forked from gitea/gitea
426 lines
11 KiB
Go
426 lines
11 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package analysisinternal exposes internal-only fields from go/analysis.
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package analysisinternal
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import (
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"bytes"
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"fmt"
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"go/ast"
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"go/token"
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"go/types"
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"strings"
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"golang.org/x/tools/go/ast/astutil"
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"golang.org/x/tools/internal/lsp/fuzzy"
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)
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var (
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GetTypeErrors func(p interface{}) []types.Error
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SetTypeErrors func(p interface{}, errors []types.Error)
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)
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func TypeErrorEndPos(fset *token.FileSet, src []byte, start token.Pos) token.Pos {
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// Get the end position for the type error.
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offset, end := fset.PositionFor(start, false).Offset, start
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if offset >= len(src) {
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return end
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}
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if width := bytes.IndexAny(src[offset:], " \n,():;[]+-*"); width > 0 {
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end = start + token.Pos(width)
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}
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return end
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}
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func ZeroValue(fset *token.FileSet, f *ast.File, pkg *types.Package, typ types.Type) ast.Expr {
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under := typ
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if n, ok := typ.(*types.Named); ok {
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under = n.Underlying()
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}
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switch u := under.(type) {
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case *types.Basic:
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switch {
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case u.Info()&types.IsNumeric != 0:
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return &ast.BasicLit{Kind: token.INT, Value: "0"}
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case u.Info()&types.IsBoolean != 0:
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return &ast.Ident{Name: "false"}
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case u.Info()&types.IsString != 0:
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return &ast.BasicLit{Kind: token.STRING, Value: `""`}
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default:
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panic("unknown basic type")
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}
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case *types.Chan, *types.Interface, *types.Map, *types.Pointer, *types.Signature, *types.Slice, *types.Array:
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return ast.NewIdent("nil")
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case *types.Struct:
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texpr := TypeExpr(fset, f, pkg, typ) // typ because we want the name here.
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if texpr == nil {
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return nil
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}
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return &ast.CompositeLit{
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Type: texpr,
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}
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}
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return nil
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}
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// IsZeroValue checks whether the given expression is a 'zero value' (as determined by output of
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// analysisinternal.ZeroValue)
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func IsZeroValue(expr ast.Expr) bool {
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switch e := expr.(type) {
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case *ast.BasicLit:
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return e.Value == "0" || e.Value == `""`
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case *ast.Ident:
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return e.Name == "nil" || e.Name == "false"
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default:
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return false
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}
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}
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func TypeExpr(fset *token.FileSet, f *ast.File, pkg *types.Package, typ types.Type) ast.Expr {
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switch t := typ.(type) {
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case *types.Basic:
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switch t.Kind() {
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case types.UnsafePointer:
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return &ast.SelectorExpr{X: ast.NewIdent("unsafe"), Sel: ast.NewIdent("Pointer")}
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default:
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return ast.NewIdent(t.Name())
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}
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case *types.Pointer:
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x := TypeExpr(fset, f, pkg, t.Elem())
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if x == nil {
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return nil
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}
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return &ast.UnaryExpr{
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Op: token.MUL,
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X: x,
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}
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case *types.Array:
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elt := TypeExpr(fset, f, pkg, t.Elem())
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if elt == nil {
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return nil
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}
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return &ast.ArrayType{
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Len: &ast.BasicLit{
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Kind: token.INT,
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Value: fmt.Sprintf("%d", t.Len()),
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},
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Elt: elt,
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}
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case *types.Slice:
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elt := TypeExpr(fset, f, pkg, t.Elem())
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if elt == nil {
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return nil
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}
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return &ast.ArrayType{
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Elt: elt,
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}
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case *types.Map:
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key := TypeExpr(fset, f, pkg, t.Key())
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value := TypeExpr(fset, f, pkg, t.Elem())
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if key == nil || value == nil {
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return nil
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}
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return &ast.MapType{
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Key: key,
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Value: value,
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}
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case *types.Chan:
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dir := ast.ChanDir(t.Dir())
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if t.Dir() == types.SendRecv {
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dir = ast.SEND | ast.RECV
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}
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value := TypeExpr(fset, f, pkg, t.Elem())
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if value == nil {
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return nil
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}
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return &ast.ChanType{
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Dir: dir,
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Value: value,
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}
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case *types.Signature:
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var params []*ast.Field
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for i := 0; i < t.Params().Len(); i++ {
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p := TypeExpr(fset, f, pkg, t.Params().At(i).Type())
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if p == nil {
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return nil
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}
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params = append(params, &ast.Field{
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Type: p,
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Names: []*ast.Ident{
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{
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Name: t.Params().At(i).Name(),
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},
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},
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})
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}
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var returns []*ast.Field
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for i := 0; i < t.Results().Len(); i++ {
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r := TypeExpr(fset, f, pkg, t.Results().At(i).Type())
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if r == nil {
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return nil
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}
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returns = append(returns, &ast.Field{
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Type: r,
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})
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}
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return &ast.FuncType{
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Params: &ast.FieldList{
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List: params,
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},
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Results: &ast.FieldList{
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List: returns,
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},
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}
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case *types.Named:
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if t.Obj().Pkg() == nil {
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return ast.NewIdent(t.Obj().Name())
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}
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if t.Obj().Pkg() == pkg {
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return ast.NewIdent(t.Obj().Name())
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}
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pkgName := t.Obj().Pkg().Name()
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// If the file already imports the package under another name, use that.
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for _, group := range astutil.Imports(fset, f) {
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for _, cand := range group {
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if strings.Trim(cand.Path.Value, `"`) == t.Obj().Pkg().Path() {
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if cand.Name != nil && cand.Name.Name != "" {
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pkgName = cand.Name.Name
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}
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}
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}
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}
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if pkgName == "." {
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return ast.NewIdent(t.Obj().Name())
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}
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return &ast.SelectorExpr{
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X: ast.NewIdent(pkgName),
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Sel: ast.NewIdent(t.Obj().Name()),
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}
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case *types.Struct:
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return ast.NewIdent(t.String())
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case *types.Interface:
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return ast.NewIdent(t.String())
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default:
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return nil
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}
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}
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type TypeErrorPass string
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const (
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NoNewVars TypeErrorPass = "nonewvars"
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NoResultValues TypeErrorPass = "noresultvalues"
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UndeclaredName TypeErrorPass = "undeclaredname"
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)
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// StmtToInsertVarBefore returns the ast.Stmt before which we can safely insert a new variable.
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// Some examples:
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//
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// Basic Example:
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// z := 1
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// y := z + x
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// If x is undeclared, then this function would return `y := z + x`, so that we
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// can insert `x := ` on the line before `y := z + x`.
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//
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// If stmt example:
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// if z == 1 {
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// } else if z == y {}
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// If y is undeclared, then this function would return `if z == 1 {`, because we cannot
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// insert a statement between an if and an else if statement. As a result, we need to find
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// the top of the if chain to insert `y := ` before.
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func StmtToInsertVarBefore(path []ast.Node) ast.Stmt {
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enclosingIndex := -1
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for i, p := range path {
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if _, ok := p.(ast.Stmt); ok {
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enclosingIndex = i
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break
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}
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}
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if enclosingIndex == -1 {
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return nil
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}
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enclosingStmt := path[enclosingIndex]
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switch enclosingStmt.(type) {
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case *ast.IfStmt:
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// The enclosingStmt is inside of the if declaration,
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// We need to check if we are in an else-if stmt and
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// get the base if statement.
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return baseIfStmt(path, enclosingIndex)
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case *ast.CaseClause:
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// Get the enclosing switch stmt if the enclosingStmt is
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// inside of the case statement.
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for i := enclosingIndex + 1; i < len(path); i++ {
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if node, ok := path[i].(*ast.SwitchStmt); ok {
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return node
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} else if node, ok := path[i].(*ast.TypeSwitchStmt); ok {
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return node
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}
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}
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}
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if len(path) <= enclosingIndex+1 {
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return enclosingStmt.(ast.Stmt)
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}
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// Check if the enclosing statement is inside another node.
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switch expr := path[enclosingIndex+1].(type) {
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case *ast.IfStmt:
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// Get the base if statement.
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return baseIfStmt(path, enclosingIndex+1)
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case *ast.ForStmt:
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if expr.Init == enclosingStmt || expr.Post == enclosingStmt {
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return expr
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}
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}
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return enclosingStmt.(ast.Stmt)
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}
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// baseIfStmt walks up the if/else-if chain until we get to
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// the top of the current if chain.
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func baseIfStmt(path []ast.Node, index int) ast.Stmt {
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stmt := path[index]
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for i := index + 1; i < len(path); i++ {
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if node, ok := path[i].(*ast.IfStmt); ok && node.Else == stmt {
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stmt = node
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continue
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}
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break
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}
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return stmt.(ast.Stmt)
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}
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// WalkASTWithParent walks the AST rooted at n. The semantics are
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// similar to ast.Inspect except it does not call f(nil).
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func WalkASTWithParent(n ast.Node, f func(n ast.Node, parent ast.Node) bool) {
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var ancestors []ast.Node
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ast.Inspect(n, func(n ast.Node) (recurse bool) {
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if n == nil {
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ancestors = ancestors[:len(ancestors)-1]
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return false
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}
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var parent ast.Node
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if len(ancestors) > 0 {
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parent = ancestors[len(ancestors)-1]
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}
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ancestors = append(ancestors, n)
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return f(n, parent)
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})
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}
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// FindMatchingIdents finds all identifiers in 'node' that match any of the given types.
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// 'pos' represents the position at which the identifiers may be inserted. 'pos' must be within
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// the scope of each of identifier we select. Otherwise, we will insert a variable at 'pos' that
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// is unrecognized.
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func FindMatchingIdents(typs []types.Type, node ast.Node, pos token.Pos, info *types.Info, pkg *types.Package) map[types.Type][]*ast.Ident {
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matches := map[types.Type][]*ast.Ident{}
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// Initialize matches to contain the variable types we are searching for.
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for _, typ := range typs {
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if typ == nil {
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continue
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}
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matches[typ] = []*ast.Ident{}
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}
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seen := map[types.Object]struct{}{}
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ast.Inspect(node, func(n ast.Node) bool {
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if n == nil {
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return false
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}
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// Prevent circular definitions. If 'pos' is within an assignment statement, do not
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// allow any identifiers in that assignment statement to be selected. Otherwise,
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// we could do the following, where 'x' satisfies the type of 'f0':
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//
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// x := fakeStruct{f0: x}
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//
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assignment, ok := n.(*ast.AssignStmt)
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if ok && pos > assignment.Pos() && pos <= assignment.End() {
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return false
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}
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if n.End() > pos {
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return n.Pos() <= pos
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}
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ident, ok := n.(*ast.Ident)
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if !ok || ident.Name == "_" {
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return true
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}
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obj := info.Defs[ident]
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if obj == nil || obj.Type() == nil {
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return true
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}
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if _, ok := obj.(*types.TypeName); ok {
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return true
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}
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// Prevent duplicates in matches' values.
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if _, ok = seen[obj]; ok {
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return true
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}
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seen[obj] = struct{}{}
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// Find the scope for the given position. Then, check whether the object
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// exists within the scope.
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innerScope := pkg.Scope().Innermost(pos)
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if innerScope == nil {
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return true
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}
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_, foundObj := innerScope.LookupParent(ident.Name, pos)
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if foundObj != obj {
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return true
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}
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// The object must match one of the types that we are searching for.
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if idents, ok := matches[obj.Type()]; ok {
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matches[obj.Type()] = append(idents, ast.NewIdent(ident.Name))
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}
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// If the object type does not exactly match any of the target types, greedily
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// find the first target type that the object type can satisfy.
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for typ := range matches {
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if obj.Type() == typ {
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continue
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}
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if equivalentTypes(obj.Type(), typ) {
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matches[typ] = append(matches[typ], ast.NewIdent(ident.Name))
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}
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}
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return true
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})
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return matches
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}
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func equivalentTypes(want, got types.Type) bool {
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if want == got || types.Identical(want, got) {
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return true
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}
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// Code segment to help check for untyped equality from (golang/go#32146).
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if rhs, ok := want.(*types.Basic); ok && rhs.Info()&types.IsUntyped > 0 {
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if lhs, ok := got.Underlying().(*types.Basic); ok {
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return rhs.Info()&types.IsConstType == lhs.Info()&types.IsConstType
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}
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}
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return types.AssignableTo(want, got)
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}
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// FindBestMatch employs fuzzy matching to evaluate the similarity of each given identifier to the
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// given pattern. We return the identifier whose name is most similar to the pattern.
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func FindBestMatch(pattern string, idents []*ast.Ident) ast.Expr {
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fuzz := fuzzy.NewMatcher(pattern)
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var bestFuzz ast.Expr
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highScore := float32(0) // minimum score is 0 (no match)
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for _, ident := range idents {
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// TODO: Improve scoring algorithm.
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score := fuzz.Score(ident.Name)
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if score > highScore {
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highScore = score
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bestFuzz = ident
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} else if score == 0 {
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// Order matters in the fuzzy matching algorithm. If we find no match
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// when matching the target to the identifier, try matching the identifier
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// to the target.
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revFuzz := fuzzy.NewMatcher(ident.Name)
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revScore := revFuzz.Score(pattern)
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if revScore > highScore {
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highScore = revScore
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bestFuzz = ident
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}
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}
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}
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return bestFuzz
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}
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