blob: a7a8d6c55638a5b0ff732f462d3c41de9497886e [file] [log] [blame]
// 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 source
import (
"bytes"
"context"
"fmt"
"go/ast"
"go/printer"
"go/types"
"strings"
"golang.org/x/tools/internal/imports"
"golang.org/x/tools/internal/lsp/protocol"
"golang.org/x/tools/internal/lsp/snippet"
"golang.org/x/tools/internal/lsp/telemetry"
"golang.org/x/tools/internal/span"
"golang.org/x/tools/internal/telemetry/log"
"golang.org/x/tools/internal/telemetry/tag"
errors "golang.org/x/xerrors"
)
// formatCompletion creates a completion item for a given candidate.
func (c *completer) item(cand candidate) (CompletionItem, error) {
obj := cand.obj
// Handle builtin types separately.
if obj.Parent() == types.Universe {
return c.formatBuiltin(cand), nil
}
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) {
params := formatParams(c.ctx, c.snapshot, c.pkg, sig, c.qf)
snip = c.functionCallSnippet(label, params)
results, writeParens := formatResults(sig.Results(), c.qf)
detail = "func" + formatFunction(params, results, writeParens)
// Add variadic "..." if we are using a function result to fill in a variadic parameter.
if sig.Results().Len() == 1 && c.expectedType.matchesVariadic(sig.Results().At(0).Type()) {
snip.WriteText("...")
}
}
switch obj := obj.(type) {
case *types.TypeName:
detail, kind = 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() {
var err error
detail, err = formatFieldType(c.ctx, c.snapshot, c.pkg, obj, c.qf)
if err != nil {
detail = types.TypeString(obj.Type(), c.qf)
}
}
if obj.IsField() {
kind = protocol.FieldCompletion
snip = c.structFieldSnippet(label, detail)
} else {
kind = protocol.VariableCompletion
}
if obj.Type() == nil {
break
}
if sig, ok := obj.Type().Underlying().(*types.Signature); ok && cand.expandFuncCall {
expandFuncCall(sig)
}
// Add variadic "..." if we are using a variable to fill in a variadic parameter.
if c.expectedType.matchesVariadic(obj.Type()) {
snip = &snippet.Builder{}
snip.WriteText(insert + "...")
}
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 = "*"
}
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.View().Session().Cache().FileSet(), c.mapper, sel, prefixOp)
if err != nil {
log.Error(c.ctx, "error generating prefix edit", err)
} else {
protocolEdits = append(protocolEdits, edits...)
}
} else {
// If there is no selector, just stick the prefix at the start.
insert = prefixOp + insert
}
label = prefixOp + label
}
detail = strings.TrimPrefix(detail, "untyped ")
item := CompletionItem{
Label: label,
InsertText: insert,
AdditionalTextEdits: protocolEdits,
Detail: detail,
Kind: kind,
Score: cand.score,
Depth: len(c.deepState.chain),
snippet: snip,
}
// If the user doesn't want documentation for completion items.
if !c.opts.documentation {
return item, nil
}
pos := c.snapshot.View().Session().Cache().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.FileURI(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
}
file, pkg, err := findPosInPackage(c.snapshot.View(), searchPkg, obj.Pos())
if err != nil {
return item, nil
}
ident, err := findIdentifier(c.ctx, c.snapshot, pkg, file, obj.Pos())
if err != nil {
return item, nil
}
hover, err := ident.Hover(c.ctx)
if err != nil {
log.Error(c.ctx, "failed to find Hover", err, telemetry.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
}
uri := span.FileURI(c.filename)
var ph ParseGoHandle
for _, h := range c.pkg.CompiledGoFiles() {
if h.File().Identity().URI == uri {
ph = h
}
}
if ph == nil {
return nil, errors.Errorf("building import completion for %v: no ParseGoHandle for %s", imp.importPath, c.filename)
}
return computeOneImportFixEdits(c.ctx, c.snapshot.View(), ph, &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(cand candidate) CompletionItem {
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
astObj, err := c.snapshot.View().LookupBuiltin(c.ctx, obj.Name())
if err != nil {
log.Error(c.ctx, "no builtin package", err)
break
}
decl, ok := astObj.Decl.(*ast.FuncDecl)
if !ok {
break
}
params, _ := formatFieldList(c.ctx, c.snapshot.View(), decl.Type.Params)
results, writeResultParens := formatFieldList(c.ctx, c.snapshot.View(), decl.Type.Results)
item.Label = obj.Name()
item.Detail = "func" + formatFunction(params, results, writeResultParens)
item.snippet = c.functionCallSnippet(obj.Name(), 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
}
var replacer = strings.NewReplacer(
`ComplexType`, `complex128`,
`FloatType`, `float64`,
`IntegerType`, `int`,
)
func formatFieldList(ctx context.Context, v View, list *ast.FieldList) ([]string, bool) {
if list == nil {
return nil, false
}
var writeResultParens bool
var result []string
for i := 0; i < len(list.List); i++ {
if i >= 1 {
writeResultParens = true
}
p := list.List[i]
cfg := printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 4}
b := &bytes.Buffer{}
if err := cfg.Fprint(b, v.Session().Cache().FileSet(), p.Type); err != nil {
log.Error(ctx, "unable to print type", nil, tag.Of("Type", p.Type))
continue
}
typ := replacer.Replace(b.String())
if len(p.Names) == 0 {
result = append(result, typ)
}
for _, name := range p.Names {
if name.Name != "" {
if i == 0 {
writeResultParens = true
}
result = append(result, fmt.Sprintf("%s %s", name.Name, typ))
} else {
result = append(result, typ)
}
}
}
return result, writeResultParens
}
// qualifier returns a function that appropriately formats a types.PkgName
// appearing in a *ast.File.
func qualifier(f *ast.File, pkg *types.Package, info *types.Info) types.Qualifier {
// Construct mapping of import paths to their defined or implicit names.
imports := make(map[*types.Package]string)
for _, imp := range f.Imports {
var obj types.Object
if imp.Name != nil {
obj = info.Defs[imp.Name]
} else {
obj = info.Implicits[imp]
}
if pkgname, ok := obj.(*types.PkgName); ok {
imports[pkgname.Imported()] = pkgname.Name()
}
}
// Define qualifier to replace full package paths with names of the imports.
return func(p *types.Package) string {
if p == pkg {
return ""
}
if name, ok := imports[p]; ok {
return name
}
return p.Name()
}
}