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unidiff.go
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unidiff.go
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package gonp
import (
"bytes"
"fmt"
"io"
)
const (
PhaseFrontDiff = iota
PhaseInDiff
PhaseBehindDiff
)
const (
DefaultContextSize = 3
)
// UniHunk is an element of unified format difference
type UniHunk[T Elem] struct {
a, b, c, d int // @@ -a,b +c,d @@
changes []SesElem[T]
}
// GetChanges is getter of changes in UniHunk
func (uniHunk *UniHunk[T]) GetChanges() []SesElem[T] {
return uniHunk.changes
}
// SprintDiffRange returns formatted string represents difference range
func (uniHunk *UniHunk[T]) SprintDiffRange() string {
return fmt.Sprintf("@@ -%d,%d +%d,%d @@\n", uniHunk.a, uniHunk.b, uniHunk.c, uniHunk.d)
}
// PrintUniHunks prints unified format difference between and b
func (diff *Diff[T]) PrintUniHunks(uniHunks []UniHunk[T]) {
fmt.Print(SprintUniHunks(uniHunks))
}
// SprintUniHunks returns string about unified format difference between a and b
func SprintUniHunks[T any](uniHunks []UniHunk[T]) string {
var buf bytes.Buffer
FprintUniHunks(&buf, uniHunks)
return buf.String()
}
// FprintUniHunks emit about unified format difference between a and b to w
func FprintUniHunks[T any](w io.Writer, uniHunks []UniHunk[T]) {
for _, uniHunk := range uniHunks {
fmt.Fprintf(w, uniHunk.SprintDiffRange())
for _, e := range uniHunk.GetChanges() {
switch e.GetType() {
case SesDelete:
fmt.Fprintf(w, "-%v\n", e.GetElem())
case SesAdd:
fmt.Fprintf(w, "+%v\n", e.GetElem())
case SesCommon:
fmt.Fprintf(w, " %v\n", e.GetElem())
}
}
}
}
// UnifiedHunks composes unified format difference between a and b
func (diff *Diff[T]) UnifiedHunks() []UniHunk[T] {
if diff.ed == 0 {
return []UniHunk[T]{}
}
uniHunks := make([]UniHunk[T], 0)
changes := make([]SesElem[T], 0)
phase := PhaseFrontDiff
cc := 0
b, d := 0, 0
for i, e := range diff.ses {
switch e.typ {
case SesDelete:
b += 1
fallthrough
case SesAdd:
switch phase {
case PhaseFrontDiff:
phase = PhaseInDiff
changes = append(changes, e)
case PhaseInDiff:
changes = append(changes, e)
cc = 0
case PhaseBehindDiff:
// do nothing
}
if e.typ == SesAdd {
d += 1
}
case SesCommon:
switch phase {
case PhaseFrontDiff:
changes = append(changes, e)
if len(changes) > diff.contextSize {
changes = changes[1:]
b -= 1
d -= 1
}
case PhaseInDiff:
changes = append(changes, e)
cc += 1
if cc == diff.contextSize {
phase = PhaseBehindDiff
}
case PhaseBehindDiff:
// do nothing
}
b += 1
d += 1
}
if phase == PhaseBehindDiff || i == len(diff.ses)-1 {
a, c := 0, 0
for _, e = range changes {
if a == 0 {
a = e.aIdx
}
if c == 0 {
c = e.bIdx
}
if a != 0 && c != 0 {
break
}
}
uniHunk := UniHunk[T]{
a: a, b: b, c: c, d: d,
changes: changes,
}
uniHunks = append(uniHunks, uniHunk)
// re-init states
cc = 0
b, d = 0, 0
changes = make([]SesElem[T], 0)
phase = PhaseFrontDiff
}
}
return uniHunks
}