shithub: vexed

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implement undo and redo

--- a/README.md

+++ b/README.md

@@ -10,6 +10,8 @@

 `i` inserts a byte before the current selection.  

 `p` inserts a byte after the current selection.  

 `x` deletes the currently selected byte.  

+`u` undo last edit.  

+`r` redo last undo'ed edit.  

 Del or q exit the program.  

 **THIS IS WORK IN PROGRESS. USE AT YOUR OWN RISK**

--- a/a.h

+++ b/a.h

@@ -1,3 +1,4 @@

+/* BUFFER */

 typedef struct Buffer Buffer;

 struct Buffer

@@ -12,6 +13,32 @@

 int delete(Buffer*, int);

 int insert(Buffer*, int);

 int append(Buffer*, int);

+

+/* UNDO */

+typedef struct Undo Undo;

+

+enum

+{

+	Udelete,

+	Uinsert,

+	Uappend,

+	Uset,

+};

+

+struct Undo

+{

+	int action;

+	int index;

+	uchar value;

+	uchar newvalue;

+};

+

+int  canundo(void);

+void undo(Undo*);

+int  canredo(void);

+void redo(Undo*);

+void pushundo(int, int, uchar, uchar);

+void patchundo(uchar);

 /* COLORS */

 enum

--- a/mkfile

+++ b/mkfile

@@ -2,7 +2,7 @@

 BIN=/$objtype/bin

 TARG=vexed

-OFILES=vexed.$O buf.$O cols.$O

+OFILES=vexed.$O buf.$O undo.$O cols.$O

 HFILES=a.h

 </sys/src/cmd/mkone

--- /dev/null

+++ b/undo.c

@@ -1,0 +1,61 @@

+#include <u.h>

+#include <libc.h>

+#include <draw.h>

+#include "a.h"

+

+enum { Stacksize = 1024 };

+Undo ustack[Stacksize];

+int ucount = 0;

+int ucur = -1;

+

+int

+canundo(void)

+{

+	return ucur >= 0;

+}

+

+void

+undo(Undo *undo)

+{

+	undo->action = ustack[ucur].action;

+	undo->index = ustack[ucur].index;

+	undo->value = ustack[ucur].value;

+	undo->newvalue = ustack[ucur].newvalue;

+	ucur -= 1;

+}

+

+int

+canredo(void)

+{

+	return ucur < ucount - 1;

+}

+

+void

+redo(Undo *undo)

+{

+	ucur += 1;

+	undo->action = ustack[ucur].action;

+	undo->index = ustack[ucur].index;

+	undo->value = ustack[ucur].value;

+	undo->newvalue = ustack[ucur].newvalue;

+}

+

+void

+pushundo(int action, int index, uchar value, uchar newvalue)

+{

+	if(ucur == Stacksize - 1)

+		return;

+	ucur += 1;

+	ucount = ucur + 1;

+	ustack[ucur].action = action;

+	ustack[ucur].index = index;

+	ustack[ucur].value = value;

+	ustack[ucur].newvalue = newvalue;

+}

+

+void

+patchundo(uchar value)

+{

+	ustack[ucur].newvalue = value;

+}

+

--- a/vexed.c

+++ b/vexed.c

@@ -8,6 +8,7 @@

 #include "a.h"

 void redraw(void);

+void drawselchange(int);

 enum

 {

@@ -23,8 +24,8 @@

 	Scrollwidth = 12,

 };

-enum { Mgoto, Mdelete, Minsert, Mappend };

-char *menu2str[] = { "go...", "delete", "insert", "append", 0 };

+enum { Mundo, Mredo, Mgoto, Mdelete, Minsert, Mappend };

+char *menu2str[] = { "undo", "redo", "go...", "delete", "insert", "append", 0 };

 Menu menu2 = { menu2str };

 enum { Msave, Mquit, };

@@ -47,6 +48,73 @@

 int sel = 0;

 void

+xundo(void)

+{

+	Undo u;

+

+	if(!canundo())

+		return;

+	undo(&u);

+	switch(u.action){

+	case Udelete:

+		if(insert(&buf, u.index) < 0)

+			sysfatal("insert: %r");

+		buf.data[u.index] = u.value;

+		break;

+	case Uinsert:

+		if(delete(&buf, u.index) < 0)

+			sysfatal("delete: %r");

+		break;

+	case Uappend:

+		if(delete(&buf, u.index + 1) < 0)

+			sysfatal("delete: %r");

+		break;

+	case Uset:

+		buf.data[u.index] = u.value;

+		break;

+	}

+	sel = u.index;

+	modified = 1;

+	blines = buf.count / 16;

+	redraw();

+}

+

+void

+xredo(void)

+{

+	Undo u;

+

+	if(!canredo())

+		return;

+	redo(&u);

+	switch(u.action){

+	case Udelete:

+		if(delete(&buf, u.index) < 0)

+			sysfatal("insert: %r");

+		sel = u.index;

+		break;

+	case Uinsert:

+		if(insert(&buf, u.index) < 0)

+			sysfatal("insert: %r");

+		sel = u.index;

+		break;

+	case Uappend:

+		if(insert(&buf, u.index + 1) < 0)

+			sysfatal("insert: %r");

+		sel = u.index + 1;

+		break;

+	case Uset:

+		buf.data[u.index] = u.newvalue;

+		break;

+	}

+	if(sel == buf.count)

+		--sel;

+	modified = 1;

+	blines = buf.count / 16;

+	redraw();

+}

+

+void

 xgoto(void)

 {

 	char b[16] = {0}, *endp;

@@ -66,6 +134,7 @@

 void

 xdelete(void)

 {

+	pushundo(Udelete, sel, buf.data[sel], 0);

 	if(delete(&buf, sel) < 0)

 		sysfatal("delete: %r");

 	if(sel == buf.count)

@@ -78,6 +147,7 @@

 void

 xinsert(void)

 {

+	pushundo(Uinsert, sel, 0, 0);

 	if(insert(&buf, sel) < 0)

 		sysfatal("insert: %r");

 	modified = 1;

@@ -88,6 +158,7 @@

 void

 xappend(void)

 {

+	pushundo(Uappend, sel, 0, 0);

 	if(append(&buf, sel) < 0)

 		sysfatal("append: %r");

 	sel += 1;

@@ -256,6 +327,12 @@

 	n = menuhit(2, mctl, &menu2, nil);

 	switch(n){

+	case Mundo:

+		xundo();

+		break;

+	case Mredo:

+		xredo();

+		break;

 	case Mgoto:

 		xgoto();

 		break;

@@ -420,6 +497,14 @@

 			redraw();

 		}

 		break;

+	case 'u':

+	case 'U':

+		xundo();

+		break;

+	case 'r':

+	case 'R':

+		xredo();

+		break;

 	case 'g':

 	case 'G':

 		xgoto();

@@ -440,9 +525,11 @@

 		if(isxdigit(k)){

 			if(e - lastk < 2 && lastv > 0) {

 				buf.data[sel] = lastv*16 + hexval(k);

+				patchundo(buf.data[sel]);

 				lastv = -1;

 			}else{

 				lastv = hexval(k);

+				pushundo(Uset, sel, buf.data[sel], lastv);

 				buf.data[sel] = lastv;

 			}

 			modified = 1;