de.undercouch.citeproc.helper.json.JsonParser Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of citeproc-java Show documentation

A Citation Style Language (CSL) Processor for Java.

There is a newer version: 3.3.0

package de.undercouch.citeproc.helper.json;

import de.undercouch.citeproc.helper.json.JsonLexer.Type;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Parses JSON tokens to maps
 * @author Michel Kraemer
 */
public class JsonParser {
    private final JsonLexer lexer;

    /**
     * Constructs a new JSON parser
     * @param lexer a JSON lexer to read from
     */
    public JsonParser(JsonLexer lexer) {
        this.lexer = lexer;
    }

    /**
     * Parses an object into a map
     * @return the parsed object
     * @throws IOException if the input stream could not be read or if
     * the input stream contained an unexpected token
     */
    public Map parseObject() throws IOException {
        Type t = lexer.readNextToken();
        if (t != Type.START_OBJECT) {
            throw new IOException("Unexpected token: " + t);
        }

        return parseObjectInternal();
    }

    /**
     * Parses an object into a map without reading the
     * {@link Type#START_OBJECT} token
     * @return the parsed object
     * @throws IOException if the input stream could not be read or if
     * the input stream contained an unexpected token
     */
    private Map parseObjectInternal() throws IOException {
        Map result = new HashMap<>();

        Type t;
        while (true) {
            t = lexer.readNextToken();
            if (t == Type.END_OBJECT) {
                break;
            }

            if (!result.isEmpty()) {
                // skip comma and read next token
                if (t != Type.COMMA) {
                    throw new IOException("Unexpected token: " + t);
                }
                t = lexer.readNextToken();
            }

            // first token must be the name
            if (t != Type.STRING) {
                throw new IOException("Unexpected token: " + t);
            }
            String name = lexer.readString();

            // skip colon
            t = lexer.readNextToken();
            if (t != Type.COLON) {
                throw new IOException("Unexpected token: " + t);
            }

            // next token must be the value
            t = lexer.readNextToken();
            Object value = readValue(t);
            result.put(name, value);
        }

        return result;
    }

    /**
     * Parses an array
     * @return the parsed array
     * @throws IOException if the input stream could not be read or if
     * the input stream contained an unexpected token
     */
    public List