Validate a string value against format constraints.
Returns true when the value matches the format,
false when it does not, and undefined when the format
is not recognised (no validator available).
diagnostics and pointer are forwarded to validators that can
surface structured diagnostics — currently the regex format, which
emits pattern-invalid for over-length or malformed input.
Validate a string value against format constraints. Returns
truewhen the value matches the format,falsewhen it does not, andundefinedwhen the format is not recognised (no validator available).diagnosticsandpointerare forwarded to validators that can surface structured diagnostics — currently theregexformat, which emitspattern-invalidfor over-length or malformed input.