--- /dev/null
+// 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
+
+ if obj == nil {
+ continue
+ }
+
+ // At the top level, dedupe by object.
+ if len(cand.path) == 0 {
+ if c.seen[obj] {
+ continue
+ }
+ c.seen[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
+}
projects / dotfiles / .git / blobdiff