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  package org.json;
  
  /*
  Copyright (c) 2002 JSON.org
  
  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 shall be used for Good, not Evil.
 
 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.
 */

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(s):
JSON.org
Version:
2
 
 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.

Parameters:
s A source string.
 
     public JSONTokener(String s) {
         this. = 0;
         this. = s;
     }


    
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. > 0) {
             this. -= 1;
         }
     }



    
Get the hex value of a character (base16).

Parameters:
c A character between '0' and '9' or between 'A' and 'F' or between 'a' and 'f'.
Returns:
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 - ('A' - 10);
         }
         if (c >= 'a' && c <= 'f') {
             return c - ('a' - 10);
         }
         return -1;
     }


    
Determine if the source string still contains characters that next() can consume.

Returns:
true if not yet at the end of the source.
 
     public boolean more() {
         return this. < this..length();
     }


    
Get the next character in the source string.

Returns:
The next character, or 0 if past the end of the source string.
    public char next() {
        if (more()) {
            char c = this..charAt(this.);
            this. += 1;
            return c;
        }
        return 0;
    }


    
Consume the next character, and check that it matches a specified character.

Parameters:
c The character to match.
Returns:
The character.
Throws:
JSONException if the character does not match.
    public char next(char cthrows JSONException {
        char n = next();
        if (n != c) {
            throw syntaxError("Expected '" + c + "' and instead saw '" +
                    n + "'");
        }
        return n;
    }


    
Get the next n characters.

Parameters:
n The number of characters to take.
Returns:
A string of n characters.
Throws:
JSONException Substring bounds error if there are not n characters remaining in the source string.
     public String next(int nthrows JSONException {
         int i = this.;
         int j = i + n;
         if (j >= this..length()) {
            throw syntaxError("Substring bounds error");
         }
         this. += n;
         return this..substring(ij);
     }


    
Get the next char in the string, skipping whitespace and comments (slashslash, slashstar, and hash).

Returns:
A character, or 0 if there are no more characters.
Throws:
JSONException
    public char nextClean() throws JSONException {
        for (;;) {
            char c = next();
            if (c == '/') {
                switch (next()) {
                case '/':
                    do {
                        c = next();
                    } while (c != '\n' && c != '\r' && c != 0);
                    break;
                case '*':
                    for (;;) {
                        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.

Parameters:
quote The quoting character, either " (double quote) or ' (single quote).
Returns:
A String.
Throws:
JSONException Unterminated string.
    public String nextString(char quotethrows JSONException {
        char c;
        StringBuffer sb = new StringBuffer();
        for (;;) {
            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.

Parameters:
d A delimiter character.
Returns:
A string.
    public String nextTo(char d) {
        StringBuffer sb = new StringBuffer();
        for (;;) {
            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.

Parameters:
delimiters A set of delimiter characters.
Returns:
A string, trimmed.
    public String nextTo(String delimiters) {
        char c;
        StringBuffer sb = new StringBuffer();
        for (;;) {
            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, Long, or String, or the JSONObject.NULL object.

Returns:
An object.
Throws:
JSONException If syntax error.
    public Object nextValue() throws JSONException {
        char c = nextClean();
        String s;
        switch (c) {
            case '"':
            case '\'':
                return nextString(c);
            case '{':
                back();
                return new JSONObject(this);
            case '[':
            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 .;
        }
        if (s.equalsIgnoreCase("false")) {
            return .;
        }
        if (s.equalsIgnoreCase("null")) {
            return .;
        }
        /*
         * 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) {
                try {
                    return new Long(s);
                } catch (Exception f) {
                    try {
                        return new Double(s);
                    }  catch (Exception g) {
                        return s;
                    }
                }
            }
        }
        return s;
    }


    
Skip characters until the next character is the requested character. If the requested character is not found, no characters are skipped.

Parameters:
to A character to skip to.
Returns:
The requested character, or zero if the requested character is not found.
    public char skipTo(char to) {
        char c;
        int index = this.;
        do {
            c = next();
            if (c == 0) {
                this. = 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.

Parameters:
to A string to skip past.
    public boolean skipPast(String to) {
        this. = this..indexOf(tothis.);
        if (this. < 0) {
            this. = this..length();
            return false;
        } 
        this. += to.length();
        return true;
    }


    
Make a JSONException to signal a syntax error.

Parameters:
message The error message.
Returns:
A JSONException object, suitable for throwing
    public JSONException syntaxError(String message) {
        return new JSONException(message + toString());
    }


    
Make a printable string of this JSONTokener.

Returns:
" at character [this.myIndex] of [this.mySource]"
    public String toString() {
        return " at character " + this. + " of " + this.;
    }
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