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/*
 * Copyright (c) 2012-2015, Microsoft Mobile
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package jsimple.json.objectmodel;

import jsimple.io.Reader;
import jsimple.json.text.JsonParsingException;
import jsimple.json.text.Token;
import jsimple.json.text.TokenType;

/**
 * @author Bret Johnson
 * @since 5/6/12 12:17 AM
 */
public final class ObjectModelParser {
    private Token token;

    /**
     * Parse the specified JSON text.  getResult() can then be used to get the resulting JSON result tree.
     *
     * @param reader JSON text to parse
     */
    public ObjectModelParser(Reader reader) {
        this.token = new Token(reader);
    }

    public JsonObjectOrArray parseRoot() {
        TokenType lookahead = token.getType();

        JsonObjectOrArray result;
        if (lookahead == TokenType.LEFT_BRACE)
            result = parseObject();
        else if (lookahead == TokenType.LEFT_BRACKET)
            result = parseArray();
        else throw new JsonParsingException("{ or [, starting an object or array", token);

        token.check(TokenType.EOF);

        return result;
    }

    private JsonObject parseObject() {
        JsonObject jsonObject = new JsonObject();

        token.checkAndAdvance(TokenType.LEFT_BRACE);

        // Handle the empty object case here (which makes the code below simpler)
        if (token.getType() == TokenType.RIGHT_BRACE) {
            advance();
            return jsonObject;
        }

        while (true) {
            Object nameObject = token.getPrimitiveValue();

            if (!(nameObject instanceof String))
                throw new JsonParsingException("string for object key", token);

            String name = (String) nameObject;
            advance();

            token.checkAndAdvance(TokenType.COLON);

            Object value = parseValue();

            jsonObject.add(name, value);

            if (token.getType() == TokenType.RIGHT_BRACE) {
                advance();
                break;
            } else if (token.getType() == TokenType.COMMA)
                advance();
            else throw new JsonParsingException(", or }", token);
        }

        return jsonObject;
    }

    public Object parseValue() {
        Object value;

        TokenType lookahead = token.getType();
        if (lookahead == TokenType.PRIMITIVE) {
            value = token.getPrimitiveValue();
            advance();
        } else if (lookahead == TokenType.LEFT_BRACE)
            value = parseObject();
        else if (lookahead == TokenType.LEFT_BRACKET)
            value = parseArray();
        else throw new JsonParsingException("primitive type, object, or array", token);

        return value;
    }

    public JsonArray parseArray() {
        JsonArray jsonArray = new JsonArray();

        token.checkAndAdvance(TokenType.LEFT_BRACKET);

        // Handle the empty array case here (which makes the code below simpler)
        if (token.getType() == TokenType.RIGHT_BRACKET) {
            advance();
            return jsonArray;
        }

        while (true) {
            Object value = parseValue();

            jsonArray.add(value);

            if (token.getType() == TokenType.RIGHT_BRACKET) {
                advance();
                break;
            } else if (token.getType() == TokenType.COMMA)
                advance();
            else throw new JsonParsingException(", or ]", token);
        }

        return jsonArray;
    }

    /**
     * Advance to the next token.
     */
    public void advance() {
        token.advance();
    }

    public TokenType getTokenType() {
        return token.getType();
    }
}