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package com.alipay.api.internal.util.json;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 不能直接使用JSONReader，请用JSONValidatingReader，所以这里改为abstract修饰。
 */
public abstract class JSONReader {

    private static final Object OBJECT_END = new Object();
    private static final Object ARRAY_END  = new Object();
    private static final Object COLON      = new Object();
    private static final Object COMMA      = new Object();
    public static final  int    FIRST      = 0;
    public static final  int    CURRENT    = 1;
    public static final  int    NEXT       = 2;

    private static Map escapes = new HashMap();

    static {
        escapes.put(Character.valueOf('"'), Character.valueOf('"'));
        escapes.put(Character.valueOf('\\'), Character.valueOf('\\'));
        escapes.put(Character.valueOf('/'), Character.valueOf('/'));
        escapes.put(Character.valueOf('b'), Character.valueOf('\b'));
        escapes.put(Character.valueOf('f'), Character.valueOf('\f'));
        escapes.put(Character.valueOf('n'), Character.valueOf('\n'));
        escapes.put(Character.valueOf('r'), Character.valueOf('\r'));
        escapes.put(Character.valueOf('t'), Character.valueOf('\t'));
    }

    private CharacterIterator it;
    private char              c;
    private Object            token;
    private StringBuffer      buf = new StringBuffer();

    private char next() {
        c = it.next();
        return c;
    }

    private void skipWhiteSpace() {
        while (Character.isWhitespace(c)) {
            next();
        }
    }

    public Object read(CharacterIterator ci, int start) {
        it = ci;
        switch (start) {
            case FIRST:
                c = it.first();
                break;
            case CURRENT:
                c = it.current();
                break;
            case NEXT:
                c = it.next();
                break;
        }
        return read();
    }

    public Object read(CharacterIterator it) {
        return read(it, NEXT);
    }

    public Object read(String string) {
        return read(new StringCharacterIterator(string), FIRST);
    }

    private Object read() {
        skipWhiteSpace();
        char ch = c;
        next();
        switch (ch) {
            case '"':
                token = string();
                break;
            case '[':
                token = array();
                break;
            case ']':
                token = ARRAY_END;
                break;
            case ',':
                token = COMMA;
                break;
            case '{':
                token = object();
                break;
            case '}':
                token = OBJECT_END;
                break;
            case ':':
                token = COLON;
                break;
            case 't':
                next();
                next();
                next(); // assumed r-u-e
                token = Boolean.TRUE;
                break;
            case 'f':
                next();
                next();
                next();
                next(); // assumed a-l-s-e
                token = Boolean.FALSE;
                break;
            case 'n':
                next();
                next();
                next(); // assumed u-l-l
                token = null;
                break;
            default:
                c = it.previous();
                if (Character.isDigit(c) || c == '-') {
                    token = number();
                }
        }
        // System.out.println("token: " + token); // enable this line to see the token stream
        return token;
    }

    private Object object() {
        Map ret = new HashMap();
        Object key = read();
        while (token != OBJECT_END) {
            read(); // should be a colon
            if (token != OBJECT_END) {
                ret.put(key, read());
                if (read() == COMMA) {
                    key = read();
                }
            }
        }

        return ret;
    }

    private Object array() {
        List