, e.g. "foo.bar.baz = "
    private static final Pattern PROP_DEF = Pattern.compile("^(\\w+(\\.\\w+)*)\\s*[:= ]");

    // Matches a value part of a property, e.g. "  value\" (continuation) or "value"
    private static final Pattern PROP_LINE = Pattern.compile("^\\s*(.*?)(\\\\?)$"); // literal "\"

    private final Map<String, String> contents;

    private GwtProperties(Map<String, String> contents) {
        this.contents = contents;
    }

    /**
     * @param key Property key to retrieve.
     * @return The string value of this key.
     */
    public String getProperty(String key) {
        return contents.get(key);
    }

    /**
     * @return The collection of property names.
     */
    public Collection<String> propertyNames() {
        return contents.keySet();
    }

    /**
     * Constructs a new {@link GwtProperties} from the given source string.
     *
     * @param source To load from.
     * @return The {@link GwtProperties} object from the source.
     */
    public static GwtProperties load(String source) {
        String[] lines = source.split("\r?\n");
        ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();

        for (int i = 0; i < lines.length; ++i) {
            String line = lines[i];
            if (line.isEmpty() || line.startsWith("#") || line.startsWith("!")) {
                continue; // skip if empty or starts with # or !
            }

            Matcher m = PROP_DEF.matcher(line);
            if (!m.find()) {
                continue;
            }
            String key = m.group(1);
            String data = "";

            line = line.substring(m.group(0).length()); // remove matched part
            for (;;) {
                Matcher lineMatch = PROP_LINE.matcher(line);
                if (!lineMatch.matches()) {
                    // Should never happen, since PROP_LINE contains .* and no hard requirements.
                    throw new RuntimeException("Properties parser failed on line: " + line);
                }
                data += lineMatch.group(1); // add content found

                // If the line ends with "/", then consume another line if possible.
                boolean isLastLine = lineMatch.group(2).isEmpty();
                if (isLastLine || i + 1 == lines.length) {
                    break;
                }
                line = lines[++i];
            }

            builder.put(key, data);
        }

        return new GwtProperties(builder.build());
    }

}