add clang.kak, providing clang based insert completion

src/rc/clang.kak

@@ -0,0 +1,37 @@
+decl str clang_filename
+decl str clang_options
+
+def clang-complete %{
+    %sh{
+        filename=$(mktemp -d -t kak-clang.XXXXXXXX)/buffer.cpp
+        echo "setb clang_filename $filename"
+        echo "write $filename"
+    }
+    # end the previous %sh{} so that its output gets interpreted by kakoune
+    # before launching the following as a background task.
+    %sh{
+        # this runs in a detached shell, asynchronously, so that kakoune does not hang while clang is running
+        # as completions references a cursor position and a buffer timestamp, only valid completions should be
+        # displayed.
+        (
+            pos=${kak_opt_clang_filename}:${kak_cursor_line}:${kak_cursor_column}
+            cp ${kak_opt_clang_filename} /tmp/kak_clang_file.cpp
+            echo $pos > /tmp/kak_clang_pos
+            output=$(clang++ -fsyntax-only -I${PWD} ${kak_opt_clang_options} -Xclang -code-completion-at=${pos} ${kak_opt_clang_filename} |
+                     grep -E "^COMPLETION:[^:]+:" | perl -pe 's/^COMPLETION:[^:]+: +//; s/\[#.*?#\]|<#.*?#>(, *|\))?|\{#.*?#\}\)?//g')
+            rm -r $(dirname ${kak_opt_clang_filename})
+            completions="${kak_cursor_line}:${kak_cursor_column}@${kak_timestamp}"
+            for cmp in ${output}; do
+                completions="${completions},${cmp}"
+            done
+            echo "eval -client $kak_client %[ echo completed; setb completions '${completions}' ]" | socat stdin UNIX-CONNECT:${kak_socket}
+        ) >& /dev/null < /dev/null &
+    }
+}
+
+def clang-enable-autocomplete %{
+    hook window InsertIdle .* %{ eval -restore-selections %{
+        exec h<a-h>
+        %sh{ [[ $kak_selection =~ .*(\.|->|::)$ ]] && echo "exec <a-space>l; echo 'completing...'; clang-complete" }
+    }}
+}