vis: keep track of most recently processed keys of input queue

Currently the key handling functions do not know through which mapping
they were invoked. As an example the `count` handler exploits the
implementation detail that the input queue is stored in contiguous
memory, meaning `keys[-1]` gives access to the digit being pressed.

This adds infrastructure to keep track of the two most recently processed
keys of the input queue.

The information is guaranteed to be accurate for the initial invocation
of the key handler but will be overwritten in case new keys are pushed
to the input queue (e.g. through vis_keys_feed).

3 files changed, 14 insertions, 1 deletions

diff --git a/vis-core.h b/vis-core.h
index debd994..cc8636d 100644
--- a/vis-core.h
+++ b/vis-core.h
@@ -174,7 +174,9 @@ struct Vis {
 	Map *options;                        /* ":set"-options */
 	Map *keymap;                         /* key translation before any bindings are matched */
 	bool keymap_disabled;                /* ignore key map for next key press, gets automatically re-enabled */
-	char key[64];                        /* last pressed key as reported from the UI */
+	char key[VIS_KEY_LENGTH_MAX];        /* last pressed key as reported from the UI */
+	char key_current[VIS_KEY_LENGTH_MAX];/* current key being processed by the input queue */
+	char key_prev[VIS_KEY_LENGTH_MAX];   /* previous key which was processed by the input queue */
 	Buffer input_queue;                  /* holds pending input keys */
 	Buffer *keys;                        /* currently active keys buffer (either the input_queue or a macro) */
 	bool errorhandler;                   /* whether we are currently in an error handler, used to avoid recursion */
diff --git a/vis.c b/vis.c
index 12d364a..790069a 100644
--- a/vis.c
+++ b/vis.c
@@ -995,6 +995,10 @@ static void vis_keys_process(Vis *vis, size_t pos) {
 			end = start;
 		} else if (binding) { /* exact match */
 			if (binding->action) {
+				size_t len = binding_end - start;
+				strcpy(vis->key_prev, vis->key_current);
+				strncpy(vis->key_current, start, len);
+				vis->key_current[len] = '\0';
 				end = (char*)binding->action->func(vis, binding_end, &binding->action->arg);
 				if (!end) {
 					end = start;
@@ -1017,6 +1021,10 @@ static void vis_keys_process(Vis *vis, size_t pos) {
 				action = map_get(vis->actions, start+1);
 				end[-1] = tmp;
 				if (action) {
+					size_t len = end - start;
+					strcpy(vis->key_prev, vis->key_current);
+					strncpy(vis->key_current, start, len);
+					vis->key_current[len] = '\0';
 					end = (char*)action->func(vis, end, &action->arg);
 					if (!end) {
 						end = start;
diff --git a/vis.h b/vis.h
index a57ff94..6ea3d1d 100644
--- a/vis.h
+++ b/vis.h
@@ -27,6 +27,9 @@ typedef struct Win Win;
 #define VIS_COMPLETE "vis-complete"
 #endif
 
+/* maximum bytes needed for string representation of a (pseudo) key */
+#define VIS_KEY_LENGTH_MAX 64
+
 typedef struct {
 	void (*init)(Vis*);
 	void (*start)(Vis*);