// Copyright 2023 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. // The nodecount program illustrates the use of packages.Load to print // the frequency of occurrence of each type of syntax node among the // selected packages. // // Example usage: // // $ nodecount golang.org/x/tools/... std // // A typical distribution is 40% identifiers, 10% literals, 8% // selectors, and 6% calls; around 3% each of BinaryExpr, BlockStmt, // AssignStmt, Field, and Comment; and the rest accounting for 20%. package main import ( "flag" "fmt" "go/ast" "log" "reflect" "sort" "golang.org/x/tools/go/packages" ) func main() { flag.Parse() // Parse specified packages. config := packages.Config{ Mode: packages.NeedSyntax | packages.NeedFiles, Tests: true, } pkgs, err := packages.Load(&config, flag.Args()...) if err != nil { log.Fatal(err) } // Count each type of syntax node. var ( byType = make(map[reflect.Type]int) total int ) packages.Visit(pkgs, nil, func(p *packages.Package) { for _, f := range p.Syntax { ast.Inspect(f, func(n ast.Node) bool { if n != nil { byType[reflect.TypeOf(n)]++ total++ } return true }) } }) // Print results (percent, count, type) in descending order. var types []reflect.Type for t := range byType { types = append(types, t) } sort.Slice(types, func(i, j int) bool { return byType[types[i]] > byType[types[j]] }) for _, t := range types { percent := 100 * float64(byType[t]) / float64(total) fmt.Printf("%6.2f%%\t%8d\t%s\n", percent, byType[t], t) } }