+++ /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
-
- // 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
-}
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