lyra-scripting/scripts/lua/ecs.lua

@@ -7,6 +7,8 @@ function Res(resource)
     return ResQuery.new(resource)
 end
 
+---@alias Query function|table|userdata
+
 ---Create a `ChangedQuery` query that will return only if the resource or component has changed
 ---since last tick.
 ---
@@ -30,7 +32,7 @@ end
 ---filter denies.
 ---
 ---@see NotQuery
----@param val function|table|userdata
+---@param val Query
 ---@return NotQuery
 function Not(val)
     return NotQuery.new(val)
@@ -40,7 +42,7 @@ end
 ---The queries are evaluated in the order they were provided.
 ---
 ---@see OrQuery
----@param ... function|table|userdata
+---@param ... Query
 ---@return OrQuery
 function Or(...)
     return OrQuery.new(...)
@@ -53,4 +55,17 @@ end
 ---@return TickOfQuery
 function TickOf(...)
     return TickOfQuery.new(...)
+end
+
+---Create any `OptionalQuery` that allows for a query to return nothing.
+---
+---If the query is a filter, its result will essentially be ignored. If the query returns `None`
+---or `AlwaysNone`, this query will return `Nil`. If the query results in a value, its value
+---will be the result of this query.
+---
+---@see OptionalQuery
+---@param q Query
+---@return OptionalQuery
+function Optional(q)
+    return OptionalQuery.new(q)
 end

lyra-scripting/src/lua/ecs/query/mod.rs

@@ -16,6 +16,9 @@ pub use or::*;
 mod tick_of;
 pub use tick_of::*;
 
+mod optional;
+pub use optional::*;
+
 use lyra_ecs::Entity;
 
 use crate::{

lyra-scripting/src/lua/ecs/query/optional.rs

@@ -0,0 +1,44 @@
+use crate::{
+    lua::FN_NAME_INTERNAL_ECS_QUERY_RESULT, ScriptEntity, ScriptWorldPtr,
+};
+
+use super::{LuaQuery, LuaQueryResult};
+
+#[derive(Clone)]
+pub struct LuaOptionalQuery(LuaQuery);
+
+impl mlua::FromLua for LuaOptionalQuery {
+    fn from_lua(value: mlua::Value, _: &mlua::Lua) -> mlua::Result<Self> {
+        let tyname = value.type_name();
+        value
+            .as_userdata()
+            .ok_or(mlua::Error::FromLuaConversionError {
+                from: tyname,
+                to: "OptionalQuery".into(),
+                message: None,
+            })
+            .and_then(|ud| ud.borrow::<Self>())
+            .map(|ud| ud.clone())
+    }
+}
+
+impl mlua::UserData for LuaOptionalQuery {
+    fn add_methods<M: mlua::UserDataMethods<Self>>(methods: &mut M) {
+        methods.add_function("new", |_, q: LuaQuery| Ok(Self(q)));
+
+        methods.add_method(
+            FN_NAME_INTERNAL_ECS_QUERY_RESULT,
+            |_, this, (world, en): (ScriptWorldPtr, ScriptEntity)| {
+                let res = this.0.get_query_result(world, en.0)?;
+
+                match res {
+                    LuaQueryResult::None => Ok(LuaQueryResult::Some(mlua::Value::Nil)),
+                    LuaQueryResult::AlwaysNone => Ok(LuaQueryResult::Some(mlua::Value::Nil)),
+                    LuaQueryResult::FilterPass => Ok(LuaQueryResult::FilterPass),
+                    LuaQueryResult::FilterDeny => Ok(LuaQueryResult::FilterPass),
+                    LuaQueryResult::Some(v) => Ok(LuaQueryResult::Some(v)),
+                }
+            },
+        );
+    }
+}

lyra-scripting/src/lua/providers/ecs.rs

@@ -1,7 +1,7 @@
 use lyra_ecs::ResourceObject;
 use lyra_reflect::Reflect;
 
-use crate::{lua::{ecs::{query::{LuaChangedQuery, LuaHasQuery, LuaNotQuery, LuaOrQuery, LuaResQuery, LuaTickOfQuery}, View}, wrappers::*, LuaContext, LuaWrapper, RegisterLuaType, FN_NAME_INTERNAL_REFLECT, FN_NAME_INTERNAL_REFLECT_TYPE}, ScriptApiProvider, ScriptBorrow, ScriptData, ScriptDynamicBundle, ScriptWorldPtr};
+use crate::{lua::{ecs::{query::{LuaChangedQuery, LuaHasQuery, LuaNotQuery, LuaOptionalQuery, LuaOrQuery, LuaResQuery, LuaTickOfQuery}, View}, wrappers::*, LuaContext, LuaWrapper, RegisterLuaType, FN_NAME_INTERNAL_REFLECT, FN_NAME_INTERNAL_REFLECT_TYPE}, ScriptApiProvider, ScriptBorrow, ScriptData, ScriptDynamicBundle, ScriptWorldPtr};
 
 //fn register_lua_proxy::<T: 
 
@@ -51,6 +51,7 @@ impl ScriptApiProvider for LyraEcsApiProvider {
         globals.set("NotQuery", ctx.create_proxy::<LuaNotQuery>()?)?;
         globals.set("OrQuery", ctx.create_proxy::<LuaOrQuery>()?)?;
         globals.set("TickOfQuery", ctx.create_proxy::<LuaTickOfQuery>()?)?;
+        globals.set("OptionalQuery", ctx.create_proxy::<LuaOptionalQuery>()?)?;
 
         expose_comp_table_wrapper::<LuaCamera>(&ctx, &globals, "Camera")?;
         expose_comp_table_wrapper::<LuaFreeFlyCamera>(&ctx, &globals, "FreeFlyCamera")?;