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// Package trees provides recursive diffs between Git tree objects.
package trees
import (
"codeberg.org/lindenii/furgit/object"
"codeberg.org/lindenii/furgit/objectid"
)
// Diff compares two trees and returns recursive differences.
//
// readTree is used to lazily load child trees by object ID when recursion
// reaches directory entries.
func Diff(a, b *object.Tree, readTree func(objectid.ObjectID) (*object.Tree, error)) ([]Entry, error) {
var out []Entry
if err := diffRecursive(a, b, nil, readTree, &out); err != nil {
return nil, err
}
return out, nil
}
func diffRecursive(a, b *object.Tree, prefix []byte, readTree func(objectid.ObjectID) (*object.Tree, error), out *[]Entry) error {
if a == nil && b == nil {
return nil
}
if a == nil {
for i := range b.Entries {
entry := &b.Entries[i]
full := joinPath(prefix, entry.Name)
*out = append(*out, Entry{Path: full, Kind: EntryKindAdded, Old: nil, New: entry})
if entry.Mode == object.FileModeDir {
sub, err := readTree(entry.ID)
if err != nil {
return err
}
if err := diffRecursive(nil, sub, full, readTree, out); err != nil {
return err
}
}
}
return nil
}
if b == nil {
for i := range a.Entries {
entry := &a.Entries[i]
full := joinPath(prefix, entry.Name)
*out = append(*out, Entry{Path: full, Kind: EntryKindDeleted, Old: entry, New: nil})
if entry.Mode == object.FileModeDir {
sub, err := readTree(entry.ID)
if err != nil {
return err
}
if err := diffRecursive(sub, nil, full, readTree, out); err != nil {
return err
}
}
}
return nil
}
i := 0
j := 0
for i < len(a.Entries) && j < len(b.Entries) {
left := &a.Entries[i]
right := &b.Entries[j]
cmp := object.TreeEntryNameCompare(
left.Name,
left.Mode,
right.Name,
right.Mode == object.FileModeDir,
)
switch {
case cmp < 0:
full := joinPath(prefix, left.Name)
*out = append(*out, Entry{Path: full, Kind: EntryKindDeleted, Old: left, New: nil})
if left.Mode == object.FileModeDir {
sub, err := readTree(left.ID)
if err != nil {
return err
}
if err := diffRecursive(sub, nil, full, readTree, out); err != nil {
return err
}
}
i++
case cmp > 0:
full := joinPath(prefix, right.Name)
*out = append(*out, Entry{Path: full, Kind: EntryKindAdded, Old: nil, New: right})
if right.Mode == object.FileModeDir {
sub, err := readTree(right.ID)
if err != nil {
return err
}
if err := diffRecursive(nil, sub, full, readTree, out); err != nil {
return err
}
}
j++
default:
full := joinPath(prefix, left.Name)
modified := left.Mode != right.Mode || left.ID != right.ID
if modified {
*out = append(*out, Entry{Path: full, Kind: EntryKindModified, Old: left, New: right})
}
if left.Mode == object.FileModeDir && right.Mode == object.FileModeDir && left.ID != right.ID {
leftSub, err := readTree(left.ID)
if err != nil {
return err
}
rightSub, err := readTree(right.ID)
if err != nil {
return err
}
if err := diffRecursive(leftSub, rightSub, full, readTree, out); err != nil {
return err
}
}
i++
j++
}
}
for ; i < len(a.Entries); i++ {
left := &a.Entries[i]
full := joinPath(prefix, left.Name)
*out = append(*out, Entry{Path: full, Kind: EntryKindDeleted, Old: left, New: nil})
if left.Mode == object.FileModeDir {
sub, err := readTree(left.ID)
if err != nil {
return err
}
if err := diffRecursive(sub, nil, full, readTree, out); err != nil {
return err
}
}
}
for ; j < len(b.Entries); j++ {
right := &b.Entries[j]
full := joinPath(prefix, right.Name)
*out = append(*out, Entry{Path: full, Kind: EntryKindAdded, Old: nil, New: right})
if right.Mode == object.FileModeDir {
sub, err := readTree(right.ID)
if err != nil {
return err
}
if err := diffRecursive(nil, sub, full, readTree, out); err != nil {
return err
}
}
}
return nil
}
|
