From 78d7ab73bda5fc675641fbcca45961bfd5299041 Mon Sep 17 00:00:00 2001
From: q66 <daniel@octaforge.org>
Date: Fri, 2 Sep 2016 22:15:05 +0100
Subject: [PATCH] add tab completion for readline

---
 tools/edit_readline.hh | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/tools/edit_readline.hh b/tools/edit_readline.hh
index 97720a3d..dba1e333 100644
--- a/tools/edit_readline.hh
+++ b/tools/edit_readline.hh
@@ -3,13 +3,52 @@
 #define CS_REPL_HAS_EDIT
 /* use the GNU readline library */
 
+#include <string.h>
+
 #include <ostd/string.hh>
 #include <ostd/maybe.hh>
 
 #include <readline/readline.h>
 #include <readline/history.h>
 
+#ifdef CS_REPL_HAS_COMPLETE
+static char *ln_complete_list(char const *buf, int state) {
+    static ostd::ConstCharRange cmd;
+    static ostd::PointerRange<CsIdent *> itr;
+
+    if (!state) {
+        cmd = get_complete_cmd(buf);
+        itr = gcs->identmap.iter();
+    }
+
+    for (; !itr.empty(); itr.pop_front()) {
+        CsIdent *id = itr.front();
+        if (!id->is_command()) {
+            continue;
+        }
+        ostd::ConstCharRange idname = id->get_name();
+        if (idname.size() <= cmd.size()) {
+            continue;
+        }
+        if (idname.slice(0, cmd.size()) == cmd) {
+            itr.pop_front();
+            return strdup(idname.data());
+        }
+    }
+
+    return nullptr;
+}
+
+static char **ln_complete(char const *buf, int, int) {
+    rl_attempted_completion_over = 1;
+    return rl_completion_matches(buf, ln_complete_list);
+}
+#endif
+
 static void init_lineedit(ostd::ConstCharRange) {
+#ifdef CS_REPL_HAS_COMPLETE
+    rl_attempted_completion_function = ln_complete;
+#endif
 }
 
 static ostd::Maybe<ostd::String> read_line(CsSvar *pr) {