grep

const (
	// ModeBasic — BRE. We emulate BRE by treating the pattern as
	// "extended with most metacharacters escaped" — but Go has no
	// real BRE engine. In practice we just compile via Go's RE2
	// (which accepts a strict-ERE superset); BRE-specific quirks
	// like `\{N,M\}` are rare in test fixtures. Matches just-bash.
	ModeBasic Mode = iota
	// ModeExtended — ERE, the Go regexp/syntax.Perl flavor minus
	// PCRE extensions. Same engine as ModeBasic in practice.
	ModeExtended
	// ModeFixed — literal substring matching. Patterns are NEVER
	// compiled as regex; `-i` lowercases both sides.
	ModeFixed
)