package diff
import (
"fmt"
"io"
"regexp"
"strconv"
"strings"
"github.com/go-git/go-git/v5/plumbing"
)
// DefaultContextLines is the default number of context lines.
const DefaultContextLines = 3
var (
splitLinesRegexp = regexp.MustCompile(`[^\n]*(\n|$)`)
operationChar = map[Operation]byte{
Add: '+',
Delete: '-',
Equal: ' ',
}
operationColorKey = map[Operation]ColorKey{
Add: New,
Delete: Old,
Equal: Context,
}
)
// UnifiedEncoder encodes an unified diff into the provided Writer. It does not
// support similarity index for renames or sorting hash representations.
type UnifiedEncoder struct {
io.Writer
// contextLines is the count of unchanged lines that will appear surrounding
// a change.
contextLines int
// colorConfig is the color configuration. The default is no color.
color ColorConfig
}
// NewUnifiedEncoder returns a new UnifiedEncoder that writes to w.
func NewUnifiedEncoder(w io.Writer, contextLines int) *UnifiedEncoder {
return &UnifiedEncoder{
Writer: w,
contextLines: contextLines,
}
}
// SetColor sets e's color configuration and returns e.
func (e *UnifiedEncoder) SetColor(colorConfig ColorConfig) *UnifiedEncoder {
e.color = colorConfig
return e
}
// Encode encodes patch.
func (e *UnifiedEncoder) Encode(patch Patch) error {
sb := &strings.Builder{}
if message := patch.Message(); message != "" {
sb.WriteString(message)
if !strings.HasSuffix(message, "\n") {
sb.WriteByte('\n')
}
}
for _, filePatch := range patch.FilePatches() {
e.writeFilePatchHeader(sb, filePatch)
g := newHunksGenerator(filePatch.Chunks(), e.contextLines)
for _, hunk := range g.Generate() {
hunk.writeTo(sb, e.color)
}
}
_, err := e.Write([]byte(sb.String()))
return err
}
func (e *UnifiedEncoder) writeFilePatchHeader(sb *strings.Builder, filePatch FilePatch) {
from, to := filePatch.Files()
if from == nil && to == nil {
return
}
isBinary := filePatch.IsBinary()
var lines []string
switch {
case from != nil && to != nil:
hashEquals := from.Hash() == to.Hash()
lines = append(lines,
fmt.Sprintf("diff --git a/%s b/%s", from.Path(), to.Path()),
)
if from.Mode() != to.Mode() {
lines = append(lines,
fmt.Sprintf("old mode %o", from.Mode()),
fmt.Sprintf("new mode %o", to.Mode()),
)
}
if from.Path() != to.Path() {
lines = append(lines,
fmt.Sprintf("rename from %s", from.Path()),
fmt.Sprintf("rename to %s", to.Path()),
)
}
if from.Mode() != to.Mode() && !hashEquals {
lines = append(lines,
fmt.Sprintf("index %s..%s", from.Hash(), to.Hash()),
)
} else if !hashEquals {
lines = append(lines,
fmt.Sprintf("index %s..%s %o", from.Hash(), to.Hash(), from.Mode()),
)
}
if !hashEquals {
lines = e.appendPathLines(lines, "a/"+from.Path(), "b/"+to.Path(), isBinary)
}
case from == nil:
lines = append(lines,
fmt.Sprintf("diff --git a/%s b/%s", to.Path(), to.Path()),
fmt.Sprintf("new file mode %o", to.Mode()),
fmt.Sprintf("index %s..%s", plumbing.ZeroHash, to.Hash()),
)
lines = e.appendPathLines(lines, "/dev/null", "b/"+to.Path(), isBinary)
case to == nil:
lines = append(lines,
fmt.Sprintf("diff --git a/%s b/%s", from.Path(), from.Path()),
fmt.Sprintf("deleted file mode %o", from.Mode()),
fmt.Sprintf("index %s..%s", from.Hash(), plumbing.ZeroHash),
)
lines = e.appendPathLines(lines, "a/"+from.Path(), "/dev/null", isBinary)
}
sb.WriteString(e.color[Meta])
sb.WriteString(lines[0])
for _, line := range lines[1:] {
sb.WriteByte('\n')
sb.WriteString(line)
}
sb.WriteString(e.color.Reset(Meta))
sb.WriteByte('\n')
}
func (e *UnifiedEncoder) appendPathLines(lines []string, fromPath, toPath string, isBinary bool) []string {
if isBinary {
return append(lines,
fmt.Sprintf("Binary files %s and %s differ", fromPath, toPath),
)
}
return append(lines,
fmt.Sprintf("--- %s", fromPath),
fmt.Sprintf("+++ %s", toPath),
)
}
type hunksGenerator struct {
fromLine, toLine int
ctxLines int
chunks []Chunk
current *hunk
hunks []*hunk
beforeContext, afterContext []string
}
func newHunksGenerator(chunks []Chunk, ctxLines int) *hunksGenerator {
return &hunksGenerator{
chunks: chunks,
ctxLines: ctxLines,
}
}
func (g *hunksGenerator) Generate() []*hunk {
for i, chunk := range g.chunks {
lines := splitLines(chunk.Content())
nLines := len(lines)
switch chunk.Type() {
case Equal:
g.fromLine += nLines
g.toLine += nLines
g.processEqualsLines(lines, i)
case Delete:
if nLines != 0 {
g.fromLine++
}
g.processHunk(i, chunk.Type())
g.fromLine += nLines - 1
g.current.AddOp(chunk.Type(), lines...)
case Add:
if nLines != 0 {
g.toLine++
}
g.processHunk(i, chunk.Type())
g.toLine += nLines - 1
g.current.AddOp(chunk.Type(), lines...)
}
if i == len(g.chunks)-1 && g.current != nil {
g.hunks = append(g.hunks, g.current)
}
}
return g.hunks
}
func (g *hunksGenerator) processHunk(i int, op Operation) {
if g.current != nil {
return
}
var ctxPrefix string
linesBefore := len(g.beforeContext)
if linesBefore > g.ctxLines {
ctxPrefix = g.beforeContext[linesBefore-g.ctxLines-1]
g.beforeContext = g.beforeContext[linesBefore-g.ctxLines:]
linesBefore = g.ctxLines
}
g.current = &hunk{ctxPrefix: strings.TrimSuffix(ctxPrefix, "\n")}
g.current.AddOp(Equal, g.beforeContext...)
switch op {
case Delete:
g.current.fromLine, g.current.toLine =
g.addLineNumbers(g.fromLine, g.toLine, linesBefore, i, Add)
case Add:
g.current.toLine, g.current.fromLine =
g.addLineNumbers(g.toLine, g.fromLine, linesBefore, i, Delete)
}
g.beforeContext = nil
}
// addLineNumbers obtains the line numbers in a new chunk.
func (g *hunksGenerator) addLineNumbers(la, lb int, linesBefore int, i int, op Operation) (cla, clb int) {
cla = la - linesBefore
// we need to search for a reference for the next diff
switch {
case linesBefore != 0 && g.ctxLines != 0:
if lb > g.ctxLines {
clb = lb - g.ctxLines + 1
} else {
clb = 1
}
case g.ctxLines == 0:
clb = lb
case i != len(g.chunks)-1:
next := g.chunks[i+1]
if next.Type() == op || next.Type() == Equal {
// this diff will be into this chunk
clb = lb + 1
}
}
return
}
func (g *hunksGenerator) processEqualsLines(ls []string, i int) {
if g.current == nil {
g.beforeContext = append(g.beforeContext, ls...)
return
}
g.afterContext = append(g.afterContext, ls...)
if len(g.afterContext) <= g.ctxLines*2 && i != len(g.chunks)-1 {
g.current.AddOp(Equal, g.afterContext...)
g.afterContext = nil
} else {
ctxLines := g.ctxLines
if ctxLines > len(g.afterContext) {
ctxLines = len(g.afterContext)
}
g.current.AddOp(Equal, g.afterContext[:ctxLines]...)
g.hunks = append(g.hunks, g.current)
g.current = nil
g.beforeContext = g.afterContext[ctxLines:]
g.afterContext = nil
}
}
func splitLines(s string) []string {
out := splitLinesRegexp.FindAllString(s, -1)
if out[len(out)-1] == "" {
out = out[:len(out)-1]
}
return out
}
type hunk struct {
fromLine int
toLine int
fromCount int
toCount int
ctxPrefix string
ops []*op
}
func (h *hunk) writeTo(sb *strings.Builder, color ColorConfig) {
sb.WriteString(color[Frag])
sb.WriteString("@@ -")
if h.fromCount == 1 {
sb.WriteString(strconv.Itoa(h.fromLine))
} else {
sb.WriteString(strconv.Itoa(h.fromLine))
sb.WriteByte(',')
sb.WriteString(strconv.Itoa(h.fromCount))
}
sb.WriteString(" +")
if h.toCount == 1 {
sb.WriteString(strconv.Itoa(h.toLine))
} else {
sb.WriteString(strconv.Itoa(h.toLine))
sb.WriteByte(',')
sb.WriteString(strconv.Itoa(h.toCount))
}
sb.WriteString(" @@")
sb.WriteString(color.Reset(Frag))
if h.ctxPrefix != "" {
sb.WriteByte(' ')
sb.WriteString(color[Func])
sb.WriteString(h.ctxPrefix)
sb.WriteString(color.Reset(Func))
}
sb.WriteByte('\n')
for _, op := range h.ops {
op.writeTo(sb, color)
}
}
func (h *hunk) AddOp(t Operation, ss ...string) {
n := len(ss)
switch t {
case Add:
h.toCount += n
case Delete:
h.fromCount += n
case Equal:
h.toCount += n
h.fromCount += n
}
for _, s := range ss {
h.ops = append(h.ops, &op{s, t})
}
}
type op struct {
text string
t Operation
}
func (o *op) writeTo(sb *strings.Builder, color ColorConfig) {
colorKey := operationColorKey[o.t]
sb.WriteString(color[colorKey])
sb.WriteByte(operationChar[o.t])
if strings.HasSuffix(o.text, "\n") {
sb.WriteString(strings.TrimSuffix(o.text, "\n"))
} else {
sb.WriteString(o.text + "\n\\ No newline at end of file")
}
sb.WriteString(color.Reset(colorKey))
sb.WriteByte('\n')
}
