addPattern method
Add inputPattern to this instance as a pattern.
If there was a previous pattern, then this appends to it, separating the
two by separator. inputPattern is first looked up in our list of
known skeletons. If it's found there, then use the corresponding pattern
for this locale. If it's not, then treat inputPattern as an explicit
pattern.
Implementation
DateFormat addPattern(String inputPattern, [String separator = ' ']) {
// TODO(alanknight): This is an expensive operation. Caching recently used
// formats, or possibly introducing an entire "locale" object that would
// cache patterns for that locale could be a good optimization.
// If we have already parsed the format fields, reset them.
_formatFieldsPrivate = null;
if (inputPattern == null) return this;
if (!_availableSkeletons.containsKey(inputPattern)) {
_appendPattern(inputPattern, separator);
} else {
_appendPattern(_availableSkeletons[inputPattern], separator);
}
return this;
}