rbuffer: Reimplement as a ring buffer and decouple from rstream

Extract the RBuffer class from rstream.c and reimplement it as a ring buffer,
a more efficient version that doesn't need to relocate memory.

The old rbuffer_read/rbuffer_write interfaces are kept for simple
reading/writing, and the RBUFFER_UNTIL_{FULL,EMPTY} macros are introduced to
hide wrapping logic when more control is required(such as passing the buffer
pointer to a library function that writes directly to the pointer)

Also add a basic infrastructure for writing helper C files that are only
compiled in the unit test library, and use this to write unit tests for RBuffer
which contains some macros that can't be accessed directly by luajit.

Helped-by: oni-link <knil.ino@gmail.com>
Reviewed-by: oni-link <knil.ino@gmail.com>
Reviewed-by: Scott Prager <splinterofchaos@gmail.com>
Reviewed-by: Justin M. Keyes <justinkz@gmail.com>
Reviewed-by: Michael Reed <m.reed@mykolab.com>

1 files changed, 15 insertions, 16 deletions

diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index 74a5d3bc2e..726335bd9a 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -79,7 +79,7 @@ void input_stop(void)
 // Low level input function
 int os_inchar(uint8_t *buf, int maxlen, int ms, int tb_change_cnt)
 {
-  if (rbuffer_pending(input_buffer)) {
+  if (rbuffer_size(input_buffer)) {
     return (int)rbuffer_read(input_buffer, (char *)buf, (size_t)maxlen);
   }
 
@@ -108,7 +108,7 @@ int os_inchar(uint8_t *buf, int maxlen, int ms, int tb_change_cnt)
     return 0;
   }
 
-  if (rbuffer_pending(input_buffer)) {
+  if (rbuffer_size(input_buffer)) {
     // Safe to convert rbuffer_read to int, it will never overflow since we use
     // relatively small buffers.
     return (int)rbuffer_read(input_buffer, (char *)buf, (size_t)maxlen);
@@ -153,7 +153,7 @@ size_t input_enqueue(String keys)
 {
   char *ptr = keys.data, *end = ptr + keys.size;
 
-  while (rbuffer_available(input_buffer) >= 6 && ptr < end) {
+  while (rbuffer_space(input_buffer) >= 6 && ptr < end) {
     uint8_t buf[6] = {0};
     unsigned int new_size = trans_special((uint8_t **)&ptr, buf, true);
 
@@ -309,16 +309,17 @@ static InbufPollResult inbuf_poll(int ms)
   return input_eof ? kInputEof : kInputNone;
 }
 
-static void read_cb(RStream *rstream, void *data, bool at_eof)
+static void read_cb(RStream *rstream, RBuffer *buf, void *data, bool at_eof)
 {
   if (at_eof) {
     input_eof = true;
   }
 
-  char *buf = rbuffer_read_ptr(read_buffer);
-  size_t buf_size = rbuffer_pending(read_buffer);
-  (void)rbuffer_write(input_buffer, buf, buf_size);
-  rbuffer_consumed(read_buffer, buf_size);
+  assert(rbuffer_space(input_buffer) >= rbuffer_size(read_buffer));
+  RBUFFER_UNTIL_EMPTY(read_buffer, ptr, len) {
+    (void)rbuffer_write(input_buffer, ptr, len);
+    rbuffer_consumed(read_buffer, len);
+  }
 }
 
 static void process_interrupts(void)
@@ -327,18 +328,16 @@ static void process_interrupts(void)
     return;
   }
 
-  char *inbuf = rbuffer_read_ptr(input_buffer);
-  size_t count = rbuffer_pending(input_buffer), consume_count = 0;
-
-  for (int i = (int)count - 1; i >= 0; i--) {
-    if (inbuf[i] == 3) {
+  size_t consume_count = 0;
+  RBUFFER_EACH_REVERSE(input_buffer, c, i) {
+    if ((uint8_t)c == 3) {
       got_int = true;
-      consume_count = (size_t)i;
+      consume_count = i;
       break;
     }
   }
 
-  if (got_int) {
+  if (got_int && consume_count) {
     // Remove everything typed before the CTRL-C
     rbuffer_consumed(input_buffer, consume_count);
   }
@@ -362,7 +361,7 @@ static int push_event_key(uint8_t *buf, int maxlen)
 static bool input_ready(void)
 {
   return typebuf_was_filled ||                 // API call filled typeahead
-         rbuffer_pending(input_buffer) > 0 ||  // Input buffer filled
+         rbuffer_size(input_buffer) ||         // Input buffer filled
          event_has_deferred();                 // Events must be processed
 }