panda.el.parse.StringParse Maven / Gradle / Ivy
package panda.el.parse;
import panda.el.ELException;
/**
* String parse
*/
public class StringParse implements Parse {
@Override
public Object fetchItem(CharQueue exp) {
switch (exp.peek()) {
case '\'':
case '"':
StringBuilder sb = new StringBuilder();
char end = exp.poll();
while (!exp.isEmpty() && exp.peek() != end) {
if (exp.peek() == '\\') {
exp.poll();
parseSp(exp, sb);
}
else {
sb.append(exp.poll());
}
}
exp.poll();
return sb.toString();
}
return NULL;
}
private void parseSp(CharQueue exp, StringBuilder sb) {
switch (exp.poll()) {
case 'n':
sb.append('\n');
break;
case 'r':
sb.append('\r');
break;
case 't':
sb.append('\t');
break;
case '\\':
sb.append('\\');
break;
case '\'':
sb.append('\'');
break;
case '\"':
sb.append('\"');
break;
case 'x':
sb.append(hex2char(exp, 2));
break;
case 'u':
sb.append(hex2char(exp, 4));
break;
case 'b':
sb.append(' ');
break;
case 'f':
sb.append('\f');
break;
default:
throw new ELException("Unexpected char after \\");
}
}
private char hex2char(CharQueue exp, int len) {
char[] hex = new char[len];
for (int i = 0; i < len; i++) {
hex[i] = exp.poll();
}
return (char)Integer.valueOf(new String(hex), 16).intValue();
}
}