undo/redo

2 files changed, 64 insertions, 6 deletions

diff --git a/txt.c b/txt.c
index 0a24b22..3107b94 100644
--- a/txt.c
+++ b/txt.c
@@ -258,6 +258,49 @@ void txt_free(Txt *t) {
 	free(t->ptbl.v);
 }
 
+void txt_hist_push(Txt *t, TxtLoc cur) {
+	if (t->hist.n > 0) {
+		TxtPieceTbl *pt = &t->hist.v[t->hist.i];
+		if (t->ptbl.n == pt->n && !memcmp(pt->v, t->ptbl.v, sizeof(TxtPiece) * pt->n)) {
+			t->hist.cur[t->hist.i] = cur;
+			return;
+		}
+	}
+	if (t->hist.i + 1 < t->hist.n) t->hist.n = t->hist.i + 1;
+	if (t->hist.n == TXT_HIST_MAX) {
+		free(t->hist.v[0].v);
+		MOVE(&t->hist.v[0], &t->hist.v[1], TXT_HIST_MAX - 1);
+		t->hist.i--;
+		t->hist.n--;
+	}
+	if (t->hist.i + 1 == t->hist.n) t->hist.i++;
+	DA_FIT(&t->hist.v[t->hist.i], t->ptbl.n);
+	memcpy(t->hist.v[t->hist.i].v, t->ptbl.v, sizeof(TxtPiece) * t->ptbl.n);
+	t->hist.v[t->hist.i].n = t->ptbl.n;
+	t->hist.cur[t->hist.i] = cur;
+	t->hist.n++;
+}
+
+int txt_hist_fwd(Txt *t, TxtLoc *cur) {
+	if (t->hist.i + 1 >= t->hist.n) return 0;
+	t->hist.i++;
+	t->ptbl.n = t->hist.v[t->hist.i].n;
+	DA_FIT(&t->ptbl, t->ptbl.n);
+	memcpy(t->ptbl.v, t->hist.v[t->hist.i].v, sizeof(TxtPiece) * t->ptbl.n);
+	*cur = t->hist.cur[t->hist.i];
+	return 1;
+}
+
+int txt_hist_back(Txt *t, TxtLoc *cur) {
+	if (t->hist.i == 0) return 0;
+	t->hist.i--;
+	t->ptbl.n = t->hist.v[t->hist.i].n;
+	DA_FIT(&t->ptbl, t->ptbl.n);
+	memcpy(t->ptbl.v, t->hist.v[t->hist.i].v, sizeof(TxtPiece) * t->ptbl.n);
+	*cur = t->hist.cur[t->hist.i];
+	return 1;
+}
+
 Str txt_collect_range(TxtLoc lo, TxtLoc hi, Arena *a) {
 	DYNARR(char) buf = { 0 };
 	while (lo.p < hi.p) {
diff --git a/txt.h b/txt.h
index 5df33a7..148369e 100644
--- a/txt.h
+++ b/txt.h
@@ -5,6 +5,8 @@
 #include "arena.h"
 #include "str.h"
 
+#define TXT_HIST_MAX 32
+
 typedef enum : u8 {
 	TXT_SRC,
 	TXT_ADD
@@ -20,18 +22,27 @@ typedef struct {
 	u32 n, c;
 } TxtBuf;
 
+typedef DYNARR(TxtPiece)  TxtPieceTbl;
+
+typedef struct {
+	struct Txt *t;
+	u32 p, i;
+} TxtLoc;
+
 typedef struct {
-	DYNARR(TxtPiece) ptbl;
+	TxtPieceTbl v[TXT_HIST_MAX];
+	TxtLoc cur[TXT_HIST_MAX];
+	u32 i, n;
+} TxtHist;
+
+typedef struct Txt {
+	TxtPieceTbl ptbl;
+	TxtHist hist;
 	TxtBuf buf[2];
 	u32 len;
 	int dirty;
 } Txt;
 
-typedef struct {
-	Txt *t;
-	u32 p, i;
-} TxtLoc;
-
 /* text buffer manipulation */
 
 TxtLoc txt_split_piece(TxtLoc l);
@@ -43,6 +54,10 @@ int txt_load(Txt *b, const char *path);
 int txt_save(Txt *b, const char *path);
 void txt_free(Txt *b);
 
+void txt_hist_push(Txt *t, TxtLoc cur);
+int txt_hist_fwd(Txt *t, TxtLoc *cur);
+int txt_hist_back(Txt *t, TxtLoc *cur);
+
 Str txt_collect_range(TxtLoc lo, TxtLoc hi, Arena *a);
 u32 txt_read_chunk(TxtLoc *lo, TxtLoc hi, char *buf, u32 sz);
 Str txt_next_chunk(TxtLoc *l);