net.vieiro.toml.TOMLSimpleQuery Maven / Gradle / Ivy

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/*
 * Copyright 2023 Antonio Vieiro .
 *
 * 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 net.vieiro.toml;

import java.util.List;
import java.util.Map;
import java.util.Optional;

/**
 * A mini-query language used to search stuff in the generated object tree,
 * without requiring an advanced expression library (OGNL, JXPath, etc.)
 */
final class TOMLSimpleQuery {
    
    @SuppressWarnings("unchecked")
    static  Optional get(Map root, String path, Class clazz) {
        Optional NOT_FOUND = Optional.empty();
        String[] parts = path.split("/");
        Object context = root;
        for (int i = 0; i < parts.length; i++) {
            String part = parts[i];
            if (part.isBlank()) {
                continue;
            }
            if (context instanceof Map) {
                // Context is a map (TOML Table)
                Map map = (Map) context;
                if (!map.containsKey(part)) {
                    return NOT_FOUND;
                }
                /* @NonNull */ Object o = map.get(part);
                if (i < parts.length - 1) {
                    context = o;
                } else {
                    return clazz.isAssignableFrom(o.getClass()) ? Optional.of((T) o) : NOT_FOUND;
                }
            } else if (context instanceof List) {
                List