com.google.idea.blaze.base.lang.buildfile.validation.GlobPatternValidator.java Source code

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Here is the source code for com.google.idea.blaze.base.lang.buildfile.validation.GlobPatternValidator.java

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/*
 * Copyright 2016 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.idea.blaze.base.lang.buildfile.validation;

import com.google.common.base.Splitter;
import javax.annotation.Nullable;

/**
 * Support for resolving globs.
 *
 * <p>
 */
public class GlobPatternValidator {

    /**
     * Validate a single glob pattern. If it's invalid, returns an error message. Otherwise, returns
     * null.
     *
     * <p>
     */
    @Nullable
    public static String validate(String pattern) {
        String error = checkPatternForError(pattern);
        if (error != null) {
            return "Invalid glob pattern: " + error;
        }
        return null;
    }

    @Nullable
    private static String checkPatternForError(String pattern) {
        if (pattern.isEmpty()) {
            return "pattern cannot be empty";
        }
        if (pattern.charAt(0) == '/') {
            return "pattern cannot be absolute";
        }
        for (int i = 0; i < pattern.length(); i++) {
            char c = pattern.charAt(i);
            switch (c) {
            case '(':
            case ')':
            case '{':
            case '}':
            case '[':
            case ']':
                return "illegal character '" + c + "'";
            }
        }
        Iterable<String> segments = Splitter.on('/').split(pattern);
        for (String segment : segments) {
            if (segment.isEmpty()) {
                return "empty segment not permitted";
            }
            if (segment.equals(".") || segment.equals("..")) {
                return "segment '" + segment + "' not permitted";
            }
            if (segment.contains("**") && !segment.equals("**")) {
                return "recursive wildcard must be its own segment";
            }
        }
        return null;
    }
}