go__parsing_demo/04-walk_packages/walk_packages.go

package main

import (
	"flag"
	"fmt"
	"os"

	"golang.org/x/tools/go/packages"
	"gopkg.in/yaml.v3"
)

func main() {
	flag.Parse()

	// Many tools pass their command-line arguments (after any flags)
	// uninterpreted to packages.Load so that it can interpret them
	// according to the conventions of the underlying build system.
	cfg := &packages.Config{
		Mode: packages.NeedCompiledGoFiles | // CompiledGoFiles in the package, as absolute source paths
				// packages.NeedDeps | // Make TypesInfo include imported types and resolve Imports beyond just names
				packages.NeedEmbedFiles | // EmbedFiles as absolute paths. For embed.FS, all resolved files
				packages.NeedEmbedPatterns | // EmbedPatterns as absolute paths. For embed.FS, the embed path
				packages.NeedExportFile | // ExportFile: the compiled package, for use with ar or go tool nm
				packages.NeedFiles | // GoFiles and OtherFiles as absolute paths
				packages.NeedImports | // Imports, as a map[string]packages.Package. Use
				packages.NeedModule | // Modules, as a packages.Module
				packages.NeedName | // e.g. main
				packages.NeedSyntax | // Syntax, a []*ast.File containing the parsed files in the package
				packages.NeedTypes | // Types, Fset (the set of files in the compile result) and IllTyped (bool)
				packages.NeedTypesInfo | // TypesInfo for all types in the compile result
				packages.NeedTypesSizes, // TypesSizes: WordSize (8) and MaxAlign (8)
	}
	pkgs, err := packages.Load(cfg, flag.Args()...)
	if err != nil {
		fmt.Fprintf(os.Stderr, "load: %v\n", err)
		os.Exit(1)
	}
	if packages.PrintErrors(pkgs) > 0 {
		os.Exit(1)
	}

	info := make(map[string][]string)
	// Print the names of the source files
	// for each package listed on the command line.
	for _, pkg := range pkgs {
		info[pkg.ID] = pkg.GoFiles
	}
	enc := yaml.NewEncoder(os.Stdout)
	enc.SetIndent(2)
	enc.Encode(info)
}