Add infrastructure to add custom motion functions

A motion function can be registered with vis_motion_register(...)
the returned id (if non negative) can then be used as an argument
to vis_motion(...)

vis-core.h

@@ -8,6 +8,7 @@
 #include "text-regex.h"
 #include "map.h"
 #include "ring-buffer.h"
+#include "array.h"
 
 /* a mode contains a set of key bindings which are currently valid.
  *
@@ -59,13 +60,15 @@ typedef struct { /* Motion implementation, takes a cursor postion and returns a
 	size_t (*vis)(Vis*, Text*, size_t pos);
 	size_t (*view)(Vis*, View*);
 	size_t (*win)(Vis*, Win*, size_t pos);
+	size_t (*user)(Vis*, Win*, void*, size_t pos);
 	enum {
 		LINEWISE  = VIS_MOTIONTYPE_LINEWISE,  /* should the covered range be extended to whole lines? */
 		CHARWISE  = VIS_MOTIONTYPE_CHARWISE,  /* scrolls window content until position is visible */
 		INCLUSIVE = 1 << 2,  /* should new position be included in operator range? */
 		IDEMPOTENT = 1 << 3, /* does the returned postion remain the same if called multiple times? */
 		JUMP = 1 << 4,
 	} type;
+	void *data;
 } Movement;
 
 typedef struct {
@@ -165,6 +168,7 @@ struct Vis {
 	Map *actions;                        /* registered editor actions / special keys commands */
 	lua_State *lua;                      /* lua context used for syntax highligthing */
 	VisEvent *event;
+	Array motions;
 };
 
 /** stuff used by multiple of the vis-* files */

vis-motions.c

@@ -5,6 +5,7 @@
 #include "text-motions.h"
 #include "text-objects.h"
 #include "text-util.h"
+#include "util.h"
 
 /** utility functions */
 
@@ -210,6 +211,23 @@ void vis_motion_type(Vis *vis, enum VisMotionType type) {
 	vis->action.type = type;
 }
 
+int vis_motion_register(Vis *vis, enum VisMotionType type, void *data,
+	size_t (*motion)(Vis*, Win*, void*, size_t pos)) {
+
+	Movement *move = calloc(1, sizeof *move);
+	if (!move)
+		return -1;
+
+	move->user = motion;
+	move->type = type;
+	move->data = data;
+
+	if (array_add(&vis->motions, move))
+		return VIS_MOVE_LAST + array_length(&vis->motions) - 1;
+	free(move);
+	return -1;
+}
+
 bool vis_motion(Vis *vis, enum VisMotion motion, ...) {
 	va_list ap;
 	va_start(ap, motion);
@@ -287,7 +305,14 @@ bool vis_motion(Vis *vis, enum VisMotion motion, ...) {
 		break;
 	}
 
-	vis->action.movement = &vis_motions[motion];
+	if (motion < LENGTH(vis_motions))
+		vis->action.movement = &vis_motions[motion];
+	else
+		vis->action.movement = array_get(&vis->motions, motion - VIS_MOVE_LAST);
+
+	if (!vis->action.movement)
+		goto err;
+
 	va_end(ap);
 	action_do(vis, &vis->action);
 	return true;

vis.c

@@ -377,6 +377,7 @@ void vis_free(Vis *vis) {
 	buffer_release(&vis->input_queue);
 	for (int i = 0; i < VIS_MODE_INVALID; i++)
 		map_free(vis_modes[i].bindings);
+	array_release_full(&vis->motions);
 	free(vis);
 }
 
@@ -488,6 +489,8 @@ void action_do(Vis *vis, Action *a) {
 					pos = a->movement->view(vis, view);
 				else if (a->movement->win)
 					pos = a->movement->win(vis, win, pos);
+				else if (a->movement->user)
+					pos = a->movement->user(vis, win, a->movement->data, pos);
 				if (pos == EPOS || a->movement->type & IDEMPOTENT)
 					break;
 			}

vis.h

@@ -242,6 +242,7 @@ enum VisMotion {
 	VIS_MOVE_TOTILL_REVERSE,
 	VIS_MOVE_SEARCH_FORWARD,
 	VIS_MOVE_SEARCH_BACKWARD,
+	VIS_MOVE_LAST, /* denotes the end of all motions */
 };
 
 /* set motion to perform, the following take an additional argument:
@@ -275,6 +276,12 @@ enum VisMotionType {
 /* force certain motion to behave in line or character wise mode */
 void vis_motion_type(Vis *vis, enum VisMotionType);
 
+/* register a motion function, if positive the return value can be used
+ * as an id for the vis_motion funntion. A negative return value indicates
+ * an error */
+int vis_motion_register(Vis*, enum VisMotionType, void *data,
+	size_t (*motion)(Vis*, Win*, void*, size_t pos));
+
 enum VisTextObject {
 	VIS_TEXTOBJECT_INNER_WORD,
 	VIS_TEXTOBJECT_OUTER_WORD,