com.facebook.buck.core.macros.MacroFinder.java Source code

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Here is the source code for com.facebook.buck.core.macros.MacroFinder.java

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/*
 * Copyright 2015-present Facebook, Inc.
 *
 * 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.facebook.buck.core.macros;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.util.Optional;

/**
 * Replace and extracts macros from input strings.
 *
 * <p>Examples: $(exe //foo:bar) $(location :bar) $(platform)
 */
public final class MacroFinder {

    private MacroFinder() {
    } // Static utility.

    public static Optional<MacroMatchResult> match(ImmutableSet<String> macros, String blob) throws MacroException {

        MacroFinderAutomaton macroFinder = new MacroFinderAutomaton(blob);
        if (!macroFinder.hasNext()) {
            return Optional.empty();
        }
        MacroMatchResult result = macroFinder.next();
        if (!result.isEscaped() && result.getStartIndex() == 0 && result.getEndIndex() == blob.length()
                && !macros.contains(result.getMacroType())) {
            throw new MacroException(
                    String.format("expanding %s: no such macro \"%s\"", blob, result.getMacroType()));
        }
        return Optional.of(result);
    }

    /**
     * Expand macros embedded in a string.
     *
     * @param replacers a map of macro names to {@link MacroReplacer} objects used to expand them.
     * @param blob the input string containing macros to be expanded
     * @param resolveEscaping whether to drop characters used to escape literal uses of `$(...)`
     * @return a copy of the input string with all macros expanded
     */
    public static <T> T replace(ImmutableMap<String, MacroReplacer<T>> replacers, String blob,
            boolean resolveEscaping, MacroCombiner<T> combiner) throws MacroException {
        // Iterate over all macros found in the string, expanding each found macro.
        int lastEnd = 0;
        MacroFinderAutomaton matcher = new MacroFinderAutomaton(blob);
        while (matcher.hasNext()) {
            MacroMatchResult matchResult = matcher.next();
            // Add everything from the original string since the last match to this one.
            combiner.addString(blob.substring(lastEnd, matchResult.getStartIndex()));

            // If the macro is escaped, add the macro text (but omit the escaping backslash)
            if (matchResult.isEscaped()) {
                combiner.addString(blob.substring(matchResult.getStartIndex() + (resolveEscaping ? 1 : 0),
                        matchResult.getEndIndex()));
            } else {
                // Call the relevant expander and add the expanded value to the string.
                MacroReplacer<T> replacer = replacers.get(matchResult.getMacroType());
                if (replacer == null) {
                    throw new MacroException(String.format("expanding %s: no such macro \"%s\"",
                            blob.substring(matchResult.getStartIndex(), matchResult.getEndIndex()),
                            matchResult.getMacroType()));
                }
                try {
                    combiner.add(replacer.replace(matchResult));
                } catch (MacroException e) {
                    throw new MacroException(String.format("expanding %s: %s",
                            blob.substring(matchResult.getStartIndex(), matchResult.getEndIndex()), e.getMessage()),
                            e);
                }
            }
            lastEnd = matchResult.getEndIndex();
        }
        // Append the remaining part of the original string after the last match.
        combiner.addString(blob.substring(lastEnd));
        return combiner.build();
    }

    public static ImmutableList<MacroMatchResult> findAll(ImmutableSet<String> macros, String blob)
            throws MacroException {

        ImmutableList.Builder<MacroMatchResult> results = ImmutableList.builder();
        MacroFinderAutomaton matcher = new MacroFinderAutomaton(blob);
        while (matcher.hasNext()) {
            MacroMatchResult matchResult = matcher.next();
            if (matchResult.isEscaped()) {
                continue;
            }
            if (!macros.contains(matchResult.getMacroType())) {
                throw new MacroException(String.format("no such macro \"%s\"", matchResult.getMacroType()));
            }
            results.add(matchResult);
        }

        return results.build();
    }
}