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// 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 completion
import (
"context"
"fmt"
"go/types"
"strings"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/imports"
"golang.org/x/tools/internal/lsp/debug/tag"
"golang.org/x/tools/internal/lsp/protocol"
"golang.org/x/tools/internal/lsp/snippet"
"golang.org/x/tools/internal/lsp/source"
"golang.org/x/tools/internal/span"
errors "golang.org/x/xerrors"
)
// item formats a candidate to a CompletionItem.
func (c *completer) item(ctx context.Context, cand candidate) (CompletionItem, error) {
obj := cand.obj
// if the object isn't a valid match against the surrounding, return early.
matchScore := c.matcher.Score(cand.name)
if matchScore <= 0 {
return CompletionItem{}, errors.New("not a surrounding match")
}
cand.score *= float64(matchScore)
// Ignore deep candidates that wont be in the MaxDeepCompletions anyway.
if len(cand.path) != 0 && !c.deepState.isHighScore(cand.score) {
return CompletionItem{}, errors.New("not a high scoring candidate")
}
// Handle builtin types separately.
if obj.Parent() == types.Universe {
return c.formatBuiltin(ctx, cand)
}
var (
label = cand.name
detail = types.TypeString(obj.Type(), c.qf)
insert = label
kind = protocol.TextCompletion
snip *snippet.Builder
protocolEdits []protocol.TextEdit
)
if obj.Type() == nil {
detail = ""
}
// expandFuncCall mutates the completion label, detail, and snippet
// to that of an invocation of sig.
expandFuncCall := func(sig *types.Signature) {
s := source.NewSignature(ctx, c.snapshot, c.pkg, sig, nil, c.qf)
snip = c.functionCallSnippet(label, s.Params())
detail = "func" + s.Format()
}
switch obj := obj.(type) {
case *types.TypeName:
detail, kind = source.FormatType(obj.Type(), c.qf)
case *types.Const:
kind = protocol.ConstantCompletion
case *types.Var:
if _, ok := obj.Type().(*types.Struct); ok {
detail = "struct{...}" // for anonymous structs
} else if obj.IsField() {
detail = source.FormatVarType(ctx, c.snapshot, c.pkg, obj, c.qf)
}
if obj.IsField() {
kind = protocol.FieldCompletion
snip = c.structFieldSnippet(cand, label, detail)
} else {
kind = protocol.VariableCompletion
}
if obj.Type() == nil {
break
}
if sig, ok := obj.Type().Underlying().(*types.Signature); ok && cand.expandFuncCall {
expandFuncCall(sig)
}
case *types.Func:
sig, ok := obj.Type().Underlying().(*types.Signature)
if !ok {
break
}
kind = protocol.FunctionCompletion
if sig != nil && sig.Recv() != nil {
kind = protocol.MethodCompletion
}
if cand.expandFuncCall {
expandFuncCall(sig)
}
case *types.PkgName:
kind = protocol.ModuleCompletion
detail = fmt.Sprintf("%q", obj.Imported().Path())
case *types.Label:
kind = protocol.ConstantCompletion
detail = "label"
}
// If this candidate needs an additional import statement,
// add the additional text edits needed.
if cand.imp != nil {
addlEdits, err := c.importEdits(cand.imp)
if err != nil {
return CompletionItem{}, err
}
protocolEdits = append(protocolEdits, addlEdits...)
if kind != protocol.ModuleCompletion {
if detail != "" {
detail += " "
}
detail += fmt.Sprintf("(from %q)", cand.imp.importPath)
}
}
// Prepend "&" or "*" operator as appropriate.
var prefixOp string
if cand.takeAddress {
prefixOp = "&"
} else if cand.makePointer {
prefixOp = "*"
} else if cand.dereference > 0 {
prefixOp = strings.Repeat("*", cand.dereference)
}
if prefixOp != "" {
// If we are in a selector, add an edit to place prefix before selector.
if sel := enclosingSelector(c.path, c.pos); sel != nil {
edits, err := prependEdit(c.snapshot.FileSet(), c.mapper, sel, prefixOp)
if err != nil {
return CompletionItem{}, err
}
protocolEdits = append(protocolEdits, edits...)
} else {
// If there is no selector, just stick the prefix at the start.
insert = prefixOp + insert
}
label = prefixOp + label
}
// Add variadic "..." if we are filling in a variadic param.
if cand.variadic {
insert += "..."
if snip != nil {
snip.WriteText("...")
}
}
detail = strings.TrimPrefix(detail, "untyped ")
// override computed detail with provided detail, if something is provided.
if cand.detail != "" {
detail = cand.detail
}
item := CompletionItem{
Label: label,
InsertText: insert,
AdditionalTextEdits: protocolEdits,
Detail: detail,
Kind: kind,
Score: cand.score,
Depth: len(cand.path),
snippet: snip,
obj: obj,
}
// If the user doesn't want documentation for completion items.
if !c.opts.documentation {
return item, nil
}
pos := c.snapshot.FileSet().Position(obj.Pos())
// We ignore errors here, because some types, like "unsafe" or "error",
// may not have valid positions that we can use to get documentation.
if !pos.IsValid() {
return item, nil
}
uri := span.URIFromPath(pos.Filename)
// Find the source file of the candidate, starting from a package
// that should have it in its dependencies.
searchPkg := c.pkg
if cand.imp != nil && cand.imp.pkg != nil {
searchPkg = cand.imp.pkg
}
pgf, pkg, err := source.FindPosInPackage(c.snapshot, searchPkg, obj.Pos())
if err != nil {
return item, nil
}
posToDecl, err := c.snapshot.PosToDecl(ctx, pgf)
if err != nil {
return CompletionItem{}, err
}
decl := posToDecl[obj.Pos()]
if decl == nil {
return item, nil
}
hover, err := source.HoverInfo(ctx, pkg, obj, decl)
if err != nil {
event.Error(ctx, "failed to find Hover", err, tag.URI.Of(uri))
return item, nil
}
item.Documentation = hover.Synopsis
if c.opts.fullDocumentation {
item.Documentation = hover.FullDocumentation
}
return item, nil
}
// importEdits produces the text edits necessary to add the given import to the current file.
func (c *completer) importEdits(imp *importInfo) ([]protocol.TextEdit, error) {
if imp == nil {
return nil, nil
}
pgf, err := c.pkg.File(span.URIFromPath(c.filename))
if err != nil {
return nil, err
}
return source.ComputeOneImportFixEdits(c.snapshot, pgf, &imports.ImportFix{
StmtInfo: imports.ImportInfo{
ImportPath: imp.importPath,
Name: imp.name,
},
// IdentName is unused on this path and is difficult to get.
FixType: imports.AddImport,
})
}
func (c *completer) formatBuiltin(ctx context.Context, cand candidate) (CompletionItem, error) {
obj := cand.obj
item := CompletionItem{
Label: obj.Name(),
InsertText: obj.Name(),
Score: cand.score,
}
switch obj.(type) {
case *types.Const:
item.Kind = protocol.ConstantCompletion
case *types.Builtin:
item.Kind = protocol.FunctionCompletion
sig, err := source.NewBuiltinSignature(ctx, c.snapshot, obj.Name())
if err != nil {
return CompletionItem{}, err
}
item.Detail = "func" + sig.Format()
item.snippet = c.functionCallSnippet(obj.Name(), sig.Params())
case *types.TypeName:
if types.IsInterface(obj.Type()) {
item.Kind = protocol.InterfaceCompletion
} else {
item.Kind = protocol.ClassCompletion
}
case *types.Nil:
item.Kind = protocol.VariableCompletion
}
return item, nil
}