Returns the next token type and initializes any state variables
accordingly.
// Skip any leading white space
while (index < length && Character.isWhitespace(expr[index]))
index++;
// Clear the current token val
tokenVal = null;
if (index == length) return TOKEN_END; // End of string
int start = index;
char currentChar = expr[index];
char nextChar = (char)0;
index++;
if (index < length) nextChar = expr[index];
// Check for a known token start
switch (currentChar) {
case '(" :
return TOKEN_LBRACE;
case ')" :
return TOKEN_RBRACE;
case '=" :
return TOKEN_EQ;
case '!" :
if (nextChar == '=") {
index++;
return TOKEN_NOT_EQ;
} else {
return TOKEN_NOT;
}
case '|" :
if (nextChar == '|") {
index++;
return TOKEN_OR;
}
break;
case '&" :
if (nextChar == '&") {
index++;
return TOKEN_AND;
}
break;
case '>" :
if (nextChar == '=") {
index++;
return TOKEN_GE; // Greater than or equal
} else {
return TOKEN_GT; // Greater than
}
case '<" :
if (nextChar == '=") {
index++;
return TOKEN_LE; // Less than or equal
} else {
return TOKEN_LT; // Less than
}
default :
// Otherwise it's a string
break;
}
int end = index;
// If it's a quoted string then end is the next unescaped quote
if (currentChar == '"" || currentChar == '\'") {
char endChar = currentChar;
boolean escaped = false;
start++;
for (; index < length; index++) {
if (expr[index] == '\\" && !escaped) {
escaped = true;
continue;
}
if (expr[index] == endChar && !escaped) break;
escaped = false;
}
end = index;
index++; // Skip the end quote
} else {
// End is the next whitespace character
for (; index < length; index++) {
if (isMetaChar(expr[index])) break;
}
end = index;
}
// Extract the string from the array
this.tokenVal = new String(expr, start, end - start);
return TOKEN_STRING;
