Standard Library

class RegexException

The exception thrown for a malformed pattern, and for a malformed or out-of-range reference in a replacement string.

since 0.1.0-alpha.1linuxwindowswasm

bases

Exception

Overview

message describes the problem. offset is the byte position in the pattern (or in the replacement string) where the problem was found, or -1 when that is not known. It is thrown by every call that takes its pattern as code: the Regex constructors and the regex:: functions. To handle a pattern that comes from data without an exception, use regex::compile, which returns None instead.

Examples

Catching a bad pattern

try {
    Regex bad = Regex("a(b");
    console.writeln("unreachable");
} catch (RegexException e) {
    console.writeln(e.message);
    console.writeln(e.offset);
}

regex: unterminated group at offset 3
3

Constructors

new

new(string msg, int off)

Create the exception.

Parameters

msg

The message.

off

The byte offset of the problem, or -1.

Examples

Throwing it by hand

try {
    throw RegexException("custom failure", 7);
} catch (RegexException e) {
    console.writeln("${e.message} at ${e.offset}");
}

custom failure at 7

Fields

offset

int offset

Byte position of the problem in the pattern or replacement string, or -1 when unknown.

See also

• compile — Compile a pattern that comes from data, without throwing.