CAPI: Add pairs/ipairs/next to CAPI to support proxies

2 files changed, 149 insertions, 0 deletions

diff --git a/lib/supple/capi.c b/lib/supple/capi.c
index 125a415..38c4f27 100644
--- a/lib/supple/capi.c
+++ b/lib/supple/capi.c
@@ -349,6 +349,80 @@ supple_capi_raw_getmm(lua_State *L)
 	return 1;
 }
 
+static int
+supple_capi_next(lua_State *L)
+{
+	int type;
+
+	lua_settop(L, 2);
+
+	type = lua_type(L, 1);
+	if (type == LUA_TTABLE) {
+		/* It is a table, so do the equiv of luaB_next */
+		if (lua_next(L, 1))
+			/* return the k/v pair we got */
+			return 2;
+		/* didn't get a k/v pair, so push a nil key and return */
+		lua_pushnil(L);
+		return 1;
+	} else {
+		/* Do we have a metatable? */
+		if (lua_getmetatable(L, 1)) {
+			/* We do, do we have a __next entry? */
+			lua_getfield(L, -1, "__next");
+			if (!lua_isnil(L, -1)) {
+				/* we do, so let's call that instead */
+				lua_insert(L, 1);
+				lua_settop(L, 3);
+				lua_call(L, 2, LUA_MULTRET);
+				return lua_gettop(L);
+			}
+		}
+	}
+	/* Fell out of the ladders so return an error */
+	return luaL_error(L, "Expected table (or iterable) as argument 1");
+}
+
+static int
+supple_capi_ipairs_iterator(lua_State *L)
+{
+	/* Obj Int -> (NewInt Value|nothing) */
+	int i = luaL_checkint(L, 2) + 1;
+	lua_pushinteger(L, i);
+	if (lua_type(L, 1) == LUA_TTABLE) {
+		lua_rawgeti(L, 1, i);
+	} else {
+		lua_pushinteger(L, i);
+		lua_gettable(L, 1); /* Use this so __index is used */
+	}
+	return lua_isnil(L, -1) ? 0 : 2;
+}
+
+static int
+supple_capi_ipairs(lua_State *L)
+{
+	/* Replacement ipairs which uses our iterator so that fetches
+	 * cross the proxy boundary transparently if needed.
+	 */
+	/* We register this with the iterator as the first upvalue */
+	lua_pushvalue(L, lua_upvalueindex(1)); /* iterator */
+	lua_pushvalue(L, 1); /* state (table?) */
+	lua_pushinteger(L, 0); /* initial value */
+	return 3;
+}
+
+static int
+supple_capi_pairs(lua_State *L)
+{
+	/* Replacement pairs which uses our next function.  It is
+	 * provided as our upvalue
+	 */
+	lua_pushvalue(L, lua_upvalueindex(1));
+	lua_pushvalue(L, 1);
+	lua_pushnil(L);
+	return 3;
+}
+
 static const struct luaL_Reg
 supple_capi_functions[] = {
 	{ "explain", supple_capi_explain },
@@ -357,6 +431,7 @@ supple_capi_functions[] = {
 	{ "rawtype", supple_capi_rawtype },
 	{ "lockdown", supple_capi_lockdown },
 	{ "raw_getmm", supple_capi_raw_getmm },
+	{ "next", supple_capi_next },
 	{ NULL, NULL }
 };
 
@@ -368,5 +443,11 @@ luaopen_supple_capi(lua_State *L)
 	lua_setfield(L, -2, "_API");
 	lua_pushnumber(L, CAPI_ABI);
 	lua_setfield(L, -2, "_ABI");
+	lua_pushcclosure(L, supple_capi_ipairs_iterator, 0);
+	lua_pushcclosure(L, supple_capi_ipairs, 1);
+	lua_setfield(L, -2, "ipairs");
+	lua_pushcclosure(L, supple_capi_next, 0);
+	lua_pushcclosure(L, supple_capi_pairs, 1);
+	lua_setfield(L, -2, "pairs");
 	return 1;
 }
diff --git a/test/test-supple.capi.lua b/test/test-supple.capi.lua
index 7438874..f46c3eb 100644
--- a/test/test-supple.capi.lua
+++ b/test/test-supple.capi.lua
@@ -170,6 +170,74 @@ function suite.capi_new_proxy_table()
    assert(tostring(proxy):match("^userdata: "), "Proxy didn't tostring nicely")
 end
 
+function suite.capi_test_next_on_table()
+   local t = { foo = "bar" }
+   local k, v = capi.next(t)
+   assert(k == "foo", "Key was not 'foo'")
+   assert(v == "bar", "Value was not 'bar'")
+   assert(capi.next(t, "foo") == nil, "Next after 'foo' was not nil")
+end
+
+function suite.capi_test_next_on_proxied_table()
+   local proxied = { foo = "bar" }
+   local proxy, mt = capi.new_proxy("table")
+   mt.__next = function(self, key)
+		  return next(proxied, key)
+	       end
+   local k, v = capi.next(proxy)
+   assert(k == "foo", "Key was not 'foo'")
+   assert(v == "bar", "Value was not 'bar'")
+   assert(capi.next(proxy, "foo") == nil, "Next after 'foo' was not nil")
+end
+
+function suite.capi_test_ipairs_on_table()
+   local tab = { "a", "b" }
+   for i, v in capi.ipairs(tab) do
+      assert(i > 0 and i < 3, "Index out of range")
+      assert((i == 1 and v == "a") or
+	     (i == 2 and v == "b"),
+	     "Key/value pair wrong")
+   end
+end
+
+function suite.capi_test_ipairs_on_proxied_table()
+   local proxied = { "a", "b" }
+   local tab, mt = capi.new_proxy("table")
+   mt.__index = function(self, idx)
+		   return proxied[idx]
+		end
+   for i, v in capi.ipairs(tab) do
+      assert(i > 0 and i < 3, "Index out of range")
+      assert((i == 1 and v == "a") or
+	     (i == 2 and v == "b"),
+	     "Key/value pair wrong")
+   end
+end
+
+function suite.capi_test_pairs_on_table()
+   local tab = { foo = "bar", baz = "meta" }
+   for k, v in capi.pairs(tab) do
+      assert(k == "foo" or k == "baz", "Key not right")
+      assert((k == "foo" and v == "bar") or
+	     (k == "baz" and v == "meta"),
+	     "key/value pair wrong")
+   end
+end
+
+function suite.capi_test_pairs_on_proxied_table()
+   local proxied = { foo = "bar", baz = "meta" }
+   local tab, mt = capi.new_proxy("table")
+   mt.__next = function(self, idx)
+		  return next(proxied, idx)
+	       end
+   for k, v in capi.pairs(tab) do
+      assert(k == "foo" or k == "baz", "Key not right")
+      assert((k == "foo" and v == "bar") or
+	     (k == "baz" and v == "meta"),
+	     "key/value pair wrong")
+   end
+end
+
 local count_ok = 0
 for _, testname in ipairs(testnames) do
 --   print("Run: " .. testname)