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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 sortslice defines an Analyzer that checks for calls
// to sort.Slice that do not use a slice type as first argument.
package sortslice
import (
"bytes"
"fmt"
"go/ast"
"go/format"
"go/types"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
"golang.org/x/tools/go/ast/inspector"
"golang.org/x/tools/go/types/typeutil"
)
const Doc = `check the argument type of sort.Slice
sort.Slice requires an argument of a slice type. Check that
the interface{} value passed to sort.Slice is actually a slice.`
var Analyzer = &analysis.Analyzer{
Name: "sortslice",
Doc: Doc,
Requires: []*analysis.Analyzer{inspect.Analyzer},
Run: run,
}
func run(pass *analysis.Pass) (interface{}, error) {
inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
nodeFilter := []ast.Node{
(*ast.CallExpr)(nil),
}
inspect.Preorder(nodeFilter, func(n ast.Node) {
call := n.(*ast.CallExpr)
fn, _ := typeutil.Callee(pass.TypesInfo, call).(*types.Func)
if fn == nil {
return
}
fnName := fn.FullName()
if fnName != "sort.Slice" && fnName != "sort.SliceStable" && fnName != "sort.SliceIsSorted" {
return
}
arg := call.Args[0]
typ := pass.TypesInfo.Types[arg].Type
switch typ.Underlying().(type) {
case *types.Slice, *types.Interface:
return
}
var fixes []analysis.SuggestedFix
switch v := typ.Underlying().(type) {
case *types.Array:
var buf bytes.Buffer
format.Node(&buf, pass.Fset, &ast.SliceExpr{
X: arg,
Slice3: false,
Lbrack: arg.End() + 1,
Rbrack: arg.End() + 3,
})
fixes = append(fixes, analysis.SuggestedFix{
Message: "Get a slice of the full array",
TextEdits: []analysis.TextEdit{{
Pos: arg.Pos(),
End: arg.End(),
NewText: buf.Bytes(),
}},
})
case *types.Pointer:
_, ok := v.Elem().Underlying().(*types.Slice)
if !ok {
break
}
var buf bytes.Buffer
format.Node(&buf, pass.Fset, &ast.StarExpr{
X: arg,
})
fixes = append(fixes, analysis.SuggestedFix{
Message: "Dereference the pointer to the slice",
TextEdits: []analysis.TextEdit{{
Pos: arg.Pos(),
End: arg.End(),
NewText: buf.Bytes(),
}},
})
case *types.Signature:
if v.Params().Len() != 0 || v.Results().Len() != 1 {
break
}
if _, ok := v.Results().At(0).Type().Underlying().(*types.Slice); !ok {
break
}
var buf bytes.Buffer
format.Node(&buf, pass.Fset, &ast.CallExpr{
Fun: arg,
})
fixes = append(fixes, analysis.SuggestedFix{
Message: "Call the function",
TextEdits: []analysis.TextEdit{{
Pos: arg.Pos(),
End: arg.End(),
NewText: buf.Bytes(),
}},
})
}
pass.Report(analysis.Diagnostic{
Pos: call.Pos(),
End: call.End(),
Message: fmt.Sprintf("%s's argument must be a slice; is called with %s", fnName, typ.String()),
SuggestedFixes: fixes,
})
})
return nil, nil
}
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