com.dianping.cat.util.json.JsonTokener Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2018, Meituan Dianping. All Rights Reserved.
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.dianping.cat.util.json;
import java.text.ParseException;
/**
* A JSONTokener takes a source string and extracts characters and tokens from
* it. It is used by the JSONObject and JSONArray constructors to parse
* JSON source strings.
*
* @author JSON.org
* @version 1
*/
public class JsonTokener {
/**
* The index of the next character.
*/
private int myIndex;
/**
* The source string being tokenized.
*/
private String mySource;
/**
* Construct a JSONTokener from a string.
*
* @param s A source string.
*/
public JsonTokener(String s) {
this.myIndex = 0;
this.mySource = s;
}
/**
* Get the hex value of a character (base16).
*
* @param c A character between '0' and '9' or between 'A' and 'F' or
* between 'a' and 'f'.
* @return An int between 0 and 15, or -1 if c was not a hex digit.
*/
public static int dehexchar(char c) {
if (c >= '0' && c <= '9') {
return c - '0';
}
if (c >= 'A' && c <= 'F') {
return c + 10 - 'A';
}
if (c >= 'a' && c <= 'f') {
return c + 10 - 'a';
}
return -1;
}
/**
* Convert %hh sequences to single characters, and
* convert plus to space.
*
* @param s A string that may contain
* + (plus) and
* %hh sequences.
* @return The unescaped string.
*/
public static String unescape(String s) {
int len = s.length();
StringBuffer b = new StringBuffer();
for (int i = 0; i < len; ++i) {
char c = s.charAt(i);
if (c == '+') {
c = ' ';
} else if (c == '%' && i + 2 < len) {
int d = dehexchar(s.charAt(i + 1));
int e = dehexchar(s.charAt(i + 2));
if (d >= 0 && e >= 0) {
c = (char) (d * 16 + e);
i += 2;
}
}
b.append(c);
}
return b.toString();
}
/**
* Back up one character. This provides a sort of lookahead capability,
* so that you can test for a digit or letter before attempting to parse
* the next number or identifier.
*/
public void back() {
if (this.myIndex > 0) {
this.myIndex -= 1;
}
}
/**
* Determine if the source string still contains characters that next()
* can consume.
*
* @return true if not yet at the end of the source.
*/
public boolean more() {
return this.myIndex < this.mySource.length();
}
/**
* Get the next character in the source string.
*
* @return The next character, or 0 if past the end of the source string.
*/
public char next() {
if (more()) {
char c = this.mySource.charAt(this.myIndex);
this.myIndex += 1;
return c;
}
return 0;
}
/**
* Consume the next character, and check that it matches a specified
* character.
*
* @param c The character to match.
* @return The character.
* @throws ParseException if the character does not match.
*/
public char next(char c) throws ParseException {
char n = next();
if (n != c) {
throw syntaxError("Expected '" + c + "' and instead saw '" + n + "'.");
}
return n;
}
/**
* Get the next n characters.
*
* @param n The number of characters to take.
* @return A string of n characters.
* @throws ParseException Substring bounds error if there are not
* n characters remaining in the source string.
*/
public String next(int n) throws ParseException {
int i = this.myIndex;
int j = i + n;
if (j >= this.mySource.length()) {
throw syntaxError("Substring bounds error");
}
this.myIndex += n;
return this.mySource.substring(i, j);
}
/**
* Get the next char in the string, skipping whitespace
* and comments (slashslash, slashstar, and hash).
*
* @return A character, or 0 if there are no more characters.
* @throws ParseException
*/
public char nextClean() throws ParseException {
while (true) {
char c = next();
if (c == '/') {
switch (next()) {
case '/':
do {
c = next();
} while (c != '\n' && c != '\r' && c != 0);
break;
case '*':
while (true) {
c = next();
if (c == 0) {
throw syntaxError("Unclosed comment.");
}
if (c == '*') {
if (next() == '/') {
break;
}
back();
}
}
break;
default:
back();
return '/';
}
} else if (c == '#') {
do {
c = next();
} while (c != '\n' && c != '\r' && c != 0);
} else if (c == 0 || c > ' ') {
return c;
}
}
}
/**
* Return the characters up to the next close quote character.
* Backslash processing is done. The formal JSON format does not
* allow strings in single quotes, but an implementation is allowed to
* accept them.
*
* @param quote The quoting character, either
* " (double quote) or
* ' (single quote).
* @return A String.
* @throws ParseException Unterminated string.
*/
public String nextString(char quote) throws ParseException {
char c;
StringBuffer sb = new StringBuffer();
while (true) {
c = next();
switch (c) {
case 0:
case '\n':
case '\r':
throw syntaxError("Unterminated string");
case '\\':
c = next();
switch (c) {
case 'b':
sb.append('\b');
break;
case 't':
sb.append('\t');
break;
case 'n':
sb.append('\n');
break;
case 'f':
sb.append('\f');
break;
case 'r':
sb.append('\r');
break;
case 'u':
sb.append((char) Integer.parseInt(next(4), 16));
break;
case 'x':
sb.append((char) Integer.parseInt(next(2), 16));
break;
default:
sb.append(c);
}
break;
default:
if (c == quote) {
return sb.toString();
}
sb.append(c);
}
}
}
/**
* Get the text up but not including the specified character or the
* end of line, whichever comes first.
*
* @param d A delimiter character.
* @return A string.
*/
public String nextTo(char d) {
StringBuffer sb = new StringBuffer();
while (true) {
char c = next();
if (c == d || c == 0 || c == '\n' || c == '\r') {
if (c != 0) {
back();
}
return sb.toString().trim();
}
sb.append(c);
}
}
/**
* Get the text up but not including one of the specified delimeter
* characters or the end of line, whichever comes first.
*
* @param delimiters A set of delimiter characters.
* @return A string, trimmed.
*/
public String nextTo(String delimiters) {
char c;
StringBuffer sb = new StringBuffer();
while (true) {
c = next();
if (delimiters.indexOf(c) >= 0 || c == 0 || c == '\n' || c == '\r') {
if (c != 0) {
back();
}
return sb.toString().trim();
}
sb.append(c);
}
}
/**
* Get the next value. The value can be a Boolean, Double, Integer,
* JSONArray, JSONObject, or String, or the JSONObject.NULL object.
*
* @return An object.
* @throws ParseException The source does not conform to JSON syntax.
*/
public Object nextValue() throws ParseException {
char c = nextClean();
String s;
switch (c) {
case '"':
case '\'':
return nextString(c);
case '{':
back();
return new JsonObject(this);
case '[':
back();
return new JsonArray(this);
}
/*
* Handle unquoted text. This could be the values true, false, or
* null, or it can be a number. An implementation (such as this one)
* is allowed to also accept non-standard forms.
*
* Accumulate characters until we reach the end of the text or a
* formatting character.
*/
StringBuffer sb = new StringBuffer();
char b = c;
while (c >= ' ' && ",:]}/\\\"[{;=#".indexOf(c) < 0) {
sb.append(c);
c = next();
}
back();
/*
* If it is true, false, or null, return the proper value.
*/
s = sb.toString().trim();
if (s.equals("")) {
throw syntaxError("Missing value.");
}
if (s.equalsIgnoreCase("true")) {
return Boolean.TRUE;
}
if (s.equalsIgnoreCase("false")) {
return Boolean.FALSE;
}
if (s.equalsIgnoreCase("null")) {
return JsonObject.NULL;
}
/*
* If it might be a number, try converting it. We support the 0- and 0x-
* conventions. If a number cannot be produced, then the value will just
* be a string. Note that the 0-, 0x-, plus, and implied string
* conventions are non-standard. A JSON parser is free to accept
* non-JSON forms as long as it accepts all correct JSON forms.
*/
if ((b >= '0' && b <= '9') || b == '.' || b == '-' || b == '+') {
if (b == '0') {
if (s.length() > 2 && (s.charAt(1) == 'x' || s.charAt(1) == 'X')) {
try {
return new Integer(Integer.parseInt(s.substring(2), 16));
} catch (Exception e) {
/* Ignore the error */
}
} else {
try {
return new Integer(Integer.parseInt(s, 8));
} catch (Exception e) {
/* Ignore the error */
}
}
}
try {
return new Integer(s);
} catch (Exception e) {
/* Ignore the error */
}
try {
return new Double(s);
} catch (Exception e) {
/* Ignore the error */
}
}
return s;
}
/**
* Skip characters until the next character is the requested character.
* If the requested character is not found, no characters are skipped.
*
* @param to A character to skip to.
* @return The requested character, or zero if the requested character
* is not found.
*/
public char skipTo(char to) {
char c;
int index = this.myIndex;
do {
c = next();
if (c == 0) {
this.myIndex = index;
return c;
}
} while (c != to);
back();
return c;
}
/**
* Skip characters until past the requested string.
* If it is not found, we are left at the end of the source.
*
* @param to A string to skip past.
*/
public void skipPast(String to) {
this.myIndex = this.mySource.indexOf(to, this.myIndex);
if (this.myIndex < 0) {
this.myIndex = this.mySource.length();
} else {
this.myIndex += to.length();
}
}
/**
* Make a ParseException to signal a syntax error.
*
* @param message The error message.
* @return A ParseException object, suitable for throwing
*/
public ParseException syntaxError(String message) {
return new ParseException(message + toString(), this.myIndex);
}
/**
* Make a printable string of this JSONTokener.
*
* @return " at character [this.myIndex] of [this.mySource]"
*/
public String toString() {
return " at character " + this.myIndex + " of " + this.mySource;
}
}© 2015 - 2025 Weber Informatics LLC | Privacy Policy