api: nvim_echo

src/nvim/api/private/helpers.c

@@ -1645,6 +1645,43 @@ bool api_object_to_bool(Object obj, const char *what,
   }
 }
 
+HlMessage parse_hl_msg(Array chunks, Error *err)
+{
+  HlMessage hl_msg = KV_INITIAL_VALUE;
+  for (size_t i = 0; i < chunks.size; i++) {
+    if (chunks.items[i].type != kObjectTypeArray) {
+      api_set_error(err, kErrorTypeValidation, "Chunk is not an array");
+      goto free_exit;
+    }
+    Array chunk = chunks.items[i].data.array;
+    if (chunk.size == 0 || chunk.size > 2
+        || chunk.items[0].type != kObjectTypeString
+        || (chunk.size == 2 && chunk.items[1].type != kObjectTypeString)) {
+      api_set_error(err, kErrorTypeValidation,
+                    "Chunk is not an array with one or two strings");
+      goto free_exit;
+    }
+
+    String str = copy_string(chunk.items[0].data.string);
+
+    int attr = 0;
+    if (chunk.size == 2) {
+      String hl = chunk.items[1].data.string;
+      if (hl.size > 0) {
+        int hl_id = syn_check_group((char_u *)hl.data, (int)hl.size);
+        attr = hl_id > 0 ? syn_id2attr(hl_id) : 0;
+      }
+    }
+    kv_push(hl_msg, ((HlMessageChunk){ .text = str, .attr = attr }));
+  }
+
+  return hl_msg;
+
+free_exit:
+  clear_hl_msg(&hl_msg);
+  return hl_msg;
+}
+
 const char *describe_ns(NS ns_id)
 {
   String name;

src/nvim/api/vim.c

@@ -990,6 +990,47 @@ void nvim_set_option(uint64_t channel_id, String name, Object value, Error *err)
   set_option_to(channel_id, NULL, SREQ_GLOBAL, name, value, err);
 }
 
+/// Echo a message.
+///
+/// @param chunks  A list of [text, hl_group] arrays, each representing a
+///                text chunk with specified highlight. `hl_group` element
+///                can be omitted for no highlight.
+/// @param history  if true, add to |message-history|.
+/// @param opts  Optional parameters. Reserved for future use.
+void nvim_echo(Array chunks, Boolean history, Dictionary opts, Error *err)
+  FUNC_API_SINCE(7)
+{
+  HlMessage hl_msg = parse_hl_msg(chunks, err);
+  if (ERROR_SET(err)) {
+    goto error;
+  }
+
+  if (opts.size > 0) {
+    api_set_error(err, kErrorTypeValidation, "opts dict isn't empty");
+    goto error;
+  }
+
+  no_wait_return++;
+  bool need_clear = true;
+  msg_start();
+  for (uint32_t i = 0; i < kv_size(hl_msg); i++) {
+    HlMessageChunk chunk = kv_A(hl_msg, i);
+    msg_multiline_attr((const char *)chunk.text.data, chunk.attr,
+                       false, &need_clear);
+  }
+  if (history) {
+    msg_ext_set_kind("echomsg");
+    add_hl_msg_hist(hl_msg);
+  } else {
+    msg_ext_set_kind("echo");
+  }
+  no_wait_return--;
+  msg_end();
+
+error:
+  clear_hl_msg(&hl_msg);
+}
+
 /// Writes a message to the Vim output buffer. Does not append "\n", the
 /// message is buffered (won't display) until a linefeed is written.
 ///

src/nvim/message.c

@@ -890,6 +890,40 @@ char_u *msg_may_trunc(int force, char_u *s)
   return s;
 }
 
+void clear_hl_msg(HlMessage *hl_msg)
+{
+  for (size_t i = 0; i < kv_size(*hl_msg); i++) {
+    xfree(kv_A(*hl_msg, i).text.data);
+  }
+  kv_destroy(*hl_msg);
+  *hl_msg = (HlMessage)KV_INITIAL_VALUE;
+}
+
+#define LINE_BUFFER_SIZE 4096
+
+void add_hl_msg_hist(HlMessage hl_msg)
+{
+  // TODO(notomo): support multi highlighted message history
+  size_t pos = 0;
+  char buf[LINE_BUFFER_SIZE];
+  for (uint32_t i = 0; i < kv_size(hl_msg); i++) {
+    HlMessageChunk chunk = kv_A(hl_msg, i);
+    for (uint32_t j = 0; j < chunk.text.size; j++) {
+      if (pos == LINE_BUFFER_SIZE - 1) {
+        buf[pos] = NUL;
+        add_msg_hist((const char *)buf, -1, MSG_HIST, true);
+        pos = 0;
+        continue;
+      }
+      buf[pos++] = chunk.text.data[j];
+    }
+  }
+  if (pos != 0) {
+    buf[pos] = NUL;
+    add_msg_hist((const char *)buf, -1, MSG_HIST, true);
+  }
+}
+
 /// @param[in]  len  Length of s or -1.
 static void add_msg_hist(const char *s, int len, int attr, bool multiline)
 {

src/nvim/message.h

@@ -8,6 +8,8 @@
 #include "nvim/macros.h"
 #include "nvim/types.h"
 #include "nvim/grid_defs.h"
+#include "nvim/api/private/defs.h"
+#include "nvim/lib/kvec.h"
 
 /*
  * Types of dialogs passed to do_dialog().
@@ -75,6 +77,13 @@
 /// Like #MSG_PUTS_ATTR, but if middle part of long messages will be replaced
 #define MSG_PUTS_LONG_ATTR(s, a)    msg_puts_long_attr((char_u *)(s), (a))
 
+typedef struct {
+  String text;
+  int attr;
+} HlMessageChunk;
+
+typedef kvec_t(HlMessageChunk) HlMessage;
+
 /// Message history for `:messages`
 typedef struct msg_hist {
   struct msg_hist *next;  ///< Next message.