package com.best.javaSdk.converter.util.jsonReader;
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import java.text.CharacterIterator;
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import java.text.StringCharacterIterator;
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public class JSONValidator {
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private JSONErrorListener listener;
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private CharacterIterator it;
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private char c;
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private int col;
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public JSONValidator(JSONErrorListener listener) {
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this.listener = listener;
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}
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public boolean validate(String input) {
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input = input.trim();
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listener.start(input);
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boolean ret = valid(input);
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listener.end();
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return ret;
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}
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private boolean valid(String input) {
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if ("".equals(input)) return true;
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boolean ret = true;
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it = new StringCharacterIterator(input);
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c = it.first();
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col = 1;
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if (!value()) {
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ret = error("value", 1);
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} else {
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skipWhiteSpace();
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if (c != CharacterIterator.DONE) {
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ret = error("end", col);
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}
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}
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return ret;
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}
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private boolean value() {
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return
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literal("true") ||
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literal("false") ||
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literal("null") ||
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string() ||
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number() ||
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object() ||
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array();
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}
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private boolean literal(String text) {
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CharacterIterator ci = new StringCharacterIterator(text);
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char t = ci.first();
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if (c != t) return false;
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int start = col;
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boolean ret = true;
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for (t = ci.next(); t != CharacterIterator.DONE; t = ci.next()) {
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if (t != nextCharacter()) {
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ret = false;
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break;
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}
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}
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nextCharacter();
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if (!ret) error("literal " + text, start);
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return ret;
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}
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private boolean array() {
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return aggregate('[', ']', false);
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}
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private boolean object() {
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return aggregate('{', '}', true);
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}
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private boolean aggregate(char entryCharacter, char exitCharacter, boolean prefix) {
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if (c != entryCharacter) return false;
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nextCharacter();
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skipWhiteSpace();
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if (c == exitCharacter) {
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nextCharacter();
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return true;
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}
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for(;;) {
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if (prefix) {
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int start = col;
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if (!string()) return error("string", start);
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skipWhiteSpace();
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if (c != ':') return error("colon", col);
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nextCharacter();
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skipWhiteSpace();
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}
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if (value()) {
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skipWhiteSpace();
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if (c == ',') {
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nextCharacter();
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} else if (c == exitCharacter) {
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break;
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} else {
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return error("comma or " + exitCharacter, col);
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}
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} else {
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return error("value", col);
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}
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skipWhiteSpace();
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}
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nextCharacter();
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return true;
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}
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private boolean number() {
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if (!Character.isDigit(c) && c != '-') return false;
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int start = col;
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if (c == '-') nextCharacter();
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if (c == '0') {
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nextCharacter();
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} else if (Character.isDigit(c)) {
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while(Character.isDigit(c)) nextCharacter();
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} else {
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return error("number", start);
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}
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if (c == '.') {
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nextCharacter();
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if (Character.isDigit(c)) {
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while(Character.isDigit(c)) nextCharacter();
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} else {
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return error("number", start);
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}
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}
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if (c == 'e' || c == 'E') {
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nextCharacter();
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if (c == '+' || c=='-') {
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nextCharacter();
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}
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if (Character.isDigit(c)) {
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while(Character.isDigit(c)) nextCharacter();
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} else {
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return error("number", start);
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}
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}
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return true;
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}
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private boolean string() {
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if (c != '"') return false;
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int start = col;
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boolean escaped = false;
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for (nextCharacter(); c != CharacterIterator.DONE; nextCharacter()) {
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if (!escaped && c == '\\') {
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escaped = true;
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} else if (escaped) {
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if (!escape()) {
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return false;
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}
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escaped = false;
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} else if (c == '"') {
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nextCharacter();
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return true;
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}
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}
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return error("quoted string", start);
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}
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private boolean escape() {
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int start = col-1;
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if ("\\\"/bfnrtu".indexOf(c) < 0) {
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return error("escape sequence \\\",\\\\,\\/,\\b,\\f,\\n,\\r,\\t or \\uxxxx", start);
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}
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if (c == 'u') {
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if (!ishex(nextCharacter()) || !ishex(nextCharacter()) ||
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!ishex(nextCharacter()) || !ishex(nextCharacter())) {
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return error("unicode escape sequence \\uxxxx", start);
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}
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}
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return true;
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}
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private boolean ishex(char d) {
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return "0123456789abcdefABCDEF".indexOf(c) >= 0;
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}
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private char nextCharacter() {
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c = it.next();
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++col;
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return c;
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}
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private void skipWhiteSpace() {
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while (Character.isWhitespace(c)) {
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nextCharacter();
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}
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}
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private boolean error(String type, int col) {
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if (listener != null) listener.error(type, col);
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return false;
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}
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}
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