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.
| Method from org.apache.tapestry5.json.JSONTokener Detail: |
|---|
 public void back() {
if (index > 0)
{
index -= 1;
}
}
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. |
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;
} Get the hex value of a character (base16). |
public boolean more() {
return index < source.length();
} Determine if the source string still contains characters that next() can consume. |
public char next() {
if (more())
{
return source.charAt(index++);
}
return 0;
} Get the next character in the source string. |
public char next(char c) {
char n = next();
if (n != c)
{
throw syntaxError("Expected '" + c + "' and instead saw '" + n + "'");
}
return n;
} Consume the next character, and check that it matches a specified character. |
public String next(int n) {
int i = index;
int j = i + n;
if (j >= source.length())
{
throw syntaxError("Substring bounds error");
}
index += n;
return source.substring(i, j);
} Get the next n characters. |
public char nextClean() {
for (; ;)
{
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;
}
}
} Get the next char in the string, skipping whitespace and comments (slashslash, slashstar, and hash). |
public String nextString(char quote) {
StringBuilder builder = new StringBuilder();
while (true)
{
char c = next();
switch (c)
{
case 0:
case '\n':
case '\r':
throw syntaxError("Unterminated string");
case '\\':
c = next();
switch (c)
{
case 'b':
builder.append('\b');
break;
case 't':
builder.append('\t');
break;
case 'n':
builder.append('\n');
break;
case 'f':
builder.append('\f');
break;
case 'r':
builder.append('\r');
break;
case 'u':
builder.append((char) Integer.parseInt(next(4), 16));
break;
case 'x':
builder.append((char) Integer.parseInt(next(2), 16));
break;
default:
builder.append(c);
}
break;
default:
if (c == quote)
{
return builder.toString();
}
builder.append(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. |
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 the specified character or the end of line, whichever comes first. |
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 text up but not including one of the specified delimeter characters or the end of line, whichever comes
first. |
public Object nextValue() {
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 Integer.parseInt(s.substring(2), 16);
}
catch (Exception e)
{
/* Ignore the error */
}
}
else
{
try
{
return 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;
} Get the next value. The value can be a Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the
JSONObject.NULL object. |
public boolean skipPast(String to) {
index = source.indexOf(to, index);
if (index < 0)
{
index = source.length();
return false;
}
index += to.length();
return true;
} Skip characters until past the requested string. If it is not found, we are left at the end of the source. |
public char skipTo(char to) {
char c;
int index = this.index;
do
{
c = next();
if (c == 0)
{
this.index = index;
return c;
}
} while (c != to);
back();
return c;
} Skip characters until the next character is the requested character. If the requested character is not found, no
characters are skipped. |
RuntimeException syntaxError(String message) {
return new RuntimeException(message + toString());
} Make a JSONException to signal a syntax error. |
public String toString() {
return " at character " + index + " of " + source;
} Make a printable string of this JSONTokener. |
org.apache.tapestry5.json.JSONTokener