cmd/compile: simplify lexer.ungetr

Change-Id: Id041c1b2d364aecd7a6613a53237f7de2c650a7e
Reviewed-on: https://go-review.googlesource.com/20599
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/compile/internal/gc/lex.go b/src/cmd/compile/internal/gc/lex.go
index f8ec00079f9edca18a32a13f6f0929cc7b5d5c6b..facda14c371d93419bff747d62bec3f8b8f520b5 100644 (file)
--- a/src/cmd/compile/internal/gc/lex.go
+++ b/src/cmd/compile/internal/gc/lex.go
@@ -885,7 +885,8 @@ const (
 
 type lexer struct {
        // source
-       bin *bufio.Reader
+       bin        *bufio.Reader
+       prevlineno int32 // line no. of most recently read character
 
        nlsemi bool // if set, '\n' and EOF translate to ';'
 
@@ -1003,7 +1004,7 @@ l0:
 
        switch c {
        case EOF:
-               l.ungetr(EOF) // return EOF again in future next call
+               l.ungetr()
                // Treat EOF as "end of line" for the purposes
                // of inserting a semicolon.
                if nlsemi {
@@ -1023,7 +1024,7 @@ l0:
        case '.':
                c1 = l.getr()
                if isDigit(c1) {
-                       l.ungetr(c1)
+                       l.ungetr()
                        l.number('.')
                        return
                }
@@ -1036,7 +1037,7 @@ l0:
                                goto lx
                        }
 
-                       l.ungetr(c1)
+                       l.ungetr()
                        c1 = '.'
                }
 
@@ -1086,7 +1087,7 @@ l0:
                        c = l.getlinepragma()
                        for {
                                if c == '\n' || c == EOF {
-                                       l.ungetr(c)
+                                       l.ungetr()
                                        goto l0
                                }
 
@@ -1240,7 +1241,7 @@ l0:
                goto l0
        }
 
-       l.ungetr(c1)
+       l.ungetr()
 
 lx:
        if Debug['x'] != 0 {
@@ -1269,7 +1270,7 @@ binop:
        c1 = l.getr()
 binop1:
        if c1 != '=' {
-               l.ungetr(c1)
+               l.ungetr()
                l.op = op
                l.prec = prec
                goto lx
@@ -1312,7 +1313,7 @@ func (l *lexer) ident(c rune) {
        }
 
        cp = nil
-       l.ungetr(c)
+       l.ungetr()
 
        name := lexbuf.Bytes()
 
@@ -1478,7 +1479,7 @@ func (l *lexer) number(c rune) {
                }
        }
 
-       l.ungetr(c)
+       l.ungetr()
 
        if isInt {
                if malformedOctal {
@@ -1591,7 +1592,7 @@ func (l *lexer) rune() {
 
        if c := l.getr(); c != '\'' {
                Yyerror("missing '")
-               l.ungetr(c)
+               l.ungetr()
        }
 
        x := new(Mpint)
@@ -1892,6 +1893,7 @@ func pragcgo(text string) {
 
 func (l *lexer) getr() rune {
 redo:
+       l.prevlineno = lexlineno
        r, w, err := l.bin.ReadRune()
        if err != nil {
                if err != io.EOF {
@@ -1918,11 +1920,9 @@ redo:
        return r
 }
 
-func (l *lexer) ungetr(r rune) {
+func (l *lexer) ungetr() {
        l.bin.UnreadRune()
-       if r == '\n' && importpkg == nil {
-               lexlineno--
-       }
+       lexlineno = l.prevlineno
 }
 
 // onechar lexes a single character within a rune or interpreted string literal,
@@ -1932,12 +1932,12 @@ func (l *lexer) onechar(quote rune) (r rune, b byte, ok bool) {
        switch c {
        case EOF:
                Yyerror("eof in string")
-               l.ungetr(EOF)
+               l.ungetr()
                return
 
        case '\n':
                Yyerror("newline in string")
-               l.ungetr('\n')
+               l.ungetr()
                return
 
        case '\\':
@@ -1971,7 +1971,7 @@ func (l *lexer) onechar(quote rune) (r rune, b byte, ok bool) {
                        }
 
                        Yyerror("non-octal character in escape sequence: %c", c)
-                       l.ungetr(c)
+                       l.ungetr()
                }
 
                if x > 255 {
@@ -2029,7 +2029,7 @@ func (l *lexer) hexchar(n int) uint32 {
                        d = uint32(c - 'A' + 10)
                default:
                        Yyerror("non-hex character in escape sequence: %c", c)
-                       l.ungetr(c)
+                       l.ungetr()
                        return x
                }
                x = x*16 + d