git-tree-walker.go

package main

import (
	"fmt"
	"log"
	"os"

	git "github.com/libgit2/git2go/v30"
)

// usage: start in git repository with tree hash as first arg
func main() {
	repo, err := git.OpenRepository(os.Getenv("PWD"))
	if err != nil {
		log.Fatalf("failed to open repo: %s", err)
	}

	hash := os.Args[1]
	fmt.Printf("parsing tree `%s`\n", hash)
	oid, err := git.NewOid(hash)
	if err != nil {
		log.Fatalf("failed to create oid: %s", err)
	}

	t, err := repo.LookupTree(oid)
	if err != nil {
		log.Fatalf("failed to lookup tree: %s", err)
	}

	tw := &treeWalker{t: t, repo: repo}
	err = tw.start()
	if err != nil {
		log.Fatalf("failed to walk tree: %s", err)
	}
}

type treeWalker struct {
	repo *git.Repository
	t *git.Tree
	space string
}

func (tw *treeWalker) start() error {
	return tw.t.Walk(tw.walk)
}

func (tw *treeWalker) push() *treeWalker {
	return &treeWalker{t: tw.t, repo: tw.repo, space: tw.space + "  "}
}

func (tw *treeWalker) walk(root string, entry *git.TreeEntry) int {
	fmt.Printf("%s%s - %s: %s %s\n", tw.space, root, entry.Name, entry.Type, entry.Id)
	if entry.Type == git.ObjectTree {
		subt, err := tw.repo.LookupTree(entry.Id)
		if err != nil {
			fmt.Printf("lookup error: %s\n", err)
			return 1
		}

		if err := subt.Walk(tw.push().walk); err != nil {
			fmt.Printf("walk error: %s\n", err)
			return 1
		}
	}
	return 0
}