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godoc: optimizations: don't call Write for 0-length data

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- guard some calls to Write that frequently may have 0-length data
- fix an invariant

R=r
CC=golang-dev
https://golang.org/cl/4179041
This commit is contained in:
Robert Griesemer 2011-02-09 15:06:05 -08:00
parent fb9e37cd9b
commit 334f52ac49
1 changed files with 15 additions and 5 deletions
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20
src/cmd/godoc/godoc.go
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@ -274,7 +274,7 @@ func relativePath(path string) string {
// ---------------------------------------------------------------------------- // ----------------------------------------------------------------------------
// Tab conversion // Tab conversion
var spaces = []byte(" ") // 16 spaces seems like a good number var spaces = []byte(" ") // 32 spaces seems like a good number
const ( const (
indenting = iota indenting = iota
@ -291,25 +291,31 @@ type tconv struct {
func (p *tconv) writeIndent() (err os.Error) { func (p *tconv) writeIndent() (err os.Error) {
i := p.indent i := p.indent
for i > len(spaces) { for i >= len(spaces) {
i -= len(spaces) i -= len(spaces)
if _, err = p.output.Write(spaces); err != nil { if _, err = p.output.Write(spaces); err != nil {
return return
} }
} }
_, err = p.output.Write(spaces[0:i]) // i < len(spaces)
if i > 0 {
_, err = p.output.Write(spaces[0:i])
}
return return
} }
func (p *tconv) Write(data []byte) (n int, err os.Error) { func (p *tconv) Write(data []byte) (n int, err os.Error) {
if len(data) == 0 {
return
}
pos := 0 // valid if p.state == collecting pos := 0 // valid if p.state == collecting
var b byte var b byte
for n, b = range data { for n, b = range data {
switch p.state { switch p.state {
case indenting: case indenting:
switch b { switch b {
case '\t', '\v': case '\t':
p.indent += *tabwidth p.indent += *tabwidth
case '\n': case '\n':
p.indent = 0 p.indent = 0
@ -336,7 +342,7 @@ func (p *tconv) Write(data []byte) (n int, err os.Error) {
} }
} }
n = len(data) n = len(data)
if p.state == collecting { if pos < n && p.state == collecting {
_, err = p.output.Write(data[pos:]) _, err = p.output.Write(data[pos:])
} }
return return
@ -352,6 +358,10 @@ func writeNode(w io.Writer, fset *token.FileSet, x interface{}) {
// to ensure a good outcome in most browsers (there may still // to ensure a good outcome in most browsers (there may still
// be tabs in comments and strings, but converting those into // be tabs in comments and strings, but converting those into
// the right number of spaces is much harder) // the right number of spaces is much harder)
//
// TODO(gri) rethink printer flags - perhaps tconv can be eliminated
// with an another printer mode (which is more efficiently
// implemented in the printer than here with another layer)
mode := printer.TabIndent | printer.UseSpaces mode := printer.TabIndent | printer.UseSpaces
(&printer.Config{mode, *tabwidth}).Fprint(&tconv{output: w}, fset, x) (&printer.Config{mode, *tabwidth}).Fprint(&tconv{output: w}, fset, x)
} }