--- /dev/null
+// 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) index for a set of Go files.
+//
+// Basic indexing algorithm:
+// - traverse all .go files of the file tree specified by root
+// - for each word (identifier) encountered, collect all occurences (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
+
+package main
+
+import (
+ "container/vector";
+ "go/ast";
+ "go/parser";
+ "go/token";
+ "os";
+ pathutil "path";
+ "sort";
+ "strings";
+)
+
+
+// ----------------------------------------------------------------------------
+// Data structures used during indexing
+
+// A RunList is a vector 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 critera) 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 struct {
+ vector.Vector;
+ less func(x, y interface{}) bool;
+}
+
+func (h *RunList) Less(i, j int) bool {
+ return h.less(h.At(i), h.At(j));
+}
+
+
+func (h *RunList) sort(less func(x, y interface{}) bool) {
+ h.less = less;
+ sort.Sort(h);
+}
+
+
+// Compress entries which are the same according to a sort criteria
+// (specified by less) into "runs".
+func (h *RunList) reduce(less func(x, y interface{}) bool, newRun func(h *RunList, i, j int) interface{}) *RunList {
+ // 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 := 0;
+ for j := 0; j < h.Len(); j++ {
+ if less(h.At(i), h.At(j)) {
+ hh.Push(newRun(h, i, j));
+ i = j; // start a new run
+ }
+ }
+ // add final run, if any
+ if i < h.Len() {
+ hh.Push(newRun(h, i, h.Len()));
+ }
+
+ return &hh;
+}
+
+
+// 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 (
+ ImportDecl SpotKind = iota;
+ ConstDecl;
+ TypeDecl;
+ VarDecl;
+ FuncDecl;
+ MethodDecl;
+ Use;
+ nKinds;
+)
+
+
+// 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) less(y SpotInfo) bool {
+ return x.Lori() < y.Lori();
+}
+
+
+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;
+}
+
+
+// A Pak describes a Go package.
+type Pak struct {
+ Path string; // directory name containing the package
+ Name string; // package name as declared by package clause
+}
+
+
+func (p *Pak) less(q *Pak) bool {
+ return p.Path < q.Path || p.Name < q.Name;
+}
+
+
+// A File describes a Go file.
+type File struct {
+ Path string; // complete file name
+ Pak Pak; // the package to which the file belongs
+}
+
+
+func (f *File) less(g *File) bool {
+ return f.Path < g.Path;
+}
+
+
+// A Spot describes a single occurence of a word.
+type Spot struct {
+ File *File;
+ Info SpotInfo;
+}
+
+
+// Spots are sorted by filename.
+func lessSpot(x, y interface{}) bool {
+ return x.(Spot).File.less(y.(Spot).File);
+}
+
+
+// A FileRun describes a run of Spots of a word in a single file.
+type FileRun struct {
+ File *File;
+ Infos []SpotInfo;
+}
+
+
+// newFileRun allocates a new *FileRun from the Spot run [i, j) in h.
+func newFileRun(h *RunList, i, j int) interface{} {
+ file := h.At(i).(Spot).File;
+ lines := make([]SpotInfo, j-i);
+ prev := 0;
+ k := 0;
+ for ; i < j; i++ {
+ info := h.At(i).(Spot).Info;
+ // ignore line duplicates
+ // (if lori is a snippet index it is unique - no need to check IsIndex())
+ lori := info.Lori();
+ if lori != prev {
+ lines[k] = info;
+ prev = lori;
+ k++;
+ }
+ }
+ return &FileRun{file, lines[0:k]};
+}
+
+
+// FileRuns are sorted by package.
+func lessFileRun(x, y interface{}) bool {
+ return x.(*FileRun).File.Pak.less(&y.(*FileRun).File.Pak);
+}
+
+
+// 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.less(p.Files[j].File);
+}
+func (p *PakRun) Swap(i, j int) {
+ p.Files[i], p.Files[j] = p.Files[j], p.Files[i];
+}
+
+
+// newPakRun allocates a new *PakRun from the *FileRun run [i, j) in h.
+func newPakRun(h *RunList, i, j int) interface{} {
+ pak := h.At(i).(*FileRun).File.Pak;
+ files := make([]*FileRun, j-i);
+ k := 0;
+ for ; i < j; i++ {
+ files[k] = h.At(i).(*FileRun);
+ k++;
+ }
+ run := &PakRun{pak, files};
+ sort.Sort(run); // files were sorted by package; sort them by file now
+ return run;
+}
+
+
+// PakRuns are sorted by package.
+func lessPakRun(x, y interface{}) bool {
+ return x.(*PakRun).Pak.less(&y.(*PakRun).Pak);
+}
+
+
+// A HitList describes a list of PakRuns.
+type HitList []*PakRun
+
+
+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, h2.Len());
+ for i := 0; i < h2.Len(); i++ {
+ h[i] = h2.At(i).(*PakRun);
+ }
+ return h;
+}
+
+
+func (h HitList) filter(pakname string) HitList {
+ // determine number of matching packages (most of the time just one)
+ n := 0;
+ for _, p := range h {
+ if p.Pak.Name == pakname {
+ n++;
+ }
+ }
+ // create filtered HitList
+ hh := make(HitList, n);
+ i := 0;
+ for _, p := range h {
+ if p.Pak.Name == pakname {
+ hh[i] = p;
+ i++;
+ }
+ }
+ return hh;
+}
+
+
+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
+}
+
+
+func lessWordPair(x, y interface{}) bool {
+ return x.(*wordPair).canon < y.(*wordPair).canon;
+}
+
+
+// newAltWords allocates a new *AltWords from the *wordPair run [i, j) in h.
+func newAltWords(h *RunList, i, j int) interface{} {
+ canon := h.At(i).(*wordPair).canon;
+ alts := make([]string, j-i);
+ k := 0;
+ for ; i < j; i++ {
+ alts[k] = h.At(i).(*wordPair).alt;
+ k++;
+ }
+ return &AltWords{canon, alts};
+}
+
+
+func (a *AltWords) filter(s string) *AltWords {
+ if len(a.Alts) == 1 && a.Alts[0] == s {
+ // there are no different alternatives
+ return nil;
+ }
+
+ // make a new AltWords with the current spelling removed
+ alts := make([]string, len(a.Alts));
+ i := 0;
+ for _, w := range a.Alts {
+ if w != s {
+ alts[i] = w;
+ i++;
+ }
+ }
+ return &AltWords{a.Canon, alts[0:i]};
+}
+
+
+// ----------------------------------------------------------------------------
+// Indexer
+
+type IndexResult struct {
+ Decls RunList; // package-level declarations (with snippets)
+ Others RunList; // all other occurences
+}
+
+
+// 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 {
+ words map[string]*IndexResult; // RunLists of Spots
+ snippets vector.Vector; // vector of *Snippets, indexed by snippet indices
+ file *File; // current file
+ decl ast.Decl; // current decl
+ nspots int; // number of spots encountered
+}
+
+
+func (x *Indexer) addSnippet(s *Snippet) int {
+ index := x.snippets.Len();
+ x.snippets.Push(s);
+ return index;
+}
+
+
+func (x *Indexer) visitComment(c *ast.CommentGroup) {
+ if c != nil {
+ ast.Walk(x, c);
+ }
+}
+
+
+func (x *Indexer) visitIdent(kind SpotKind, id *ast.Ident) {
+ if id != nil {
+ lists, found := x.words[id.Value];
+ if !found {
+ lists = new(IndexResult);
+ x.words[id.Value] = lists;
+ }
+
+ if kind == Use || x.decl == nil {
+ // not a declaration or no snippet required
+ info := makeSpotInfo(kind, id.Pos().Line, false);
+ lists.Others.Push(Spot{x.file, info});
+ } else {
+ // a declaration with snippet
+ index := x.addSnippet(NewSnippet(x.decl, id));
+ info := makeSpotInfo(kind, index, true);
+ lists.Decls.Push(Spot{x.file, info});
+ }
+
+ x.nspots++;
+ }
+}
+
+
+func (x *Indexer) visitSpec(spec ast.Spec, isVarDecl bool) {
+ switch n := spec.(type) {
+ case *ast.ImportSpec:
+ x.visitComment(n.Doc);
+ x.visitIdent(ImportDecl, n.Name);
+ for _, s := range n.Path {
+ ast.Walk(x, s);
+ }
+ x.visitComment(n.Comment);
+
+ case *ast.ValueSpec:
+ x.visitComment(n.Doc);
+ kind := ConstDecl;
+ if isVarDecl {
+ kind = VarDecl;
+ }
+ for _, n := range n.Names {
+ x.visitIdent(kind, n);
+ }
+ ast.Walk(x, n.Type);
+ for _, v := range n.Values {
+ ast.Walk(x, v);
+ }
+ x.visitComment(n.Comment);
+
+ case *ast.TypeSpec:
+ x.visitComment(n.Doc);
+ x.visitIdent(TypeDecl, n.Name);
+ ast.Walk(x, n.Type);
+ x.visitComment(n.Comment);
+ }
+}
+
+
+func (x *Indexer) Visit(node interface{}) bool {
+ // TODO(gri): methods in interface types are categorized as VarDecl
+ switch n := node.(type) {
+ case *ast.Ident:
+ x.visitIdent(Use, n);
+
+ case *ast.Field:
+ x.decl = nil; // no snippets for fields
+ x.visitComment(n.Doc);
+ for _, m := range n.Names {
+ x.visitIdent(VarDecl, m);
+ }
+ ast.Walk(x, n.Type);
+ for _, s := range n.Tag {
+ ast.Walk(x, s);
+ }
+ x.visitComment(n.Comment);
+
+ case *ast.DeclStmt:
+ if decl, ok := n.Decl.(*ast.GenDecl); ok {
+ // local declarations can only be *ast.GenDecls
+ x.decl = nil; // no snippets for local declarations
+ x.visitComment(decl.Doc);
+ for _, s := range decl.Specs {
+ x.visitSpec(s, decl.Tok == token.VAR);
+ }
+ } else {
+ // handle error case gracefully
+ ast.Walk(x, n.Decl);
+ }
+
+ case *ast.GenDecl:
+ x.decl = n;
+ x.visitComment(n.Doc);
+ for _, s := range n.Specs {
+ x.visitSpec(s, n.Tok == token.VAR);
+ }
+
+ case *ast.FuncDecl:
+ x.visitComment(n.Doc);
+ 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.Type);
+ }
+
+ default:
+ return true;
+ }
+
+ return false;
+}
+
+
+func (x *Indexer) VisitDir(path string, d *os.Dir) bool {
+ return true;
+}
+
+
+func (x *Indexer) VisitFile(path string, d *os.Dir) {
+ if !isGoFile(d) {
+ return;
+ }
+
+ file, err := parser.ParseFile(path, nil, parser.ParseComments);
+ if err != nil {
+ return; // ignore files with (parse) errors
+ }
+
+ dir, _ := pathutil.Split(path);
+ pak := Pak{dir, file.Name.Value};
+ x.file = &File{path, pak};
+ ast.Walk(x, file);
+}
+
+
+// ----------------------------------------------------------------------------
+// Index
+
+type LookupResult struct {
+ Decls HitList; // package-level declarations (with snippets)
+ Others HitList; // all other occurences
+}
+
+
+type Index struct {
+ 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
+ nspots int; // number of spots indexed (a measure of the index size)
+}
+
+
+func canonical(w string) string {
+ return strings.ToLower(w);
+}
+
+
+// NewIndex creates a new index for the file tree rooted at root.
+func NewIndex(root string) *Index {
+ var x Indexer;
+
+ // initialize Indexer
+ x.words = make(map[string]*IndexResult);
+
+ // collect all Spots
+ pathutil.Walk(root, &x, nil);
+
+ // 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.Push(&wordPair{canonical(w), w});
+ }
+
+ // 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 < alist.Len(); i++ {
+ a := alist.At(i).(*AltWords);
+ alts[a.Canon] = a;
+ }
+
+ // convert snippet vector into a list
+ snippets := make([]*Snippet, x.snippets.Len());
+ for i := 0; i < x.snippets.Len(); i++ {
+ snippets[i] = x.snippets.At(i).(*Snippet);
+ }
+
+ return &Index{words, alts, snippets, x.nspots};
+}
+
+
+// Size returns the number of different words and
+// spots indexed as a measure for the index size.
+func (x *Index) Size() (nwords int, nspots int) {
+ return len(x.words), x.nspots;
+}
+
+
+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;
+}
+
+
+// For a given string s, which is either a single identifier or a qualified
+// identifier, Lookup returns a LookupResult, and a list of alternative
+// spellings, if any.
+func (x *Index) Lookup(s string) (match *LookupResult, alt *AltWords) {
+ ss := strings.Split(s, ".", 0);
+
+ switch len(ss) {
+ case 1:
+ match, alt = x.LookupWord(ss[0]);
+
+ case 2:
+ pakname := ss[0];
+ match, alt = x.LookupWord(ss[1]);
+ if match != nil {
+ // found a match - filter by package name
+ decls := match.Decls.filter(pakname);
+ others := match.Others.filter(pakname);
+ match = &LookupResult{decls, others};
+ }
+ if alt != nil {
+ // alternative spellings found - add package name
+ // TODO(gri): At the moment this is not very smart
+ // and likely will produce suggestions that have
+ // no match. Should filter incorrect alternatives.
+ canon := pakname + "." + alt.Canon; // for completeness (currently not used)
+ alts := make([]string, len(alt.Alts));
+ for i, a := range alt.Alts {
+ alts[i] = pakname+"."+a;
+ }
+ alt = &AltWords{canon, alts};
+ }
+ }
+
+ return;
+}
+
+
+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;
+}