ffi.new and ffi.cast now support more than argument for structs and arrays

e.g. ffi.new('int[3]', 1, 2, 3)

This is done by trying to set the value using the constructor argument (if
there is only one) and failing that (or if there is more than one), pack it in
a table and then try again. This could probably be smarter and not create the
temporary table, but would require quite a bit more refactoring.

Fixes #25

1 files changed, 53 insertions, 3 deletions

diff --git a/ffi.c b/ffi.c
index 97ef747..7556dc9 100644
--- a/ffi.c
+++ b/ffi.c
@@ -1023,13 +1023,22 @@ static void get_variable_array_size(lua_State* L, int idx, struct ctype* ct)
     }
 }
 
+static int try_set_value(lua_State* L)
+{
+    void* p = lua_touserdata(L, 2);
+    struct ctype* ct = (struct ctype*) lua_touserdata(L, 4);
+    int check_ptrs = lua_toboolean(L, 5);
+    set_value(L, 1, p, 3, ct, check_ptrs);
+    return 0;
+}
+
 static int do_new(lua_State* L, int is_cast)
 {
+    int cargs, i;
     void* p;
     struct ctype ct;
     int check_ptrs = !is_cast;
 
-    setmintop(L, 3);
     check_ctype(L, 1, &ct);
 
     /* don't push a callback when we have a c function, as cb:set needs a
@@ -1046,6 +1055,7 @@ static int do_new(lua_State* L, int is_cast)
         return 1;
     }
 
+    /* this removes the vararg argument if its needed, and errors if its invalid */
     if (!is_cast) {
         get_variable_array_size(L, 2, &ct);
     }
@@ -1065,9 +1075,49 @@ static int do_new(lua_State* L, int is_cast)
         lua_pop(L, 2); /* user_mt and gc_upval */
     }
 
-    if (!lua_isnil(L, 2)) {
-        set_value(L, 2, p, -2, &ct, check_ptrs);
+    /* stack is:
+     * ctype arg
+     * ctor args ... 0+
+     * ctype usr
+     * cdata
+     */
+
+    cargs = lua_gettop(L) - 3;
+
+    if (cargs == 0) {
+        return 1;
+    }
+
+    if (cargs == 1) {
+        /* try packed form first
+         * packed: ffi.new('int[3]', {1})
+         * unpacked: ffi.new('int[3]', 1)
+         */
+        lua_pushcfunction(L, &try_set_value);
+        lua_pushvalue(L, 2); /* ctor arg */
+        lua_pushlightuserdata(L, p);
+        lua_pushvalue(L, -5); /* ctype usr */
+        lua_pushlightuserdata(L, &ct);
+        lua_pushboolean(L, check_ptrs);
+
+        if (!lua_pcall(L, 5, 0, 0)) {
+            return 1;
+        }
+
+        /* remove any errors */
+        lua_settop(L, 4);
+    }
+
+    /* if we have more than 2 ctor arguments then they must be unpacked, e.g.
+     * ffi.new('int[3]', 1, 2, 3) */
+    lua_createtable(L, cargs, 0);
+    lua_replace(L, 1);
+    for (i = 1; i <= cargs; i++) {
+        lua_pushvalue(L, i + 1);
+        lua_rawseti(L, 1, i);
     }
+    assert(lua_gettop(L) == cargs + 3);
+    set_value(L, 1, p, -2, &ct, check_ptrs);
 
     return 1;
 }