Method scanCharacterEscape

internal/scanner/regexp.go:436–474

CharacterEscape ::= | `c` ControlLetter | IdentityEscape | (Other sequences handled by `scanEscapeSequence`) IdentityEscape ::= | '^' | '$' | '/' | '\' | '.' | '*' | '+' | '?' | '(' | ')' | '[' | ']' | '{' | '}' | '|' | [~AnyUnicodeMode] (any other non-identifier characters)

(atomEscape bool)

//	| '^' | '$' | '/' | '\' | '.' | '*' | '+' | '?' | '(' | ')' | '[' | ']' | '{' | '}' | '|'
//	| [~AnyUnicodeMode] (any other non-identifier characters)
func (p *regExpParser) scanCharacterEscape(atomEscape bool) string {
	debug.Assert(p.pos() > 0 && p.text()[p.pos()-1] == '\\')
	ch := p.char()
	switch ch {
	case -1:
		p.error(diagnostics.Undetermined_character_escape, p.pos()-1, 1)
		return "\\"
	case 'c':
		p.incPos(1)
		ch = p.char()
		if stringutil.IsASCIILetter(ch) {
			p.incPos(1)
			return string(ch & 0x1f)
		}
		if p.anyUnicodeModeOrNonAnnexB {
			p.error(diagnostics.X_c_must_be_followed_by_an_ASCII_letter, p.pos()-2, 2)
		} else if atomEscape {
			p.incPos(-1)
			return "\\"
		}
		return string(ch)
	case '^', '$', '/', '\\', '.', '*', '+', '?', '(', ')', '[', ']', '{', '}', '|':
		p.incPos(1)
		return string(ch)
	default:
		p.incPos(-1) // back up to include the backslash for scanEscapeSequence
		flags := EscapeSequenceScanningFlagsRegularExpression
		if p.annexB {
			flags |= EscapeSequenceScanningFlagsAnnexB
		}
		if p.anyUnicodeMode {
			flags |= EscapeSequenceScanningFlagsAnyUnicodeMode
		}
		if atomEscape {
			flags |= EscapeSequenceScanningFlagsAtomEscape
		}
		return p.scanner.scanEscapeSequence(flags)
	}
}

func (p *regExpParser) scanGroupName(isReference bool) {
	debug.Assert(p.pos() > 0 && p.text()[p.pos()-1] == '<')