Update and fix staticcheck

vendor/honnef.co/go/tools/pattern/lexer.go

@@ -0,0 +1,221 @@
+package pattern
+
+import (
+	"fmt"
+	"go/token"
+	"unicode"
+	"unicode/utf8"
+)
+
+type lexer struct {
+	f *token.File
+
+	input string
+	start int
+	pos   int
+	width int
+	items chan item
+}
+
+type itemType int
+
+const eof = -1
+
+const (
+	itemError itemType = iota
+	itemLeftParen
+	itemRightParen
+	itemLeftBracket
+	itemRightBracket
+	itemTypeName
+	itemVariable
+	itemAt
+	itemColon
+	itemBlank
+	itemString
+	itemEOF
+)
+
+func (typ itemType) String() string {
+	switch typ {
+	case itemError:
+		return "ERROR"
+	case itemLeftParen:
+		return "("
+	case itemRightParen:
+		return ")"
+	case itemLeftBracket:
+		return "["
+	case itemRightBracket:
+		return "]"
+	case itemTypeName:
+		return "TYPE"
+	case itemVariable:
+		return "VAR"
+	case itemAt:
+		return "@"
+	case itemColon:
+		return ":"
+	case itemBlank:
+		return "_"
+	case itemString:
+		return "STRING"
+	case itemEOF:
+		return "EOF"
+	default:
+		return fmt.Sprintf("itemType(%d)", typ)
+	}
+}
+
+type item struct {
+	typ itemType
+	val string
+	pos int
+}
+
+type stateFn func(*lexer) stateFn
+
+func (l *lexer) run() {
+	for state := lexStart; state != nil; {
+		state = state(l)
+	}
+	close(l.items)
+}
+
+func (l *lexer) emitValue(t itemType, value string) {
+	l.items <- item{t, value, l.start}
+	l.start = l.pos
+}
+
+func (l *lexer) emit(t itemType) {
+	l.items <- item{t, l.input[l.start:l.pos], l.start}
+	l.start = l.pos
+}
+
+func lexStart(l *lexer) stateFn {
+	switch r := l.next(); {
+	case r == eof:
+		l.emit(itemEOF)
+		return nil
+	case unicode.IsSpace(r):
+		l.ignore()
+	case r == '(':
+		l.emit(itemLeftParen)
+	case r == ')':
+		l.emit(itemRightParen)
+	case r == '[':
+		l.emit(itemLeftBracket)
+	case r == ']':
+		l.emit(itemRightBracket)
+	case r == '@':
+		l.emit(itemAt)
+	case r == ':':
+		l.emit(itemColon)
+	case r == '_':
+		l.emit(itemBlank)
+	case r == '"':
+		l.backup()
+		return lexString
+	case unicode.IsUpper(r):
+		l.backup()
+		return lexType
+	case unicode.IsLower(r):
+		l.backup()
+		return lexVariable
+	default:
+		return l.errorf("unexpected character %c", r)
+	}
+	return lexStart
+}
+
+func (l *lexer) next() (r rune) {
+	if l.pos >= len(l.input) {
+		l.width = 0
+		return eof
+	}
+	r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
+
+	if r == '\n' {
+		l.f.AddLine(l.pos)
+	}
+
+	l.pos += l.width
+
+	return r
+}
+
+func (l *lexer) ignore() {
+	l.start = l.pos
+}
+
+func (l *lexer) backup() {
+	l.pos -= l.width
+}
+
+func (l *lexer) errorf(format string, args ...interface{}) stateFn {
+	// TODO(dh): emit position information in errors
+	l.items <- item{
+		itemError,
+		fmt.Sprintf(format, args...),
+		l.start,
+	}
+	return nil
+}
+
+func isAlphaNumeric(r rune) bool {
+	return r >= '0' && r <= '9' ||
+		r >= 'a' && r <= 'z' ||
+		r >= 'A' && r <= 'Z'
+}
+
+func lexString(l *lexer) stateFn {
+	l.next() // skip quote
+	escape := false
+
+	var runes []rune
+	for {
+		switch r := l.next(); r {
+		case eof:
+			return l.errorf("unterminated string")
+		case '"':
+			if !escape {
+				l.emitValue(itemString, string(runes))
+				return lexStart
+			} else {
+				runes = append(runes, '"')
+				escape = false
+			}
+		case '\\':
+			if escape {
+				runes = append(runes, '\\')
+				escape = false
+			} else {
+				escape = true
+			}
+		default:
+			runes = append(runes, r)
+		}
+	}
+}
+
+func lexType(l *lexer) stateFn {
+	l.next()
+	for {
+		if !isAlphaNumeric(l.next()) {
+			l.backup()
+			l.emit(itemTypeName)
+			return lexStart
+		}
+	}
+}
+
+func lexVariable(l *lexer) stateFn {
+	l.next()
+	for {
+		if !isAlphaNumeric(l.next()) {
+			l.backup()
+			l.emit(itemVariable)
+			return lexStart
+		}
+	}
+}