From 5a8cccb37e6832197fac3afa0fa39cf83283d5af Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Sun, 16 Jun 2019 11:02:11 +0200
Subject: [PATCH] Add an enable_if() to Block, for convenience.

---
 nageru/scene.cpp | 14 ++++++++++++++
 nageru/scene.h   |  1 +
 nageru/theme.cpp |  1 +
 3 files changed, 16 insertions(+)

diff --git a/nageru/scene.cpp b/nageru/scene.cpp
index 6c3a039..ccb3b1b 100644
--- a/nageru/scene.cpp
+++ b/nageru/scene.cpp
@@ -531,6 +531,20 @@ int Block_enable(lua_State *L)
 	return 0;
 }
 
+int Block_enable_if(lua_State *L)
+{
+	assert(lua_gettop(L) == 2);
+	Block *block = *(Block **)luaL_checkudata(L, 1, "Block");
+
+	if (block->alternatives.size() != 2 ||
+	    block->alternatives[1]->effect_type != IDENTITY_EFFECT) {
+		luaL_error(L, "enable_if() called on something that wasn't added with add_optional_effect()");
+	}
+	bool enabled = checkbool(L, 2);
+	block->currently_chosen_alternative = enabled ? 0 : 1;
+	return 0;
+}
+
 int Block_disable(lua_State *L)
 {
 	assert(lua_gettop(L) == 1);
diff --git a/nageru/scene.h b/nageru/scene.h
index b659429..7d83a27 100644
--- a/nageru/scene.h
+++ b/nageru/scene.h
@@ -110,6 +110,7 @@ struct Block {
 int Block_display(lua_State* L);
 int Block_choose(lua_State* L);
 int Block_enable(lua_State *L);
+int Block_enable_if(lua_State *L);
 int Block_disable(lua_State *L);
 int Block_set_int(lua_State *L);
 int Block_set_float(lua_State *L);
diff --git a/nageru/theme.cpp b/nageru/theme.cpp
index 53b7543..d31a4b9 100644
--- a/nageru/theme.cpp
+++ b/nageru/theme.cpp
@@ -793,6 +793,7 @@ const luaL_Reg Block_funcs[] = {
 	{ "display", Block_display },
 	{ "choose", Block_choose },
 	{ "enable", Block_enable },
+	{ "enable_if", Block_enable_if },
 	{ "disable", Block_disable },
 	{ "set_int", Block_set_int },
 	{ "set_float", Block_set_float },
-- 
2.39.2