blob: 3c3717119675b18ad9f0336dc69b041a60f15482 [file] [log] [blame]
// Copyright 2020 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/doc"
"go/printer"
"go/token"
"go/types"
"strings"
"golang.org/x/tools/gopls/internal/bug"
"golang.org/x/tools/gopls/internal/lsp/protocol"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/event/tag"
"golang.org/x/tools/internal/tokeninternal"
"golang.org/x/tools/internal/typeparams"
)
// FormatType returns the detail and kind for a types.Type.
func FormatType(typ types.Type, qf types.Qualifier) (detail string, kind protocol.CompletionItemKind) {
if types.IsInterface(typ) {
detail = "interface{...}"
kind = protocol.InterfaceCompletion
} else if _, ok := typ.(*types.Struct); ok {
detail = "struct{...}"
kind = protocol.StructCompletion
} else if typ != typ.Underlying() {
detail, kind = FormatType(typ.Underlying(), qf)
} else {
detail = types.TypeString(typ, qf)
kind = protocol.ClassCompletion
}
return detail, kind
}
type signature struct {
name, doc string
typeParams, params, results []string
variadic bool
needResultParens bool
}
func (s *signature) Format() string {
var b strings.Builder
b.WriteByte('(')
for i, p := range s.params {
if i > 0 {
b.WriteString(", ")
}
b.WriteString(p)
}
b.WriteByte(')')
// Add space between parameters and results.
if len(s.results) > 0 {
b.WriteByte(' ')
}
if s.needResultParens {
b.WriteByte('(')
}
for i, r := range s.results {
if i > 0 {
b.WriteString(", ")
}
b.WriteString(r)
}
if s.needResultParens {
b.WriteByte(')')
}
return b.String()
}
func (s *signature) TypeParams() []string {
return s.typeParams
}
func (s *signature) Params() []string {
return s.params
}
// NewBuiltinSignature returns signature for the builtin object with a given
// name, if a builtin object with the name exists.
func NewBuiltinSignature(ctx context.Context, s Snapshot, name string) (*signature, error) {
builtin, err := s.BuiltinFile(ctx)
if err != nil {
return nil, err
}
obj := builtin.File.Scope.Lookup(name)
if obj == nil {
return nil, fmt.Errorf("no builtin object for %s", name)
}
decl, ok := obj.Decl.(*ast.FuncDecl)
if !ok {
return nil, fmt.Errorf("no function declaration for builtin: %s", name)
}
if decl.Type == nil {
return nil, fmt.Errorf("no type for builtin decl %s", decl.Name)
}
var variadic bool
if decl.Type.Params.List != nil {
numParams := len(decl.Type.Params.List)
lastParam := decl.Type.Params.List[numParams-1]
if _, ok := lastParam.Type.(*ast.Ellipsis); ok {
variadic = true
}
}
fset := tokeninternal.FileSetFor(builtin.Tok)
params, _ := formatFieldList(ctx, fset, decl.Type.Params, variadic)
results, needResultParens := formatFieldList(ctx, fset, decl.Type.Results, false)
d := decl.Doc.Text()
switch s.View().Options().HoverKind {
case SynopsisDocumentation:
d = doc.Synopsis(d)
case NoDocumentation:
d = ""
}
return &signature{
doc: d,
name: name,
needResultParens: needResultParens,
params: params,
results: results,
variadic: variadic,
}, nil
}
// replacer replaces some synthetic "type classes" used in the builtin file
// with their most common constituent type.
var replacer = strings.NewReplacer(
`ComplexType`, `complex128`,
`FloatType`, `float64`,
`IntegerType`, `int`,
)
func formatFieldList(ctx context.Context, fset *token.FileSet, list *ast.FieldList, variadic bool) ([]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, fset, p.Type); err != nil {
event.Error(ctx, "unable to print type", nil, tag.Type.Of(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)
}
}
}
if variadic {
result[len(result)-1] = strings.Replace(result[len(result)-1], "[]", "...", 1)
}
return result, writeResultParens
}
// FormatTypeParams turns TypeParamList into its Go representation, such as:
// [T, Y]. Note that it does not print constraints as this is mainly used for
// formatting type params in method receivers.
func FormatTypeParams(tparams *typeparams.TypeParamList) string {
if tparams == nil || tparams.Len() == 0 {
return ""
}
var buf bytes.Buffer
buf.WriteByte('[')
for i := 0; i < tparams.Len(); i++ {
if i > 0 {
buf.WriteString(", ")
}
buf.WriteString(tparams.At(i).Obj().Name())
}
buf.WriteByte(']')
return buf.String()
}
// NewSignature returns formatted signature for a types.Signature struct.
func NewSignature(ctx context.Context, s Snapshot, pkg Package, sig *types.Signature, comment *ast.CommentGroup, qf types.Qualifier, mq MetadataQualifier) (*signature, error) {
var tparams []string
tpList := typeparams.ForSignature(sig)
for i := 0; i < tpList.Len(); i++ {
tparam := tpList.At(i)
// TODO: is it possible to reuse the logic from FormatVarType here?
s := tparam.Obj().Name() + " " + tparam.Constraint().String()
tparams = append(tparams, s)
}
params := make([]string, 0, sig.Params().Len())
for i := 0; i < sig.Params().Len(); i++ {
el := sig.Params().At(i)
typ, err := FormatVarType(ctx, s, pkg, el, qf, mq)
if err != nil {
return nil, err
}
p := typ
if el.Name() != "" {
p = el.Name() + " " + typ
}
params = append(params, p)
}
var needResultParens bool
results := make([]string, 0, sig.Results().Len())
for i := 0; i < sig.Results().Len(); i++ {
if i >= 1 {
needResultParens = true
}
el := sig.Results().At(i)
typ, err := FormatVarType(ctx, s, pkg, el, qf, mq)
if err != nil {
return nil, err
}
if el.Name() == "" {
results = append(results, typ)
} else {
if i == 0 {
needResultParens = true
}
results = append(results, el.Name()+" "+typ)
}
}
var d string
if comment != nil {
d = comment.Text()
}
switch s.View().Options().HoverKind {
case SynopsisDocumentation:
d = doc.Synopsis(d)
case NoDocumentation:
d = ""
}
return &signature{
doc: d,
typeParams: tparams,
params: params,
results: results,
variadic: sig.Variadic(),
needResultParens: needResultParens,
}, nil
}
// FormatVarType formats a *types.Var, accounting for type aliases.
// To do this, it looks in the AST of the file in which the object is declared.
// On any errors, it always falls back to types.TypeString.
//
// TODO(rfindley): this function could return the actual name used in syntax,
// for better parameter names.
func FormatVarType(ctx context.Context, snapshot Snapshot, srcpkg Package, obj *types.Var, qf types.Qualifier, mq MetadataQualifier) (string, error) {
// TODO(rfindley): This looks wrong. The previous comment said:
// "If the given expr refers to a type parameter, then use the
// object's Type instead of the type parameter declaration. This helps
// format the instantiated type as opposed to the original undeclared
// generic type".
//
// But of course, if obj is a type param, we are formatting a generic type
// and not an instantiated type. Handling for instantiated types must be done
// at a higher level.
//
// Left this during refactoring in order to preserve pre-existing logic.
if typeparams.IsTypeParam(obj.Type()) {
return types.TypeString(obj.Type(), qf), nil
}
if obj.Pkg() == nil || !obj.Pos().IsValid() {
// This is defensive, though it is extremely unlikely we'll ever have a
// builtin var.
return types.TypeString(obj.Type(), qf), nil
}
// TODO(rfindley): parsing to produce candidates can be costly; consider
// using faster methods.
targetpgf, pos, err := parseFull(ctx, snapshot, srcpkg.FileSet(), obj.Pos())
if err != nil {
return "", err // e.g. ctx cancelled
}
targetMeta := findFileInDeps(snapshot, srcpkg.Metadata(), targetpgf.URI)
if targetMeta == nil {
// If we have an object from type-checking, it should exist in a file in
// the forward transitive closure.
return "", bug.Errorf("failed to find file %q in deps of %q", targetpgf.URI, srcpkg.Metadata().ID)
}
decl, spec, field := findDeclInfo([]*ast.File{targetpgf.File}, pos)
// We can't handle type parameters correctly, so we fall back on TypeString
// for parameterized decls.
if decl, _ := decl.(*ast.FuncDecl); decl != nil {
if typeparams.ForFuncType(decl.Type).NumFields() > 0 {
return types.TypeString(obj.Type(), qf), nil // in generic function
}
if decl.Recv != nil && len(decl.Recv.List) > 0 {
if x, _, _, _ := typeparams.UnpackIndexExpr(decl.Recv.List[0].Type); x != nil {
return types.TypeString(obj.Type(), qf), nil // in method of generic type
}
}
}
if spec, _ := spec.(*ast.TypeSpec); spec != nil && typeparams.ForTypeSpec(spec).NumFields() > 0 {
return types.TypeString(obj.Type(), qf), nil // in generic type decl
}
if field == nil {
// TODO(rfindley): we should never reach here from an ordinary var, so
// should probably return an error here.
return types.TypeString(obj.Type(), qf), nil
}
expr := field.Type
rq := requalifier(snapshot, targetpgf.File, targetMeta, mq)
// The type names in the AST may not be correctly qualified.
// Determine the package name to use based on the package that originated
// the query and the package in which the type is declared.
// We then qualify the value by cloning the AST node and editing it.
expr = qualifyTypeExpr(expr, rq)
// If the request came from a different package than the one in which the
// types are defined, we may need to modify the qualifiers.
return FormatNodeFile(targetpgf.Tok, expr), nil
}
// qualifyTypeExpr clones the type expression expr after re-qualifying type
// names using the given function, which accepts the current syntactic
// qualifier (possibly "" for unqualified idents), and returns a new qualifier
// (again, possibly "" if the identifier should be unqualified).
//
// The resulting expression may be inaccurate: without type-checking we don't
// properly account for "." imported identifiers or builtins.
//
// TODO(rfindley): add many more tests for this function.
func qualifyTypeExpr(expr ast.Expr, qf func(string) string) ast.Expr {
switch expr := expr.(type) {
case *ast.ArrayType:
return &ast.ArrayType{
Lbrack: expr.Lbrack,
Elt: qualifyTypeExpr(expr.Elt, qf),
Len: expr.Len,
}
case *ast.BinaryExpr:
if expr.Op != token.OR {
return expr
}
return &ast.BinaryExpr{
X: qualifyTypeExpr(expr.X, qf),
OpPos: expr.OpPos,
Op: expr.Op,
Y: qualifyTypeExpr(expr.Y, qf),
}
case *ast.ChanType:
return &ast.ChanType{
Arrow: expr.Arrow,
Begin: expr.Begin,
Dir: expr.Dir,
Value: qualifyTypeExpr(expr.Value, qf),
}
case *ast.Ellipsis:
return &ast.Ellipsis{
Ellipsis: expr.Ellipsis,
Elt: qualifyTypeExpr(expr.Elt, qf),
}
case *ast.FuncType:
return &ast.FuncType{
Func: expr.Func,
Params: qualifyFieldList(expr.Params, qf),
Results: qualifyFieldList(expr.Results, qf),
}
case *ast.Ident:
// Unqualified type (builtin, package local, or dot-imported).
// Don't qualify names that look like builtins.
//
// Without type-checking this may be inaccurate. It could be made accurate
// by doing syntactic object resolution for the entire package, but that
// does not seem worthwhile and we generally want to avoid using
// ast.Object, which may be inaccurate.
if obj := types.Universe.Lookup(expr.Name); obj != nil {
return expr
}
newName := qf("")
if newName != "" {
return &ast.SelectorExpr{
X: &ast.Ident{
NamePos: expr.Pos(),
Name: newName,
},
Sel: expr,
}
}
return expr
case *ast.IndexExpr:
return &ast.IndexExpr{
X: qualifyTypeExpr(expr.X, qf),
Lbrack: expr.Lbrack,
Index: qualifyTypeExpr(expr.Index, qf),
Rbrack: expr.Rbrack,
}
case *typeparams.IndexListExpr:
indices := make([]ast.Expr, len(expr.Indices))
for i, idx := range expr.Indices {
indices[i] = qualifyTypeExpr(idx, qf)
}
return &typeparams.IndexListExpr{
X: qualifyTypeExpr(expr.X, qf),
Lbrack: expr.Lbrack,
Indices: indices,
Rbrack: expr.Rbrack,
}
case *ast.InterfaceType:
return &ast.InterfaceType{
Interface: expr.Interface,
Methods: qualifyFieldList(expr.Methods, qf),
Incomplete: expr.Incomplete,
}
case *ast.MapType:
return &ast.MapType{
Map: expr.Map,
Key: qualifyTypeExpr(expr.Key, qf),
Value: qualifyTypeExpr(expr.Value, qf),
}
case *ast.ParenExpr:
return &ast.ParenExpr{
Lparen: expr.Lparen,
Rparen: expr.Rparen,
X: qualifyTypeExpr(expr.X, qf),
}
case *ast.SelectorExpr:
if id, ok := expr.X.(*ast.Ident); ok {
// qualified type
newName := qf(id.Name)
if newName == "" {
return expr.Sel
}
return &ast.SelectorExpr{
X: &ast.Ident{
NamePos: id.NamePos,
Name: newName,
},
Sel: expr.Sel,
}
}
return expr
case *ast.StarExpr:
return &ast.StarExpr{
Star: expr.Star,
X: qualifyTypeExpr(expr.X, qf),
}
case *ast.StructType:
return &ast.StructType{
Struct: expr.Struct,
Fields: qualifyFieldList(expr.Fields, qf),
Incomplete: expr.Incomplete,
}
default:
return expr
}
}
func qualifyFieldList(fl *ast.FieldList, qf func(string) string) *ast.FieldList {
if fl == nil {
return nil
}
if fl.List == nil {
return &ast.FieldList{
Closing: fl.Closing,
Opening: fl.Opening,
}
}
list := make([]*ast.Field, 0, len(fl.List))
for _, f := range fl.List {
list = append(list, &ast.Field{
Comment: f.Comment,
Doc: f.Doc,
Names: f.Names,
Tag: f.Tag,
Type: qualifyTypeExpr(f.Type, qf),
})
}
return &ast.FieldList{
Closing: fl.Closing,
Opening: fl.Opening,
List: list,
}
}