OpBeginText                    // matches empty string at beginning of text
	OpEndText                      // matches empty string at end of text
	OpWordBoundary                 // matches word boundary `\b`
	OpNoWordBoundary               // matches word non-boundary `\B`
	OpCapture                      // capturing subexpression with index Cap, optional name Name
	OpStar                         // matches Sub[0] zero or more times

				case 'A':
					p.op(OpBeginText)
					t = t[2:]
					break BigSwitch
				case 'b':
					p.op(OpWordBoundary)
					t = t[2:]
					break BigSwitch
				case 'B':
					p.op(OpNoWordBoundary)
					t = t[2:]
					break BigSwitch
				case 'C':
					// any byte; not supported
					return nil, &Error{ErrInvalidEscape, t[:2]}
				case 'Q':
					// \Q ... \E: the ... is always literals

		{"OpCharClass", Const, 0},
		{"OpConcat", Const, 0},
		{"OpEmptyMatch", Const, 0},
		{"OpEndLine", Const, 0},
		{"OpEndText", Const, 0},
		{"OpLiteral", Const, 0},
		{"OpNoMatch", Const, 0},
		{"OpNoWordBoundary", Const, 0},
		{"OpPlus", Const, 0},
		{"OpQuest", Const, 0},
		{"OpRepeat", Const, 0},
		{"OpStar", Const, 0},
		{"OpWordBoundary", Const, 0},
		{"POSIX", Const, 0},
		{"Parse", Func, 0},