godoc: show packages matching a query at the top

Also: fix layout of textual search results and
fix a field reference in the respective template.

Fixes #1987.

R=rsc, r
CC=golang-dev
https://golang.org/cl/4962061

lib/godoc/search.html

@@ -17,6 +17,17 @@
 	{{end}}
 	</p>
 {{end}}
+{{with .Pak}}
+	<h2 id="Packages">Package {{html $.Query}}</h2>
+	<p>
+	<table class="layout">
+	{{range .}}
+		{{$pkg_html := pkgLink .Pak.Path | html}}
+		<tr><td><a href="/{{$pkg_html}}">{{$pkg_html}}</a></td></tr>
+	{{end}}
+	</table>
+	</p>
+{{end}}
 {{with .Hit}}
 	{{with .Decls}}
 		<h2 id="Global">Package-level declarations</h2>

lib/godoc/search.txt

@@ -1,33 +1,39 @@
 QUERY
 	{{.Query}}
-{{with .Alert}}
-{{.}}
+
+{{with .Alert}}{{.}}
 {{end}}{{/* .Alert */}}{{/*
 
 ---------------------------------------
 
-*/}}{{with .Alt}}
-DID YOU MEAN
+*/}}{{with .Alt}}DID YOU MEAN
+
 {{range .Alts}}	{{.}}
-{{end}}{{end}}{{/* .Alts */}}{{/*
+{{end}}{{end}}{{/* .Alt */}}{{/*
 
 ---------------------------------------
 
-*/}}{{with .Hit}}{{with .Decls}}
-PACKAGE-LEVEL DECLARATIONS
+*/}}{{with .Pak}}PACKAGE {{$.Query}}
+
+{{range .}}{{.Pak.Path}}
+{{end}}
+{{end}}{{/* .Pak */}}{{/*
+
+---------------------------------------
+
+*/}}{{with .Hit}}{{with .Decls}}PACKAGE-LEVEL DECLARATIONS
 
 {{range .}}package {{.Pak.Name}}
-{{range $file := .Files}}{{range .Groups}}{{range .Infos}}	{{srcLink $file.File.Path}}:{{infoLine .}}{{end}}
+{{range $file := .Files}}{{range .Groups}}{{range .}}	{{srcLink $file.File.Path}}:{{infoLine .}}{{end}}
 {{end}}{{end}}{{/* .Files */}}
 {{end}}{{end}}{{/* .Decls */}}{{/*
 
 ---------------------------------------
 
-*/}}{{with .Others}}
-LOCAL DECLARATIONS AND USES
+*/}}{{with .Others}}LOCAL DECLARATIONS AND USES
 
 {{range .}}package {{.Pak.Name}}
-{{range $file := .Files}}{{range .Groups}}{{range .Infos}}	{{srcLink $file.File.Path}}:{{infoLine .}}
+{{range $file := .Files}}{{range .Groups}}{{range .}}	{{srcLink $file.File.Path}}:{{infoLine .}}
 {{end}}{{end}}{{end}}{{/* .Files */}}
 {{end}}{{end}}{{/* .Others */}}{{end}}{{/* .Hit */}}{{/*
 

src/cmd/godoc/godoc.go

@@ -1016,6 +1016,7 @@ type SearchResult struct {
 	Alert string // error or warning message
 
 	// identifier matches
+	Pak HitList       // packages matching Query
 	Hit *LookupResult // identifier matches of Query
 	Alt *AltWords     // alternative identifiers to look for
 
@@ -1034,7 +1035,7 @@ func lookup(query string) (result SearchResult) {
 
 		// identifier search
 		var err os.Error
-		result.Hit, result.Alt, err = index.Lookup(query)
+		result.Pak, result.Hit, result.Alt, err = index.Lookup(query)
 		if err != nil && *maxResults <= 0 {
 			// ignore the error if full text search is enabled
 			// since the query may be a valid regular expression

src/cmd/godoc/index.go

@@ -344,6 +344,8 @@ func reduce(h0 RunList) HitList {
 	return h
 }
 
+// filter returns a new HitList created by filtering
+// all PakRuns from h that have a matching pakname.
 func (h HitList) filter(pakname string) HitList {
 	var hh HitList
 	for _, p := range h {
@@ -867,7 +869,7 @@ func (x *Index) Stats() Statistics {
 	return x.stats
 }
 
-func (x *Index) LookupWord(w string) (match *LookupResult, alt *AltWords) {
+func (x *Index) lookupWord(w string) (match *LookupResult, alt *AltWords) {
 	match = x.words[w]
 	alt = x.alts[canonical(w)]
 	// remove current spelling from alternatives
@@ -891,9 +893,10 @@ func isIdentifier(s string) bool {
 }
 
 // For a given query, which is either a single identifier or a qualified
-// identifier, Lookup returns a LookupResult, and a list of alternative
-// spellings, if any. If the query syntax is wrong, an error is reported.
-func (x *Index) Lookup(query string) (match *LookupResult, alt *AltWords, err os.Error) {
+// identifier, Lookup returns a list of packages, a LookupResult, and a
+// list of alternative spellings, if any. Any and all results may be nil.
+// If the query syntax is wrong, an error is reported.
+func (x *Index) Lookup(query string) (paks HitList, match *LookupResult, alt *AltWords, err os.Error) {
 	ss := strings.Split(query, ".")
 
 	// check query syntax
@@ -904,15 +907,23 @@ func (x *Index) Lookup(query string) (match *LookupResult, alt *AltWords, err os
 		}
 	}
 
+	// handle simple and qualified identifiers
 	switch len(ss) {
 	case 1:
-		match, alt = x.LookupWord(ss[0])
+		ident := ss[0]
+		match, alt = x.lookupWord(ident)
+		if match != nil {
+			// found a match - filter packages with same name
+			// for the list of packages called ident, if any
+			paks = match.Others.filter(ident)
+		}
 
 	case 2:
-		pakname := ss[0]
-		match, alt = x.LookupWord(ss[1])
+		pakname, ident := ss[0], ss[1]
+		match, alt = x.lookupWord(ident)
 		if match != nil {
 			// found a match - filter by package name
+			// (no paks - package names are not qualified)
 			decls := match.Decls.filter(pakname)
 			others := match.Others.filter(pakname)
 			match = &LookupResult{decls, others}