| // 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 cmd |
| |
| import ( |
| "context" |
| "flag" |
| "fmt" |
| |
| "golang.org/x/tools/gopls/internal/lsp/protocol" |
| "golang.org/x/tools/gopls/internal/span" |
| "golang.org/x/tools/internal/tool" |
| ) |
| |
| // signature implements the signature verb for gopls |
| type signature struct { |
| app *Application |
| } |
| |
| func (r *signature) Name() string { return "signature" } |
| func (r *signature) Parent() string { return r.app.Name() } |
| func (r *signature) Usage() string { return "<position>" } |
| func (r *signature) ShortHelp() string { return "display selected identifier's signature" } |
| func (r *signature) DetailedHelp(f *flag.FlagSet) { |
| fmt.Fprint(f.Output(), ` |
| Example: |
| |
| $ # 1-indexed location (:line:column or :#offset) of the target identifier |
| $ gopls signature helper/helper.go:8:6 |
| $ gopls signature helper/helper.go:#53 |
| `) |
| printFlagDefaults(f) |
| } |
| |
| func (r *signature) Run(ctx context.Context, args ...string) error { |
| if len(args) != 1 { |
| return tool.CommandLineErrorf("signature expects 1 argument (position)") |
| } |
| |
| conn, err := r.app.connect(ctx) |
| if err != nil { |
| return err |
| } |
| defer conn.terminate(ctx) |
| |
| from := span.Parse(args[0]) |
| file := conn.openFile(ctx, from.URI()) |
| if file.err != nil { |
| return file.err |
| } |
| |
| loc, err := file.mapper.SpanLocation(from) |
| if err != nil { |
| return err |
| } |
| |
| p := protocol.SignatureHelpParams{ |
| TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc), |
| } |
| |
| s, err := conn.SignatureHelp(ctx, &p) |
| if err != nil { |
| return err |
| } |
| |
| if s == nil || len(s.Signatures) == 0 { |
| return tool.CommandLineErrorf("%v: not a function", from) |
| } |
| |
| // there is only ever one possible signature, |
| // see toProtocolSignatureHelp in lsp/signature_help.go |
| signature := s.Signatures[0] |
| fmt.Printf("%s\n", signature.Label) |
| switch x := signature.Documentation.Value.(type) { |
| case string: |
| if x != "" { |
| fmt.Printf("\n%s\n", x) |
| } |
| case protocol.MarkupContent: |
| if x.Value != "" { |
| fmt.Printf("\n%s\n", x.Value) |
| } |
| } |
| |
| return nil |
| } |