in src/main/java/org/apache/commons/text/ExtendedMessageFormat.java [427:455]
private String parseFormatDescription(final String pattern, final ParsePosition pos) {
final int start = pos.getIndex();
seekNonWs(pattern, pos);
final int text = pos.getIndex();
int depth = 1;
while (pos.getIndex() < pattern.length()) {
switch (pattern.charAt(pos.getIndex())) {
case START_FE:
depth++;
next(pos);
break;
case END_FE:
depth--;
if (depth == 0) {
return pattern.substring(text, pos.getIndex());
}
next(pos);
break;
case QUOTE:
getQuotedString(pattern, pos);
break;
default:
next(pos);
break;
}
}
throw new IllegalArgumentException(
"Unterminated format element at position " + start);
}