| // Copyright 2020 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" |
| "fmt" |
| "go/ast" |
| "go/token" |
| "go/types" |
| "log" |
| "reflect" |
| "strings" |
| "sync" |
| "text/template" |
| |
| "golang.org/x/tools/gopls/internal/lsp/protocol" |
| "golang.org/x/tools/gopls/internal/lsp/snippet" |
| "golang.org/x/tools/gopls/internal/lsp/source" |
| "golang.org/x/tools/internal/event" |
| "golang.org/x/tools/internal/imports" |
| ) |
| |
| // Postfix snippets are artificial methods that allow the user to |
| // compose common operations in an "argument oriented" fashion. For |
| // example, instead of "sort.Slice(someSlice, ...)" a user can expand |
| // "someSlice.sort!". |
| |
| // postfixTmpl represents a postfix snippet completion candidate. |
| type postfixTmpl struct { |
| // label is the completion candidate's label presented to the user. |
| label string |
| |
| // details is passed along to the client as the candidate's details. |
| details string |
| |
| // body is the template text. See postfixTmplArgs for details on the |
| // facilities available to the template. |
| body string |
| |
| tmpl *template.Template |
| } |
| |
| // postfixTmplArgs are the template execution arguments available to |
| // the postfix snippet templates. |
| type postfixTmplArgs struct { |
| // StmtOK is true if it is valid to replace the selector with a |
| // statement. For example: |
| // |
| // func foo() { |
| // bar.sort! // statement okay |
| // |
| // someMethod(bar.sort!) // statement not okay |
| // } |
| StmtOK bool |
| |
| // X is the textual SelectorExpr.X. For example, when completing |
| // "foo.bar.print!", "X" is "foo.bar". |
| X string |
| |
| // Obj is the types.Object of SelectorExpr.X, if any. |
| Obj types.Object |
| |
| // Type is the type of "foo.bar" in "foo.bar.print!". |
| Type types.Type |
| |
| scope *types.Scope |
| snip snippet.Builder |
| importIfNeeded func(pkgPath string, scope *types.Scope) (name string, edits []protocol.TextEdit, err error) |
| edits []protocol.TextEdit |
| qf types.Qualifier |
| varNames map[string]bool |
| } |
| |
| var postfixTmpls = []postfixTmpl{{ |
| label: "sort", |
| details: "sort.Slice()", |
| body: `{{if and (eq .Kind "slice") .StmtOK -}} |
| {{.Import "sort"}}.Slice({{.X}}, func({{.VarName nil "i"}}, {{.VarName nil "j"}} int) bool { |
| {{.Cursor}} |
| }) |
| {{- end}}`, |
| }, { |
| label: "last", |
| details: "s[len(s)-1]", |
| body: `{{if and (eq .Kind "slice") .Obj -}} |
| {{.X}}[len({{.X}})-1] |
| {{- end}}`, |
| }, { |
| label: "reverse", |
| details: "reverse slice", |
| body: `{{if and (eq .Kind "slice") .StmtOK -}} |
| {{$i := .VarName nil "i"}}{{$j := .VarName nil "j" -}} |
| for {{$i}}, {{$j}} := 0, len({{.X}})-1; {{$i}} < {{$j}}; {{$i}}, {{$j}} = {{$i}}+1, {{$j}}-1 { |
| {{.X}}[{{$i}}], {{.X}}[{{$j}}] = {{.X}}[{{$j}}], {{.X}}[{{$i}}] |
| } |
| {{end}}`, |
| }, { |
| label: "range", |
| details: "range over slice", |
| body: `{{if and (eq .Kind "slice") .StmtOK -}} |
| for {{.VarName nil "i"}}, {{.VarName .ElemType "v"}} := range {{.X}} { |
| {{.Cursor}} |
| } |
| {{- end}}`, |
| }, { |
| label: "append", |
| details: "append and re-assign slice", |
| body: `{{if and (eq .Kind "slice") .StmtOK .Obj -}} |
| {{.X}} = append({{.X}}, {{.Cursor}}) |
| {{- end}}`, |
| }, { |
| label: "append", |
| details: "append to slice", |
| body: `{{if and (eq .Kind "slice") (not .StmtOK) -}} |
| append({{.X}}, {{.Cursor}}) |
| {{- end}}`, |
| }, { |
| label: "copy", |
| details: "duplicate slice", |
| body: `{{if and (eq .Kind "slice") .StmtOK .Obj -}} |
| {{$v := (.VarName nil (printf "%sCopy" .X))}}{{$v}} := make([]{{.TypeName .ElemType}}, len({{.X}})) |
| copy({{$v}}, {{.X}}) |
| {{end}}`, |
| }, { |
| label: "range", |
| details: "range over map", |
| body: `{{if and (eq .Kind "map") .StmtOK -}} |
| for {{.VarName .KeyType "k"}}, {{.VarName .ElemType "v"}} := range {{.X}} { |
| {{.Cursor}} |
| } |
| {{- end}}`, |
| }, { |
| label: "clear", |
| details: "clear map contents", |
| body: `{{if and (eq .Kind "map") .StmtOK -}} |
| {{$k := (.VarName .KeyType "k")}}for {{$k}} := range {{.X}} { |
| delete({{.X}}, {{$k}}) |
| } |
| {{end}}`, |
| }, { |
| label: "keys", |
| details: "create slice of keys", |
| body: `{{if and (eq .Kind "map") .StmtOK -}} |
| {{$keysVar := (.VarName nil "keys")}}{{$keysVar}} := make([]{{.TypeName .KeyType}}, 0, len({{.X}})) |
| {{$k := (.VarName .KeyType "k")}}for {{$k}} := range {{.X}} { |
| {{$keysVar}} = append({{$keysVar}}, {{$k}}) |
| } |
| {{end}}`, |
| }, { |
| label: "range", |
| details: "range over channel", |
| body: `{{if and (eq .Kind "chan") .StmtOK -}} |
| for {{.VarName .ElemType "e"}} := range {{.X}} { |
| {{.Cursor}} |
| } |
| {{- end}}`, |
| }, { |
| label: "var", |
| details: "assign to variables", |
| body: `{{if and (eq .Kind "tuple") .StmtOK -}} |
| {{$a := .}}{{range $i, $v := .Tuple}}{{if $i}}, {{end}}{{$a.VarName $v.Type $v.Name}}{{end}} := {{.X}} |
| {{- end}}`, |
| }, { |
| label: "var", |
| details: "assign to variable", |
| body: `{{if and (ne .Kind "tuple") .StmtOK -}} |
| {{.VarName .Type ""}} := {{.X}} |
| {{- end}}`, |
| }, { |
| label: "print", |
| details: "print to stdout", |
| body: `{{if and (ne .Kind "tuple") .StmtOK -}} |
| {{.Import "fmt"}}.Printf("{{.EscapeQuotes .X}}: %v\n", {{.X}}) |
| {{- end}}`, |
| }, { |
| label: "print", |
| details: "print to stdout", |
| body: `{{if and (eq .Kind "tuple") .StmtOK -}} |
| {{.Import "fmt"}}.Println({{.X}}) |
| {{- end}}`, |
| }, { |
| label: "split", |
| details: "split string", |
| body: `{{if (eq (.TypeName .Type) "string") -}} |
| {{.Import "strings"}}.Split({{.X}}, "{{.Cursor}}") |
| {{- end}}`, |
| }, { |
| label: "join", |
| details: "join string slice", |
| body: `{{if and (eq .Kind "slice") (eq (.TypeName .ElemType) "string") -}} |
| {{.Import "strings"}}.Join({{.X}}, "{{.Cursor}}") |
| {{- end}}`, |
| }} |
| |
| // Cursor indicates where the client's cursor should end up after the |
| // snippet is done. |
| func (a *postfixTmplArgs) Cursor() string { |
| a.snip.WriteFinalTabstop() |
| return "" |
| } |
| |
| // Import makes sure the package corresponding to path is imported, |
| // returning the identifier to use to refer to the package. |
| func (a *postfixTmplArgs) Import(path string) (string, error) { |
| name, edits, err := a.importIfNeeded(path, a.scope) |
| if err != nil { |
| return "", fmt.Errorf("couldn't import %q: %w", path, err) |
| } |
| a.edits = append(a.edits, edits...) |
| return name, nil |
| } |
| |
| func (a *postfixTmplArgs) EscapeQuotes(v string) string { |
| return strings.ReplaceAll(v, `"`, `\\"`) |
| } |
| |
| // ElemType returns the Elem() type of xType, if applicable. |
| func (a *postfixTmplArgs) ElemType() types.Type { |
| if e, _ := a.Type.(interface{ Elem() types.Type }); e != nil { |
| return e.Elem() |
| } |
| return nil |
| } |
| |
| // Kind returns the underlying kind of type, e.g. "slice", "struct", |
| // etc. |
| func (a *postfixTmplArgs) Kind() string { |
| t := reflect.TypeOf(a.Type.Underlying()) |
| return strings.ToLower(strings.TrimPrefix(t.String(), "*types.")) |
| } |
| |
| // KeyType returns the type of X's key. KeyType panics if X is not a |
| // map. |
| func (a *postfixTmplArgs) KeyType() types.Type { |
| return a.Type.Underlying().(*types.Map).Key() |
| } |
| |
| // Tuple returns the tuple result vars if X is a call expression. |
| func (a *postfixTmplArgs) Tuple() []*types.Var { |
| tuple, _ := a.Type.(*types.Tuple) |
| if tuple == nil { |
| return nil |
| } |
| |
| typs := make([]*types.Var, 0, tuple.Len()) |
| for i := 0; i < tuple.Len(); i++ { |
| typs = append(typs, tuple.At(i)) |
| } |
| return typs |
| } |
| |
| // TypeName returns the textual representation of type t. |
| func (a *postfixTmplArgs) TypeName(t types.Type) (string, error) { |
| if t == nil || t == types.Typ[types.Invalid] { |
| return "", fmt.Errorf("invalid type: %v", t) |
| } |
| return types.TypeString(t, a.qf), nil |
| } |
| |
| // VarName returns a suitable variable name for the type t. If t |
| // implements the error interface, "err" is used. If t is not a named |
| // type then nonNamedDefault is used. Otherwise a name is made by |
| // abbreviating the type name. If the resultant name is already in |
| // scope, an integer is appended to make a unique name. |
| func (a *postfixTmplArgs) VarName(t types.Type, nonNamedDefault string) string { |
| if t == nil { |
| t = types.Typ[types.Invalid] |
| } |
| |
| var name string |
| // go/types predicates are undefined on types.Typ[types.Invalid]. |
| if !types.Identical(t, types.Typ[types.Invalid]) && types.Implements(t, errorIntf) { |
| name = "err" |
| } else if _, isNamed := source.Deref(t).(*types.Named); !isNamed { |
| name = nonNamedDefault |
| } |
| |
| if name == "" { |
| name = types.TypeString(t, func(p *types.Package) string { |
| return "" |
| }) |
| name = abbreviateTypeName(name) |
| } |
| |
| if dot := strings.LastIndex(name, "."); dot > -1 { |
| name = name[dot+1:] |
| } |
| |
| uniqueName := name |
| for i := 2; ; i++ { |
| if s, _ := a.scope.LookupParent(uniqueName, token.NoPos); s == nil && !a.varNames[uniqueName] { |
| break |
| } |
| uniqueName = fmt.Sprintf("%s%d", name, i) |
| } |
| |
| a.varNames[uniqueName] = true |
| |
| return uniqueName |
| } |
| |
| func (c *completer) addPostfixSnippetCandidates(ctx context.Context, sel *ast.SelectorExpr) { |
| if !c.opts.postfix { |
| return |
| } |
| |
| initPostfixRules() |
| |
| if sel == nil || sel.Sel == nil { |
| return |
| } |
| |
| selType := c.pkg.GetTypesInfo().TypeOf(sel.X) |
| if selType == nil { |
| return |
| } |
| |
| // Skip empty tuples since there is no value to operate on. |
| if tuple, ok := selType.Underlying().(*types.Tuple); ok && tuple == nil { |
| return |
| } |
| |
| tokFile := c.pkg.FileSet().File(c.pos) |
| |
| // Only replace sel with a statement if sel is already a statement. |
| var stmtOK bool |
| for i, n := range c.path { |
| if n == sel && i < len(c.path)-1 { |
| switch p := c.path[i+1].(type) { |
| case *ast.ExprStmt: |
| stmtOK = true |
| case *ast.AssignStmt: |
| // In cases like: |
| // |
| // foo.<> |
| // bar = 123 |
| // |
| // detect that "foo." makes up the entire statement since the |
| // apparent selector spans lines. |
| stmtOK = tokFile.Line(c.pos) < tokFile.Line(p.TokPos) |
| } |
| break |
| } |
| } |
| |
| scope := c.pkg.GetTypes().Scope().Innermost(c.pos) |
| if scope == nil { |
| return |
| } |
| |
| // afterDot is the position after selector dot, e.g. "|" in |
| // "foo.|print". |
| afterDot := sel.Sel.Pos() |
| |
| // We must detect dangling selectors such as: |
| // |
| // foo.<> |
| // bar |
| // |
| // and adjust afterDot so that we don't mistakenly delete the |
| // newline thinking "bar" is part of our selector. |
| if startLine := tokFile.Line(sel.Pos()); startLine != tokFile.Line(afterDot) { |
| if tokFile.Line(c.pos) != startLine { |
| return |
| } |
| afterDot = c.pos |
| } |
| |
| for _, rule := range postfixTmpls { |
| // When completing foo.print<>, "print" is naturally overwritten, |
| // but we need to also remove "foo." so the snippet has a clean |
| // slate. |
| edits, err := c.editText(sel.Pos(), afterDot, "") |
| if err != nil { |
| event.Error(ctx, "error calculating postfix edits", err) |
| return |
| } |
| |
| tmplArgs := postfixTmplArgs{ |
| X: source.FormatNode(c.pkg.FileSet(), sel.X), |
| StmtOK: stmtOK, |
| Obj: exprObj(c.pkg.GetTypesInfo(), sel.X), |
| Type: selType, |
| qf: c.qf, |
| importIfNeeded: c.importIfNeeded, |
| scope: scope, |
| varNames: make(map[string]bool), |
| } |
| |
| // Feed the template straight into the snippet builder. This |
| // allows templates to build snippets as they are executed. |
| err = rule.tmpl.Execute(&tmplArgs.snip, &tmplArgs) |
| if err != nil { |
| event.Error(ctx, "error executing postfix template", err) |
| continue |
| } |
| |
| if strings.TrimSpace(tmplArgs.snip.String()) == "" { |
| continue |
| } |
| |
| score := c.matcher.Score(rule.label) |
| if score <= 0 { |
| continue |
| } |
| |
| c.items = append(c.items, CompletionItem{ |
| Label: rule.label + "!", |
| Detail: rule.details, |
| Score: float64(score) * 0.01, |
| Kind: protocol.SnippetCompletion, |
| snippet: &tmplArgs.snip, |
| AdditionalTextEdits: append(edits, tmplArgs.edits...), |
| }) |
| } |
| } |
| |
| var postfixRulesOnce sync.Once |
| |
| func initPostfixRules() { |
| postfixRulesOnce.Do(func() { |
| var idx int |
| for _, rule := range postfixTmpls { |
| var err error |
| rule.tmpl, err = template.New("postfix_snippet").Parse(rule.body) |
| if err != nil { |
| log.Panicf("error parsing postfix snippet template: %v", err) |
| } |
| postfixTmpls[idx] = rule |
| idx++ |
| } |
| postfixTmpls = postfixTmpls[:idx] |
| }) |
| } |
| |
| // importIfNeeded returns the package identifier and any necessary |
| // edits to import package pkgPath. |
| func (c *completer) importIfNeeded(pkgPath string, scope *types.Scope) (string, []protocol.TextEdit, error) { |
| defaultName := imports.ImportPathToAssumedName(pkgPath) |
| |
| // Check if file already imports pkgPath. |
| for _, s := range c.file.Imports { |
| // TODO(adonovan): what if pkgPath has a vendor/ suffix? |
| // This may be the cause of go.dev/issue/56291. |
| if source.UnquoteImportPath(s) == source.ImportPath(pkgPath) { |
| if s.Name == nil { |
| return defaultName, nil, nil |
| } |
| if s.Name.Name != "_" { |
| return s.Name.Name, nil, nil |
| } |
| } |
| } |
| |
| // Give up if the package's name is already in use by another object. |
| if _, obj := scope.LookupParent(defaultName, token.NoPos); obj != nil { |
| return "", nil, fmt.Errorf("import name %q of %q already in use", defaultName, pkgPath) |
| } |
| |
| edits, err := c.importEdits(&importInfo{ |
| importPath: pkgPath, |
| }) |
| if err != nil { |
| return "", nil, err |
| } |
| |
| return defaultName, edits, nil |
| } |