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// Copyright 2019 Luke Shumaker <lukeshu@parabola.nu>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"fmt"
"io"
"os"
"sort"
"git.lukeshu.com/go/libfastimport"
"github.com/pkg/errors"
)
func abort(err error) {
fmt.Fprintln(os.Stderr, "Error:", err)
os.Exit(1)
}
type Tree []libfastimport.FileModify
func (t Tree) Len() int { return len(t) }
func (t Tree) Less(i, j int) bool { return t[i].Path < t[j].Path }
func (t Tree) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
func TreesEqual(a, b Tree) bool {
if len(a) != len(b) {
return false
}
for i := range a {
if a[i] != b[i] {
return false
}
}
return true
}
// expects --full-tree
func main() {
frontend := libfastimport.NewFrontend(os.Stdin, nil, nil)
backend := libfastimport.NewBackend(os.Stdout, nil, nil)
replace := map[string]string{}
fixupMark := func(m string) string {
if r, ok := replace[m]; ok {
return r
}
return m
}
ancestors := map[string]map[string]struct{}{}
trees := map[string]Tree{}
addCommit := func(c string, parents []string, tree Tree) {
cAncestors := map[string]struct{}{}
for _, parent := range parents {
parent = fixupMark(parent)
cAncestors[parent] = struct{}{}
for ancestor := range ancestors[parent] {
cAncestors[ancestor] = struct{}{}
}
}
ancestors[c] = cAncestors
trees[c] = tree
}
// subsumedBy(c, commits) determines if commit 'c' is an
// ancestor of any of the commits given in 'commits'.
subsumedBy := func(c string, commits []string) bool {
for _, c2 := range commits {
c2 = fixupMark(c2)
if c2 == c {
continue
}
if _, ok := ancestors[c2][c]; ok {
return true
}
}
return false
}
pruneParents := func(commits []string) []string {
var ret []string
for _, c := range commits {
c = fixupMark(c)
if !subsumedBy(c, commits) {
ret = append(ret, c)
}
}
return ret
}
commitMeta := libfastimport.CmdCommit{}
commitFile := Tree{}
for {
cmd, err := frontend.ReadCmd()
if err != nil {
if err == io.EOF {
break
}
abort(err)
}
switch cmdt := cmd.(type) {
case libfastimport.CmdCommit:
commitMeta = cmdt
commitFile = Tree{}
case libfastimport.CmdCommitEnd:
mark := fmt.Sprintf(":%d", commitMeta.Mark)
parents := pruneParents(append([]string{commitMeta.From}, commitMeta.Merge...))
sort.Stable(commitFile)
// decide whether to skip this commit
if len(parents) == 1 && TreesEqual(trees[parents[0]], commitFile) {
replace[mark] = parents[0]
continue
}
// remember the commit
addCommit(mark, parents, commitFile)
// emit the commit
commitMeta.From = parents[0]
commitMeta.Merge = parents[1:]
if err := backend.Do(commitMeta); err != nil {
abort(err)
}
if err := backend.Do(libfastimport.FileDeleteAll{}); err != nil {
abort(err)
}
for _, file := range commitFile {
if err := backend.Do(file); err != nil {
abort(err)
}
}
case libfastimport.FileDeleteAll:
// do nothing
case libfastimport.FileModify:
commitFile = append(commitFile, cmdt)
case libfastimport.CmdBlob, libfastimport.CmdCheckpoint, libfastimport.CmdReset, libfastimport.CmdFeature, libfastimport.CmdOption, libfastimport.CmdDone:
err := backend.Do(cmd)
if err != nil {
abort(err)
}
case libfastimport.CmdComment:
default:
abort(errors.Errorf("Unexpected command: %[1]T(%#[1]v)", cmd))
}
}
}
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