blob: 9f12051a091cef31544874d6fcf3d50e50749a1c [file] [log] [blame]
// 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 lsp
import (
"bytes"
"context"
"fmt"
"strings"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/lsp/debug/tag"
"golang.org/x/tools/internal/lsp/protocol"
"golang.org/x/tools/internal/lsp/source"
"golang.org/x/tools/internal/lsp/source/completion"
"golang.org/x/tools/internal/span"
)
func (s *Server) completion(ctx context.Context, params *protocol.CompletionParams) (*protocol.CompletionList, error) {
snapshot, fh, ok, release, err := s.beginFileRequest(ctx, params.TextDocument.URI, source.UnknownKind)
defer release()
if !ok {
return nil, err
}
var candidates []completion.CompletionItem
var surrounding *completion.Selection
switch fh.Kind() {
case source.Go:
candidates, surrounding, err = completion.Completion(ctx, snapshot, fh, params.Position, params.Context.TriggerCharacter)
case source.Mod:
candidates, surrounding = nil, nil
}
if err != nil {
event.Error(ctx, "no completions found", err, tag.Position.Of(params.Position))
}
if candidates == nil {
return &protocol.CompletionList{
Items: []protocol.CompletionItem{},
}, nil
}
// We might need to adjust the position to account for the prefix.
rng, err := surrounding.Range()
if err != nil {
return nil, err
}
// internal/span treats end of file as the beginning of the next line, even
// when it's not newline-terminated. We correct for that behaviour here if
// end of file is not newline-terminated. See golang/go#41029.
src, err := fh.Read()
if err != nil {
return nil, err
}
numLines := len(bytes.Split(src, []byte("\n")))
tok := snapshot.FileSet().File(surrounding.Start())
eof := tok.Pos(tok.Size())
// For newline-terminated files, the line count reported by go/token should
// be lower than the actual number of lines we see when splitting by \n. If
// they're the same, the file isn't newline-terminated.
if tok.Size() > 0 && tok.LineCount() == numLines {
// Get the span for the last character in the file-1. This is
// technically incorrect, but will get span to point to the previous
// line.
spn, err := span.NewRange(snapshot.FileSet(), eof-1, eof-1).Span()
if err != nil {
return nil, err
}
m := &protocol.ColumnMapper{
URI: fh.URI(),
Converter: span.NewContentConverter(fh.URI().Filename(), src),
Content: src,
}
eofRng, err := m.Range(spn)
if err != nil {
return nil, err
}
// Instead of using the computed range, correct for our earlier
// position adjustment by adding 1 to the column, not the line number.
pos := protocol.Position{
Line: eofRng.Start.Line,
Character: eofRng.Start.Character + 1,
}
if surrounding.Start() >= eof {
rng.Start = pos
}
if surrounding.End() >= eof {
rng.End = pos
}
}
// When using deep completions/fuzzy matching, report results as incomplete so
// client fetches updated completions after every key stroke.
options := snapshot.View().Options()
incompleteResults := options.DeepCompletion || options.Matcher == source.Fuzzy
items := toProtocolCompletionItems(candidates, rng, options)
return &protocol.CompletionList{
IsIncomplete: incompleteResults,
Items: items,
}, nil
}
func toProtocolCompletionItems(candidates []completion.CompletionItem, rng protocol.Range, options source.Options) []protocol.CompletionItem {
var (
items = make([]protocol.CompletionItem, 0, len(candidates))
numDeepCompletionsSeen int
)
for i, candidate := range candidates {
// Limit the number of deep completions to not overwhelm the user in cases
// with dozens of deep completion matches.
if candidate.Depth > 0 {
if !options.DeepCompletion {
continue
}
if numDeepCompletionsSeen >= completion.MaxDeepCompletions {
continue
}
numDeepCompletionsSeen++
}
insertText := candidate.InsertText
if options.InsertTextFormat == protocol.SnippetTextFormat {
insertText = candidate.Snippet()
}
// This can happen if the client has snippets disabled but the
// candidate only supports snippet insertion.
if insertText == "" {
continue
}
item := protocol.CompletionItem{
Label: candidate.Label,
Detail: candidate.Detail,
Kind: candidate.Kind,
TextEdit: &protocol.TextEdit{
NewText: insertText,
Range: rng,
},
InsertTextFormat: options.InsertTextFormat,
AdditionalTextEdits: candidate.AdditionalTextEdits,
// This is a hack so that the client sorts completion results in the order
// according to their score. This can be removed upon the resolution of
// https://github.com/Microsoft/language-server-protocol/issues/348.
SortText: fmt.Sprintf("%05d", i),
// Trim operators (VSCode doesn't like weird characters in
// filterText).
FilterText: strings.TrimLeft(candidate.InsertText, "&*"),
Preselect: i == 0,
Documentation: candidate.Documentation,
}
items = append(items, item)
}
return items
}