internal/godoc: delete indexing code

We no longer serve search from the golang.org site.

Change-Id: I8b855cf664f175c0dc46a91e3017df1bebb28281
Reviewed-on: https://go-review.googlesource.com/c/website/+/293427
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/_content/lib/godoc/godoc.html b/_content/lib/godoc/godoc.html
index e22af76..c50b8b3 100644
--- a/_content/lib/godoc/godoc.html
+++ b/_content/lib/godoc/godoc.html
@@ -12,9 +12,6 @@
 <link href="https://fonts.googleapis.com/css?family=Work+Sans:600|Roboto:400,700" rel="stylesheet">
 <link href="https://fonts.googleapis.com/css?family=Product+Sans&text=Supported%20by%20Google&display=swap" rel="stylesheet">
 <link type="text/css" rel="stylesheet" href="/lib/godoc/style.css">
-{{if .SearchBox}}
-<link rel="search" type="application/opensearchdescription+xml" title="godoc" href="/opensearch.xml" />
-{{end}}
 <script>window.initFuncs = [];</script>
 {{with .GoogleAnalytics}}
 <script>
diff --git a/_content/lib/godoc/opensearch.xml b/_content/lib/godoc/opensearch.xml
deleted file mode 100644
index 1b652db..0000000
--- a/_content/lib/godoc/opensearch.xml
+++ /dev/null
@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/">
-  <ShortName>godoc</ShortName>
-  <Description>The Go Programming Language</Description>
-  <Tags>go golang</Tags>
-  <Contact />
-  <Url type="text/html" template="{{.BaseURL}}/search?q={searchTerms}" />
-  <Image height="15" width="16" type="image/x-icon">/favicon.ico</Image>
-  <OutputEncoding>UTF-8</OutputEncoding>
-  <InputEncoding>UTF-8</InputEncoding>
-</OpenSearchDescription>
diff --git a/_content/lib/godoc/search.html b/_content/lib/godoc/search.html
deleted file mode 100644
index 3714e1d..0000000
--- a/_content/lib/godoc/search.html
+++ /dev/null
@@ -1,66 +0,0 @@
-<!--
-	Copyright 2009 The Go Authors. All rights reserved.
-	Use of this source code is governed by a BSD-style
-	license that can be found in the LICENSE file.
--->
-
-{{ $colCount := tocColCount .}}
-{{/* Generate the TOC */}}
-<nav class="search-nav" style="column-count: {{$colCount}}" role="navigation">
-{{range $key, $val := .Idents}}
-	{{if $val}}
-		<a href="#{{$key.Name}}">{{$key.Name}}</a>
-		<br />
-	{{end}}
-{{end}}
-
-{{if not .Idents}}
-	{{with .Pak}}
-		<a href="#Packages">Package {{html $.Query}}</a>
-		<br />
-	{{end}}
-{{end}}
-
-{{with .Hit}}
-	{{with .Decls}}
-		<a href="#Global">Package-level declarations</a>
-		<br />
-		{{range .}}
-			{{$pkg_html := pkgLink .Pak.Path | html}}
-			<a href="#Global_{{$pkg_html}}" class="indent">package {{html .Pak.Name}}</a>
-			<br />
-		{{end}}
-	{{end}}
-	{{with .Others}}
-		<a href="#Local">Local declarations and uses</a>
-		<br />
-		{{range .}}
-			{{$pkg_html := pkgLink .Pak.Path | html}}
-			<a href="#Local_{{$pkg_html}}" class="indent">package {{html .Pak.Name}}</a>
-			<br />
-		{{end}}
-	{{end}}
-{{end}}
-
-{{with .Textual}}
-	{{if $.Complete}}
-		<a href="#Textual">{{html $.Found}} textual occurrences</a>
-	{{else}}
-		<a href="#Textual">More than {{html $.Found}} textual occurrences</a>
-	{{end}}
-{{end}}
-</nav>
-
-{{with .Alert}}
-	<p>
-	<span class="alert" style="font-size:120%">{{html .}}</span>
-	</p>
-{{end}}
-{{with .Alt}}
-	<p>
-	<span class="alert" style="font-size:120%">Did you mean: </span>
-	{{range .Alts}}
-		<a href="search?q={{urlquery .}}" style="font-size:120%">{{html .}}</a>
-	{{end}}
-	</p>
-{{end}}
diff --git a/_content/lib/godoc/searchcode.html b/_content/lib/godoc/searchcode.html
deleted file mode 100644
index a032e64..0000000
--- a/_content/lib/godoc/searchcode.html
+++ /dev/null
@@ -1,64 +0,0 @@
-<!--
-	Copyright 2009 The Go Authors. All rights reserved.
-	Use of this source code is governed by a BSD-style
-	license that can be found in the LICENSE file.
--->
-{{$query_url := urlquery .Query}}
-{{if not .Idents}}
-	{{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}}
-{{end}}
-{{with .Hit}}
-	{{with .Decls}}
-		<h2 id="Global">Package-level declarations</h2>
-		{{range .}}
-			{{$pkg_html := pkgLink .Pak.Path | html}}
-			<h3 id="Global_{{$pkg_html}}">package <a href="/{{$pkg_html}}">{{html .Pak.Name}}</a></h3>
-			{{range .Files}}
-				{{$file := .File.Path}}
-				{{range .Groups}}
-					{{range .}}
-						{{$line := infoLine .}}
-						<a href="{{queryLink $file $query_url $line | html}}">{{$file}}:{{$line}}</a>
-						{{infoSnippet_html .}}
-					{{end}}
-				{{end}}
-			{{end}}
-		{{end}}
-	{{end}}
-	{{with .Others}}
-		<h2 id="Local">Local declarations and uses</h2>
-		{{range .}}
-			{{$pkg_html := pkgLink .Pak.Path | html}}
-			<h3 id="Local_{{$pkg_html}}">package <a href="/{{$pkg_html}}">{{html .Pak.Name}}</a></h3>
-			{{range .Files}}
-				{{$file := .File.Path}}
-				<a href="{{queryLink $file $query_url 0 | html}}">{{$file}}</a>
-				<table class="layout">
-				{{range .Groups}}
-					<tr>
-					<td width="25"></td>
-					<th align="left" valign="top">{{index . 0 | infoKind_html}}</th>
-					<td align="left" width="4"></td>
-					<td>
-					{{range .}}
-						{{$line := infoLine .}}
-						<a href="{{queryLink $file $query_url $line | html}}">{{$line}}</a>
-					{{end}}
-					</td>
-					</tr>
-				{{end}}
-				</table>
-			{{end}}
-		{{end}}
-	{{end}}
-{{end}}
diff --git a/_content/lib/godoc/searchdoc.html b/_content/lib/godoc/searchdoc.html
deleted file mode 100644
index 679c02c..0000000
--- a/_content/lib/godoc/searchdoc.html
+++ /dev/null
@@ -1,24 +0,0 @@
-<!--
-	Copyright 2009 The Go Authors. All rights reserved.
-	Use of this source code is governed by a BSD-style
-	license that can be found in the LICENSE file.
--->
-{{range $key, $val := .Idents}}
-	{{if $val}}
-		<h2 id="{{$key.Name}}">{{$key.Name}}</h2>
-		{{range $val}}
-			{{$pkg_html := pkgLink .Path | html}}
-			{{if eq "Packages" $key.Name}}
-				<a href="/{{$pkg_html}}">{{html .Path}}</a>
-			{{else}}
-				{{$doc_html := docLink .Path .Name| html}}
-				<a href="/{{$pkg_html}}">{{html .Package}}</a>.<a href="{{$doc_html}}">{{.Name}}</a>
-			{{end}}
-			{{if .Doc}}
-				<p>{{comment_html .Doc}}</p>
-			{{else}}
-				<p><em>No documentation available</em></p>
-			{{end}}
-		{{end}}
-	{{end}}
-{{end}}
diff --git a/_content/lib/godoc/searchtxt.html b/_content/lib/godoc/searchtxt.html
deleted file mode 100644
index 7e4a978..0000000
--- a/_content/lib/godoc/searchtxt.html
+++ /dev/null
@@ -1,42 +0,0 @@
-<!--
-	Copyright 2009 The Go Authors. All rights reserved.
-	Use of this source code is governed by a BSD-style
-	license that can be found in the LICENSE file.
--->
-{{$query_url := urlquery .Query}}
-{{with .Textual}}
-	{{if $.Complete}}
-		<h2 id="Textual">{{html $.Found}} textual occurrences</h2>
-	{{else}}
-		<h2 id="Textual">More than {{html $.Found}} textual occurrences</h2>
-		<p>
-		<span class="alert" style="font-size:120%">Not all files or lines containing "{{html $.Query}}" are shown.</span>
-		</p>
-	{{end}}
-	<p>
-	<table class="layout">
-	{{range .}}
-		{{$file := .Filename}}
-		<tr>
-		<td align="left" valign="top">
-		<a href="{{queryLink $file $query_url 0}}">{{$file}}</a>:
-		</td>
-		<td align="left" width="4"></td>
-		<th align="left" valign="top">{{len .Lines}}</th>
-		<td align="left" width="4"></td>
-		<td align="left">
-		{{range .Lines}}
-			<a href="{{queryLink $file $query_url .}}">{{html .}}</a>
-		{{end}}
-		{{if not $.Complete}}
-			...
-		{{end}}
-		</td>
-		</tr>
-	{{end}}
-	{{if not $.Complete}}
-		<tr><td align="left">...</td></tr>
-	{{end}}
-	</table>
-	</p>
-{{end}}
diff --git a/cmd/golangorg/handlers.go b/cmd/golangorg/handlers.go
index faccde7..c1919c9 100644
--- a/cmd/golangorg/handlers.go
+++ b/cmd/golangorg/handlers.go
@@ -121,11 +121,6 @@
 	p.GodocHTML = readTemplate("godoc.html")
 	p.PackageHTML = readTemplate("package.html")
 	p.PackageRootHTML = readTemplate("packageroot.html")
-	p.SearchHTML = readTemplate("search.html")
-	p.SearchDocHTML = readTemplate("searchdoc.html")
-	p.SearchCodeHTML = readTemplate("searchcode.html")
-	p.SearchTxtHTML = readTemplate("searchtxt.html")
-	p.SearchDescXML = readTemplate("opensearch.xml")
 }
 
 type fmtResponse struct {
diff --git a/cmd/golangorg/main.go b/cmd/golangorg/main.go
index 6384472..60f0294 100644
--- a/cmd/golangorg/main.go
+++ b/cmd/golangorg/main.go
@@ -93,7 +93,6 @@
 
 	corpus := godoc.NewCorpus(fs)
 	corpus.Verbose = *verbose
-	corpus.IndexEnabled = false
 	if err := corpus.Init(); err != nil {
 		log.Fatal(err)
 	}
diff --git a/internal/godoc/corpus.go b/internal/godoc/corpus.go
index 153e132..74a2488 100644
--- a/internal/godoc/corpus.go
+++ b/internal/godoc/corpus.go
@@ -24,48 +24,6 @@
 	// Verbose logging.
 	Verbose bool
 
-	// IndexEnabled controls whether indexing is enabled.
-	IndexEnabled bool
-
-	// IndexFiles specifies a glob pattern specifying index files.
-	// If not empty, the index is read from these files in sorted
-	// order.
-	IndexFiles string
-
-	// IndexThrottle specifies the indexing throttle value
-	// between 0.0 and 1.0. At 0.0, the indexer always sleeps.
-	// At 1.0, the indexer never sleeps. Because 0.0 is useless
-	// and redundant with setting IndexEnabled to false, the
-	// zero value for IndexThrottle means 0.9.
-	IndexThrottle float64
-
-	// IndexInterval specifies the time to sleep between reindexing
-	// all the sources.
-	// If zero, a default is used. If negative, the index is only
-	// built once.
-	IndexInterval time.Duration
-
-	// IndexDocs enables indexing of Go documentation.
-	// This will produce search results for exported types, functions,
-	// methods, variables, and constants, and will link to the godoc
-	// documentation for those identifiers.
-	IndexDocs bool
-
-	// IndexGoCode enables indexing of Go source code.
-	// This will produce search results for internal and external identifiers
-	// and will link to both declarations and uses of those identifiers in
-	// source code.
-	IndexGoCode bool
-
-	// IndexFullText enables full-text indexing.
-	// This will provide search results for any matching text in any file that
-	// is indexed, including non-Go files (see whitelisted in index.go).
-	// Regexp searching is supported via full-text indexing.
-	IndexFullText bool
-
-	// MaxResults optionally specifies the maximum results for indexing.
-	MaxResults int
-
 	// SummarizePackage optionally specifies a function to
 	// summarize a package. It exists as an optimization to
 	// avoid reading files to parse package comments.
@@ -78,13 +36,6 @@
 	// package listing.
 	SummarizePackage func(pkg string) (summary string, showList, ok bool)
 
-	// IndexDirectory optionally specifies a function to determine
-	// whether the provided directory should be indexed.  The dir
-	// will be of the form "/src/cmd/6a", "/doc/play",
-	// "/src/io", etc.
-	// If nil, all directories are indexed if indexing is enabled.
-	IndexDirectory func(dir string) bool
-
 	// Send a value on this channel to trigger a metadata refresh.
 	// It is buffered so that if a signal is not lost if sent
 	// during a refresh.
@@ -95,9 +46,6 @@
 	fsModified  util.RWValue // timestamp of last call to invalidateIndex
 	docMetadata util.RWValue // mapping from paths to *Metadata
 
-	// SearchIndex is the search index in use.
-	searchIndex util.RWValue
-
 	// flag to check whether a corpus is initialized or not
 	initMu   sync.RWMutex
 	initDone bool
@@ -114,22 +62,10 @@
 	c := &Corpus{
 		fs:                    fs,
 		refreshMetadataSignal: make(chan bool, 1),
-
-		MaxResults:    1000,
-		IndexEnabled:  true,
-		IndexDocs:     true,
-		IndexGoCode:   true,
-		IndexFullText: true,
 	}
 	return c
 }
 
-func (c *Corpus) CurrentIndex() (*Index, time.Time) {
-	v, t := c.searchIndex.Get()
-	idx, _ := v.(*Index)
-	return idx, t
-}
-
 func (c *Corpus) FSModifiedTime() time.Time {
 	_, ts := c.fsModified.Get()
 	return ts
@@ -156,6 +92,5 @@
 		return errors.New("godoc: corpus fstree is nil")
 	}
 	c.fsTree.Set(dir)
-	c.invalidateIndex()
 	return nil
 }
diff --git a/internal/godoc/godoc.go b/internal/godoc/godoc.go
index 2a0c05c..faec584 100644
--- a/internal/godoc/godoc.go
+++ b/internal/godoc/godoc.go
@@ -69,11 +69,6 @@
 		"fileInfoName": fileInfoNameFunc,
 		"fileInfoTime": fileInfoTimeFunc,
 
-		// access to search result information
-		"infoKind_html":    infoKind_htmlFunc,
-		"infoLine":         p.infoLineFunc,
-		"infoSnippet_html": p.infoSnippet_htmlFunc,
-
 		// formatting of AST nodes
 		"node":         p.nodeFunc,
 		"node_html":    p.node_htmlFunc,
@@ -105,9 +100,6 @@
 
 		// check whether to display third party section or not
 		"hasThirdParty": hasThirdParty,
-
-		// get the no. of columns to split the toc in search page
-		"tocColCount": tocColCount,
 	}
 	if p.URLForSrc != nil {
 		p.funcMap["srcLink"] = p.URLForSrc
@@ -142,48 +134,6 @@
 	return "" // don't return epoch if time is obviously not set
 }
 
-// The strings in infoKinds must be properly html-escaped.
-var infoKinds = [nKinds]string{
-	PackageClause: "package&nbsp;clause",
-	ImportDecl:    "import&nbsp;decl",
-	ConstDecl:     "const&nbsp;decl",
-	TypeDecl:      "type&nbsp;decl",
-	VarDecl:       "var&nbsp;decl",
-	FuncDecl:      "func&nbsp;decl",
-	MethodDecl:    "method&nbsp;decl",
-	Use:           "use",
-}
-
-func infoKind_htmlFunc(info SpotInfo) string {
-	return infoKinds[info.Kind()] // infoKind entries are html-escaped
-}
-
-func (p *Presentation) infoLineFunc(info SpotInfo) int {
-	line := info.Lori()
-	if info.IsIndex() {
-		index, _ := p.Corpus.searchIndex.Get()
-		if index != nil {
-			line = index.(*Index).Snippet(line).Line
-		} else {
-			// no line information available because
-			// we don't have an index - this should
-			// never happen; be conservative and don't
-			// crash
-			line = 0
-		}
-	}
-	return line
-}
-
-func (p *Presentation) infoSnippet_htmlFunc(info SpotInfo) string {
-	if info.IsIndex() {
-		index, _ := p.Corpus.searchIndex.Get()
-		// Snippet.Text was HTML-escaped when it was generated
-		return index.(*Index).Snippet(info.Lori()).Text
-	}
-	return `<span class="alert">no snippet text available</span>`
-}
-
 func (p *Presentation) nodeFunc(info *PageInfo, node interface{}) string {
 	var buf bytes.Buffer
 	p.writeNode(&buf, info, info.FSet, node)
diff --git a/internal/godoc/index.go b/internal/godoc/index.go
deleted file mode 100644
index a9c0859..0000000
--- a/internal/godoc/index.go
+++ /dev/null
@@ -1,1580 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// This file contains the infrastructure to create an
-// identifier and full-text index for a set of Go files.
-//
-// Algorithm for identifier index:
-// - traverse all .go files of the file tree specified by root
-// - for each identifier (word) encountered, collect all occurrences (spots)
-//   into a list; this produces a list of spots for each word
-// - reduce the lists: from a list of spots to a list of FileRuns,
-//   and from a list of FileRuns into a list of PakRuns
-// - make a HitList from the PakRuns
-//
-// Details:
-// - keep two lists per word: one containing package-level declarations
-//   that have snippets, and one containing all other spots
-// - keep the snippets in a separate table indexed by snippet index
-//   and store the snippet index in place of the line number in a SpotInfo
-//   (the line number for spots with snippets is stored in the snippet)
-// - at the end, create lists of alternative spellings for a given
-//   word
-//
-// Algorithm for full text index:
-// - concatenate all source code in a byte buffer (in memory)
-// - add the files to a file set in lockstep as they are added to the byte
-//   buffer such that a byte buffer offset corresponds to the Pos value for
-//   that file location
-// - create a suffix array from the concatenated sources
-//
-// String lookup in full text index:
-// - use the suffix array to lookup a string's offsets - the offsets
-//   correspond to the Pos values relative to the file set
-// - translate the Pos values back into file and line information and
-//   sort the result
-
-package godoc
-
-import (
-	"bufio"
-	"bytes"
-	"encoding/gob"
-	"errors"
-	"fmt"
-	"go/ast"
-	"go/doc"
-	"go/parser"
-	"go/token"
-	"index/suffixarray"
-	"io"
-	"log"
-	"os"
-	pathpkg "path"
-	"path/filepath"
-	"regexp"
-	"runtime"
-	"sort"
-	"strconv"
-	"strings"
-	"sync"
-	"time"
-	"unicode"
-
-	"golang.org/x/website/internal/godoc/util"
-	"golang.org/x/website/internal/godoc/vfs"
-)
-
-// ----------------------------------------------------------------------------
-// InterfaceSlice is a helper type for sorting interface
-// slices according to some slice-specific sort criteria.
-
-type comparer func(x, y interface{}) bool
-
-type interfaceSlice struct {
-	slice []interface{}
-	less  comparer
-}
-
-// ----------------------------------------------------------------------------
-// RunList
-
-// A RunList is a list of entries that can be sorted according to some
-// criteria. A RunList may be compressed by grouping "runs" of entries
-// which are equal (according to the sort criteria) into a new RunList of
-// runs. For instance, a RunList containing pairs (x, y) may be compressed
-// into a RunList containing pair runs (x, {y}) where each run consists of
-// a list of y's with the same x.
-type RunList []interface{}
-
-func (h RunList) sort(less comparer) {
-	sort.Sort(&interfaceSlice{h, less})
-}
-
-func (p *interfaceSlice) Len() int           { return len(p.slice) }
-func (p *interfaceSlice) Less(i, j int) bool { return p.less(p.slice[i], p.slice[j]) }
-func (p *interfaceSlice) Swap(i, j int)      { p.slice[i], p.slice[j] = p.slice[j], p.slice[i] }
-
-// Compress entries which are the same according to a sort criteria
-// (specified by less) into "runs".
-func (h RunList) reduce(less comparer, newRun func(h RunList) interface{}) RunList {
-	if len(h) == 0 {
-		return nil
-	}
-	// len(h) > 0
-
-	// create runs of entries with equal values
-	h.sort(less)
-
-	// for each run, make a new run object and collect them in a new RunList
-	var hh RunList
-	i, x := 0, h[0]
-	for j, y := range h {
-		if less(x, y) {
-			hh = append(hh, newRun(h[i:j]))
-			i, x = j, h[j] // start a new run
-		}
-	}
-	// add final run, if any
-	if i < len(h) {
-		hh = append(hh, newRun(h[i:]))
-	}
-
-	return hh
-}
-
-// ----------------------------------------------------------------------------
-// KindRun
-
-// Debugging support. Disable to see multiple entries per line.
-const removeDuplicates = true
-
-// A KindRun is a run of SpotInfos of the same kind in a given file.
-// The kind (3 bits) is stored in each SpotInfo element; to find the
-// kind of a KindRun, look at any of its elements.
-type KindRun []SpotInfo
-
-// KindRuns are sorted by line number or index. Since the isIndex bit
-// is always the same for all infos in one list we can compare lori's.
-func (k KindRun) Len() int           { return len(k) }
-func (k KindRun) Less(i, j int) bool { return k[i].Lori() < k[j].Lori() }
-func (k KindRun) Swap(i, j int)      { k[i], k[j] = k[j], k[i] }
-
-// FileRun contents are sorted by Kind for the reduction into KindRuns.
-func lessKind(x, y interface{}) bool { return x.(SpotInfo).Kind() < y.(SpotInfo).Kind() }
-
-// newKindRun allocates a new KindRun from the SpotInfo run h.
-func newKindRun(h RunList) interface{} {
-	run := make(KindRun, len(h))
-	for i, x := range h {
-		run[i] = x.(SpotInfo)
-	}
-
-	// Spots were sorted by file and kind to create this run.
-	// Within this run, sort them by line number or index.
-	sort.Sort(run)
-
-	if removeDuplicates {
-		// Since both the lori and kind field must be
-		// same for duplicates, and since the isIndex
-		// bit is always the same for all infos in one
-		// list we can simply compare the entire info.
-		k := 0
-		prev := SpotInfo(1<<32 - 1) // an unlikely value
-		for _, x := range run {
-			if x != prev {
-				run[k] = x
-				k++
-				prev = x
-			}
-		}
-		run = run[0:k]
-	}
-
-	return run
-}
-
-// ----------------------------------------------------------------------------
-// FileRun
-
-// A Pak describes a Go package.
-type Pak struct {
-	Path string // path of directory containing the package
-	Name string // package name as declared by package clause
-}
-
-// Paks are sorted by name (primary key) and by import path (secondary key).
-func (p *Pak) less(q *Pak) bool {
-	return p.Name < q.Name || p.Name == q.Name && p.Path < q.Path
-}
-
-// A File describes a Go file.
-type File struct {
-	Name string // directory-local file name
-	Pak  *Pak   // the package to which the file belongs
-}
-
-// Path returns the file path of f.
-func (f *File) Path() string {
-	return pathpkg.Join(f.Pak.Path, f.Name)
-}
-
-// A Spot describes a single occurrence of a word.
-type Spot struct {
-	File *File
-	Info SpotInfo
-}
-
-// A FileRun is a list of KindRuns belonging to the same file.
-type FileRun struct {
-	File   *File
-	Groups []KindRun
-}
-
-// Spots are sorted by file path for the reduction into FileRuns.
-func lessSpot(x, y interface{}) bool {
-	fx := x.(Spot).File
-	fy := y.(Spot).File
-	// same as "return fx.Path() < fy.Path()" but w/o computing the file path first
-	px := fx.Pak.Path
-	py := fy.Pak.Path
-	return px < py || px == py && fx.Name < fy.Name
-}
-
-// newFileRun allocates a new FileRun from the Spot run h.
-func newFileRun(h RunList) interface{} {
-	file := h[0].(Spot).File
-
-	// reduce the list of Spots into a list of KindRuns
-	h1 := make(RunList, len(h))
-	for i, x := range h {
-		h1[i] = x.(Spot).Info
-	}
-	h2 := h1.reduce(lessKind, newKindRun)
-
-	// create the FileRun
-	groups := make([]KindRun, len(h2))
-	for i, x := range h2 {
-		groups[i] = x.(KindRun)
-	}
-	return &FileRun{file, groups}
-}
-
-// ----------------------------------------------------------------------------
-// PakRun
-
-// A PakRun describes a run of *FileRuns of a package.
-type PakRun struct {
-	Pak   *Pak
-	Files []*FileRun
-}
-
-// Sorting support for files within a PakRun.
-func (p *PakRun) Len() int           { return len(p.Files) }
-func (p *PakRun) Less(i, j int) bool { return p.Files[i].File.Name < p.Files[j].File.Name }
-func (p *PakRun) Swap(i, j int)      { p.Files[i], p.Files[j] = p.Files[j], p.Files[i] }
-
-// FileRuns are sorted by package for the reduction into PakRuns.
-func lessFileRun(x, y interface{}) bool {
-	return x.(*FileRun).File.Pak.less(y.(*FileRun).File.Pak)
-}
-
-// newPakRun allocates a new PakRun from the *FileRun run h.
-func newPakRun(h RunList) interface{} {
-	pak := h[0].(*FileRun).File.Pak
-	files := make([]*FileRun, len(h))
-	for i, x := range h {
-		files[i] = x.(*FileRun)
-	}
-	run := &PakRun{pak, files}
-	sort.Sort(run) // files were sorted by package; sort them by file now
-	return run
-}
-
-// ----------------------------------------------------------------------------
-// HitList
-
-// A HitList describes a list of PakRuns.
-type HitList []*PakRun
-
-// PakRuns are sorted by package.
-func lessPakRun(x, y interface{}) bool { return x.(*PakRun).Pak.less(y.(*PakRun).Pak) }
-
-func reduce(h0 RunList) HitList {
-	// reduce a list of Spots into a list of FileRuns
-	h1 := h0.reduce(lessSpot, newFileRun)
-	// reduce a list of FileRuns into a list of PakRuns
-	h2 := h1.reduce(lessFileRun, newPakRun)
-	// sort the list of PakRuns by package
-	h2.sort(lessPakRun)
-	// create a HitList
-	h := make(HitList, len(h2))
-	for i, p := range h2 {
-		h[i] = p.(*PakRun)
-	}
-	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 {
-		if p.Pak.Name == pakname {
-			hh = append(hh, p)
-		}
-	}
-	return hh
-}
-
-// ----------------------------------------------------------------------------
-// AltWords
-
-type wordPair struct {
-	canon string // canonical word spelling (all lowercase)
-	alt   string // alternative spelling
-}
-
-// An AltWords describes a list of alternative spellings for a
-// canonical (all lowercase) spelling of a word.
-type AltWords struct {
-	Canon string   // canonical word spelling (all lowercase)
-	Alts  []string // alternative spelling for the same word
-}
-
-// wordPairs are sorted by their canonical spelling.
-func lessWordPair(x, y interface{}) bool { return x.(*wordPair).canon < y.(*wordPair).canon }
-
-// newAltWords allocates a new AltWords from the *wordPair run h.
-func newAltWords(h RunList) interface{} {
-	canon := h[0].(*wordPair).canon
-	alts := make([]string, len(h))
-	for i, x := range h {
-		alts[i] = x.(*wordPair).alt
-	}
-	return &AltWords{canon, alts}
-}
-
-func (a *AltWords) filter(s string) *AltWords {
-	var alts []string
-	for _, w := range a.Alts {
-		if w != s {
-			alts = append(alts, w)
-		}
-	}
-	if len(alts) > 0 {
-		return &AltWords{a.Canon, alts}
-	}
-	return nil
-}
-
-// Ident stores information about external identifiers in order to create
-// links to package documentation.
-type Ident struct {
-	Path    string // e.g. "net/http"
-	Package string // e.g. "http"
-	Name    string // e.g. "NewRequest"
-	Doc     string // e.g. "NewRequest returns a new Request..."
-}
-
-// byImportCount sorts the given slice of Idents by the import
-// counts of the packages to which they belong.
-type byImportCount struct {
-	Idents      []Ident
-	ImportCount map[string]int
-}
-
-func (ic byImportCount) Len() int {
-	return len(ic.Idents)
-}
-
-func (ic byImportCount) Less(i, j int) bool {
-	ri := ic.ImportCount[ic.Idents[i].Path]
-	rj := ic.ImportCount[ic.Idents[j].Path]
-	if ri == rj {
-		return ic.Idents[i].Path < ic.Idents[j].Path
-	}
-	return ri > rj
-}
-
-func (ic byImportCount) Swap(i, j int) {
-	ic.Idents[i], ic.Idents[j] = ic.Idents[j], ic.Idents[i]
-}
-
-func (ic byImportCount) String() string {
-	buf := bytes.NewBuffer([]byte("["))
-	for _, v := range ic.Idents {
-		buf.WriteString(fmt.Sprintf("\n\t%s, %s (%d)", v.Path, v.Name, ic.ImportCount[v.Path]))
-	}
-	buf.WriteString("\n]")
-	return buf.String()
-}
-
-// filter creates a new Ident list where the results match the given
-// package name.
-func (ic byImportCount) filter(pakname string) []Ident {
-	if ic.Idents == nil {
-		return nil
-	}
-	var res []Ident
-	for _, i := range ic.Idents {
-		if i.Package == pakname {
-			res = append(res, i)
-		}
-	}
-	return res
-}
-
-// top returns the top n identifiers.
-func (ic byImportCount) top(n int) []Ident {
-	if len(ic.Idents) > n {
-		return ic.Idents[:n]
-	}
-	return ic.Idents
-}
-
-// ----------------------------------------------------------------------------
-// Indexer
-
-type IndexResult struct {
-	Decls  RunList // package-level declarations (with snippets)
-	Others RunList // all other occurrences
-}
-
-// Statistics provides statistics information for an index.
-type Statistics struct {
-	Bytes int // total size of indexed source files
-	Files int // number of indexed source files
-	Lines int // number of lines (all files)
-	Words int // number of different identifiers
-	Spots int // number of identifier occurrences
-}
-
-// An Indexer maintains the data structures and provides the machinery
-// for indexing .go files under a file tree. It implements the path.Visitor
-// interface for walking file trees, and the ast.Visitor interface for
-// walking Go ASTs.
-type Indexer struct {
-	c          *Corpus
-	fset       *token.FileSet // file set for all indexed files
-	fsOpenGate chan bool      // send pre fs.Open; receive on close
-
-	mu            sync.Mutex              // guards all the following
-	sources       bytes.Buffer            // concatenated sources
-	strings       map[string]string       // interned string
-	packages      map[Pak]*Pak            // interned *Paks
-	words         map[string]*IndexResult // RunLists of Spots
-	snippets      []*Snippet              // indices are stored in SpotInfos
-	current       *token.File             // last file added to file set
-	file          *File                   // AST for current file
-	decl          ast.Decl                // AST for current decl
-	stats         Statistics
-	throttle      *util.Throttle
-	importCount   map[string]int                 // package path ("net/http") => count
-	packagePath   map[string]map[string]bool     // "template" => "text/template" => true
-	exports       map[string]map[string]SpotKind // "net/http" => "ListenAndServe" => FuncDecl
-	curPkgExports map[string]SpotKind
-	idents        map[SpotKind]map[string][]Ident // kind => name => list of Idents
-}
-
-func (x *Indexer) intern(s string) string {
-	if s, ok := x.strings[s]; ok {
-		return s
-	}
-	x.strings[s] = s
-	return s
-}
-
-func (x *Indexer) lookupPackage(path, name string) *Pak {
-	// In the source directory tree, more than one package may
-	// live in the same directory. For the packages map, construct
-	// a key that includes both the directory path and the package
-	// name.
-	key := Pak{Path: x.intern(path), Name: x.intern(name)}
-	pak := x.packages[key]
-	if pak == nil {
-		pak = &key
-		x.packages[key] = pak
-	}
-	return pak
-}
-
-func (x *Indexer) addSnippet(s *Snippet) int {
-	index := len(x.snippets)
-	x.snippets = append(x.snippets, s)
-	return index
-}
-
-func (x *Indexer) visitIdent(kind SpotKind, id *ast.Ident) {
-	if id == nil {
-		return
-	}
-	name := x.intern(id.Name)
-
-	switch kind {
-	case TypeDecl, FuncDecl, ConstDecl, VarDecl:
-		x.curPkgExports[name] = kind
-	}
-
-	lists, found := x.words[name]
-	if !found {
-		lists = new(IndexResult)
-		x.words[name] = lists
-	}
-
-	if kind == Use || x.decl == nil {
-		if x.c.IndexGoCode {
-			// not a declaration or no snippet required
-			info := makeSpotInfo(kind, x.current.Line(id.Pos()), false)
-			lists.Others = append(lists.Others, Spot{x.file, info})
-		}
-	} else {
-		// a declaration with snippet
-		index := x.addSnippet(NewSnippet(x.fset, x.decl, id))
-		info := makeSpotInfo(kind, index, true)
-		lists.Decls = append(lists.Decls, Spot{x.file, info})
-	}
-
-	x.stats.Spots++
-}
-
-func (x *Indexer) visitFieldList(kind SpotKind, flist *ast.FieldList) {
-	for _, f := range flist.List {
-		x.decl = nil // no snippets for fields
-		for _, name := range f.Names {
-			x.visitIdent(kind, name)
-		}
-		ast.Walk(x, f.Type)
-		// ignore tag - not indexed at the moment
-	}
-}
-
-func (x *Indexer) visitSpec(kind SpotKind, spec ast.Spec) {
-	switch n := spec.(type) {
-	case *ast.ImportSpec:
-		x.visitIdent(ImportDecl, n.Name)
-		if n.Path != nil {
-			if imp, err := strconv.Unquote(n.Path.Value); err == nil {
-				x.importCount[x.intern(imp)]++
-			}
-		}
-
-	case *ast.ValueSpec:
-		for _, n := range n.Names {
-			x.visitIdent(kind, n)
-		}
-		ast.Walk(x, n.Type)
-		for _, v := range n.Values {
-			ast.Walk(x, v)
-		}
-
-	case *ast.TypeSpec:
-		x.visitIdent(TypeDecl, n.Name)
-		ast.Walk(x, n.Type)
-	}
-}
-
-func (x *Indexer) visitGenDecl(decl *ast.GenDecl) {
-	kind := VarDecl
-	if decl.Tok == token.CONST {
-		kind = ConstDecl
-	}
-	x.decl = decl
-	for _, s := range decl.Specs {
-		x.visitSpec(kind, s)
-	}
-}
-
-func (x *Indexer) Visit(node ast.Node) ast.Visitor {
-	switch n := node.(type) {
-	case nil:
-		// nothing to do
-
-	case *ast.Ident:
-		x.visitIdent(Use, n)
-
-	case *ast.FieldList:
-		x.visitFieldList(VarDecl, n)
-
-	case *ast.InterfaceType:
-		x.visitFieldList(MethodDecl, n.Methods)
-
-	case *ast.DeclStmt:
-		// local declarations should only be *ast.GenDecls;
-		// ignore incorrect ASTs
-		if decl, ok := n.Decl.(*ast.GenDecl); ok {
-			x.decl = nil // no snippets for local declarations
-			x.visitGenDecl(decl)
-		}
-
-	case *ast.GenDecl:
-		x.decl = n
-		x.visitGenDecl(n)
-
-	case *ast.FuncDecl:
-		kind := FuncDecl
-		if n.Recv != nil {
-			kind = MethodDecl
-			ast.Walk(x, n.Recv)
-		}
-		x.decl = n
-		x.visitIdent(kind, n.Name)
-		ast.Walk(x, n.Type)
-		if n.Body != nil {
-			ast.Walk(x, n.Body)
-		}
-
-	case *ast.File:
-		x.decl = nil
-		x.visitIdent(PackageClause, n.Name)
-		for _, d := range n.Decls {
-			ast.Walk(x, d)
-		}
-
-	default:
-		return x
-	}
-
-	return nil
-}
-
-// addFile adds a file to the index if possible and returns the file set file
-// and the file's AST if it was successfully parsed as a Go file. If addFile
-// failed (that is, if the file was not added), it returns file == nil.
-func (x *Indexer) addFile(f vfs.ReadSeekCloser, filename string, goFile bool) (file *token.File, ast *ast.File) {
-	defer f.Close()
-
-	// The file set's base offset and x.sources size must be in lock-step;
-	// this permits the direct mapping of suffix array lookup results to
-	// to corresponding Pos values.
-	//
-	// When a file is added to the file set, its offset base increases by
-	// the size of the file + 1; and the initial base offset is 1. Add an
-	// extra byte to the sources here.
-	x.sources.WriteByte(0)
-
-	// If the sources length doesn't match the file set base at this point
-	// the file set implementation changed or we have another error.
-	base := x.fset.Base()
-	if x.sources.Len() != base {
-		panic("internal error: file base incorrect")
-	}
-
-	// append file contents (src) to x.sources
-	if _, err := x.sources.ReadFrom(f); err == nil {
-		src := x.sources.Bytes()[base:]
-
-		if goFile {
-			// parse the file and in the process add it to the file set
-			if ast, err = parser.ParseFile(x.fset, filename, src, parser.ParseComments); err == nil {
-				file = x.fset.File(ast.Pos()) // ast.Pos() is inside the file
-				return
-			}
-			// file has parse errors, and the AST may be incorrect -
-			// set lines information explicitly and index as ordinary
-			// text file (cannot fall through to the text case below
-			// because the file has already been added to the file set
-			// by the parser)
-			file = x.fset.File(token.Pos(base)) // token.Pos(base) is inside the file
-			file.SetLinesForContent(src)
-			ast = nil
-			return
-		}
-
-		if util.IsText(src) {
-			// only add the file to the file set (for the full text index)
-			file = x.fset.AddFile(filename, x.fset.Base(), len(src))
-			file.SetLinesForContent(src)
-			return
-		}
-	}
-
-	// discard possibly added data
-	x.sources.Truncate(base - 1) // -1 to remove added byte 0 since no file was added
-	return
-}
-
-// Design note: Using an explicit white list of permitted files for indexing
-// makes sure that the important files are included and massively reduces the
-// number of files to index. The advantage over a blacklist is that unexpected
-// (non-blacklisted) files won't suddenly explode the index.
-
-// Files are whitelisted if they have a file name or extension
-// present as key in whitelisted.
-var whitelisted = map[string]bool{
-	".bash":        true,
-	".c":           true,
-	".cc":          true,
-	".cpp":         true,
-	".cxx":         true,
-	".css":         true,
-	".go":          true,
-	".goc":         true,
-	".h":           true,
-	".hh":          true,
-	".hpp":         true,
-	".hxx":         true,
-	".html":        true,
-	".js":          true,
-	".out":         true,
-	".py":          true,
-	".s":           true,
-	".sh":          true,
-	".txt":         true,
-	".xml":         true,
-	"AUTHORS":      true,
-	"CONTRIBUTORS": true,
-	"LICENSE":      true,
-	"Makefile":     true,
-	"PATENTS":      true,
-	"README":       true,
-}
-
-// isWhitelisted returns true if a file is on the list
-// of "permitted" files for indexing. The filename must
-// be the directory-local name of the file.
-func isWhitelisted(filename string) bool {
-	key := pathpkg.Ext(filename)
-	if key == "" {
-		// file has no extension - use entire filename
-		key = filename
-	}
-	return whitelisted[key]
-}
-
-func (x *Indexer) indexDocs(dirname string, filename string, astFile *ast.File) {
-	pkgName := x.intern(astFile.Name.Name)
-	if pkgName == "main" {
-		return
-	}
-	pkgPath := x.intern(strings.TrimPrefix(strings.TrimPrefix(dirname, "/src/"), "pkg/"))
-	astPkg := ast.Package{
-		Name: pkgName,
-		Files: map[string]*ast.File{
-			filename: astFile,
-		},
-	}
-	var m doc.Mode
-	docPkg := doc.New(&astPkg, dirname, m)
-	addIdent := func(sk SpotKind, name string, docstr string) {
-		if x.idents[sk] == nil {
-			x.idents[sk] = make(map[string][]Ident)
-		}
-		name = x.intern(name)
-		x.idents[sk][name] = append(x.idents[sk][name], Ident{
-			Path:    pkgPath,
-			Package: pkgName,
-			Name:    name,
-			Doc:     doc.Synopsis(docstr),
-		})
-	}
-
-	if x.idents[PackageClause] == nil {
-		x.idents[PackageClause] = make(map[string][]Ident)
-	}
-	// List of words under which the package identifier will be stored.
-	// This includes the package name and the components of the directory
-	// in which it resides.
-	words := strings.Split(pathpkg.Dir(pkgPath), "/")
-	if words[0] == "." {
-		words = []string{}
-	}
-	name := x.intern(docPkg.Name)
-	synopsis := doc.Synopsis(docPkg.Doc)
-	words = append(words, name)
-	pkgIdent := Ident{
-		Path:    pkgPath,
-		Package: pkgName,
-		Name:    name,
-		Doc:     synopsis,
-	}
-	for _, word := range words {
-		word = x.intern(word)
-		found := false
-		pkgs := x.idents[PackageClause][word]
-		for i, p := range pkgs {
-			if p.Path == pkgPath {
-				if docPkg.Doc != "" {
-					p.Doc = synopsis
-					pkgs[i] = p
-				}
-				found = true
-				break
-			}
-		}
-		if !found {
-			x.idents[PackageClause][word] = append(x.idents[PackageClause][word], pkgIdent)
-		}
-	}
-
-	for _, c := range docPkg.Consts {
-		for _, name := range c.Names {
-			addIdent(ConstDecl, name, c.Doc)
-		}
-	}
-	for _, t := range docPkg.Types {
-		addIdent(TypeDecl, t.Name, t.Doc)
-		for _, c := range t.Consts {
-			for _, name := range c.Names {
-				addIdent(ConstDecl, name, c.Doc)
-			}
-		}
-		for _, v := range t.Vars {
-			for _, name := range v.Names {
-				addIdent(VarDecl, name, v.Doc)
-			}
-		}
-		for _, f := range t.Funcs {
-			addIdent(FuncDecl, f.Name, f.Doc)
-		}
-		for _, f := range t.Methods {
-			addIdent(MethodDecl, f.Name, f.Doc)
-			// Change the name of methods to be "<typename>.<methodname>".
-			// They will still be indexed as <methodname>.
-			idents := x.idents[MethodDecl][f.Name]
-			idents[len(idents)-1].Name = x.intern(t.Name + "." + f.Name)
-		}
-	}
-	for _, v := range docPkg.Vars {
-		for _, name := range v.Names {
-			addIdent(VarDecl, name, v.Doc)
-		}
-	}
-	for _, f := range docPkg.Funcs {
-		addIdent(FuncDecl, f.Name, f.Doc)
-	}
-}
-
-func (x *Indexer) indexGoFile(dirname string, filename string, file *token.File, astFile *ast.File) {
-	pkgName := astFile.Name.Name
-
-	if x.c.IndexGoCode {
-		x.current = file
-		pak := x.lookupPackage(dirname, pkgName)
-		x.file = &File{filename, pak}
-		ast.Walk(x, astFile)
-	}
-
-	if x.c.IndexDocs {
-		// Test files are already filtered out in visitFile if IndexGoCode and
-		// IndexFullText are false.  Otherwise, check here.
-		isTestFile := (x.c.IndexGoCode || x.c.IndexFullText) &&
-			(strings.HasSuffix(filename, "_test.go") || strings.HasPrefix(dirname, "/test/"))
-		if !isTestFile {
-			x.indexDocs(dirname, filename, astFile)
-		}
-	}
-
-	ppKey := x.intern(pkgName)
-	if _, ok := x.packagePath[ppKey]; !ok {
-		x.packagePath[ppKey] = make(map[string]bool)
-	}
-	pkgPath := x.intern(strings.TrimPrefix(strings.TrimPrefix(dirname, "/src/"), "pkg/"))
-	x.packagePath[ppKey][pkgPath] = true
-
-	// Merge in exported symbols found walking this file into
-	// the map for that package.
-	if len(x.curPkgExports) > 0 {
-		dest, ok := x.exports[pkgPath]
-		if !ok {
-			dest = make(map[string]SpotKind)
-			x.exports[pkgPath] = dest
-		}
-		for k, v := range x.curPkgExports {
-			dest[k] = v
-		}
-	}
-}
-
-func (x *Indexer) visitFile(dirname string, fi os.FileInfo) {
-	if fi.IsDir() || !x.c.IndexEnabled {
-		return
-	}
-
-	filename := pathpkg.Join(dirname, fi.Name())
-	goFile := isGoFile(fi)
-
-	switch {
-	case x.c.IndexFullText:
-		if !isWhitelisted(fi.Name()) {
-			return
-		}
-	case x.c.IndexGoCode:
-		if !goFile {
-			return
-		}
-	case x.c.IndexDocs:
-		if !goFile ||
-			strings.HasSuffix(fi.Name(), "_test.go") ||
-			strings.HasPrefix(dirname, "/test/") {
-			return
-		}
-	default:
-		// No indexing turned on.
-		return
-	}
-
-	x.fsOpenGate <- true
-	defer func() { <-x.fsOpenGate }()
-
-	// open file
-	f, err := x.c.fs.Open(filename)
-	if err != nil {
-		return
-	}
-
-	x.mu.Lock()
-	defer x.mu.Unlock()
-
-	x.throttle.Throttle()
-
-	x.curPkgExports = make(map[string]SpotKind)
-	file, fast := x.addFile(f, filename, goFile)
-	if file == nil {
-		return // addFile failed
-	}
-
-	if fast != nil {
-		x.indexGoFile(dirname, fi.Name(), file, fast)
-	}
-
-	// update statistics
-	x.stats.Bytes += file.Size()
-	x.stats.Files++
-	x.stats.Lines += file.LineCount()
-}
-
-// indexOptions contains information that affects the contents of an index.
-type indexOptions struct {
-	// Docs provides documentation search results.
-	// It is only consulted if IndexEnabled is true.
-	// The default values is true.
-	Docs bool
-
-	// GoCode provides Go source code search results.
-	// It is only consulted if IndexEnabled is true.
-	// The default values is true.
-	GoCode bool
-
-	// FullText provides search results from all files.
-	// It is only consulted if IndexEnabled is true.
-	// The default values is true.
-	FullText bool
-
-	// MaxResults optionally specifies the maximum results for indexing.
-	// The default is 1000.
-	MaxResults int
-}
-
-// ----------------------------------------------------------------------------
-// Index
-
-type LookupResult struct {
-	Decls  HitList // package-level declarations (with snippets)
-	Others HitList // all other occurrences
-}
-
-type Index struct {
-	fset        *token.FileSet           // file set used during indexing; nil if no textindex
-	suffixes    *suffixarray.Index       // suffixes for concatenated sources; nil if no textindex
-	words       map[string]*LookupResult // maps words to hit lists
-	alts        map[string]*AltWords     // maps canonical(words) to lists of alternative spellings
-	snippets    []*Snippet               // all snippets, indexed by snippet index
-	stats       Statistics
-	importCount map[string]int                 // package path ("net/http") => count
-	packagePath map[string]map[string]bool     // "template" => "text/template" => true
-	exports     map[string]map[string]SpotKind // "net/http" => "ListenAndServe" => FuncDecl
-	idents      map[SpotKind]map[string][]Ident
-	opts        indexOptions
-}
-
-func canonical(w string) string { return strings.ToLower(w) }
-
-// Somewhat arbitrary, but I figure low enough to not hurt disk-based filesystems
-// consuming file descriptors, where some systems have low 256 or 512 limits.
-// Go should have a built-in way to cap fd usage under the ulimit.
-const (
-	maxOpenFiles = 200
-	maxOpenDirs  = 50
-)
-
-func (c *Corpus) throttle() float64 {
-	if c.IndexThrottle <= 0 {
-		return 0.9
-	}
-	if c.IndexThrottle > 1.0 {
-		return 1.0
-	}
-	return c.IndexThrottle
-}
-
-// NewIndex creates a new index for the .go files provided by the corpus.
-func (c *Corpus) NewIndex() *Index {
-	// initialize Indexer
-	// (use some reasonably sized maps to start)
-	x := &Indexer{
-		c:           c,
-		fset:        token.NewFileSet(),
-		fsOpenGate:  make(chan bool, maxOpenFiles),
-		strings:     make(map[string]string),
-		packages:    make(map[Pak]*Pak, 256),
-		words:       make(map[string]*IndexResult, 8192),
-		throttle:    util.NewThrottle(c.throttle(), 100*time.Millisecond), // run at least 0.1s at a time
-		importCount: make(map[string]int),
-		packagePath: make(map[string]map[string]bool),
-		exports:     make(map[string]map[string]SpotKind),
-		idents:      make(map[SpotKind]map[string][]Ident, 4),
-	}
-
-	// index all files in the directories given by dirnames
-	var wg sync.WaitGroup // outstanding ReadDir + visitFile
-	dirGate := make(chan bool, maxOpenDirs)
-	for dirname := range c.fsDirnames() {
-		if c.IndexDirectory != nil && !c.IndexDirectory(dirname) {
-			continue
-		}
-		dirGate <- true
-		wg.Add(1)
-		go func(dirname string) {
-			defer func() { <-dirGate }()
-			defer wg.Done()
-
-			list, err := c.fs.ReadDir(dirname)
-			if err != nil {
-				log.Printf("ReadDir(%q): %v; skipping directory", dirname, err)
-				return // ignore this directory
-			}
-			for _, fi := range list {
-				wg.Add(1)
-				go func(fi os.FileInfo) {
-					defer wg.Done()
-					x.visitFile(dirname, fi)
-				}(fi)
-			}
-		}(dirname)
-	}
-	wg.Wait()
-
-	if !c.IndexFullText {
-		// the file set, the current file, and the sources are
-		// not needed after indexing if no text index is built -
-		// help GC and clear them
-		x.fset = nil
-		x.sources.Reset()
-		x.current = nil // contains reference to fset!
-	}
-
-	// for each word, reduce the RunLists into a LookupResult;
-	// also collect the word with its canonical spelling in a
-	// word list for later computation of alternative spellings
-	words := make(map[string]*LookupResult)
-	var wlist RunList
-	for w, h := range x.words {
-		decls := reduce(h.Decls)
-		others := reduce(h.Others)
-		words[w] = &LookupResult{
-			Decls:  decls,
-			Others: others,
-		}
-		wlist = append(wlist, &wordPair{canonical(w), w})
-		x.throttle.Throttle()
-	}
-	x.stats.Words = len(words)
-
-	// reduce the word list {canonical(w), w} into
-	// a list of AltWords runs {canonical(w), {w}}
-	alist := wlist.reduce(lessWordPair, newAltWords)
-
-	// convert alist into a map of alternative spellings
-	alts := make(map[string]*AltWords)
-	for i := 0; i < len(alist); i++ {
-		a := alist[i].(*AltWords)
-		alts[a.Canon] = a
-	}
-
-	// create text index
-	var suffixes *suffixarray.Index
-	if c.IndexFullText {
-		suffixes = suffixarray.New(x.sources.Bytes())
-	}
-
-	// sort idents by the number of imports of their respective packages
-	for _, idMap := range x.idents {
-		for _, ir := range idMap {
-			sort.Sort(byImportCount{ir, x.importCount})
-		}
-	}
-
-	return &Index{
-		fset:        x.fset,
-		suffixes:    suffixes,
-		words:       words,
-		alts:        alts,
-		snippets:    x.snippets,
-		stats:       x.stats,
-		importCount: x.importCount,
-		packagePath: x.packagePath,
-		exports:     x.exports,
-		idents:      x.idents,
-		opts: indexOptions{
-			Docs:       x.c.IndexDocs,
-			GoCode:     x.c.IndexGoCode,
-			FullText:   x.c.IndexFullText,
-			MaxResults: x.c.MaxResults,
-		},
-	}
-}
-
-var ErrFileIndexVersion = errors.New("file index version out of date")
-
-const fileIndexVersion = 3
-
-// fileIndex is the subset of Index that's gob-encoded for use by
-// Index.Write and Index.Read.
-type fileIndex struct {
-	Version     int
-	Words       map[string]*LookupResult
-	Alts        map[string]*AltWords
-	Snippets    []*Snippet
-	Fulltext    bool
-	Stats       Statistics
-	ImportCount map[string]int
-	PackagePath map[string]map[string]bool
-	Exports     map[string]map[string]SpotKind
-	Idents      map[SpotKind]map[string][]Ident
-	Opts        indexOptions
-}
-
-func (x *fileIndex) Write(w io.Writer) error {
-	return gob.NewEncoder(w).Encode(x)
-}
-
-func (x *fileIndex) Read(r io.Reader) error {
-	return gob.NewDecoder(r).Decode(x)
-}
-
-// WriteTo writes the index x to w.
-func (x *Index) WriteTo(w io.Writer) (n int64, err error) {
-	w = countingWriter{&n, w}
-	fulltext := false
-	if x.suffixes != nil {
-		fulltext = true
-	}
-	fx := fileIndex{
-		Version:     fileIndexVersion,
-		Words:       x.words,
-		Alts:        x.alts,
-		Snippets:    x.snippets,
-		Fulltext:    fulltext,
-		Stats:       x.stats,
-		ImportCount: x.importCount,
-		PackagePath: x.packagePath,
-		Exports:     x.exports,
-		Idents:      x.idents,
-		Opts:        x.opts,
-	}
-	if err := fx.Write(w); err != nil {
-		return 0, err
-	}
-	if fulltext {
-		encode := func(x interface{}) error {
-			return gob.NewEncoder(w).Encode(x)
-		}
-		if err := x.fset.Write(encode); err != nil {
-			return 0, err
-		}
-		if err := x.suffixes.Write(w); err != nil {
-			return 0, err
-		}
-	}
-	return n, nil
-}
-
-// ReadFrom reads the index from r into x; x must not be nil.
-// If r does not also implement io.ByteReader, it will be wrapped in a bufio.Reader.
-// If the index is from an old version, the error is ErrFileIndexVersion.
-func (x *Index) ReadFrom(r io.Reader) (n int64, err error) {
-	// We use the ability to read bytes as a plausible surrogate for buffering.
-	if _, ok := r.(io.ByteReader); !ok {
-		r = bufio.NewReader(r)
-	}
-	r = countingReader{&n, r.(byteReader)}
-	var fx fileIndex
-	if err := fx.Read(r); err != nil {
-		return n, err
-	}
-	if fx.Version != fileIndexVersion {
-		return 0, ErrFileIndexVersion
-	}
-	x.words = fx.Words
-	x.alts = fx.Alts
-	x.snippets = fx.Snippets
-	x.stats = fx.Stats
-	x.importCount = fx.ImportCount
-	x.packagePath = fx.PackagePath
-	x.exports = fx.Exports
-	x.idents = fx.Idents
-	x.opts = fx.Opts
-	if fx.Fulltext {
-		x.fset = token.NewFileSet()
-		decode := func(x interface{}) error {
-			return gob.NewDecoder(r).Decode(x)
-		}
-		if err := x.fset.Read(decode); err != nil {
-			return n, err
-		}
-		x.suffixes = new(suffixarray.Index)
-		if err := x.suffixes.Read(r); err != nil {
-			return n, err
-		}
-	}
-	return n, nil
-}
-
-// Stats returns index statistics.
-func (x *Index) Stats() Statistics {
-	return x.stats
-}
-
-// ImportCount returns a map from import paths to how many times they were seen.
-func (x *Index) ImportCount() map[string]int {
-	return x.importCount
-}
-
-// PackagePath returns a map from short package name to a set
-// of full package path names that use that short package name.
-func (x *Index) PackagePath() map[string]map[string]bool {
-	return x.packagePath
-}
-
-// Exports returns a map from full package path to exported
-// symbol name to its type.
-func (x *Index) Exports() map[string]map[string]SpotKind {
-	return x.exports
-}
-
-// Idents returns a map from identifier type to exported
-// symbol name to the list of identifiers matching that name.
-func (x *Index) Idents() map[SpotKind]map[string][]Ident {
-	return x.idents
-}
-
-func (x *Index) lookupWord(w string) (match *LookupResult, alt *AltWords) {
-	match = x.words[w]
-	alt = x.alts[canonical(w)]
-	// remove current spelling from alternatives
-	// (if there is no match, the alternatives do
-	// not contain the current spelling)
-	if match != nil && alt != nil {
-		alt = alt.filter(w)
-	}
-	return
-}
-
-// isIdentifier reports whether s is a Go identifier.
-func isIdentifier(s string) bool {
-	for i, ch := range s {
-		if unicode.IsLetter(ch) || ch == '_' || i > 0 && unicode.IsDigit(ch) {
-			continue
-		}
-		return false
-	}
-	return len(s) > 0
-}
-
-// For a given query, which is either a single identifier or a qualified
-// identifier, Lookup returns a SearchResult containing packages, a LookupResult, a
-// list of alternative spellings, and identifiers, 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) (*SearchResult, error) {
-	ss := strings.Split(query, ".")
-
-	// check query syntax
-	for _, s := range ss {
-		if !isIdentifier(s) {
-			return nil, errors.New("all query parts must be identifiers")
-		}
-	}
-	rslt := &SearchResult{
-		Query:  query,
-		Idents: make(map[SpotKind][]Ident, 5),
-	}
-	// handle simple and qualified identifiers
-	switch len(ss) {
-	case 1:
-		ident := ss[0]
-		rslt.Hit, rslt.Alt = x.lookupWord(ident)
-		if rslt.Hit != nil {
-			// found a match - filter packages with same name
-			// for the list of packages called ident, if any
-			rslt.Pak = rslt.Hit.Others.filter(ident)
-		}
-		for k, v := range x.idents {
-			const rsltLimit = 50
-			ids := byImportCount{v[ident], x.importCount}
-			rslt.Idents[k] = ids.top(rsltLimit)
-		}
-
-	case 2:
-		pakname, ident := ss[0], ss[1]
-		rslt.Hit, rslt.Alt = x.lookupWord(ident)
-		if rslt.Hit != nil {
-			// found a match - filter by package name
-			// (no paks - package names are not qualified)
-			decls := rslt.Hit.Decls.filter(pakname)
-			others := rslt.Hit.Others.filter(pakname)
-			rslt.Hit = &LookupResult{decls, others}
-		}
-		for k, v := range x.idents {
-			ids := byImportCount{v[ident], x.importCount}
-			rslt.Idents[k] = ids.filter(pakname)
-		}
-
-	default:
-		return nil, errors.New("query is not a (qualified) identifier")
-	}
-
-	return rslt, nil
-}
-
-func (x *Index) Snippet(i int) *Snippet {
-	// handle illegal snippet indices gracefully
-	if 0 <= i && i < len(x.snippets) {
-		return x.snippets[i]
-	}
-	return nil
-}
-
-type positionList []struct {
-	filename string
-	line     int
-}
-
-func (list positionList) Len() int           { return len(list) }
-func (list positionList) Less(i, j int) bool { return list[i].filename < list[j].filename }
-func (list positionList) Swap(i, j int)      { list[i], list[j] = list[j], list[i] }
-
-// unique returns the list sorted and with duplicate entries removed
-func unique(list []int) []int {
-	sort.Ints(list)
-	var last int
-	i := 0
-	for _, x := range list {
-		if i == 0 || x != last {
-			last = x
-			list[i] = x
-			i++
-		}
-	}
-	return list[0:i]
-}
-
-// A FileLines value specifies a file and line numbers within that file.
-type FileLines struct {
-	Filename string
-	Lines    []int
-}
-
-// LookupRegexp returns the number of matches and the matches where a regular
-// expression r is found in the full text index. At most n matches are
-// returned (thus found <= n).
-//
-func (x *Index) LookupRegexp(r *regexp.Regexp, n int) (found int, result []FileLines) {
-	if x.suffixes == nil || n <= 0 {
-		return
-	}
-	// n > 0
-
-	var list positionList
-	// FindAllIndex may returns matches that span across file boundaries.
-	// Such matches are unlikely, buf after eliminating them we may end up
-	// with fewer than n matches. If we don't have enough at the end, redo
-	// the search with an increased value n1, but only if FindAllIndex
-	// returned all the requested matches in the first place (if it
-	// returned fewer than that there cannot be more).
-	for n1 := n; found < n; n1 += n - found {
-		found = 0
-		matches := x.suffixes.FindAllIndex(r, n1)
-		// compute files, exclude matches that span file boundaries,
-		// and map offsets to file-local offsets
-		list = make(positionList, len(matches))
-		for _, m := range matches {
-			// by construction, an offset corresponds to the Pos value
-			// for the file set - use it to get the file and line
-			p := token.Pos(m[0])
-			if file := x.fset.File(p); file != nil {
-				if base := file.Base(); base <= m[1] && m[1] <= base+file.Size() {
-					// match [m[0], m[1]) is within the file boundaries
-					list[found].filename = file.Name()
-					list[found].line = file.Line(p)
-					found++
-				}
-			}
-		}
-		if found == n || len(matches) < n1 {
-			// found all matches or there's no chance to find more
-			break
-		}
-	}
-	list = list[0:found]
-	sort.Sort(list) // sort by filename
-
-	// collect matches belonging to the same file
-	var last string
-	var lines []int
-	addLines := func() {
-		if len(lines) > 0 {
-			// remove duplicate lines
-			result = append(result, FileLines{last, unique(lines)})
-			lines = nil
-		}
-	}
-	for _, m := range list {
-		if m.filename != last {
-			addLines()
-			last = m.filename
-		}
-		lines = append(lines, m.line)
-	}
-	addLines()
-
-	return
-}
-
-// InvalidateIndex should be called whenever any of the file systems
-// under godoc's observation change so that the indexer is kicked on.
-func (c *Corpus) invalidateIndex() {
-	c.fsModified.Set(nil)
-	c.refreshMetadata()
-}
-
-// feedDirnames feeds the directory names of all directories
-// under the file system given by root to channel c.
-//
-func (c *Corpus) feedDirnames(ch chan<- string) {
-	if dir, _ := c.fsTree.Get(); dir != nil {
-		for d := range dir.(*Directory).iter(false) {
-			ch <- d.Path
-		}
-	}
-}
-
-// fsDirnames() returns a channel sending all directory names
-// of all the file systems under godoc's observation.
-//
-func (c *Corpus) fsDirnames() <-chan string {
-	ch := make(chan string, 256) // buffered for fewer context switches
-	go func() {
-		c.feedDirnames(ch)
-		close(ch)
-	}()
-	return ch
-}
-
-// CompatibleWith reports whether the Index x is compatible with the corpus
-// indexing options set in c.
-func (x *Index) CompatibleWith(c *Corpus) bool {
-	return x.opts.Docs == c.IndexDocs &&
-		x.opts.GoCode == c.IndexGoCode &&
-		x.opts.FullText == c.IndexFullText &&
-		x.opts.MaxResults == c.MaxResults
-}
-
-func (c *Corpus) readIndex(filenames string) error {
-	matches, err := filepath.Glob(filenames)
-	if err != nil {
-		return err
-	} else if matches == nil {
-		return fmt.Errorf("no index files match %q", filenames)
-	}
-	sort.Strings(matches) // make sure files are in the right order
-	files := make([]io.Reader, 0, len(matches))
-	for _, filename := range matches {
-		f, err := os.Open(filename)
-		if err != nil {
-			return err
-		}
-		defer f.Close()
-		files = append(files, f)
-	}
-	return c.ReadIndexFrom(io.MultiReader(files...))
-}
-
-// ReadIndexFrom sets the current index from the serialized version found in r.
-func (c *Corpus) ReadIndexFrom(r io.Reader) error {
-	x := new(Index)
-	if _, err := x.ReadFrom(r); err != nil {
-		return err
-	}
-	if !x.CompatibleWith(c) {
-		return fmt.Errorf("index file options are incompatible: %v", x.opts)
-	}
-	c.searchIndex.Set(x)
-	return nil
-}
-
-func (c *Corpus) UpdateIndex() {
-	if c.Verbose {
-		log.Printf("updating index...")
-	}
-	start := time.Now()
-	index := c.NewIndex()
-	stop := time.Now()
-	c.searchIndex.Set(index)
-	if c.Verbose {
-		secs := stop.Sub(start).Seconds()
-		stats := index.Stats()
-		log.Printf("index updated (%gs, %d bytes of source, %d files, %d lines, %d unique words, %d spots)",
-			secs, stats.Bytes, stats.Files, stats.Lines, stats.Words, stats.Spots)
-	}
-	memstats := new(runtime.MemStats)
-	runtime.ReadMemStats(memstats)
-	if c.Verbose {
-		log.Printf("before GC: bytes = %d footprint = %d", memstats.HeapAlloc, memstats.Sys)
-	}
-	runtime.GC()
-	runtime.ReadMemStats(memstats)
-	if c.Verbose {
-		log.Printf("after  GC: bytes = %d footprint = %d", memstats.HeapAlloc, memstats.Sys)
-	}
-}
-
-// RunIndexer runs forever, indexing.
-func (c *Corpus) RunIndexer() {
-	// initialize the index from disk if possible
-	if c.IndexFiles != "" {
-		c.initFSTree()
-		if err := c.readIndex(c.IndexFiles); err != nil {
-			log.Printf("error reading index from file %s: %v", c.IndexFiles, err)
-		}
-		return
-	}
-
-	// Repeatedly update the package directory tree and index.
-	for {
-		c.initFSTree()
-		c.UpdateIndex()
-		if c.IndexInterval < 0 {
-			return
-		}
-		delay := 5 * time.Minute // by default, reindex every 5 minutes
-		if c.IndexInterval > 0 {
-			delay = c.IndexInterval
-		}
-		time.Sleep(delay)
-	}
-}
-
-type countingWriter struct {
-	n *int64
-	w io.Writer
-}
-
-func (c countingWriter) Write(p []byte) (n int, err error) {
-	n, err = c.w.Write(p)
-	*c.n += int64(n)
-	return
-}
-
-type byteReader interface {
-	io.Reader
-	io.ByteReader
-}
-
-type countingReader struct {
-	n *int64
-	r byteReader
-}
-
-func (c countingReader) Read(p []byte) (n int, err error) {
-	n, err = c.r.Read(p)
-	*c.n += int64(n)
-	return
-}
-
-func (c countingReader) ReadByte() (b byte, err error) {
-	b, err = c.r.ReadByte()
-	*c.n += 1
-	return
-}
diff --git a/internal/godoc/index_test.go b/internal/godoc/index_test.go
deleted file mode 100644
index 3718699..0000000
--- a/internal/godoc/index_test.go
+++ /dev/null
@@ -1,323 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package godoc
-
-import (
-	"bytes"
-	"reflect"
-	"sort"
-	"strings"
-	"testing"
-
-	"golang.org/x/website/internal/godoc/vfs/mapfs"
-)
-
-func newCorpus(t *testing.T) *Corpus {
-	c := NewCorpus(mapfs.New(map[string]string{
-		"src/foo/foo.go": `// Package foo is an example.
-package foo
-
-import "bar"
-
-const Pi = 3.1415
-
-var Foos []Foo
-
-// Foo is stuff.
-type Foo struct{}
-
-func New() *Foo {
-   return new(Foo)
-}
-`,
-		"src/bar/bar.go": `// Package bar is another example to test races.
-package bar
-`,
-		"src/other/bar/bar.go": `// Package bar is another bar package.
-package bar
-func X() {}
-`,
-		"src/skip/skip.go": `// Package skip should be skipped.
-package skip
-func Skip() {}
-`,
-		"src/bar/readme.txt": `Whitelisted text file.
-`,
-		"src/bar/baz.zzz": `Text file not whitelisted.
-`,
-	}))
-	c.IndexEnabled = true
-	c.IndexDirectory = func(dir string) bool {
-		return !strings.Contains(dir, "skip")
-	}
-
-	if err := c.Init(); err != nil {
-		t.Fatal(err)
-	}
-	return c
-}
-
-func TestIndex(t *testing.T) {
-	for _, docs := range []bool{true, false} {
-		for _, goCode := range []bool{true, false} {
-			for _, fullText := range []bool{true, false} {
-				c := newCorpus(t)
-				c.IndexDocs = docs
-				c.IndexGoCode = goCode
-				c.IndexFullText = fullText
-				c.UpdateIndex()
-				ix, _ := c.CurrentIndex()
-				if ix == nil {
-					t.Fatal("no index")
-				}
-				t.Logf("docs, goCode, fullText = %v,%v,%v", docs, goCode, fullText)
-				testIndex(t, c, ix)
-			}
-		}
-	}
-}
-
-func TestIndexWriteRead(t *testing.T) {
-	type key struct {
-		docs, goCode, fullText bool
-	}
-	type val struct {
-		buf *bytes.Buffer
-		c   *Corpus
-	}
-	m := map[key]val{}
-
-	for _, docs := range []bool{true, false} {
-		for _, goCode := range []bool{true, false} {
-			for _, fullText := range []bool{true, false} {
-				k := key{docs, goCode, fullText}
-				c := newCorpus(t)
-				c.IndexDocs = docs
-				c.IndexGoCode = goCode
-				c.IndexFullText = fullText
-				c.UpdateIndex()
-				ix, _ := c.CurrentIndex()
-				if ix == nil {
-					t.Fatal("no index")
-				}
-				var buf bytes.Buffer
-				nw, err := ix.WriteTo(&buf)
-				if err != nil {
-					t.Fatalf("Index.WriteTo: %v", err)
-				}
-				m[k] = val{bytes.NewBuffer(buf.Bytes()), c}
-				ix2 := new(Index)
-				nr, err := ix2.ReadFrom(&buf)
-				if err != nil {
-					t.Fatalf("Index.ReadFrom: %v", err)
-				}
-				if nr != nw {
-					t.Errorf("Wrote %d bytes to index but read %d", nw, nr)
-				}
-				testIndex(t, c, ix)
-			}
-		}
-	}
-	// Test CompatibleWith
-	for k1, v1 := range m {
-		ix := new(Index)
-		if _, err := ix.ReadFrom(v1.buf); err != nil {
-			t.Fatalf("Index.ReadFrom: %v", err)
-		}
-		for k2, v2 := range m {
-			if got, want := ix.CompatibleWith(v2.c), k1 == k2; got != want {
-				t.Errorf("CompatibleWith = %v; want %v for %v, %v", got, want, k1, k2)
-			}
-		}
-	}
-}
-
-func testIndex(t *testing.T, c *Corpus, ix *Index) {
-	if _, ok := ix.words["Skip"]; ok {
-		t.Errorf("the word Skip was found; expected it to be skipped")
-	}
-	checkStats(t, c, ix)
-	checkImportCount(t, c, ix)
-	checkPackagePath(t, c, ix)
-	checkExports(t, c, ix)
-	checkIdents(t, c, ix)
-}
-
-// checkStats checks the Index's statistics.
-// Some statistics are only set when we're indexing Go code.
-func checkStats(t *testing.T, c *Corpus, ix *Index) {
-	want := Statistics{}
-	if c.IndexFullText {
-		want.Bytes = 314
-		want.Files = 4
-		want.Lines = 21
-	} else if c.IndexDocs || c.IndexGoCode {
-		want.Bytes = 291
-		want.Files = 3
-		want.Lines = 20
-	}
-	if c.IndexGoCode {
-		want.Words = 8
-		want.Spots = 12
-	}
-	if got := ix.Stats(); !reflect.DeepEqual(got, want) {
-		t.Errorf("Stats = %#v; want %#v", got, want)
-	}
-}
-
-// checkImportCount checks the Index's import count map.
-// It is only set when we're indexing Go code.
-func checkImportCount(t *testing.T, c *Corpus, ix *Index) {
-	want := map[string]int{}
-	if c.IndexGoCode {
-		want = map[string]int{
-			"bar": 1,
-		}
-	}
-	if got := ix.ImportCount(); !reflect.DeepEqual(got, want) {
-		t.Errorf("ImportCount = %v; want %v", got, want)
-	}
-}
-
-// checkPackagePath checks the Index's package path map.
-// It is set if at least one of the indexing options is enabled.
-func checkPackagePath(t *testing.T, c *Corpus, ix *Index) {
-	want := map[string]map[string]bool{}
-	if c.IndexDocs || c.IndexGoCode || c.IndexFullText {
-		want = map[string]map[string]bool{
-			"foo": {
-				"foo": true,
-			},
-			"bar": {
-				"bar":       true,
-				"other/bar": true,
-			},
-		}
-	}
-	if got := ix.PackagePath(); !reflect.DeepEqual(got, want) {
-		t.Errorf("PackagePath = %v; want %v", got, want)
-	}
-}
-
-// checkExports checks the Index's exports map.
-// It is only set when we're indexing Go code.
-func checkExports(t *testing.T, c *Corpus, ix *Index) {
-	want := map[string]map[string]SpotKind{}
-	if c.IndexGoCode {
-		want = map[string]map[string]SpotKind{
-			"foo": {
-				"Pi":   ConstDecl,
-				"Foos": VarDecl,
-				"Foo":  TypeDecl,
-				"New":  FuncDecl,
-			},
-			"other/bar": {
-				"X": FuncDecl,
-			},
-		}
-	}
-	if got := ix.Exports(); !reflect.DeepEqual(got, want) {
-		t.Errorf("Exports = %v; want %v", got, want)
-	}
-}
-
-// checkIdents checks the Index's indents map.
-// It is only set when we're indexing documentation.
-func checkIdents(t *testing.T, c *Corpus, ix *Index) {
-	want := map[SpotKind]map[string][]Ident{}
-	if c.IndexDocs {
-		want = map[SpotKind]map[string][]Ident{
-			PackageClause: {
-				"bar": {
-					{"bar", "bar", "bar", "Package bar is another example to test races."},
-					{"other/bar", "bar", "bar", "Package bar is another bar package."},
-				},
-				"foo":   {{"foo", "foo", "foo", "Package foo is an example."}},
-				"other": {{"other/bar", "bar", "bar", "Package bar is another bar package."}},
-			},
-			ConstDecl: {
-				"Pi": {{"foo", "foo", "Pi", ""}},
-			},
-			VarDecl: {
-				"Foos": {{"foo", "foo", "Foos", ""}},
-			},
-			TypeDecl: {
-				"Foo": {{"foo", "foo", "Foo", "Foo is stuff."}},
-			},
-			FuncDecl: {
-				"New": {{"foo", "foo", "New", ""}},
-				"X":   {{"other/bar", "bar", "X", ""}},
-			},
-		}
-	}
-	if got := ix.Idents(); !reflect.DeepEqual(got, want) {
-		t.Errorf("Idents = %v; want %v", got, want)
-	}
-}
-
-func TestIdentResultSort(t *testing.T) {
-	ic := map[string]int{
-		"/a/b/pkg1": 10,
-		"/a/b/pkg2": 2,
-		"/b/d/pkg3": 20,
-	}
-	for _, tc := range []struct {
-		ir  []Ident
-		exp []Ident
-	}{
-		{
-			ir: []Ident{
-				{"/a/b/pkg2", "pkg2", "MyFunc2", ""},
-				{"/b/d/pkg3", "pkg3", "MyFunc3", ""},
-				{"/a/b/pkg1", "pkg1", "MyFunc1", ""},
-			},
-			exp: []Ident{
-				{"/b/d/pkg3", "pkg3", "MyFunc3", ""},
-				{"/a/b/pkg1", "pkg1", "MyFunc1", ""},
-				{"/a/b/pkg2", "pkg2", "MyFunc2", ""},
-			},
-		},
-		{
-			ir: []Ident{
-				{"/a/a/pkg1", "pkg1", "MyFunc1", ""},
-				{"/a/b/pkg1", "pkg1", "MyFunc1", ""},
-			},
-			exp: []Ident{
-				{"/a/b/pkg1", "pkg1", "MyFunc1", ""},
-				{"/a/a/pkg1", "pkg1", "MyFunc1", ""},
-			},
-		},
-	} {
-		if sort.Sort(byImportCount{tc.ir, ic}); !reflect.DeepEqual(tc.ir, tc.exp) {
-			t.Errorf("got: %v, want %v", tc.ir, tc.exp)
-		}
-	}
-}
-
-func TestIdentFilter(t *testing.T) {
-	ic := map[string]int{}
-	for _, tc := range []struct {
-		ir  []Ident
-		pak string
-		exp []Ident
-	}{
-		{
-			ir: []Ident{
-				{"/a/b/pkg2", "pkg2", "MyFunc2", ""},
-				{"/b/d/pkg3", "pkg3", "MyFunc3", ""},
-				{"/a/b/pkg1", "pkg1", "MyFunc1", ""},
-			},
-			pak: "pkg2",
-			exp: []Ident{
-				{"/a/b/pkg2", "pkg2", "MyFunc2", ""},
-			},
-		},
-	} {
-		res := byImportCount{tc.ir, ic}.filter(tc.pak)
-		if !reflect.DeepEqual(res, tc.exp) {
-			t.Errorf("got: %v, want %v", res, tc.exp)
-		}
-	}
-}
diff --git a/internal/godoc/page.go b/internal/godoc/page.go
index a892a5a..279d803 100644
--- a/internal/godoc/page.go
+++ b/internal/godoc/page.go
@@ -25,7 +25,6 @@
 	GoogleCN bool // page is being served from golang.google.cn
 
 	// filled in by ServePage
-	SearchBox       bool
 	Playground      bool
 	Version         string
 	GoogleAnalytics string
@@ -35,7 +34,6 @@
 	if page.Tabtitle == "" {
 		page.Tabtitle = page.Title
 	}
-	page.SearchBox = p.Corpus.IndexEnabled
 	page.Playground = p.ShowPlayground
 	page.Version = runtime.Version()
 	page.GoogleAnalytics = p.GoogleAnalytics
diff --git a/internal/godoc/pres.go b/internal/godoc/pres.go
index bb0057b..cc01204 100644
--- a/internal/godoc/pres.go
+++ b/internal/godoc/pres.go
@@ -13,9 +13,6 @@
 	"golang.org/x/website/internal/godoc/vfs/httpfs"
 )
 
-// SearchResultFunc functions return an HTML body for displaying search results.
-type SearchResultFunc func(p *Presentation, result SearchResult) []byte
-
 // Presentation generates output from a corpus.
 type Presentation struct {
 	Corpus *Corpus
@@ -30,12 +27,7 @@
 	ExampleHTML,
 	GodocHTML,
 	PackageHTML,
-	PackageRootHTML,
-	SearchHTML,
-	SearchDocHTML,
-	SearchCodeHTML,
-	SearchTxtHTML,
-	SearchDescXML *template.Template // If not nil, register a /opensearch.xml handler with this template.
+	PackageRootHTML *template.Template
 
 	// TabWidth optionally specifies the tab width.
 	TabWidth int
@@ -75,10 +67,6 @@
 	// the query string highlighted.
 	URLForSrcQuery func(src, query string, line int) string
 
-	// SearchResults optionally specifies a list of functions returning an HTML
-	// body for displaying search results.
-	SearchResults []SearchResultFunc
-
 	// GoogleAnalytics optionally adds Google Analytics via the provided
 	// tracking ID to each page.
 	GoogleAnalytics string
@@ -89,8 +77,6 @@
 }
 
 // NewPresentation returns a new Presentation from a corpus.
-// It sets SearchResults to:
-// [SearchResultDoc SearchResultCode SearchResultTxt].
 func NewPresentation(c *Corpus) *Presentation {
 	if c == nil {
 		panic("nil Corpus")
@@ -102,11 +88,6 @@
 
 		TabWidth:  4,
 		DeclLinks: true,
-		SearchResults: []SearchResultFunc{
-			(*Presentation).SearchResultDoc,
-			(*Presentation).SearchResultCode,
-			(*Presentation).SearchResultTxt,
-		},
 	}
 	p.cmdHandler = handlerServer{
 		p:       p,
@@ -125,10 +106,6 @@
 	p.cmdHandler.registerWithMux(p.mux)
 	p.pkgHandler.registerWithMux(p.mux)
 	p.mux.HandleFunc("/", p.ServeFile)
-	p.mux.HandleFunc("/search", p.HandleSearch)
-	if p.SearchDescXML != nil {
-		p.mux.HandleFunc("/opensearch.xml", p.serveSearchDesc)
-	}
 	return p
 }
 
diff --git a/internal/godoc/search.go b/internal/godoc/search.go
deleted file mode 100644
index 0e7509a..0000000
--- a/internal/godoc/search.go
+++ /dev/null
@@ -1,186 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package godoc
-
-import (
-	"bytes"
-	"fmt"
-	"net/http"
-	"regexp"
-	"strings"
-)
-
-type SearchResult struct {
-	Query string
-	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
-
-	// textual matches
-	Found    int         // number of textual occurrences found
-	Textual  []FileLines // textual matches of Query
-	Complete bool        // true if all textual occurrences of Query are reported
-	Idents   map[SpotKind][]Ident
-}
-
-func (c *Corpus) Lookup(query string) SearchResult {
-	result := &SearchResult{Query: query}
-
-	index, timestamp := c.CurrentIndex()
-	if index != nil {
-		// identifier search
-		if r, err := index.Lookup(query); err == nil {
-			result = r
-		} else if err != nil && !c.IndexFullText {
-			// ignore the error if full text search is enabled
-			// since the query may be a valid regular expression
-			result.Alert = "Error in query string: " + err.Error()
-			return *result
-		}
-
-		// full text search
-		if c.IndexFullText && query != "" {
-			rx, err := regexp.Compile(query)
-			if err != nil {
-				result.Alert = "Error in query regular expression: " + err.Error()
-				return *result
-			}
-			// If we get maxResults+1 results we know that there are more than
-			// maxResults results and thus the result may be incomplete (to be
-			// precise, we should remove one result from the result set, but
-			// nobody is going to count the results on the result page).
-			result.Found, result.Textual = index.LookupRegexp(rx, c.MaxResults+1)
-			result.Complete = result.Found <= c.MaxResults
-			if !result.Complete {
-				result.Found-- // since we looked for maxResults+1
-			}
-		}
-	}
-
-	// is the result accurate?
-	if c.IndexEnabled {
-		if ts := c.FSModifiedTime(); timestamp.Before(ts) {
-			// The index is older than the latest file system change under godoc's observation.
-			result.Alert = "Indexing in progress: result may be inaccurate"
-		}
-	} else {
-		result.Alert = "Search index disabled: no results available"
-	}
-
-	return *result
-}
-
-// SearchResultDoc optionally specifies a function returning an HTML body
-// displaying search results matching godoc documentation.
-func (p *Presentation) SearchResultDoc(result SearchResult) []byte {
-	return applyTemplate(p.SearchDocHTML, "searchDocHTML", result)
-}
-
-// SearchResultCode optionally specifies a function returning an HTML body
-// displaying search results matching source code.
-func (p *Presentation) SearchResultCode(result SearchResult) []byte {
-	return applyTemplate(p.SearchCodeHTML, "searchCodeHTML", result)
-}
-
-// SearchResultTxt optionally specifies a function returning an HTML body
-// displaying search results of textual matches.
-func (p *Presentation) SearchResultTxt(result SearchResult) []byte {
-	return applyTemplate(p.SearchTxtHTML, "searchTxtHTML", result)
-}
-
-// HandleSearch obtains results for the requested search and returns a page
-// to display them.
-func (p *Presentation) HandleSearch(w http.ResponseWriter, r *http.Request) {
-	query := strings.TrimSpace(r.FormValue("q"))
-	result := p.Corpus.Lookup(query)
-
-	var contents bytes.Buffer
-	for _, f := range p.SearchResults {
-		contents.Write(f(p, result))
-	}
-
-	var title string
-	if haveResults := contents.Len() > 0; haveResults {
-		title = fmt.Sprintf(`Results for query: %v`, query)
-		if !p.Corpus.IndexEnabled {
-			result.Alert = ""
-		}
-	} else {
-		title = fmt.Sprintf(`No results found for query %q`, query)
-	}
-
-	body := bytes.NewBuffer(applyTemplate(p.SearchHTML, "searchHTML", result))
-	body.Write(contents.Bytes())
-
-	p.ServePage(w, Page{
-		Title:    title,
-		Tabtitle: query,
-		Query:    query,
-		Body:     body.Bytes(),
-		GoogleCN: googleCN(r),
-	})
-}
-
-func (p *Presentation) serveSearchDesc(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("Content-Type", "application/opensearchdescription+xml")
-	data := map[string]interface{}{
-		"BaseURL": fmt.Sprintf("http://%s", r.Host),
-	}
-	applyTemplateToResponseWriter(w, p.SearchDescXML, &data)
-}
-
-// tocColCount returns the no. of columns
-// to split the toc table to.
-func tocColCount(result SearchResult) int {
-	tocLen := tocLen(result)
-	colCount := 0
-	// Simple heuristic based on visual aesthetic in manual testing.
-	switch {
-	case tocLen <= 10:
-		colCount = 1
-	case tocLen <= 20:
-		colCount = 2
-	case tocLen <= 80:
-		colCount = 3
-	default:
-		colCount = 4
-	}
-	return colCount
-}
-
-// tocLen calculates the no. of items in the toc table
-// by going through various fields in the SearchResult
-// that is rendered in the UI.
-func tocLen(result SearchResult) int {
-	tocLen := 0
-	for _, val := range result.Idents {
-		if len(val) != 0 {
-			tocLen++
-		}
-	}
-	// If no identifiers, then just one item for the header text "Package <result.Query>".
-	// See searchcode.html for further details.
-	if len(result.Idents) == 0 {
-		tocLen++
-	}
-	if result.Hit != nil {
-		if len(result.Hit.Decls) > 0 {
-			tocLen += len(result.Hit.Decls)
-			// We need one extra item for the header text "Package-level declarations".
-			tocLen++
-		}
-		if len(result.Hit.Others) > 0 {
-			tocLen += len(result.Hit.Others)
-			// We need one extra item for the header text "Local declarations and uses".
-			tocLen++
-		}
-	}
-	// For "textual occurrences".
-	tocLen++
-	return tocLen
-}
diff --git a/internal/godoc/snippet.go b/internal/godoc/snippet.go
deleted file mode 100644
index 1750478..0000000
--- a/internal/godoc/snippet.go
+++ /dev/null
@@ -1,123 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// This file contains the infrastructure to create a code
-// snippet for search results.
-//
-// Note: At the moment, this only creates HTML snippets.
-
-package godoc
-
-import (
-	"bytes"
-	"fmt"
-	"go/ast"
-	"go/token"
-)
-
-type Snippet struct {
-	Line int
-	Text string // HTML-escaped
-}
-
-func (p *Presentation) newSnippet(fset *token.FileSet, decl ast.Decl, id *ast.Ident) *Snippet {
-	// TODO instead of pretty-printing the node, should use the original source instead
-	var buf1 bytes.Buffer
-	p.writeNode(&buf1, nil, fset, decl)
-	// wrap text with <pre> tag
-	var buf2 bytes.Buffer
-	buf2.WriteString("<pre>")
-	FormatText(&buf2, buf1.Bytes(), -1, true, id.Name, nil)
-	buf2.WriteString("</pre>")
-	return &Snippet{fset.Position(id.Pos()).Line, buf2.String()}
-}
-
-func findSpec(list []ast.Spec, id *ast.Ident) ast.Spec {
-	for _, spec := range list {
-		switch s := spec.(type) {
-		case *ast.ImportSpec:
-			if s.Name == id {
-				return s
-			}
-		case *ast.ValueSpec:
-			for _, n := range s.Names {
-				if n == id {
-					return s
-				}
-			}
-		case *ast.TypeSpec:
-			if s.Name == id {
-				return s
-			}
-		}
-	}
-	return nil
-}
-
-func (p *Presentation) genSnippet(fset *token.FileSet, d *ast.GenDecl, id *ast.Ident) *Snippet {
-	s := findSpec(d.Specs, id)
-	if s == nil {
-		return nil //  declaration doesn't contain id - exit gracefully
-	}
-
-	// only use the spec containing the id for the snippet
-	dd := &ast.GenDecl{
-		Doc:    d.Doc,
-		TokPos: d.Pos(),
-		Tok:    d.Tok,
-		Lparen: d.Lparen,
-		Specs:  []ast.Spec{s},
-		Rparen: d.Rparen,
-	}
-
-	return p.newSnippet(fset, dd, id)
-}
-
-func (p *Presentation) funcSnippet(fset *token.FileSet, d *ast.FuncDecl, id *ast.Ident) *Snippet {
-	if d.Name != id {
-		return nil //  declaration doesn't contain id - exit gracefully
-	}
-
-	// only use the function signature for the snippet
-	dd := &ast.FuncDecl{
-		Doc:  d.Doc,
-		Recv: d.Recv,
-		Name: d.Name,
-		Type: d.Type,
-	}
-
-	return p.newSnippet(fset, dd, id)
-}
-
-// NewSnippet creates a text snippet from a declaration decl containing an
-// identifier id. Parts of the declaration not containing the identifier
-// may be removed for a more compact snippet.
-func NewSnippet(fset *token.FileSet, decl ast.Decl, id *ast.Ident) *Snippet {
-	// TODO(bradfitz, adg): remove this function.  But it's used by indexer, which
-	// doesn't have a *Presentation, and NewSnippet needs a TabWidth.
-	var p Presentation
-	p.TabWidth = 4
-	return p.NewSnippet(fset, decl, id)
-}
-
-// NewSnippet creates a text snippet from a declaration decl containing an
-// identifier id. Parts of the declaration not containing the identifier
-// may be removed for a more compact snippet.
-func (p *Presentation) NewSnippet(fset *token.FileSet, decl ast.Decl, id *ast.Ident) *Snippet {
-	var s *Snippet
-	switch d := decl.(type) {
-	case *ast.GenDecl:
-		s = p.genSnippet(fset, d, id)
-	case *ast.FuncDecl:
-		s = p.funcSnippet(fset, d, id)
-	}
-
-	// handle failure gracefully
-	if s == nil {
-		var buf bytes.Buffer
-		fmt.Fprintf(&buf, `<span class="alert">could not generate a snippet for <span class="highlight">%s</span></span>`, id.Name)
-		s = &Snippet{fset.Position(id.Pos()).Line, buf.String()}
-	}
-	return s
-}
diff --git a/internal/godoc/spot.go b/internal/godoc/spot.go
deleted file mode 100644
index 95ffa4b..0000000
--- a/internal/godoc/spot.go
+++ /dev/null
@@ -1,83 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package godoc
-
-// ----------------------------------------------------------------------------
-// SpotInfo
-
-// A SpotInfo value describes a particular identifier spot in a given file;
-// It encodes three values: the SpotKind (declaration or use), a line or
-// snippet index "lori", and whether it's a line or index.
-//
-// The following encoding is used:
-//
-//   bits    32   4    1       0
-//   value    [lori|kind|isIndex]
-//
-type SpotInfo uint32
-
-// SpotKind describes whether an identifier is declared (and what kind of
-// declaration) or used.
-type SpotKind uint32
-
-const (
-	PackageClause SpotKind = iota
-	ImportDecl
-	ConstDecl
-	TypeDecl
-	VarDecl
-	FuncDecl
-	MethodDecl
-	Use
-	nKinds
-)
-
-var (
-	// These must match the SpotKind values above.
-	name = []string{
-		"Packages",
-		"Imports",
-		"Constants",
-		"Types",
-		"Variables",
-		"Functions",
-		"Methods",
-		"Uses",
-		"Unknown",
-	}
-)
-
-func (x SpotKind) Name() string { return name[x] }
-
-func init() {
-	// sanity check: if nKinds is too large, the SpotInfo
-	// accessor functions may need to be updated
-	if nKinds > 8 {
-		panic("internal error: nKinds > 8")
-	}
-}
-
-// makeSpotInfo makes a SpotInfo.
-func makeSpotInfo(kind SpotKind, lori int, isIndex bool) SpotInfo {
-	// encode lori: bits [4..32)
-	x := SpotInfo(lori) << 4
-	if int(x>>4) != lori {
-		// lori value doesn't fit - since snippet indices are
-		// most certainly always smaller then 1<<28, this can
-		// only happen for line numbers; give it no line number (= 0)
-		x = 0
-	}
-	// encode kind: bits [1..4)
-	x |= SpotInfo(kind) << 1
-	// encode isIndex: bit 0
-	if isIndex {
-		x |= 1
-	}
-	return x
-}
-
-func (x SpotInfo) Kind() SpotKind { return SpotKind(x >> 1 & 7) }
-func (x SpotInfo) Lori() int      { return int(x >> 4) }
-func (x SpotInfo) IsIndex() bool  { return x&1 != 0 }
diff --git a/internal/godoc/util/throttle.go b/internal/godoc/util/throttle.go
deleted file mode 100644
index 53d9ba6..0000000
--- a/internal/godoc/util/throttle.go
+++ /dev/null
@@ -1,88 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package util
-
-import "time"
-
-// A Throttle permits throttling of a goroutine by
-// calling the Throttle method repeatedly.
-//
-type Throttle struct {
-	f  float64       // f = (1-r)/r for 0 < r < 1
-	dt time.Duration // minimum run time slice; >= 0
-	tr time.Duration // accumulated time running
-	ts time.Duration // accumulated time stopped
-	tt time.Time     // earliest throttle time (= time Throttle returned + tm)
-}
-
-// NewThrottle creates a new Throttle with a throttle value r and
-// a minimum allocated run time slice of dt:
-//
-//	r == 0: "empty" throttle; the goroutine is always sleeping
-//	r == 1: full throttle; the goroutine is never sleeping
-//
-// A value of r == 0.6 throttles a goroutine such that it runs
-// approx. 60% of the time, and sleeps approx. 40% of the time.
-// Values of r < 0 or r > 1 are clamped down to values between 0 and 1.
-// Values of dt < 0 are set to 0.
-//
-func NewThrottle(r float64, dt time.Duration) *Throttle {
-	var f float64
-	switch {
-	case r <= 0:
-		f = -1 // indicates always sleep
-	case r >= 1:
-		f = 0 // assume r == 1 (never sleep)
-	default:
-		// 0 < r < 1
-		f = (1 - r) / r
-	}
-	if dt < 0 {
-		dt = 0
-	}
-	return &Throttle{f: f, dt: dt, tt: time.Now().Add(dt)}
-}
-
-// Throttle calls time.Sleep such that over time the ratio tr/ts between
-// accumulated run (tr) and sleep times (ts) approximates the value 1/(1-r)
-// where r is the throttle value. Throttle returns immediately (w/o sleeping)
-// if less than tm ns have passed since the last call to Throttle.
-//
-func (p *Throttle) Throttle() {
-	if p.f < 0 {
-		select {} // always sleep
-	}
-
-	t0 := time.Now()
-	if t0.Before(p.tt) {
-		return // keep running (minimum time slice not exhausted yet)
-	}
-
-	// accumulate running time
-	p.tr += t0.Sub(p.tt) + p.dt
-
-	// compute sleep time
-	// Over time we want:
-	//
-	//	tr/ts = r/(1-r)
-	//
-	// Thus:
-	//
-	//	ts = tr*f with f = (1-r)/r
-	//
-	// After some incremental run time δr added to the total run time
-	// tr, the incremental sleep-time δs to get to the same ratio again
-	// after waking up from time.Sleep is:
-	if δs := time.Duration(float64(p.tr)*p.f) - p.ts; δs > 0 {
-		time.Sleep(δs)
-	}
-
-	// accumulate (actual) sleep time
-	t1 := time.Now()
-	p.ts += t1.Sub(t0)
-
-	// set earliest next throttle time
-	p.tt = t1.Add(p.dt)
-}