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/*******************************************************************************
* Original work Copyright (c) 2013, 2016 EclipseSource.
* Modified work Copyright (c) 2019-2024, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.internal.json;
import java.io.IOException;
import java.io.Reader;
/**
* A parser for a single JsonValue which is not an object or array.
* Underlying reader must be pointing to the beginning of a value.
*/
public class JsonReducedValueParser {
/**
* It is important that default buffer size is small. It takes a
* significant time to read and convert UTF8 text to Java string.
* This parser intends to parse only a single value from a json
* text. There is no need to fill the buffer with useless text.
*/
private static final int DEFAULT_BUFFER_SIZE = 20;
private Reader reader;
private char[] buffer;
private int bufferOffset;
private int index;
private int fill;
private int line;
private int lineOffset;
private int current;
private StringBuilder captureBuffer;
private int captureStart;
public JsonReducedValueParser() {
}
/**
* Reads a single value from the given reader and parses it as
* JsonValue. The input must be pointing to the beginning of a
* JsonLiteral, not JsonArray or JsonObject.
*
* @param reader the reader to read the input from
* @throws IOException if an I/O error occurs in the reader
* @throws ParseException if the input is not valid JSON
*/
public JsonValue parse(Reader reader) throws IOException {
return parse(reader, DEFAULT_BUFFER_SIZE);
}
/**
* Reads a single value from the given reader and parses it as JsonValue.
* The input must be pointing to the beginning of a JsonLiteral,
* not JsonArray or JsonObject.
*
* @param reader the reader to read the input from
* @param buffersize the size of the input buffer in chars
* @throws IOException if an I/O error occurs in the reader
* @throws ParseException if the input is not valid JSON
*/
public JsonValue parse(Reader reader, int buffersize) throws IOException {
if (reader == null) {
throw new NullPointerException("reader is null");
}
if (buffersize <= 0) {
throw new IllegalArgumentException("buffersize is zero or negative");
}
this.reader = reader;
buffer = new char[buffersize];
bufferOffset = 0;
index = 0;
fill = 0;
line = 1;
lineOffset = 0;
current = 0;
captureStart = -1;
read();
return readValue();
}
private JsonValue readValue() throws IOException {
switch (current) {
case 'n':
return readNull();
case 't':
return readTrue();
case 'f':
return readFalse();
case '"':
return readString();
case '-':
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
return readNumber();
default:
throw expected("value");
}
}
private JsonValue readNull() throws IOException {
read();
readRequiredChar('u');
readRequiredChar('l');
readRequiredChar('l');
return Json.NULL;
}
private JsonValue readTrue() throws IOException {
read();
readRequiredChar('r');
readRequiredChar('u');
readRequiredChar('e');
return Json.TRUE;
}
private JsonValue readFalse() throws IOException {
read();
readRequiredChar('a');
readRequiredChar('l');
readRequiredChar('s');
readRequiredChar('e');
return Json.FALSE;
}
private void readRequiredChar(char ch) throws IOException {
if (!readChar(ch)) {
throw expected("'" + ch + "'");
}
}
private JsonString readString() throws IOException {
return new JsonString(readStringInternal());
}
private String readStringInternal() throws IOException {
read();
startCapture();
while (current != '"') {
if (current == '\\') {
pauseCapture();
readEscape();
startCapture();
} else if (current < 0x20) {
throw expected("valid string character");
} else {
read();
}
}
String string = endCapture();
read();
return string;
}
private void readEscape() throws IOException {
read();
switch (current) {
case '"':
case '/':
case '\\':
captureBuffer.append((char) current);
break;
case 'b':
captureBuffer.append('\b');
break;
case 'f':
captureBuffer.append('\f');
break;
case 'n':
captureBuffer.append('\n');
break;
case 'r':
captureBuffer.append('\r');
break;
case 't':
captureBuffer.append('\t');
break;
case 'u':
char[] hexChars = new char[4];
for (int i = 0; i < 4; i++) {
read();
if (!isHexDigit()) {
throw expected("hexadecimal digit");
}
hexChars[i] = (char) current;
}
captureBuffer.append((char) Integer.parseInt(new String(hexChars), 16));
break;
default:
throw expected("valid escape sequence");
}
read();
}
private JsonNumber readNumber() throws IOException {
startCapture();
readChar('-');
int firstDigit = current;
if (!readDigit()) {
throw expected("digit");
}
if (firstDigit != '0') {
while (readDigit()) {
}
}
readFraction();
readExponent();
return new JsonNumber(endCapture());
}
private boolean readFraction() throws IOException {
if (!readChar('.')) {
return false;
}
if (!readDigit()) {
throw expected("digit");
}
while (readDigit()) {
}
return true;
}
private boolean readExponent() throws IOException {
if (!readChar('e') && !readChar('E')) {
return false;
}
if (!readChar('+')) {
readChar('-');
}
if (!readDigit()) {
throw expected("digit");
}
while (readDigit()) {
}
return true;
}
private boolean readChar(char ch) throws IOException {
if (current != ch) {
return false;
}
read();
return true;
}
private boolean readDigit() throws IOException {
if (!isDigit()) {
return false;
}
read();
return true;
}
private void read() throws IOException {
if (index == fill) {
if (captureStart != -1) {
captureBuffer.append(buffer, captureStart, fill - captureStart);
captureStart = 0;
}
bufferOffset += fill;
fill = reader.read(buffer, 0, buffer.length);
index = 0;
if (fill == -1) {
current = -1;
index++;
return;
}
}
if (current == '\n') {
line++;
lineOffset = bufferOffset + index;
}
current = buffer[index++];
}
private void startCapture() {
if (captureBuffer == null) {
captureBuffer = new StringBuilder();
}
captureStart = index - 1;
}
private void pauseCapture() {
int end = current == -1 ? index : index - 1;
captureBuffer.append(buffer, captureStart, end - captureStart);
captureStart = -1;
}
private String endCapture() {
int start = captureStart;
int end = index - 1;
captureStart = -1;
if (captureBuffer.length() > 0) {
captureBuffer.append(buffer, start, end - start);
String captured = captureBuffer.toString();
captureBuffer.setLength(0);
return captured;
}
return new String(buffer, start, end - start);
}
Location getLocation() {
int offset = bufferOffset + index - 1;
int column = offset - lineOffset + 1;
return new Location(offset, line, column);
}
private ParseException expected(String expected) {
if (isEndOfText()) {
return error("Unexpected end of input");
}
return error("Expected " + expected);
}
private ParseException error(String message) {
return new ParseException(message, getLocation());
}
private boolean isDigit() {
return current >= '0' && current <= '9';
}
private boolean isHexDigit() {
return current >= '0' && current <= '9'
|| current >= 'a' && current <= 'f'
|| current >= 'A' && current <= 'F';
}
private boolean isEndOfText() {
return current == -1;
}
}
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