4949e6a995
git-svn-id: svn://svn.code.sf.net/p/writer2latex/code/trunk@72 f0f2a975-2e09-46c8-9428-3b39399b9f3c
435 lines
No EOL
12 KiB
Java
435 lines
No EOL
12 KiB
Java
package org.json;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.Reader;
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import java.io.StringReader;
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/*
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Copyright (c) 2002 JSON.org
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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The Software shall be used for Good, not Evil.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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/**
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* A JSONTokener takes a source string and extracts characters and tokens from
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* it. It is used by the JSONObject and JSONArray constructors to parse
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* JSON source strings.
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* @author JSON.org
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* @version 2010-02-02
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*/
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public class JSONTokener {
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private int character;
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private boolean eof;
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private int index;
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private int line;
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private char previous;
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private Reader reader;
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private boolean usePrevious;
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/**
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* Construct a JSONTokener from a reader.
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*
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* @param reader A reader.
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*/
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public JSONTokener(Reader reader) {
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this.reader = reader.markSupported() ?
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reader : new BufferedReader(reader);
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this.eof = false;
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this.usePrevious = false;
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this.previous = 0;
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this.index = 0;
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this.character = 1;
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this.line = 1;
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}
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/**
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* Construct a JSONTokener from a string.
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*
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* @param s A source string.
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*/
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public JSONTokener(String s) {
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this(new StringReader(s));
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}
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/**
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* Back up one character. This provides a sort of lookahead capability,
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* so that you can test for a digit or letter before attempting to parse
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* the next number or identifier.
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*/
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public void back() throws JSONException {
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if (usePrevious || index <= 0) {
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throw new JSONException("Stepping back two steps is not supported");
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}
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this.index -= 1;
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this.character -= 1;
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this.usePrevious = true;
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this.eof = false;
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}
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/**
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* Get the hex value of a character (base16).
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* @param c A character between '0' and '9' or between 'A' and 'F' or
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* between 'a' and 'f'.
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* @return An int between 0 and 15, or -1 if c was not a hex digit.
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*/
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public static int dehexchar(char c) {
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if (c >= '0' && c <= '9') {
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return c - '0';
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}
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if (c >= 'A' && c <= 'F') {
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return c - ('A' - 10);
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}
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if (c >= 'a' && c <= 'f') {
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return c - ('a' - 10);
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}
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return -1;
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}
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public boolean end() {
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return eof && !usePrevious;
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}
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/**
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* Determine if the source string still contains characters that next()
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* can consume.
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* @return true if not yet at the end of the source.
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*/
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public boolean more() throws JSONException {
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next();
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if (end()) {
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return false;
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}
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back();
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return true;
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}
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/**
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* Get the next character in the source string.
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*
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* @return The next character, or 0 if past the end of the source string.
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*/
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public char next() throws JSONException {
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int c;
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if (this.usePrevious) {
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this.usePrevious = false;
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c = this.previous;
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} else {
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try {
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c = this.reader.read();
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} catch (IOException exception) {
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throw new JSONException(exception);
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}
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if (c <= 0) { // End of stream
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this.eof = true;
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c = 0;
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}
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}
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this.index += 1;
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if (this.previous == '\r') {
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this.line += 1;
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this.character = c == '\n' ? 0 : 1;
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} else if (c == '\n') {
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this.line += 1;
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this.character = 0;
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} else {
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this.character += 1;
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}
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this.previous = (char) c;
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return this.previous;
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}
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/**
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* Consume the next character, and check that it matches a specified
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* character.
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* @param c The character to match.
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* @return The character.
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* @throws JSONException if the character does not match.
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*/
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public char next(char c) throws JSONException {
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char n = next();
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if (n != c) {
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throw syntaxError("Expected '" + c + "' and instead saw '" +
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n + "'");
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}
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return n;
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}
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/**
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* Get the next n characters.
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*
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* @param n The number of characters to take.
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* @return A string of n characters.
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* @throws JSONException
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* Substring bounds error if there are not
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* n characters remaining in the source string.
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*/
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public String next(int n) throws JSONException {
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if (n == 0) {
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return "";
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}
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char[] buffer = new char[n];
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int pos = 0;
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while (pos < n) {
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buffer[pos] = next();
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if (end()) {
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throw syntaxError("Substring bounds error");
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}
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pos += 1;
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}
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return new String(buffer);
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}
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/**
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* Get the next char in the string, skipping whitespace.
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* @throws JSONException
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* @return A character, or 0 if there are no more characters.
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*/
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public char nextClean() throws JSONException {
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for (;;) {
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char c = next();
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if (c == 0 || c > ' ') {
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return c;
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}
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}
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}
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/**
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* Return the characters up to the next close quote character.
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* Backslash processing is done. The formal JSON format does not
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* allow strings in single quotes, but an implementation is allowed to
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* accept them.
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* @param quote The quoting character, either
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* <code>"</code> <small>(double quote)</small> or
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* <code>'</code> <small>(single quote)</small>.
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* @return A String.
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* @throws JSONException Unterminated string.
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*/
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public String nextString(char quote) throws JSONException {
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char c;
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StringBuffer sb = new StringBuffer();
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for (;;) {
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c = next();
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switch (c) {
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case 0:
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case '\n':
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case '\r':
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throw syntaxError("Unterminated string");
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case '\\':
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c = next();
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switch (c) {
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case 'b':
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sb.append('\b');
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break;
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case 't':
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sb.append('\t');
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break;
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case 'n':
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sb.append('\n');
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break;
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case 'f':
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sb.append('\f');
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break;
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case 'r':
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sb.append('\r');
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break;
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case 'u':
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sb.append((char)Integer.parseInt(next(4), 16));
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break;
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case '"':
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case '\'':
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case '\\':
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case '/':
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sb.append(c);
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break;
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default:
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throw syntaxError("Illegal escape.");
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}
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break;
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default:
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if (c == quote) {
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return sb.toString();
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}
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sb.append(c);
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}
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}
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}
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/**
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* Get the text up but not including the specified character or the
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* end of line, whichever comes first.
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* @param d A delimiter character.
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* @return A string.
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*/
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public String nextTo(char d) throws JSONException {
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StringBuffer sb = new StringBuffer();
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for (;;) {
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char c = next();
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if (c == d || c == 0 || c == '\n' || c == '\r') {
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if (c != 0) {
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back();
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}
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return sb.toString().trim();
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}
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sb.append(c);
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}
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}
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/**
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* Get the text up but not including one of the specified delimiter
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* characters or the end of line, whichever comes first.
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* @param delimiters A set of delimiter characters.
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* @return A string, trimmed.
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*/
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public String nextTo(String delimiters) throws JSONException {
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char c;
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StringBuffer sb = new StringBuffer();
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for (;;) {
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c = next();
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if (delimiters.indexOf(c) >= 0 || c == 0 ||
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c == '\n' || c == '\r') {
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if (c != 0) {
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back();
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}
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return sb.toString().trim();
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}
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sb.append(c);
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}
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}
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/**
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* Get the next value. The value can be a Boolean, Double, Integer,
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* JSONArray, JSONObject, Long, or String, or the JSONObject.NULL object.
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* @throws JSONException If syntax error.
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*
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* @return An object.
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*/
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public Object nextValue() throws JSONException {
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char c = nextClean();
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String s;
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switch (c) {
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case '"':
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case '\'':
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return nextString(c);
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case '{':
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back();
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return new JSONObject(this);
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case '[':
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case '(':
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back();
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return new JSONArray(this);
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}
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/*
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* Handle unquoted text. This could be the values true, false, or
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* null, or it can be a number. An implementation (such as this one)
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* is allowed to also accept non-standard forms.
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*
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* Accumulate characters until we reach the end of the text or a
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* formatting character.
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*/
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StringBuffer sb = new StringBuffer();
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while (c >= ' ' && ",:]}/\\\"[{;=#".indexOf(c) < 0) {
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sb.append(c);
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c = next();
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}
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back();
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s = sb.toString().trim();
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if (s.equals("")) {
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throw syntaxError("Missing value");
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}
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return JSONObject.stringToValue(s);
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}
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/**
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* Skip characters until the next character is the requested character.
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* If the requested character is not found, no characters are skipped.
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* @param to A character to skip to.
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* @return The requested character, or zero if the requested character
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* is not found.
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*/
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public char skipTo(char to) throws JSONException {
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char c;
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try {
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int startIndex = this.index;
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int startCharacter = this.character;
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int startLine = this.line;
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reader.mark(Integer.MAX_VALUE);
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do {
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c = next();
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if (c == 0) {
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reader.reset();
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this.index = startIndex;
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this.character = startCharacter;
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this.line = startLine;
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return c;
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}
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} while (c != to);
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} catch (IOException exc) {
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throw new JSONException(exc);
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}
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back();
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return c;
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}
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/**
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* Make a JSONException to signal a syntax error.
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*
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* @param message The error message.
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* @return A JSONException object, suitable for throwing
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*/
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public JSONException syntaxError(String message) {
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return new JSONException(message + toString());
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}
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/**
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* Make a printable string of this JSONTokener.
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*
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* @return " at {index} [character {character} line {line}]"
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*/
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public String toString() {
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return " at " + index + " [character " + this.character + " line " + this.line + "]";
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}
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} |