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go/scanner: the position of '\n's chars must be the last position of the current line

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Background: This didn't matter until recently, because '\n' don't appear as token starts
in source code and thus the exact position was irrelevant (and set as was easiest in the
code). With auto semicolon insertion, a virtual semicolon may be inserted when a '\n' is
seen. The position of the semicolon is the position of the '\n'. Without this fix, these
semicolons appeared on the next line instead of the line where they were inserted.  This
affected the association of comments to declarations in the parser. As a result, some
lead comments where considered line comments, not collected in the ast, and not shown in
godoc pages. (This affected only godoc pages, not gofmt-formatted programs).

Fixes #592.

R=rsc
CC=golang-dev
https://golang.org/cl/224068
This commit is contained in:
Robert Griesemer 2010-02-26 11:23:12 -08:00
parent 8c5404746f
commit 9520a68268
2 changed files with 12 additions and 8 deletions
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14
src/pkg/go/scanner/scanner.go
View File

@ -46,13 +46,15 @@ func (S *Scanner) next() {
if S.offset < len(S.src) {
S.pos.Offset = S.offset
S.pos.Column++
if S.ch == '\n' {
// next character starts a new line
S.pos.Line++
S.pos.Column = 1
}
r, w := int(S.src[S.offset]), 1
switch {
case r == 0:
S.error(S.pos, "illegal character NUL")
case r == '\n':
S.pos.Line++
S.pos.Column = 0
case r >= 0x80:
// not ASCII
r, w = utf8.DecodeRune(S.src[S.offset:])
@ -168,7 +170,7 @@ func (S *Scanner) scanComment(pos token.Position) {
// valid //line filename:line comment;
// update scanner position
S.pos.Filename = string(text[len(prefix):i])
S.pos.Line = line
S.pos.Line = line - 1 // -1 since the '\n' has not been consumed yet
}
}
}
@ -211,7 +213,7 @@ func (S *Scanner) findNewline(pos token.Position) bool {
newline = true
break
}
S.skipWhitespace()
S.skipWhitespace() // S.insertSemi is set
if S.ch == '\n' {
newline = true
break
@ -526,7 +528,7 @@ scanAgain:
case -1:
tok = token.EOF
case '\n':
// we only reach here of S.insertSemi was
// we only reach here if S.insertSemi was
// set in the first place and exited early
// from S.skipWhitespace()
S.insertSemi = false // newline consumed

6
src/pkg/go/scanner/scanner_test.go
View File

@ -219,11 +219,12 @@ func TestScan(t *testing.T) {
for _, e := range tokens {
src += e.lit + whitespace
}
src_linecount := newlineCount(src)
whitespace_linecount := newlineCount(whitespace)
// verify scan
index := 0
epos := token.Position{"", 0, 1, 1}
epos := token.Position{"", 0, 1, 1} // expected position
nerrors := Tokenize("", []byte(src), &testErrorHandler{t}, ScanComments,
func(pos token.Position, tok token.Token, litb []byte) bool {
e := elt{token.EOF, "", special}
@ -233,7 +234,8 @@ func TestScan(t *testing.T) {
lit := string(litb)
if tok == token.EOF {
lit = "<EOF>"
epos.Column = 0
epos.Line = src_linecount
epos.Column = 1
}
checkPos(t, lit, pos, epos)
if tok != e.tok {