text: // 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"
  	"encoding/json"
  	"flag"
  	"fmt"
  	"os"
  	"strings"
  
  	"github.com/govim/govim/cmd/govim/internal/golang_org_x_tools/lsp/protocol"
  	"github.com/govim/govim/cmd/govim/internal/golang_org_x_tools/lsp/source"
  	"github.com/govim/govim/cmd/govim/internal/golang_org_x_tools/span"
  	"github.com/govim/govim/cmd/govim/internal/golang_org_x_tools/tool"
  	errors "golang.org/x/xerrors"
  )
  
  // A Definition is the result of a 'definition' query.
  type Definition struct {
  	Span        span.Span `json:"span"`        // span of the definition
  	Description string    `json:"description"` // description of the denoted object
  }
  
  // These constant is printed in the help, and then used in a test to verify the
  // help is still valid.
  // They refer to "Set" in "flag.FlagSet" from the DetailedHelp method below.
  const (
  	exampleLine   = 44
  	exampleColumn = 47
  	exampleOffset = 1270
  )
  
  // definition implements the definition verb for gopls.
  type definition struct {
  	app *Application
  
  	JSON              bool `flag:"json" help:"emit output in JSON format"`
  	MarkdownSupported bool `flag:"markdown" help:"support markdown in responses"`
  }
  
  func (d *definition) Name() string      { return "definition" }
  func (d *definition) Usage() string     { return "<position>" }
  func (d *definition) ShortHelp() string { return "show declaration of selected identifier" }
  func (d *definition) DetailedHelp(f *flag.FlagSet) {
  	fmt.Fprintf(f.Output(), `
  Example: show the definition of the identifier at syntax at offset %[1]v in this file (flag.FlagSet):
  
  $ gopls definition internal/lsp/cmd/definition.go:%[1]v:%[2]v
  $ gopls definition internal/lsp/cmd/definition.go:#%[3]v
  
  	gopls query definition flags are:
  `, exampleLine, exampleColumn, exampleOffset)
  	f.PrintDefaults()
  }
  
  // Run performs the definition query as specified by args and prints the
  // results to stdout.
  func (d *definition) Run(ctx context.Context, args ...string) error {
  	if len(args) != 1 {
  		return tool.CommandLineErrorf("definition expects 1 argument")
  	}
  	// Plaintext makes more sense for the command line.
  	opts := d.app.options
  	d.app.options = func(o *source.Options) {
  		if opts != nil {
  			opts(o)
  		}
  		o.PreferredContentFormat = protocol.PlainText
  		if d.MarkdownSupported {
  			o.PreferredContentFormat = protocol.Markdown
  		}
  	}
  	conn, err := d.app.connect(ctx)
  	if err != nil {
  		return err
  	}
  	defer conn.terminate(ctx)
  	from := span.Parse(args[0])
  	file := conn.AddFile(ctx, from.URI())
  	if file.err != nil {
  		return file.err
  	}
  	loc, err := file.mapper.Location(from)
  	if err != nil {
  		return err
  	}
  	tdpp := protocol.TextDocumentPositionParams{
  		TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
  		Position:     loc.Range.Start,
  	}
  	p := protocol.DefinitionParams{
  		TextDocumentPositionParams: tdpp,
  	}
  	locs, err := conn.Definition(ctx, &p)
  	if err != nil {
  		return errors.Errorf("%v: %v", from, err)
  	}
  
  	if len(locs) == 0 {
  		return errors.Errorf("%v: not an identifier", from)
  	}
  	q := protocol.HoverParams{
  		TextDocumentPositionParams: tdpp,
  	}
  	hover, err := conn.Hover(ctx, &q)
  	if err != nil {
  		return errors.Errorf("%v: %v", from, err)
  	}
  	if hover == nil {
  		return errors.Errorf("%v: not an identifier", from)
  	}
  	file = conn.AddFile(ctx, fileURI(locs[0].URI))
  	if file.err != nil {
  		return errors.Errorf("%v: %v", from, file.err)
  	}
  	definition, err := file.mapper.Span(locs[0])
  	if err != nil {
  		return errors.Errorf("%v: %v", from, err)
  	}
  	description := strings.TrimSpace(hover.Contents.Value)
  	result := &Definition{
  		Span:        definition,
  		Description: description,
  	}
  	if d.JSON {
  		enc := json.NewEncoder(os.Stdout)
  		enc.SetIndent("", "\t")
  		return enc.Encode(result)
  	}
  	fmt.Printf("%v: defined here as %s", result.Span, result.Description)
  	return nil
  }
  