github.com/jd-ly/tools@v0.5.7/internal/lsp/cmd/signature.go (about)

     1  // Copyright 2019 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package cmd
     6  
     7  import (
     8  	"context"
     9  	"flag"
    10  	"fmt"
    11  
    12  	"github.com/jd-ly/tools/internal/lsp/protocol"
    13  	"github.com/jd-ly/tools/internal/span"
    14  	"github.com/jd-ly/tools/internal/tool"
    15  )
    16  
    17  // signature implements the signature verb for gopls
    18  type signature struct {
    19  	app *Application
    20  }
    21  
    22  func (r *signature) Name() string      { return "signature" }
    23  func (r *signature) Usage() string     { return "<position>" }
    24  func (r *signature) ShortHelp() string { return "display selected identifier's signature" }
    25  func (r *signature) DetailedHelp(f *flag.FlagSet) {
    26  	fmt.Fprint(f.Output(), `
    27  Example:
    28  
    29    $ # 1-indexed location (:line:column or :#offset) of the target identifier
    30    $ gopls signature helper/helper.go:8:6
    31    $ gopls signature helper/helper.go:#53
    32  
    33    gopls signature flags are:
    34  `)
    35  	f.PrintDefaults()
    36  }
    37  
    38  func (r *signature) Run(ctx context.Context, args ...string) error {
    39  	if len(args) != 1 {
    40  		return tool.CommandLineErrorf("signature expects 1 argument (position)")
    41  	}
    42  
    43  	conn, err := r.app.connect(ctx)
    44  	if err != nil {
    45  		return err
    46  	}
    47  	defer conn.terminate(ctx)
    48  
    49  	from := span.Parse(args[0])
    50  	file := conn.AddFile(ctx, from.URI())
    51  	if file.err != nil {
    52  		return file.err
    53  	}
    54  
    55  	loc, err := file.mapper.Location(from)
    56  	if err != nil {
    57  		return err
    58  	}
    59  
    60  	tdpp := protocol.TextDocumentPositionParams{
    61  		TextDocument: protocol.TextDocumentIdentifier{
    62  			URI: protocol.URIFromSpanURI(from.URI()),
    63  		},
    64  		Position: loc.Range.Start,
    65  	}
    66  	p := protocol.SignatureHelpParams{
    67  		TextDocumentPositionParams: tdpp,
    68  	}
    69  
    70  	s, err := conn.SignatureHelp(ctx, &p)
    71  	if err != nil {
    72  		return err
    73  	}
    74  
    75  	if s == nil || len(s.Signatures) == 0 {
    76  		return tool.CommandLineErrorf("%v: not a function", from)
    77  	}
    78  
    79  	// there is only ever one possible signature,
    80  	// see toProtocolSignatureHelp in lsp/signature_help.go
    81  	signature := s.Signatures[0]
    82  	fmt.Printf("%s\n", signature.Label)
    83  	if signature.Documentation != "" {
    84  		fmt.Printf("\n%s\n", signature.Documentation)
    85  	}
    86  
    87  	return nil
    88  }