godoc: fix quadratic and ASCII-only struct field linkification
Fixes two problems with adding the #StructType.FieldName anchors for
linkified struct fields:
* the old code was quadratic
* the old code only dealt with ASCII only
Change-Id: If03a367a94d05d3d470e1326dfb573037088ff78
Reviewed-on: https://go-review.googlesource.com/35486
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/godoc/godoc.go b/godoc/godoc.go
index 8bda89a..1063244 100644
--- a/godoc/godoc.go
+++ b/godoc/godoc.go
@@ -233,24 +233,28 @@
if st.Fields == nil {
return
}
- var scratch bytes.Buffer
+ // needsLink is a set of identifiers that still need to be
+ // linked, where value == key, to avoid an allocation in func
+ // linkedField.
+ needsLink := make(map[string]string)
+
for _, f := range st.Fields.List {
if len(f.Names) == 0 {
continue
}
fieldName := f.Names[0].Name
- scratch.Reset()
- var added bool
- foreachLine(buf.Bytes(), func(line []byte) {
- if !added && isLineForStructFieldID(line, fieldName) {
- added = true
- fmt.Fprintf(&scratch, `<span id="%s.%s"></span>`, name, fieldName)
- }
- scratch.Write(line)
- })
- buf.Reset()
- buf.Write(scratch.Bytes())
+ needsLink[fieldName] = fieldName
}
+ var newBuf bytes.Buffer
+ foreachLine(buf.Bytes(), func(line []byte) {
+ if fieldName := linkedField(line, needsLink); fieldName != "" {
+ fmt.Fprintf(&newBuf, `<span id="%s.%s"></span>`, name, fieldName)
+ delete(needsLink, fieldName)
+ }
+ newBuf.Write(line)
+ })
+ buf.Reset()
+ buf.Write(newBuf.Bytes())
}
// foreachLine calls fn for each line of in, where a line includes
@@ -270,9 +274,12 @@
// commentPrefix is the line prefix for comments after they've been HTMLified.
var commentPrefix = []byte(`<span class="comment">// `)
-// isLineForStructFieldID reports whether line is a line we should
-// add a <span id="#StructName.FieldName"> to. Only the fieldName is provided.
-func isLineForStructFieldID(line []byte, fieldName string) bool {
+// linkedField determines whether the given line starts with an
+// identifer in the provided ids map (mapping from identifier to the
+// same identifier). The line can start with either an identifier or
+// an identifier in a comment. If one matches, it returns the
+// identifier that matched. Otherwise it returns the empty string.
+func linkedField(line []byte, ids map[string]string) string {
line = bytes.TrimSpace(line)
// For fields with a doc string of the
@@ -292,13 +299,39 @@
//
// TODO: do this better, so it works for all
// comments, including unconventional ones.
- // For comments
if bytes.HasPrefix(line, commentPrefix) {
- if matchesIdentBoundary(line[len(commentPrefix):], fieldName) {
- return true
- }
+ line = line[len(commentPrefix):]
}
- return matchesIdentBoundary(line, fieldName)
+ id := scanIdentifier(line)
+ if len(id) == 0 {
+ // No leading identifier. Avoid map lookup for
+ // somewhat common case.
+ return ""
+ }
+ return ids[string(id)]
+}
+
+// scanIdentifier scans a valid Go identifier off the front of v and
+// either returns a subslice of v if there's a valid identifier, or
+// returns a zero-length slice.
+func scanIdentifier(v []byte) []byte {
+ var n int // number of leading bytes of v belonging to an identifier
+ for {
+ r, width := utf8.DecodeRune(v[n:])
+ if !(isLetter(r) || n > 0 && isDigit(r)) {
+ break
+ }
+ n += width
+ }
+ return v[:n]
+}
+
+func isLetter(ch rune) bool {
+ return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
+}
+
+func isDigit(ch rune) bool {
+ return '0' <= ch && ch <= '9' || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
}
// matchesIdentBoundary reports whether line matches /^ident\b/.
