prysm-pulse/tools/analyzers/slicedirect/analyzer.go

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// Package slicedirect implements a static analyzer to ensure that code does not contain
// applications of [:] on expressions which are already slices.
package slicedirect
import (
"errors"
"go/ast"
"go/types"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/go/analysis/passes/inspect"
"golang.org/x/tools/go/ast/inspector"
)
// Doc explaining the tool.
const Doc = "Tool to detect unnecessary slice-to-slice conversion by applying [:] to a slice expression."
// Analyzer runs static analysis.
var Analyzer = &analysis.Analyzer{
Name: "slicedirect",
Doc: Doc,
Requires: []*analysis.Analyzer{inspect.Analyzer},
Run: run,
}
func run(pass *analysis.Pass) (interface{}, error) {
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inspection, ok := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
if !ok {
return nil, errors.New("analyzer is not type *inspector.Inspector")
}
nodeFilter := []ast.Node{
(*ast.SliceExpr)(nil),
}
typeInfo := types.Info{Types: make(map[ast.Expr]types.TypeAndValue)}
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inspection.Preorder(nodeFilter, func(node ast.Node) {
sliceExpr, ok := node.(*ast.SliceExpr)
if !ok {
return
}
if err := types.CheckExpr(pass.Fset, pass.Pkg, sliceExpr.X.Pos(), sliceExpr.X, &typeInfo); err != nil {
return
}
if sliceExpr.Low != nil || sliceExpr.High != nil {
return
}
switch x := typeInfo.Types[sliceExpr.X].Type.(type) {
case *types.Slice:
pass.Reportf(sliceExpr.Pos(), "Expression is already a slice.")
case *types.Basic:
if x.String() == "string" {
pass.Reportf(sliceExpr.Pos(), "Expression is already a slice.")
}
}
})
return nil, nil
}