| // Copyright 2018 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 source |
| |
| import ( |
| "context" |
| "go/ast" |
| "go/token" |
| "go/types" |
| "strings" |
| "time" |
| |
| "golang.org/x/tools/go/ast/astutil" |
| "golang.org/x/tools/internal/imports" |
| "golang.org/x/tools/internal/lsp/fuzzy" |
| "golang.org/x/tools/internal/lsp/protocol" |
| "golang.org/x/tools/internal/lsp/snippet" |
| "golang.org/x/tools/internal/span" |
| "golang.org/x/tools/internal/telemetry/log" |
| "golang.org/x/tools/internal/telemetry/trace" |
| errors "golang.org/x/xerrors" |
| ) |
| |
| type CompletionItem struct { |
| // Label is the primary text the user sees for this completion item. |
| Label string |
| |
| // Detail is supplemental information to present to the user. |
| // This often contains the type or return type of the completion item. |
| Detail string |
| |
| // InsertText is the text to insert if this item is selected. |
| // Any of the prefix that has already been typed is not trimmed. |
| // The insert text does not contain snippets. |
| InsertText string |
| |
| Kind protocol.CompletionItemKind |
| |
| // An optional array of additional TextEdits that are applied when |
| // selecting this completion. |
| // |
| // Additional text edits should be used to change text unrelated to the current cursor position |
| // (for example adding an import statement at the top of the file if the completion item will |
| // insert an unqualified type). |
| AdditionalTextEdits []protocol.TextEdit |
| |
| // Depth is how many levels were searched to find this completion. |
| // For example when completing "foo<>", "fooBar" is depth 0, and |
| // "fooBar.Baz" is depth 1. |
| Depth int |
| |
| // Score is the internal relevance score. |
| // A higher score indicates that this completion item is more relevant. |
| Score float64 |
| |
| // snippet is the LSP snippet for the completion item. The LSP |
| // specification contains details about LSP snippets. For example, a |
| // snippet for a function with the following signature: |
| // |
| // func foo(a, b, c int) |
| // |
| // would be: |
| // |
| // foo(${1:a int}, ${2: b int}, ${3: c int}) |
| // |
| // If Placeholders is false in the CompletionOptions, the above |
| // snippet would instead be: |
| // |
| // foo(${1:}) |
| snippet *snippet.Builder |
| |
| // Documentation is the documentation for the completion item. |
| Documentation string |
| } |
| |
| // Snippet is a convenience returns the snippet if available, otherwise |
| // the InsertText. |
| // used for an item, depending on if the callee wants placeholders or not. |
| func (i *CompletionItem) Snippet() string { |
| if i.snippet != nil { |
| return i.snippet.String() |
| } |
| return i.InsertText |
| } |
| |
| // Scoring constants are used for weighting the relevance of different candidates. |
| const ( |
| // stdScore is the base score for all completion items. |
| stdScore float64 = 1.0 |
| |
| // highScore indicates a very relevant completion item. |
| highScore float64 = 10.0 |
| |
| // lowScore indicates an irrelevant or not useful completion item. |
| lowScore float64 = 0.01 |
| ) |
| |
| // matcher matches a candidate's label against the user input. The |
| // returned score reflects the quality of the match. A score of zero |
| // indicates no match, and a score of one means a perfect match. |
| type matcher interface { |
| Score(candidateLabel string) (score float32) |
| } |
| |
| // prefixMatcher implements case sensitive prefix matching. |
| type prefixMatcher string |
| |
| func (pm prefixMatcher) Score(candidateLabel string) float32 { |
| if strings.HasPrefix(candidateLabel, string(pm)) { |
| return 1 |
| } |
| return -1 |
| } |
| |
| // insensitivePrefixMatcher implements case insensitive prefix matching. |
| type insensitivePrefixMatcher string |
| |
| func (ipm insensitivePrefixMatcher) Score(candidateLabel string) float32 { |
| if strings.HasPrefix(strings.ToLower(candidateLabel), string(ipm)) { |
| return 1 |
| } |
| return -1 |
| } |
| |
| // completer contains the necessary information for a single completion request. |
| type completer struct { |
| snapshot Snapshot |
| pkg Package |
| |
| qf types.Qualifier |
| opts CompletionOptions |
| |
| // view is the View associated with this completion request. |
| view View |
| |
| // ctx is the context associated with this completion request. |
| ctx context.Context |
| |
| // filename is the name of the file associated with this completion request. |
| filename string |
| |
| // file is the AST of the file associated with this completion request. |
| file *ast.File |
| |
| // pos is the position at which the request was triggered. |
| pos token.Pos |
| |
| // path is the path of AST nodes enclosing the position. |
| path []ast.Node |
| |
| // seen is the map that ensures we do not return duplicate results. |
| seen map[types.Object]bool |
| |
| // items is the list of completion items returned. |
| items []CompletionItem |
| |
| // surrounding describes the identifier surrounding the position. |
| surrounding *Selection |
| |
| // expectedType contains information about the type we expect the completion |
| // candidate to be. It will be the zero value if no information is available. |
| expectedType typeInference |
| |
| // enclosingFunction is the function declaration enclosing the position. |
| enclosingFunction *types.Signature |
| |
| // enclosingCompositeLiteral contains information about the composite literal |
| // enclosing the position. |
| enclosingCompositeLiteral *compLitInfo |
| |
| // deepState contains the current state of our deep completion search. |
| deepState deepCompletionState |
| |
| // matcher matches the candidates against the surrounding prefix. |
| matcher matcher |
| |
| // methodSetCache caches the types.NewMethodSet call, which is relatively |
| // expensive and can be called many times for the same type while searching |
| // for deep completions. |
| methodSetCache map[methodSetKey]*types.MethodSet |
| |
| // mapper converts the positions in the file from which the completion originated. |
| mapper *protocol.ColumnMapper |
| |
| // startTime is when we started processing this completion request. It does |
| // not include any time the request spent in the queue. |
| startTime time.Time |
| } |
| |
| type compLitInfo struct { |
| // cl is the *ast.CompositeLit enclosing the position. |
| cl *ast.CompositeLit |
| |
| // clType is the type of cl. |
| clType types.Type |
| |
| // kv is the *ast.KeyValueExpr enclosing the position, if any. |
| kv *ast.KeyValueExpr |
| |
| // inKey is true if we are certain the position is in the key side |
| // of a key-value pair. |
| inKey bool |
| |
| // maybeInFieldName is true if inKey is false and it is possible |
| // we are completing a struct field name. For example, |
| // "SomeStruct{<>}" will be inKey=false, but maybeInFieldName=true |
| // because we _could_ be completing a field name. |
| maybeInFieldName bool |
| } |
| |
| type methodSetKey struct { |
| typ types.Type |
| addressable bool |
| } |
| |
| // A Selection represents the cursor position and surrounding identifier. |
| type Selection struct { |
| content string |
| cursor token.Pos |
| mappedRange |
| } |
| |
| func (p Selection) Prefix() string { |
| return p.content[:p.cursor-p.spanRange.Start] |
| } |
| |
| func (c *completer) setSurrounding(ident *ast.Ident) { |
| if c.surrounding != nil { |
| return |
| } |
| if !(ident.Pos() <= c.pos && c.pos <= ident.End()) { |
| return |
| } |
| c.surrounding = &Selection{ |
| content: ident.Name, |
| cursor: c.pos, |
| mappedRange: mappedRange{ |
| spanRange: span.NewRange(c.view.Session().Cache().FileSet(), ident.Pos(), ident.End()), |
| m: c.mapper, |
| }, |
| } |
| |
| if c.opts.FuzzyMatching { |
| c.matcher = fuzzy.NewMatcher(c.surrounding.Prefix(), fuzzy.Symbol) |
| } else if c.opts.CaseSensitive { |
| c.matcher = prefixMatcher(c.surrounding.Prefix()) |
| } else { |
| c.matcher = insensitivePrefixMatcher(strings.ToLower(c.surrounding.Prefix())) |
| } |
| } |
| |
| func (c *completer) getSurrounding() *Selection { |
| if c.surrounding == nil { |
| c.surrounding = &Selection{ |
| content: "", |
| cursor: c.pos, |
| mappedRange: mappedRange{ |
| spanRange: span.NewRange(c.view.Session().Cache().FileSet(), c.pos, c.pos), |
| m: c.mapper, |
| }, |
| } |
| } |
| return c.surrounding |
| } |
| |
| // found adds a candidate completion. We will also search through the object's |
| // members for more candidates. |
| func (c *completer) found(obj types.Object, score float64, imp *imports.ImportInfo) { |
| if obj.Pkg() != nil && obj.Pkg() != c.pkg.GetTypes() && !obj.Exported() { |
| // obj is not accessible because it lives in another package and is not |
| // exported. Don't treat it as a completion candidate. |
| return |
| } |
| |
| if c.inDeepCompletion() { |
| // When searching deep, just 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 c.deepState.chain { |
| if seenObj == obj { |
| return |
| } |
| } |
| } else { |
| // At the top level, dedupe by object. |
| if c.seen[obj] { |
| return |
| } |
| c.seen[obj] = true |
| } |
| |
| // If we are running out of budgeted time we must limit our search for deep |
| // completion candidates. |
| if c.shouldPrune() { |
| return |
| } |
| |
| cand := candidate{ |
| obj: obj, |
| score: score, |
| imp: imp, |
| } |
| |
| if c.matchingCandidate(&cand) { |
| cand.score *= highScore |
| } 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. |
| c.literal(obj.Type()) |
| } |
| |
| // Favor shallow matches by lowering weight according to depth. |
| cand.score -= cand.score * float64(len(c.deepState.chain)) / 10 |
| if cand.score < 0 { |
| cand.score = 0 |
| } |
| |
| cand.name = c.deepState.chainString(obj.Name()) |
| matchScore := c.matcher.Score(cand.name) |
| if matchScore > 0 { |
| cand.score *= float64(matchScore) |
| |
| // Avoid calling c.item() for deep candidates that wouldn't be in the top |
| // MaxDeepCompletions anyway. |
| if !c.inDeepCompletion() || c.deepState.isHighScore(cand.score) { |
| if item, err := c.item(cand); err == nil { |
| c.items = append(c.items, item) |
| } else { |
| log.Error(c.ctx, "error generating completion item", err) |
| } |
| } |
| } |
| |
| c.deepSearch(obj) |
| } |
| |
| // candidate represents a completion candidate. |
| type candidate struct { |
| // obj is the types.Object to complete to. |
| obj types.Object |
| |
| // score is used to rank candidates. |
| score float64 |
| |
| // name is the deep object name path, e.g. "foo.bar" |
| name string |
| |
| // expandFuncCall is true if obj should be invoked in the completion. |
| // For example, expandFuncCall=true yields "foo()", expandFuncCall=false yields "foo". |
| expandFuncCall bool |
| |
| // imp is the import that needs to be added to this package in order |
| // for this candidate to be valid. nil if no import needed. |
| imp *imports.ImportInfo |
| } |
| |
| // ErrIsDefinition is an error that informs the user they got no |
| // completions because they tried to complete the name of a new object |
| // being defined. |
| type ErrIsDefinition struct { |
| objStr string |
| } |
| |
| func (e ErrIsDefinition) Error() string { |
| msg := "this is a definition" |
| if e.objStr != "" { |
| msg += " of " + e.objStr |
| } |
| return msg |
| } |
| |
| // Completion returns a list of possible candidates for completion, given a |
| // a file and a position. |
| // |
| // The selection is computed based on the preceding identifier and can be used by |
| // the client to score the quality of the completion. For instance, some clients |
| // may tolerate imperfect matches as valid completion results, since users may make typos. |
| func Completion(ctx context.Context, view View, f File, pos protocol.Position, opts CompletionOptions) ([]CompletionItem, *Selection, error) { |
| ctx, done := trace.StartSpan(ctx, "source.Completion") |
| defer done() |
| |
| startTime := time.Now() |
| |
| snapshot, cphs, err := view.CheckPackageHandles(ctx, f) |
| if err != nil { |
| return nil, nil, err |
| } |
| cph := NarrowestCheckPackageHandle(cphs) |
| pkg, err := cph.Check(ctx) |
| if err != nil { |
| return nil, nil, err |
| } |
| ph, err := pkg.File(f.URI()) |
| if err != nil { |
| return nil, nil, err |
| } |
| file, m, _, err := ph.Cached(ctx) |
| if err != nil { |
| return nil, nil, err |
| } |
| spn, err := m.PointSpan(pos) |
| if err != nil { |
| return nil, nil, err |
| } |
| rng, err := spn.Range(m.Converter) |
| if err != nil { |
| return nil, nil, err |
| } |
| // Completion is based on what precedes the cursor. |
| // Find the path to the position before pos. |
| path, _ := astutil.PathEnclosingInterval(file, rng.Start-1, rng.Start-1) |
| if path == nil { |
| return nil, nil, errors.Errorf("cannot find node enclosing position") |
| } |
| // Skip completion inside comments. |
| for _, g := range file.Comments { |
| if g.Pos() <= rng.Start && rng.Start <= g.End() { |
| return nil, nil, nil |
| } |
| } |
| // Skip completion inside any kind of literal. |
| if _, ok := path[0].(*ast.BasicLit); ok { |
| return nil, nil, nil |
| } |
| |
| clInfo := enclosingCompositeLiteral(path, rng.Start, pkg.GetTypesInfo()) |
| c := &completer{ |
| pkg: pkg, |
| snapshot: snapshot, |
| qf: qualifier(file, pkg.GetTypes(), pkg.GetTypesInfo()), |
| view: view, |
| ctx: ctx, |
| filename: f.URI().Filename(), |
| file: file, |
| path: path, |
| pos: rng.Start, |
| seen: make(map[types.Object]bool), |
| enclosingFunction: enclosingFunction(path, rng.Start, pkg.GetTypesInfo()), |
| enclosingCompositeLiteral: clInfo, |
| opts: opts, |
| // default to a matcher that always matches |
| matcher: prefixMatcher(""), |
| methodSetCache: make(map[methodSetKey]*types.MethodSet), |
| mapper: m, |
| startTime: startTime, |
| } |
| |
| if opts.Deep { |
| // Initialize max search depth to unlimited. |
| c.deepState.maxDepth = -1 |
| } |
| |
| // Set the filter surrounding. |
| if ident, ok := path[0].(*ast.Ident); ok { |
| c.setSurrounding(ident) |
| } |
| |
| c.expectedType = expectedType(c) |
| |
| // Struct literals are handled entirely separately. |
| if c.wantStructFieldCompletions() { |
| if err := c.structLiteralFieldName(); err != nil { |
| return nil, nil, err |
| } |
| return c.items, c.getSurrounding(), nil |
| } |
| |
| switch n := path[0].(type) { |
| case *ast.Ident: |
| // Is this the Sel part of a selector? |
| if sel, ok := path[1].(*ast.SelectorExpr); ok && sel.Sel == n { |
| if err := c.selector(sel); err != nil { |
| return nil, nil, err |
| } |
| return c.items, c.getSurrounding(), nil |
| } |
| // reject defining identifiers |
| if obj, ok := pkg.GetTypesInfo().Defs[n]; ok { |
| if v, ok := obj.(*types.Var); ok && v.IsField() && v.Embedded() { |
| // An anonymous field is also a reference to a type. |
| } else { |
| objStr := "" |
| if obj != nil { |
| qual := types.RelativeTo(pkg.GetTypes()) |
| objStr = types.ObjectString(obj, qual) |
| } |
| return nil, nil, ErrIsDefinition{objStr: objStr} |
| } |
| } |
| if err := c.lexical(); err != nil { |
| return nil, nil, err |
| } |
| |
| // The function name hasn't been typed yet, but the parens are there: |
| // recv.‸(arg) |
| case *ast.TypeAssertExpr: |
| // Create a fake selector expression. |
| if err := c.selector(&ast.SelectorExpr{X: n.X}); err != nil { |
| return nil, nil, err |
| } |
| |
| case *ast.SelectorExpr: |
| // The go parser inserts a phantom "_" Sel node when the selector is |
| // not followed by an identifier or a "(". The "_" isn't actually in |
| // the text, so don't think it is our surrounding. |
| // TODO: Find a way to differentiate between phantom "_" and real "_", |
| // perhaps by checking if "_" is present in file contents. |
| if n.Sel.Name != "_" || c.pos != n.Sel.Pos() { |
| c.setSurrounding(n.Sel) |
| } |
| |
| if err := c.selector(n); err != nil { |
| return nil, nil, err |
| } |
| |
| default: |
| // fallback to lexical completions |
| if err := c.lexical(); err != nil { |
| return nil, nil, err |
| } |
| } |
| |
| return c.items, c.getSurrounding(), nil |
| } |
| |
| func (c *completer) wantStructFieldCompletions() bool { |
| clInfo := c.enclosingCompositeLiteral |
| if clInfo == nil { |
| return false |
| } |
| |
| return clInfo.isStruct() && (clInfo.inKey || clInfo.maybeInFieldName) |
| } |
| |
| func (c *completer) wantTypeName() bool { |
| return c.expectedType.wantTypeName |
| } |
| |
| // selector finds completions for the specified selector expression. |
| func (c *completer) selector(sel *ast.SelectorExpr) error { |
| // Is sel a qualified identifier? |
| if id, ok := sel.X.(*ast.Ident); ok { |
| if pkgname, ok := c.pkg.GetTypesInfo().Uses[id].(*types.PkgName); ok { |
| c.packageMembers(pkgname) |
| return nil |
| } |
| } |
| |
| // Invariant: sel is a true selector. |
| tv, ok := c.pkg.GetTypesInfo().Types[sel.X] |
| if !ok { |
| return errors.Errorf("cannot resolve %s", sel.X) |
| } |
| |
| return c.methodsAndFields(tv.Type, tv.Addressable()) |
| } |
| |
| func (c *completer) packageMembers(pkg *types.PkgName) { |
| scope := pkg.Imported().Scope() |
| for _, name := range scope.Names() { |
| c.found(scope.Lookup(name), stdScore, nil) |
| } |
| } |
| |
| func (c *completer) methodsAndFields(typ types.Type, addressable bool) error { |
| mset := c.methodSetCache[methodSetKey{typ, addressable}] |
| if mset == nil { |
| if addressable && !types.IsInterface(typ) && !isPointer(typ) { |
| // Add methods of *T, which includes methods with receiver T. |
| mset = types.NewMethodSet(types.NewPointer(typ)) |
| } else { |
| // Add methods of T. |
| mset = types.NewMethodSet(typ) |
| } |
| c.methodSetCache[methodSetKey{typ, addressable}] = mset |
| } |
| |
| for i := 0; i < mset.Len(); i++ { |
| c.found(mset.At(i).Obj(), stdScore, nil) |
| } |
| |
| // Add fields of T. |
| for _, f := range fieldSelections(typ) { |
| c.found(f, stdScore, nil) |
| } |
| return nil |
| } |
| |
| // lexical finds completions in the lexical environment. |
| func (c *completer) lexical() error { |
| var scopes []*types.Scope // scopes[i], where i<len(path), is the possibly nil Scope of path[i]. |
| for _, n := range c.path { |
| // Include *FuncType scope if pos is inside the function body. |
| switch node := n.(type) { |
| case *ast.FuncDecl: |
| if node.Body != nil && nodeContains(node.Body, c.pos) { |
| n = node.Type |
| } |
| case *ast.FuncLit: |
| if node.Body != nil && nodeContains(node.Body, c.pos) { |
| n = node.Type |
| } |
| } |
| scopes = append(scopes, c.pkg.GetTypesInfo().Scopes[n]) |
| } |
| scopes = append(scopes, c.pkg.GetTypes().Scope(), types.Universe) |
| |
| builtinIota := types.Universe.Lookup("iota") |
| |
| // Track seen variables to avoid showing completions for shadowed variables. |
| // This works since we look at scopes from innermost to outermost. |
| seen := make(map[string]struct{}) |
| |
| // Process scopes innermost first. |
| for i, scope := range scopes { |
| if scope == nil { |
| continue |
| } |
| for _, name := range scope.Names() { |
| declScope, obj := scope.LookupParent(name, c.pos) |
| if declScope != scope { |
| continue // Name was declared in some enclosing scope, or not at all. |
| } |
| // If obj's type is invalid, find the AST node that defines the lexical block |
| // containing the declaration of obj. Don't resolve types for packages. |
| if _, ok := obj.(*types.PkgName); !ok && obj.Type() == types.Typ[types.Invalid] { |
| // Match the scope to its ast.Node. If the scope is the package scope, |
| // use the *ast.File as the starting node. |
| var node ast.Node |
| if i < len(c.path) { |
| node = c.path[i] |
| } else if i == len(c.path) { // use the *ast.File for package scope |
| node = c.path[i-1] |
| } |
| if node != nil { |
| if resolved := resolveInvalid(obj, node, c.pkg.GetTypesInfo()); resolved != nil { |
| obj = resolved |
| } |
| } |
| } |
| |
| // Don't suggest "iota" outside of const decls. |
| if obj == builtinIota && !c.inConstDecl() { |
| continue |
| } |
| |
| // If we haven't already added a candidate for an object with this name. |
| if _, ok := seen[obj.Name()]; !ok { |
| seen[obj.Name()] = struct{}{} |
| c.found(obj, stdScore, nil) |
| } |
| } |
| } |
| |
| if c.opts.Unimported { |
| // Suggest packages that have not been imported yet. |
| pkgs, err := CandidateImports(c.ctx, c.view, c.filename) |
| if err != nil { |
| return err |
| } |
| score := stdScore |
| // Rank unimported packages significantly lower than other results. |
| score *= 0.07 |
| for _, pkg := range pkgs { |
| if _, ok := seen[pkg.IdentName]; !ok { |
| // Do not add the unimported packages to seen, since we can have |
| // multiple packages of the same name as completion suggestions, since |
| // only one will be chosen. |
| obj := types.NewPkgName(0, nil, pkg.IdentName, types.NewPackage(pkg.StmtInfo.ImportPath, pkg.IdentName)) |
| c.found(obj, score, &pkg.StmtInfo) |
| } |
| } |
| } |
| |
| if c.expectedType.objType != nil { |
| // If we have an expected type and it is _not_ a named type, see |
| // if an object literal makes a good candidate. Named types are |
| // handled during the normal lexical object search. For example, |
| // if our expected type is "[]int", this will add a candidate of |
| // "[]int{}". |
| if _, named := deref(c.expectedType.objType).(*types.Named); !named { |
| c.literal(c.expectedType.objType) |
| } |
| } |
| |
| return nil |
| } |
| |
| func nodeContains(n ast.Node, pos token.Pos) bool { |
| return n != nil && n.Pos() <= pos && pos < n.End() |
| } |
| |
| func (c *completer) inConstDecl() bool { |
| for _, n := range c.path { |
| if decl, ok := n.(*ast.GenDecl); ok && decl.Tok == token.CONST { |
| return true |
| } |
| } |
| return false |
| } |
| |
| // structLiteralFieldName finds completions for struct field names inside a struct literal. |
| func (c *completer) structLiteralFieldName() error { |
| clInfo := c.enclosingCompositeLiteral |
| |
| // Mark fields of the composite literal that have already been set, |
| // except for the current field. |
| addedFields := make(map[*types.Var]bool) |
| for _, el := range clInfo.cl.Elts { |
| if kvExpr, ok := el.(*ast.KeyValueExpr); ok { |
| if clInfo.kv == kvExpr { |
| continue |
| } |
| |
| if key, ok := kvExpr.Key.(*ast.Ident); ok { |
| if used, ok := c.pkg.GetTypesInfo().Uses[key]; ok { |
| if usedVar, ok := used.(*types.Var); ok { |
| addedFields[usedVar] = true |
| } |
| } |
| } |
| } |
| } |
| |
| switch t := clInfo.clType.(type) { |
| case *types.Struct: |
| for i := 0; i < t.NumFields(); i++ { |
| field := t.Field(i) |
| if !addedFields[field] { |
| c.found(field, highScore, nil) |
| } |
| } |
| |
| // Add lexical completions if we aren't certain we are in the key part of a |
| // key-value pair. |
| if clInfo.maybeInFieldName { |
| return c.lexical() |
| } |
| default: |
| return c.lexical() |
| } |
| |
| return nil |
| } |
| |
| func (cl *compLitInfo) isStruct() bool { |
| _, ok := cl.clType.(*types.Struct) |
| return ok |
| } |
| |
| // enclosingCompositeLiteral returns information about the composite literal enclosing the |
| // position. |
| func enclosingCompositeLiteral(path []ast.Node, pos token.Pos, info *types.Info) *compLitInfo { |
| for _, n := range path { |
| switch n := n.(type) { |
| case *ast.CompositeLit: |
| // The enclosing node will be a composite literal if the user has just |
| // opened the curly brace (e.g. &x{<>) or the completion request is triggered |
| // from an already completed composite literal expression (e.g. &x{foo: 1, <>}) |
| // |
| // The position is not part of the composite literal unless it falls within the |
| // curly braces (e.g. "foo.Foo<>Struct{}"). |
| if !(n.Lbrace <= pos && pos <= n.Rbrace) { |
| return nil |
| } |
| |
| tv, ok := info.Types[n] |
| if !ok { |
| return nil |
| } |
| |
| clInfo := compLitInfo{ |
| cl: n, |
| clType: deref(tv.Type).Underlying(), |
| } |
| |
| var ( |
| expr ast.Expr |
| hasKeys bool |
| ) |
| for _, el := range n.Elts { |
| // Remember the expression that the position falls in, if any. |
| if el.Pos() <= pos && pos <= el.End() { |
| expr = el |
| } |
| |
| if kv, ok := el.(*ast.KeyValueExpr); ok { |
| hasKeys = true |
| // If expr == el then we know the position falls in this expression, |
| // so also record kv as the enclosing *ast.KeyValueExpr. |
| if expr == el { |
| clInfo.kv = kv |
| break |
| } |
| } |
| } |
| |
| if clInfo.kv != nil { |
| // If in a *ast.KeyValueExpr, we know we are in the key if the position |
| // is to the left of the colon (e.g. "Foo{F<>: V}". |
| clInfo.inKey = pos <= clInfo.kv.Colon |
| } else if hasKeys { |
| // If we aren't in a *ast.KeyValueExpr but the composite literal has |
| // other *ast.KeyValueExprs, we must be on the key side of a new |
| // *ast.KeyValueExpr (e.g. "Foo{F: V, <>}"). |
| clInfo.inKey = true |
| } else { |
| switch clInfo.clType.(type) { |
| case *types.Struct: |
| if len(n.Elts) == 0 { |
| // If the struct literal is empty, next could be a struct field |
| // name or an expression (e.g. "Foo{<>}" could become "Foo{F:}" |
| // or "Foo{someVar}"). |
| clInfo.maybeInFieldName = true |
| } else if len(n.Elts) == 1 { |
| // If there is one expression and the position is in that expression |
| // and the expression is an identifier, we may be writing a field |
| // name or an expression (e.g. "Foo{F<>}"). |
| _, clInfo.maybeInFieldName = expr.(*ast.Ident) |
| } |
| case *types.Map: |
| // If we aren't in a *ast.KeyValueExpr we must be adding a new key |
| // to the map. |
| clInfo.inKey = true |
| } |
| } |
| |
| return &clInfo |
| default: |
| if breaksExpectedTypeInference(n) { |
| return nil |
| } |
| } |
| } |
| |
| return nil |
| } |
| |
| // enclosingFunction returns the signature of the function enclosing the given position. |
| func enclosingFunction(path []ast.Node, pos token.Pos, info *types.Info) *types.Signature { |
| for _, node := range path { |
| switch t := node.(type) { |
| case *ast.FuncDecl: |
| if obj, ok := info.Defs[t.Name]; ok { |
| return obj.Type().(*types.Signature) |
| } |
| case *ast.FuncLit: |
| if typ, ok := info.Types[t]; ok { |
| return typ.Type.(*types.Signature) |
| } |
| } |
| } |
| return nil |
| } |
| |
| func (c *completer) expectedCompositeLiteralType() types.Type { |
| clInfo := c.enclosingCompositeLiteral |
| switch t := clInfo.clType.(type) { |
| case *types.Slice: |
| if clInfo.inKey { |
| return types.Typ[types.Int] |
| } |
| return t.Elem() |
| case *types.Array: |
| if clInfo.inKey { |
| return types.Typ[types.Int] |
| } |
| return t.Elem() |
| case *types.Map: |
| if clInfo.inKey { |
| return t.Key() |
| } |
| return t.Elem() |
| case *types.Struct: |
| // If we are completing a key (i.e. field name), there is no expected type. |
| if clInfo.inKey { |
| return nil |
| } |
| |
| // If we are in a key-value pair, but not in the key, then we must be on the |
| // value side. The expected type of the value will be determined from the key. |
| if clInfo.kv != nil { |
| if key, ok := clInfo.kv.Key.(*ast.Ident); ok { |
| for i := 0; i < t.NumFields(); i++ { |
| if field := t.Field(i); field.Name() == key.Name { |
| return field.Type() |
| } |
| } |
| } |
| } else { |
| // If we aren't in a key-value pair and aren't in the key, we must be using |
| // implicit field names. |
| |
| // The order of the literal fields must match the order in the struct definition. |
| // Find the element that the position belongs to and suggest that field's type. |
| if i := indexExprAtPos(c.pos, clInfo.cl.Elts); i < t.NumFields() { |
| return t.Field(i).Type() |
| } |
| } |
| } |
| return nil |
| } |
| |
| // typeModifier represents an operator that changes the expected type. |
| type typeModifier int |
| |
| const ( |
| star typeModifier = iota // dereference operator for expressions, pointer indicator for types |
| reference // reference ("&") operator |
| chanRead // channel read ("<-") operator |
| ) |
| |
| // typeInference holds information we have inferred about a type that can be |
| // used at the current position. |
| type typeInference struct { |
| // objType is the desired type of an object used at the query position. |
| objType types.Type |
| |
| // variadic is true if objType is a slice type from an initial |
| // variadic param. |
| variadic bool |
| |
| // wantTypeName is true if we expect the name of a type. |
| wantTypeName bool |
| |
| // modifiers are prefixes such as "*", "&" or "<-" that influence how |
| // a candidate type relates to the expected type. |
| modifiers []typeModifier |
| |
| // assertableFrom is a type that must be assertable to our candidate type. |
| assertableFrom types.Type |
| |
| // convertibleTo is a type our candidate type must be convertible to. |
| convertibleTo types.Type |
| } |
| |
| // expectedType returns information about the expected type for an expression at |
| // the query position. |
| func expectedType(c *completer) typeInference { |
| if ti := expectTypeName(c); ti.wantTypeName { |
| return ti |
| } |
| |
| if c.enclosingCompositeLiteral != nil { |
| return typeInference{objType: c.expectedCompositeLiteralType()} |
| } |
| |
| var ( |
| modifiers []typeModifier |
| variadic bool |
| typ types.Type |
| convertibleTo types.Type |
| ) |
| |
| Nodes: |
| for i, node := range c.path { |
| switch node := node.(type) { |
| case *ast.BinaryExpr: |
| // Determine if query position comes from left or right of op. |
| e := node.X |
| if c.pos < node.OpPos { |
| e = node.Y |
| } |
| if tv, ok := c.pkg.GetTypesInfo().Types[e]; ok { |
| typ = tv.Type |
| break Nodes |
| } |
| case *ast.AssignStmt: |
| // Only rank completions if you are on the right side of the token. |
| if c.pos > node.TokPos { |
| i := indexExprAtPos(c.pos, node.Rhs) |
| if i >= len(node.Lhs) { |
| i = len(node.Lhs) - 1 |
| } |
| if tv, ok := c.pkg.GetTypesInfo().Types[node.Lhs[i]]; ok { |
| typ = tv.Type |
| break Nodes |
| } |
| } |
| return typeInference{} |
| case *ast.CallExpr: |
| // Only consider CallExpr args if position falls between parens. |
| if node.Lparen <= c.pos && c.pos <= node.Rparen { |
| // For type conversions like "int64(foo)" we can only infer our |
| // desired type is convertible to int64. |
| if typ := typeConversion(node, c.pkg.GetTypesInfo()); typ != nil { |
| convertibleTo = typ |
| break Nodes |
| } |
| |
| if tv, ok := c.pkg.GetTypesInfo().Types[node.Fun]; ok { |
| if sig, ok := tv.Type.(*types.Signature); ok { |
| if sig.Params().Len() == 0 { |
| return typeInference{} |
| } |
| i := indexExprAtPos(c.pos, node.Args) |
| // Make sure not to run past the end of expected parameters. |
| if i >= sig.Params().Len() { |
| i = sig.Params().Len() - 1 |
| } |
| typ = sig.Params().At(i).Type() |
| variadic = sig.Variadic() && i == sig.Params().Len()-1 |
| break Nodes |
| } |
| } |
| } |
| return typeInference{} |
| case *ast.ReturnStmt: |
| if sig := c.enclosingFunction; sig != nil { |
| // Find signature result that corresponds to our return statement. |
| if resultIdx := indexExprAtPos(c.pos, node.Results); resultIdx < len(node.Results) { |
| if resultIdx < sig.Results().Len() { |
| typ = sig.Results().At(resultIdx).Type() |
| break Nodes |
| } |
| } |
| } |
| return typeInference{} |
| case *ast.CaseClause: |
| if swtch, ok := findSwitchStmt(c.path[i+1:], c.pos, node).(*ast.SwitchStmt); ok { |
| if tv, ok := c.pkg.GetTypesInfo().Types[swtch.Tag]; ok { |
| typ = tv.Type |
| break Nodes |
| } |
| } |
| return typeInference{} |
| case *ast.SliceExpr: |
| // Make sure position falls within the brackets (e.g. "foo[a:<>]"). |
| if node.Lbrack < c.pos && c.pos <= node.Rbrack { |
| typ = types.Typ[types.Int] |
| break Nodes |
| } |
| return typeInference{} |
| case *ast.IndexExpr: |
| // Make sure position falls within the brackets (e.g. "foo[<>]"). |
| if node.Lbrack < c.pos && c.pos <= node.Rbrack { |
| if tv, ok := c.pkg.GetTypesInfo().Types[node.X]; ok { |
| switch t := tv.Type.Underlying().(type) { |
| case *types.Map: |
| typ = t.Key() |
| case *types.Slice, *types.Array: |
| typ = types.Typ[types.Int] |
| default: |
| return typeInference{} |
| } |
| break Nodes |
| } |
| } |
| return typeInference{} |
| case *ast.SendStmt: |
| // Make sure we are on right side of arrow (e.g. "foo <- <>"). |
| if c.pos > node.Arrow+1 { |
| if tv, ok := c.pkg.GetTypesInfo().Types[node.Chan]; ok { |
| if ch, ok := tv.Type.Underlying().(*types.Chan); ok { |
| typ = ch.Elem() |
| break Nodes |
| } |
| } |
| } |
| return typeInference{} |
| case *ast.StarExpr: |
| modifiers = append(modifiers, star) |
| case *ast.UnaryExpr: |
| switch node.Op { |
| case token.AND: |
| modifiers = append(modifiers, reference) |
| case token.ARROW: |
| modifiers = append(modifiers, chanRead) |
| } |
| default: |
| if breaksExpectedTypeInference(node) { |
| return typeInference{} |
| } |
| } |
| } |
| |
| return typeInference{ |
| variadic: variadic, |
| objType: typ, |
| modifiers: modifiers, |
| convertibleTo: convertibleTo, |
| } |
| } |
| |
| // applyTypeModifiers applies the list of type modifiers to a type. |
| func (ti typeInference) applyTypeModifiers(typ types.Type) types.Type { |
| for _, mod := range ti.modifiers { |
| switch mod { |
| case star: |
| // For every "*" deref operator, remove a pointer layer from candidate type. |
| typ = deref(typ) |
| case reference: |
| // For every "&" ref operator, add another pointer layer to candidate type. |
| typ = types.NewPointer(typ) |
| case chanRead: |
| // For every "<-" operator, remove a layer of channelness. |
| if ch, ok := typ.(*types.Chan); ok { |
| typ = ch.Elem() |
| } |
| } |
| } |
| return typ |
| } |
| |
| // applyTypeNameModifiers applies the list of type modifiers to a type name. |
| func (ti typeInference) applyTypeNameModifiers(typ types.Type) types.Type { |
| for _, mod := range ti.modifiers { |
| switch mod { |
| case star: |
| // For every "*" indicator, add a pointer layer to type name. |
| typ = types.NewPointer(typ) |
| } |
| } |
| return typ |
| } |
| |
| // findSwitchStmt returns an *ast.CaseClause's corresponding *ast.SwitchStmt or |
| // *ast.TypeSwitchStmt. path should start from the case clause's first ancestor. |
| func findSwitchStmt(path []ast.Node, pos token.Pos, c *ast.CaseClause) ast.Stmt { |
| // Make sure position falls within a "case <>:" clause. |
| if exprAtPos(pos, c.List) == nil { |
| return nil |
| } |
| // A case clause is always nested within a block statement in a switch statement. |
| if len(path) < 2 { |
| return nil |
| } |
| if _, ok := path[0].(*ast.BlockStmt); !ok { |
| return nil |
| } |
| switch s := path[1].(type) { |
| case *ast.SwitchStmt: |
| return s |
| case *ast.TypeSwitchStmt: |
| return s |
| default: |
| return nil |
| } |
| } |
| |
| // breaksExpectedTypeInference reports if an expression node's type is unrelated |
| // to its child expression node types. For example, "Foo{Bar: x.Baz(<>)}" should |
| // expect a function argument, not a composite literal value. |
| func breaksExpectedTypeInference(n ast.Node) bool { |
| switch n.(type) { |
| case *ast.FuncLit, *ast.CallExpr, *ast.TypeAssertExpr, *ast.IndexExpr, *ast.SliceExpr, *ast.CompositeLit: |
| return true |
| default: |
| return false |
| } |
| } |
| |
| // expectTypeName returns information about the expected type name at position. |
| func expectTypeName(c *completer) typeInference { |
| var ( |
| wantTypeName bool |
| modifiers []typeModifier |
| assertableFrom types.Type |
| ) |
| |
| Nodes: |
| for i, p := range c.path { |
| switch n := p.(type) { |
| case *ast.FieldList: |
| // Expect a type name if pos is in a FieldList. This applies to |
| // FuncType params/results, FuncDecl receiver, StructType, and |
| // InterfaceType. We don't need to worry about the field name |
| // because completion bails out early if pos is in an *ast.Ident |
| // that defines an object. |
| wantTypeName = true |
| break Nodes |
| case *ast.CaseClause: |
| // Expect type names in type switch case clauses. |
| if swtch, ok := findSwitchStmt(c.path[i+1:], c.pos, n).(*ast.TypeSwitchStmt); ok { |
| // The case clause types must be assertable from the type switch parameter. |
| ast.Inspect(swtch.Assign, func(n ast.Node) bool { |
| if ta, ok := n.(*ast.TypeAssertExpr); ok { |
| assertableFrom = c.pkg.GetTypesInfo().TypeOf(ta.X) |
| return false |
| } |
| return true |
| }) |
| wantTypeName = true |
| break Nodes |
| } |
| return typeInference{} |
| case *ast.TypeAssertExpr: |
| // Expect type names in type assert expressions. |
| if n.Lparen < c.pos && c.pos <= n.Rparen { |
| // The type in parens must be assertable from the expression type. |
| assertableFrom = c.pkg.GetTypesInfo().TypeOf(n.X) |
| wantTypeName = true |
| break Nodes |
| } |
| return typeInference{} |
| case *ast.StarExpr: |
| modifiers = append(modifiers, star) |
| default: |
| if breaksExpectedTypeInference(p) { |
| return typeInference{} |
| } |
| } |
| } |
| |
| return typeInference{ |
| wantTypeName: wantTypeName, |
| modifiers: modifiers, |
| assertableFrom: assertableFrom, |
| } |
| } |
| |
| // matchingType reports whether a type matches the expected type. |
| func (c *completer) matchingType(T types.Type) bool { |
| fakeObj := types.NewVar(token.NoPos, c.pkg.GetTypes(), "", T) |
| return c.matchingCandidate(&candidate{obj: fakeObj}) |
| } |
| |
| // matchingCandidate reports whether a candidate matches our type |
| // inferences. |
| func (c *completer) matchingCandidate(cand *candidate) bool { |
| if isTypeName(cand.obj) { |
| return c.matchingTypeName(cand) |
| } |
| |
| objType := cand.obj.Type() |
| |
| // Default to invoking *types.Func candidates. This is so function |
| // completions in an empty statement (or other cases with no expected type) |
| // are invoked by default. |
| cand.expandFuncCall = isFunc(cand.obj) |
| |
| typeMatches := func(candType types.Type) bool { |
| // Take into account any type modifiers on the expected type. |
| candType = c.expectedType.applyTypeModifiers(candType) |
| |
| if c.expectedType.objType != nil { |
| wantType := types.Default(c.expectedType.objType) |
| |
| // Handle untyped values specially since AssignableTo gives false negatives |
| // for them (see https://golang.org/issue/32146). |
| if candBasic, ok := candType.(*types.Basic); ok && candBasic.Info()&types.IsUntyped > 0 { |
| if wantBasic, ok := wantType.Underlying().(*types.Basic); ok { |
| // Check that their constant kind (bool|int|float|complex|string) matches. |
| // This doesn't take into account the constant value, so there will be some |
| // false positives due to integer sign and overflow. |
| return candBasic.Info()&types.IsConstType == wantBasic.Info()&types.IsConstType |
| } |
| return false |
| } |
| |
| // AssignableTo covers the case where the types are equal, but also handles |
| // cases like assigning a concrete type to an interface type. |
| return types.AssignableTo(candType, wantType) |
| } |
| |
| return false |
| } |
| |
| if typeMatches(objType) { |
| // If obj's type matches, we don't want to expand to an invocation of obj. |
| cand.expandFuncCall = false |
| return true |
| } |
| |
| // Try using a function's return type as its type. |
| if sig, ok := objType.Underlying().(*types.Signature); ok && sig.Results().Len() == 1 { |
| if typeMatches(sig.Results().At(0).Type()) { |
| // If obj's return value matches the expected type, we need to invoke obj |
| // in the completion. |
| cand.expandFuncCall = true |
| return true |
| } |
| } |
| |
| if c.expectedType.convertibleTo != nil { |
| return types.ConvertibleTo(objType, c.expectedType.convertibleTo) |
| } |
| |
| return false |
| } |
| |
| func (c *completer) matchingTypeName(cand *candidate) bool { |
| if !c.wantTypeName() { |
| return false |
| } |
| |
| // Take into account any type name modifier prefixes. |
| actual := c.expectedType.applyTypeNameModifiers(cand.obj.Type()) |
| |
| if c.expectedType.assertableFrom != nil { |
| // Don't suggest the starting type in type assertions. For example, |
| // if "foo" is an io.Writer, don't suggest "foo.(io.Writer)". |
| if types.Identical(c.expectedType.assertableFrom, actual) { |
| return false |
| } |
| |
| if intf, ok := c.expectedType.assertableFrom.Underlying().(*types.Interface); ok { |
| if !types.AssertableTo(intf, actual) { |
| return false |
| } |
| } |
| } |
| |
| // Default to saying any type name is a match. |
| return true |
| } |