| // Copyright 2019 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 completion |
| |
| import ( |
| "context" |
| "go/types" |
| "strings" |
| "time" |
| ) |
| |
| // MaxDeepCompletions limits deep completion results because in most cases |
| // there are too many to be useful. |
| const MaxDeepCompletions = 3 |
| |
| // deepCompletionState stores our state as we search for deep completions. |
| // "deep completion" refers to searching into objects' fields and methods to |
| // find more completion candidates. |
| type deepCompletionState struct { |
| // enabled indicates wether deep completion is permitted. |
| enabled bool |
| |
| // queueClosed is used to disable adding new sub-fields to search queue |
| // once we're running out of our time budget. |
| queueClosed bool |
| |
| // searchQueue holds the current breadth first search queue. |
| searchQueue []candidate |
| |
| // highScores tracks the highest deep candidate scores we have found |
| // so far. This is used to avoid work for low scoring deep candidates. |
| highScores [MaxDeepCompletions]float64 |
| |
| // candidateCount is the count of unique deep candidates encountered |
| // so far. |
| candidateCount int |
| } |
| |
| // enqueue adds a candidate to the search queue. |
| func (s *deepCompletionState) enqueue(cand candidate) { |
| s.searchQueue = append(s.searchQueue, cand) |
| } |
| |
| // dequeue removes and returns the leftmost element from the search queue. |
| func (s *deepCompletionState) dequeue() *candidate { |
| var cand *candidate |
| cand, s.searchQueue = &s.searchQueue[0], s.searchQueue[1:] |
| return cand |
| } |
| |
| // scorePenalty computes a deep candidate score penalty. A candidate is |
| // penalized based on depth to favor shallower candidates. We also give a |
| // slight bonus to unexported objects and a slight additional penalty to |
| // function objects. |
| func (s *deepCompletionState) scorePenalty(cand *candidate) float64 { |
| var deepPenalty float64 |
| for _, dc := range cand.path { |
| deepPenalty++ |
| |
| if !dc.Exported() { |
| deepPenalty -= 0.1 |
| } |
| |
| if _, isSig := dc.Type().Underlying().(*types.Signature); isSig { |
| deepPenalty += 0.1 |
| } |
| } |
| |
| // Normalize penalty to a max depth of 10. |
| return deepPenalty / 10 |
| } |
| |
| // isHighScore returns whether score is among the top MaxDeepCompletions deep |
| // candidate scores encountered so far. If so, it adds score to highScores, |
| // possibly displacing an existing high score. |
| func (s *deepCompletionState) isHighScore(score float64) bool { |
| // Invariant: s.highScores is sorted with highest score first. Unclaimed |
| // positions are trailing zeros. |
| |
| // If we beat an existing score then take its spot. |
| for i, deepScore := range s.highScores { |
| if score <= deepScore { |
| continue |
| } |
| |
| if deepScore != 0 && i != len(s.highScores)-1 { |
| // If this wasn't an empty slot then we need to scooch everyone |
| // down one spot. |
| copy(s.highScores[i+1:], s.highScores[i:]) |
| } |
| s.highScores[i] = score |
| return true |
| } |
| |
| return false |
| } |
| |
| // newPath returns path from search root for an object following a given |
| // candidate. |
| func (s *deepCompletionState) newPath(cand *candidate, obj types.Object, invoke bool) ([]types.Object, []string) { |
| name := obj.Name() |
| if invoke { |
| name += "()" |
| } |
| |
| // copy the slice since we don't want to overwrite the original slice. |
| path := append([]types.Object{}, cand.path...) |
| names := append([]string{}, cand.names...) |
| |
| return append(path, obj), append(names, name) |
| } |
| |
| // deepSearch searches a candidate and its subordinate objects for completion |
| // items if deep completion is enabled and adds the valid candidates to |
| // completion items. |
| func (c *completer) deepSearch(ctx context.Context) { |
| outer: |
| for len(c.deepState.searchQueue) > 0 { |
| cand := c.deepState.dequeue() |
| obj := cand.obj |
| |
| // At the top level, dedupe by object. |
| if len(cand.path) == 0 { |
| if c.seen[cand.obj] { |
| continue |
| } |
| c.seen[cand.obj] = true |
| } |
| |
| // If obj is not accessible because it lives in another package and is |
| // not exported, don't treat it as a completion candidate unless it's |
| // a package completion candidate. |
| if !c.completionContext.packageCompletion && |
| obj.Pkg() != nil && obj.Pkg() != c.pkg.GetTypes() && !obj.Exported() { |
| continue |
| } |
| |
| // If we want a type name, don't offer non-type name candidates. |
| // However, do offer package names since they can contain type names, |
| // and do offer any candidate without a type since we aren't sure if it |
| // is a type name or not (i.e. unimported candidate). |
| if c.wantTypeName() && obj.Type() != nil && !isTypeName(obj) && !isPkgName(obj) { |
| continue |
| } |
| |
| // When searching deep, make sure we don't have a cycle in our chain. |
| // We don't dedupe by object because we want to allow both "foo.Baz" |
| // and "bar.Baz" even though "Baz" is represented the same types.Object |
| // in both. |
| for _, seenObj := range cand.path { |
| if seenObj == obj { |
| continue outer |
| } |
| } |
| |
| c.addCandidate(ctx, cand) |
| |
| c.deepState.candidateCount++ |
| if c.opts.budget > 0 && c.deepState.candidateCount%100 == 0 { |
| spent := float64(time.Since(c.startTime)) / float64(c.opts.budget) |
| select { |
| case <-ctx.Done(): |
| return |
| default: |
| // If we are almost out of budgeted time, no further elements |
| // should be added to the queue. This ensures remaining time is |
| // used for processing current queue. |
| if !c.deepState.queueClosed && spent >= 0.85 { |
| c.deepState.queueClosed = true |
| } |
| } |
| } |
| |
| // if deep search is disabled, don't add any more candidates. |
| if !c.deepState.enabled || c.deepState.queueClosed { |
| continue |
| } |
| |
| // Searching members for a type name doesn't make sense. |
| if isTypeName(obj) { |
| continue |
| } |
| if obj.Type() == nil { |
| continue |
| } |
| |
| // Don't search embedded fields because they were already included in their |
| // parent's fields. |
| if v, ok := obj.(*types.Var); ok && v.Embedded() { |
| continue |
| } |
| |
| if sig, ok := obj.Type().Underlying().(*types.Signature); ok { |
| // If obj is a function that takes no arguments and returns one |
| // value, keep searching across the function call. |
| if sig.Params().Len() == 0 && sig.Results().Len() == 1 { |
| path, names := c.deepState.newPath(cand, obj, true) |
| // The result of a function call is not addressable. |
| candidates := c.methodsAndFields(sig.Results().At(0).Type(), false, cand.imp) |
| for _, newCand := range candidates { |
| newCand.path, newCand.names = path, names |
| c.deepState.enqueue(newCand) |
| } |
| } |
| } |
| |
| path, names := c.deepState.newPath(cand, obj, false) |
| switch obj := obj.(type) { |
| case *types.PkgName: |
| candidates := c.packageMembers(obj.Imported(), stdScore, cand.imp) |
| for _, newCand := range candidates { |
| newCand.path, newCand.names = path, names |
| c.deepState.enqueue(newCand) |
| } |
| default: |
| candidates := c.methodsAndFields(obj.Type(), cand.addressable, cand.imp) |
| for _, newCand := range candidates { |
| newCand.path, newCand.names = path, names |
| c.deepState.enqueue(newCand) |
| } |
| } |
| } |
| } |
| |
| // addCandidate adds a completion candidate to suggestions, without searching |
| // its members for more candidates. |
| func (c *completer) addCandidate(ctx context.Context, cand *candidate) { |
| obj := cand.obj |
| if c.matchingCandidate(cand) { |
| cand.score *= highScore |
| |
| if p := c.penalty(cand); p > 0 { |
| cand.score *= (1 - p) |
| } |
| } else if isTypeName(obj) { |
| // If obj is a *types.TypeName that didn't otherwise match, check |
| // if a literal object of this type makes a good candidate. |
| |
| // We only care about named types (i.e. don't want builtin types). |
| if _, isNamed := obj.Type().(*types.Named); isNamed { |
| c.literal(ctx, obj.Type(), cand.imp) |
| } |
| } |
| |
| // Lower score of method calls so we prefer fields and vars over calls. |
| if cand.expandFuncCall { |
| if sig, ok := obj.Type().Underlying().(*types.Signature); ok && sig.Recv() != nil { |
| cand.score *= 0.9 |
| } |
| } |
| |
| // Prefer private objects over public ones. |
| if !obj.Exported() && obj.Parent() != types.Universe { |
| cand.score *= 1.1 |
| } |
| |
| // Favor shallow matches by lowering score according to depth. |
| cand.score -= cand.score * c.deepState.scorePenalty(cand) |
| |
| if cand.score < 0 { |
| cand.score = 0 |
| } |
| |
| cand.name = strings.Join(append(cand.names, cand.obj.Name()), ".") |
| if item, err := c.item(ctx, *cand); err == nil { |
| c.items = append(c.items, item) |
| } |
| } |
| |
| // penalty reports a score penalty for cand in the range (0, 1). |
| // For example, a candidate is penalized if it has already been used |
| // in another switch case statement. |
| func (c *completer) penalty(cand *candidate) float64 { |
| for _, p := range c.inference.penalized { |
| if c.objChainMatches(cand, p.objChain) { |
| return p.penalty |
| } |
| } |
| |
| return 0 |
| } |
| |
| // objChainMatches reports whether cand combined with the surrounding |
| // object prefix matches chain. |
| func (c *completer) objChainMatches(cand *candidate, chain []types.Object) bool { |
| // For example, when completing: |
| // |
| // foo.ba<> |
| // |
| // If we are considering the deep candidate "bar.baz", cand is baz, |
| // objChain is [foo] and deepChain is [bar]. We would match the |
| // chain [foo, bar, baz]. |
| if len(chain) != len(c.inference.objChain)+len(cand.path)+1 { |
| return false |
| } |
| |
| if chain[len(chain)-1] != cand.obj { |
| return false |
| } |
| |
| for i, o := range c.inference.objChain { |
| if chain[i] != o { |
| return false |
| } |
| } |
| |
| for i, o := range cand.path { |
| if chain[i+len(c.inference.objChain)] != o { |
| return false |
| } |
| } |
| |
| return true |
| } |