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package object
import (
"bytes"
"fmt"
"sort"
objectid "codeberg.org/lindenii/furgit/object/id"
objecttype "codeberg.org/lindenii/furgit/object/type"
)
// FileMode represents the mode of a file in a Git tree.
type FileMode uint32
const (
FileModeDir FileMode = 0o40000
FileModeRegular FileMode = 0o100644
FileModeExecutable FileMode = 0o100755
FileModeSymlink FileMode = 0o120000
FileModeGitlink FileMode = 0o160000
)
// TreeEntry represents a single entry in a tree.
type TreeEntry struct {
Mode FileMode
Name []byte
ID objectid.ObjectID
}
// Tree represents a Git tree object.
type Tree struct {
Entries []TreeEntry
}
// ObjectType returns TypeTree.
func (tree *Tree) ObjectType() objecttype.Type {
_ = tree
return objecttype.TypeTree
}
// Entry looks up a tree entry by name.
func (tree *Tree) Entry(name []byte) *TreeEntry {
if len(tree.Entries) == 0 {
return nil
}
if e := tree.entry(name, true); e != nil {
return e
}
return tree.entry(name, false)
}
// InsertEntry inserts a tree entry while preserving Git ordering.
func (tree *Tree) InsertEntry(newEntry TreeEntry) error {
if tree.entry(newEntry.Name, true) != nil || tree.entry(newEntry.Name, false) != nil {
return fmt.Errorf("object: tree: entry %q already exists", newEntry.Name)
}
newIsTree := newEntry.Mode == FileModeDir
insertAt := sort.Search(len(tree.Entries), func(i int) bool {
return TreeEntryNameCompare(tree.Entries[i].Name, tree.Entries[i].Mode, newEntry.Name, newIsTree) >= 0
})
tree.Entries = append(tree.Entries, TreeEntry{})
copy(tree.Entries[insertAt+1:], tree.Entries[insertAt:])
tree.Entries[insertAt] = newEntry
return nil
}
// RemoveEntry removes a tree entry by name.
func (tree *Tree) RemoveEntry(name []byte) error {
if len(tree.Entries) == 0 {
return fmt.Errorf("object: tree: entry %q not found", name)
}
for i := range tree.Entries {
if bytes.Equal(tree.Entries[i].Name, name) {
copy(tree.Entries[i:], tree.Entries[i+1:])
tree.Entries = tree.Entries[:len(tree.Entries)-1]
return nil
}
}
return fmt.Errorf("object: tree: entry %q not found", name)
}
func (tree *Tree) entry(name []byte, searchIsTree bool) *TreeEntry {
low, high := 0, len(tree.Entries)-1
for low <= high {
mid := low + (high-low)/2
entry := &tree.Entries[mid]
cmp := TreeEntryNameCompare(entry.Name, entry.Mode, name, searchIsTree)
if cmp == 0 {
if bytes.Equal(entry.Name, name) {
return entry
}
return nil
}
if cmp < 0 {
low = mid + 1
} else {
high = mid - 1
}
}
return nil
}
// TreeEntryNameCompare compares names using Git tree ordering rules.
func TreeEntryNameCompare(entryName []byte, entryMode FileMode, searchName []byte, searchIsTree bool) int {
isEntryTree := entryMode == FileModeDir
entryLen := len(entryName)
if isEntryTree {
entryLen++
}
searchLen := len(searchName)
if searchIsTree {
searchLen++
}
n := min(searchLen, entryLen)
for i := range n {
var ec, sc byte
if i < len(entryName) {
ec = entryName[i]
} else {
ec = '/'
}
if i < len(searchName) {
sc = searchName[i]
} else {
sc = '/'
}
if ec < sc {
return -1
}
if ec > sc {
return 1
}
}
if entryLen < searchLen {
return -1
}
if entryLen > searchLen {
return 1
}
return 0
}
|
