lit := s.segment()
	if len(lit) >= 2 {
		if tok := keywordMap[hash(lit)]; tok != 0 && tokStrFast(tok) == string(lit) {
			s.nlsemi = contains(1<<_Break|1<<_Continue|1<<_Fallthrough|1<<_Return, tok)
			s.tok = tok
			return
		}
	}

	s.nlsemi = true
	s.lit = string(lit)
	s.tok = _Name
}

// tokStrFast is a faster version of token.String, which assumes that tok

			tok(n.Map, len("map")))

	case *ast.ParenExpr:
		children = append(children,
			tok(n.Lparen, len("(")),
			tok(n.Rparen, len(")")))

	case *ast.RangeStmt:
		children = append(children,
			tok(n.For, len("for")),
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.ReturnStmt:
		children = append(children,
			tok(n.Return, len("return")))

	case *ast.SelectStmt:
		children = append(children,

	s := t.s
	for {
		t.tok = ScanToken(s.Scan())
		if t.tok != scanner.Comment {
			break
		}
		text := s.TokenText()
		t.line += strings.Count(text, "\n")
		if constraint.IsGoBuild(text) {
			t.tok = BuildComment
			break
		}
	}
	switch t.tok {
	case '\n':
		t.line++
	case '-':
		if s.Peek() == '>' {
			s.Next()
			t.tok = ARR
			return ARR
		}
	case '@':

		tsv      [4][4]string // large enough for example above
	)
	s.Init(strings.NewReader(src))
	s.Whitespace ^= 1<<'\t' | 1<<'\n' // don't skip tabs and new lines

	for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
		switch tok {
		case '\n':
			row++
			col = 0
		case '\t':
			col++
		default:
			tsv[row][col] = s.TokenText()
		}
	}

	fmt.Print(tsv)

	// Output:

	nesting := 0
	var tokens []Token
	for {
		tok := in.Stack.Next()
		if tok == scanner.EOF || tok == '\n' {
			in.Error("unterminated arg list invoking macro:", macro.name)
		}
		if nesting == 0 && (tok == ')' || tok == ',') {
			return tokens, tok
		}
		if tok == '(' {
			nesting++
		}
		if tok == ')' {
			nesting--
		}
		tokens = append(tokens, Make(tok, in.Stack.Text()))
	}
}

	if p.trace && p.pos.IsValid() {
		s := p.tok.String()
		switch {
		case p.tok.IsLiteral():
			p.printTrace(s, p.lit)
		case p.tok.IsOperator(), p.tok.IsKeyword():
			p.printTrace("\"" + s + "\"")
		default:
			p.printTrace(s)
		}
	}

	for {
		p.pos, p.tok, p.lit = p.scanner.Scan()
		if p.tok == token.COMMENT {
			if p.top && strings.HasPrefix(p.lit, "//go:build") {

type exprToken struct {
	tok    string
	prec   int
	prefix func(*exprParser) val
	infix  func(val, val) val
}

var exprTokens []exprToken

func init() { // init to break init cycle
	exprTokens = []exprToken{
		{tok: "&&", prec: 1, infix: func(x, y val) val { return x && y }},
		{tok: "||", prec: 2, infix: func(x, y val) val { return x || y }},
		{tok: "!", prec: 3, prefix: (*exprParser).not},

// delimiters; it returns false otherwise.
func (tok Token) IsOperator() bool {
	return (operator_beg < tok && tok < operator_end) || tok == TILDE
}

// IsKeyword returns true for tokens corresponding to keywords;
// it returns false otherwise.
func (tok Token) IsKeyword() bool { return keyword_beg < tok && tok < keyword_end }

// IsExported reports whether name starts with an upper-case letter.

			if tok == '\n' || tok == ';' || (nesting == 0 && (tok == ',' || tok == ':')) {
				if tok == ':' {
					// Remember this location so we can swap the operands below.
					if colon >= 0 {
						p.errorf("invalid ':' in operand")
						return word, cond, operands, true
					}
					colon = len(operands)
				}
				break
			}
			if tok == '(' || tok == '[' {
				nesting++
			}
			if tok == ')' || tok == ']' {

		// make the error message more specific
		if p.tok == token.SEMICOLON && p.lit[0] == '\n' {
			msg += ", found newline"
		} else {
			msg += ", found '" + p.tok.String() + "'"
			if p.tok.IsLiteral() {
				msg += " " + p.lit
			}
		}
	}
	p.error(pos, msg)
}

func (p *parser) expect(tok token.Token) token.Pos {
	pos := p.pos
	if p.tok != tok {
		p.errorExpected(pos, "'"+tok.String()+"'")
	}