Merge pull request #14 from BlackMATov/dev

Dev

.vscode/settings.json

@@ -4,5 +4,12 @@
         "files.insertFinalNewline": true,
         "files.trimFinalNewlines": true,
         "files.trimTrailingWhitespace": true
+    },
+    "markdown.extension.toc.levels": "2..6",
+    "markdown.extension.toc.omittedFromToc": {
+        "README.md": [
+            "# Changelog",
+            "# API Reference"
+        ]
     }
 }

GUIDES.md

@@ -0,0 +1,22 @@
+# Guidelines
+
+## Checklists
+
+### New Version Releasing
+
+1. Ensure all tests pass on CI.
+2. Update the version number in `evolved.lua`.
+3. Update the **Changelog** section in `README.md`.
+4. Create a new rockspec file in `rockspecs`.
+5. Commit the changes with a message like `vX.Y.Z`.
+6. Push and merge the changes to the `main` branch.
+7. Create the release on GitHub.
+8. Upload the new package to LuaRocks.
+
+### Adding a New Top-Level Function
+1. Insert the new function into the `evolved` table in `evolved.lua`.
+2. Create tests for the function in `develop/testing/function_name_tests.lua`.
+3. Add the new test to `develop/all.lua`.
+4. Document the function in the **Cheat Sheet** and **API Reference** sections of `README.md`.
+5. Provide a description in the **Overview** section of `README.md`.
+6. Describe the update in the **Changelog** section of `README.md`.

README.md

@@ -1,4 +1,4 @@
-# evolved.lua (work in progress)
+# evolved.lua
 
 > Evolved ECS (Entity-Component-System) for Lua
 
@@ -19,6 +19,45 @@
 
 [evolved]: https://github.com/BlackMATov/evolved.lua
 
+- [Introduction](#introduction)
+  - [Performance](#performance)
+  - [Simplicity](#simplicity)
+  - [Flexibility](#flexibility)
+- [Installation](#installation)
+- [Quick Start](#quick-start)
+- [Overview](#overview)
+  - [Identifiers](#identifiers)
+  - [Entities, Fragments, and Components](#entities-fragments-and-components)
+    - [Traits](#traits)
+    - [Singletons](#singletons)
+  - [Chunks](#chunks)
+  - [Structural Changes](#structural-changes)
+    - [Spawning Entities](#spawning-entities)
+    - [Entity Builders](#entity-builders)
+  - [Access Operations](#access-operations)
+  - [Modifying Operations](#modifying-operations)
+  - [Debug Mode](#debug-mode)
+  - [Queries](#queries)
+    - [Deferred Operations](#deferred-operations)
+    - [Batch Operations](#batch-operations)
+  - [Systems](#systems)
+  - [Predefined Traits](#predefined-traits)
+    - [Fragment Tags](#fragment-tags)
+    - [Fragment Hooks](#fragment-hooks)
+    - [Unique Fragments](#unique-fragments)
+    - [Explicit Fragments](#explicit-fragments)
+    - [Shared Components](#shared-components)
+    - [Fragment Requirements](#fragment-requirements)
+    - [Destruction Policies](#destruction-policies)
+- [Cheat Sheet](#cheat-sheet)
+  - [Aliases](#aliases)
+  - [Predefs](#predefs)
+  - [Functions](#functions)
+  - [Classes](#classes)
+    - [Chunk](#chunk)
+    - [Builder](#builder)
+- [License](#license)
+
 ## Introduction
 
 `evolved.lua` is a fast and flexible ECS (Entity-Component-System) library for Lua. It is designed to be simple and easy to use, while providing all the features needed to create complex systems with blazing performance. Before we start exploring the library, let's take a look at the main advantages of using `evolved.lua`:
@@ -41,211 +80,21 @@ And yes, the library has some unusual concepts at its core, but once you get the
 
 On the other hand, `evolved.lua` tries to be minimalistic and does not provide features that can be implemented outside the library. I'm trying to find a balance between minimalism and the number of possibilities, which forces me to make flexible decisions in the library's design. I hope you will find this balance acceptable.
 
-## Requirements
-
-- [lua](https://www.lua.org/) **>= 5.1**
-- [luajit](https://luajit.org/) **>= 2.0**
-
 ## Installation
 
-You can install `evolved.lua` using [luarocks](https://luarocks.org/) with the following command:
+`evolved.lua` is a single-file pure Lua library and does not require any external dependencies. It is designed to work with [Lua 5.1](https://www.lua.org/) and later, [LuaJIT](https://luajit.org/), and [Luau](https://luau.org/) (Roblox).
+
+All you need to start using the library is the [evolved.lua](./evolved.lua) source file. You can download it from the [releases](https://github.com/BlackMATov/evolved.lua/releases) page or clone the [repository](https://github.com/BlackMATov/evolved.lua) and copy the file to your project.
+
+If you are using [LuaRocks](https://luarocks.org/), you can install the library using the following command:
 
 ```bash
 luarocks install evolved.lua
 ```
 
-Or just clone the [repository](https://github.com/BlackMATov/evolved.lua) and copy the [evolved.lua](evolved.lua) file to your project.
-
 ## Quick Start
 
-To start using `evolved.lua`, read the [Overview](#overview) section first. It will give you a basic understanding of how the library works and how to use it. After that, check the full-featured [Example](develop/example.lua), which demonstrates complex usage of the library. Finally, refer to the [Cheat Sheet](#cheat-sheet) for a quick reference of all the functions and classes provided by the library.
-
-Enjoy! :suspect:
-
-## Cheat Sheet
-
-### Aliases
-
-```
-id :: implementation-specific
-
-entity :: id
-fragment :: id
-query :: id
-system :: id
-
-component :: any
-storage :: component[]
-
-default :: component
-duplicate :: {component -> component}
-
-execute :: {chunk, entity[], integer}
-prologue :: {}
-epilogue :: {}
-
-set_hook :: {entity, fragment, component, component?}
-assign_hook :: {entity, fragment, component, component}
-insert_hook :: {entity, fragment, component}
-remove_hook :: {entity, fragment, component}
-
-each_state :: implementation-specific
-execute_state :: implementation-specific
-
-each_iterator :: {each_state? -> fragment?, component?}
-execute_iterator :: {execute_state? -> chunk?, entity[]?, integer?}
-```
-
-### Predefs
-
-```
-TAG :: fragment
-NAME :: fragment
-
-UNIQUE :: fragment
-EXPLICIT :: fragment
-
-DEFAULT :: fragment
-DUPLICATE :: fragment
-
-PREFAB :: fragment
-DISABLED :: fragment
-
-INCLUDES :: fragment
-EXCLUDES :: fragment
-
-ON_SET :: fragment
-ON_ASSIGN :: fragment
-ON_INSERT :: fragment
-ON_REMOVE :: fragment
-
-GROUP :: fragment
-
-QUERY :: fragment
-EXECUTE :: fragment
-
-PROLOGUE :: fragment
-EPILOGUE :: fragment
-
-DESTRUCTION_POLICY :: fragment
-DESTRUCTION_POLICY_DESTROY_ENTITY :: id
-DESTRUCTION_POLICY_REMOVE_FRAGMENT :: id
-```
-
-### Functions
-
-```
-id :: integer? -> id...
-
-pack :: integer, integer -> id
-unpack :: id -> integer, integer
-
-defer :: boolean
-commit :: boolean
-
-spawn :: <fragment, component>? -> entity
-clone :: entity -> <fragment, component>? -> entity
-
-alive :: entity -> boolean
-alive_all :: entity... -> boolean
-alive_any :: entity... -> boolean
-
-empty :: entity -> boolean
-empty_all :: entity... -> boolean
-empty_any :: entity... -> boolean
-
-has :: entity, fragment -> boolean
-has_all :: entity, fragment... -> boolean
-has_any :: entity, fragment... -> boolean
-
-get :: entity, fragment...  -> component...
-
-set :: entity, fragment, component -> ()
-remove :: entity, fragment... -> ()
-clear :: entity... -> ()
-destroy :: entity... -> ()
-
-batch_set :: query, fragment, component -> ()
-batch_remove :: query, fragment... -> ()
-batch_clear :: query... -> ()
-batch_destroy :: query... -> ()
-
-each :: entity -> {each_state? -> fragment?, component?}, each_state?
-execute :: query -> {execute_state? -> chunk?, entity[]?, integer?}, execute_state?
-
-process :: system... -> ()
-
-debug_mode :: boolean -> ()
-collect_garbage :: ()
-```
-
-### Classes
-
-#### Chunk
-
-```
-chunk :: fragment, fragment... -> chunk, entity[], integer
-
-chunk_mt:alive :: boolean
-chunk_mt:empty :: boolean
-
-chunk_mt:has :: fragment -> boolean
-chunk_mt:has_all :: fragment... -> boolean
-chunk_mt:has_any :: fragment... -> boolean
-
-chunk_mt:entities :: entity[], integer
-chunk_mt:fragments :: fragment[], integer
-chunk_mt:components :: fragment... -> storage...
-```
-
-#### Builder
-
-```
-builder :: builder
-
-builder_mt:spawn :: entity
-builder_mt:clone :: entity -> entity
-
-builder_mt:has :: fragment -> boolean
-builder_mt:has_all :: fragment... -> boolean
-builder_mt:has_any :: fragment... -> boolean
-
-builder_mt:get :: fragment... -> component...
-
-builder_mt:set :: fragment, component -> builder
-builder_mt:remove :: fragment... -> builder
-builder_mt:clear :: builder
-
-builder_mt:tag :: builder
-builder_mt:name :: string -> builder
-
-builder_mt:unique :: builder
-builder_mt:explicit :: builder
-
-builder_mt:default :: component -> builder
-builder_mt:duplicate :: {component -> component} -> builder
-
-builder_mt:prefab :: builder
-builder_mt:disabled :: builder
-
-builder_mt:include :: fragment... -> builder
-builder_mt:exclude :: fragment... -> builder
-
-builder_mt:on_set :: {entity, fragment, component, component?} -> builder
-builder_mt:on_assign :: {entity, fragment, component, component} -> builder
-builder_mt:on_insert :: {entity, fragment, component} -> builder
-builder_mt:on_remove :: {entity, fragment} -> builder
-
-builder_mt:group :: system -> builder
-
-builder_mt:query :: query -> builder
-builder_mt:execute :: {chunk, entity[], integer} -> builder
-
-builder_mt:prologue :: {} -> builder
-builder_mt:epilogue :: {} -> builder
-
-builder_mt:destruction_policy :: id -> builder
-```
+To get started with `evolved.lua`, read the [Overview](#overview) section to understand the basic concepts and how to use the library. After that, check the [Example](develop/example.lua), which demonstrates complex usage of the library. Finally, refer to the [Cheat Sheet](#cheat-sheet) for a quick reference of all the functions and classes provided by the library.
 
 ## Overview
 
@@ -823,6 +672,28 @@ The [`evolved.process`](#evolvedprocess) function is used to process systems. It
 function evolved.process(...) end
 ```
 
+If you don't specify a query for the system, the system itself will be treated as a query. This means the system can contain `evolved.INCLUDES` and `evolved.EXCLUDES` fragments, and it will be processed according to them. This is useful for creating systems with unique queries that don't need to be reused in other systems.
+
+```lua
+local evolved = require 'evolved'
+
+local health = evolved.id()
+
+local system = evolved.builder()
+    :include(health)
+    :execute(function(chunk, entity_list, entity_count)
+        local health_components = chunk:components(health)
+
+        for i = 1, entity_count do
+            health_components[i] = math.max(
+                health_components[i] - 1,
+                0)
+        end
+    end):spawn()
+
+evolved.process(system)
+```
+
 To group systems together, you can use the [`evolved.GROUP`](#evolvedgroup) fragment. Systems with a specified group will be processed when you call the [`evolved.process`](#evolvedprocess) function with this group. For example, you can group all physics systems together and process them in one [`evolved.process`](#evolvedprocess) call.
 
 ```lua
@@ -895,7 +766,7 @@ The prologue and epilogue fragments do not require an explicit query. They will
 > [!NOTE]
 > And one more thing about systems. Execution callbacks are called in the [deferred scope](#deferred-operations), which means that all modifying operations inside the callback will be queued and applied after the system has processed all chunks. But prologue and epilogue callbacks are not called in the deferred scope, so all modifying operations inside them will be applied immediately. This is done to avoid confusion and to make it clear that prologue and epilogue callbacks are not part of the chunk processing.
 
-### Advanced Topics
+### Predefined Traits
 
 #### Fragment Tags
 
@@ -1039,6 +910,35 @@ local enemy2 = evolved.builder()
 assert(evolved.get(enemy1, position) ~= evolved.get(enemy2, position))
 ```
 
+#### Fragment Requirements
+
+Sometimes you want to add additional fragments to an entity when it receives a specific fragment. For example, you might want to add `position` and `velocity` fragments when an entity is given a `physical` fragment. This can be done using the [`evolved.REQUIRES`](#evolvedrequires) fragment trait. This trait expects a list of fragments that will be added to the entity when the fragment is inserted.
+
+```lua
+local evolved = require 'evolved'
+
+local position = evolved.builder()
+    :default(vector2(0, 0))
+    :duplicate(vector2_duplicate)
+    :spawn()
+
+local velocity = evolved.builder()
+    :default(vector2(0, 0))
+    :duplicate(vector2_duplicate)
+    :spawn()
+
+local physical = evolved.builder()
+    :tag()
+    :require(position, velocity)
+    :spawn()
+
+local enemy = evolved.builder()
+    :set(physical)
+    :spawn()
+
+assert(evolved.has_all(enemy, position, velocity))
+```
+
 #### Destruction Policies
 
 Typically, fragments remain alive for the entire lifetime of the program. However, in some cases, you might want to destroy fragments when they are no longer needed. For example, you can use some runtime entities as fragments for other entities. In this case, you might want to destroy such fragments even while they are still attached to other entities. Since entities cannot have destroyed fragments, a destruction policy must be applied to resolve this. By default, the library will remove the destroyed fragment from all entities that have it.
@@ -1086,6 +986,208 @@ evolved.destroy(world)
 assert(not evolved.alive(entity))
 ```
 
+## Cheat Sheet
+
+### Aliases
+
+```
+id :: implementation-specific
+
+entity :: id
+fragment :: id
+query :: id
+system :: id
+
+component :: any
+storage :: component[]
+
+default :: component
+duplicate :: {component -> component}
+
+execute :: {chunk, entity[], integer}
+prologue :: {}
+epilogue :: {}
+
+set_hook :: {entity, fragment, component, component?}
+assign_hook :: {entity, fragment, component, component}
+insert_hook :: {entity, fragment, component}
+remove_hook :: {entity, fragment, component}
+
+each_state :: implementation-specific
+execute_state :: implementation-specific
+
+each_iterator :: {each_state? -> fragment?, component?}
+execute_iterator :: {execute_state? -> chunk?, entity[]?, integer?}
+```
+
+### Predefs
+
+```
+TAG :: fragment
+NAME :: fragment
+
+UNIQUE :: fragment
+EXPLICIT :: fragment
+
+DEFAULT :: fragment
+DUPLICATE :: fragment
+
+PREFAB :: fragment
+DISABLED :: fragment
+
+INCLUDES :: fragment
+EXCLUDES :: fragment
+REQUIRES :: fragment
+
+ON_SET :: fragment
+ON_ASSIGN :: fragment
+ON_INSERT :: fragment
+ON_REMOVE :: fragment
+
+GROUP :: fragment
+
+QUERY :: fragment
+EXECUTE :: fragment
+
+PROLOGUE :: fragment
+EPILOGUE :: fragment
+
+DESTRUCTION_POLICY :: fragment
+DESTRUCTION_POLICY_DESTROY_ENTITY :: id
+DESTRUCTION_POLICY_REMOVE_FRAGMENT :: id
+```
+
+### Functions
+
+```
+id :: integer? -> id...
+
+pack :: integer, integer -> id
+unpack :: id -> integer, integer
+
+defer :: boolean
+commit :: boolean
+
+spawn :: <fragment, component>? -> entity
+clone :: entity -> <fragment, component>? -> entity
+
+alive :: entity -> boolean
+alive_all :: entity... -> boolean
+alive_any :: entity... -> boolean
+
+empty :: entity -> boolean
+empty_all :: entity... -> boolean
+empty_any :: entity... -> boolean
+
+has :: entity, fragment -> boolean
+has_all :: entity, fragment... -> boolean
+has_any :: entity, fragment... -> boolean
+
+get :: entity, fragment...  -> component...
+
+set :: entity, fragment, component -> ()
+remove :: entity, fragment... -> ()
+clear :: entity... -> ()
+destroy :: entity... -> ()
+
+batch_set :: query, fragment, component -> ()
+batch_remove :: query, fragment... -> ()
+batch_clear :: query... -> ()
+batch_destroy :: query... -> ()
+
+each :: entity -> {each_state? -> fragment?, component?}, each_state?
+execute :: query -> {execute_state? -> chunk?, entity[]?, integer?}, execute_state?
+
+process :: system... -> ()
+
+debug_mode :: boolean -> ()
+collect_garbage :: ()
+```
+
+### Classes
+
+#### Chunk
+
+```
+chunk :: fragment, fragment... -> chunk, entity[], integer
+
+chunk_mt:alive :: boolean
+chunk_mt:empty :: boolean
+
+chunk_mt:has :: fragment -> boolean
+chunk_mt:has_all :: fragment... -> boolean
+chunk_mt:has_any :: fragment... -> boolean
+
+chunk_mt:entities :: entity[], integer
+chunk_mt:fragments :: fragment[], integer
+chunk_mt:components :: fragment... -> storage...
+```
+
+#### Builder
+
+```
+builder :: builder
+
+builder_mt:spawn :: entity
+builder_mt:clone :: entity -> entity
+
+builder_mt:has :: fragment -> boolean
+builder_mt:has_all :: fragment... -> boolean
+builder_mt:has_any :: fragment... -> boolean
+
+builder_mt:get :: fragment... -> component...
+
+builder_mt:set :: fragment, component -> builder
+builder_mt:remove :: fragment... -> builder
+builder_mt:clear :: builder
+
+builder_mt:tag :: builder
+builder_mt:name :: string -> builder
+
+builder_mt:unique :: builder
+builder_mt:explicit :: builder
+
+builder_mt:default :: component -> builder
+builder_mt:duplicate :: {component -> component} -> builder
+
+builder_mt:prefab :: builder
+builder_mt:disabled :: builder
+
+builder_mt:include :: fragment... -> builder
+builder_mt:exclude :: fragment... -> builder
+builder_mt:require :: fragment... -> builder
+
+builder_mt:on_set :: {entity, fragment, component, component?} -> builder
+builder_mt:on_assign :: {entity, fragment, component, component} -> builder
+builder_mt:on_insert :: {entity, fragment, component} -> builder
+builder_mt:on_remove :: {entity, fragment} -> builder
+
+builder_mt:group :: system -> builder
+
+builder_mt:query :: query -> builder
+builder_mt:execute :: {chunk, entity[], integer} -> builder
+
+builder_mt:prologue :: {} -> builder
+builder_mt:epilogue :: {} -> builder
+
+builder_mt:destruction_policy :: id -> builder
+```
+
+## License
+
+`evolved.lua` is licensed under the [MIT License][license]. For more details, see the [LICENSE.md](./LICENSE.md) file in the repository.
+
+# Changelog
+
+## v1.1.0
+
+- [`Systems`](#systems) can be queries themselves now
+- Added the new [`evolved.REQUIRES`](#evolvedrequires) fragment trait
+
+## v1.0.0
+
+- Initial release
+
 # API Reference
 
 ## Predefs
@@ -1110,6 +1212,8 @@ assert(not evolved.alive(entity))
 
 ### `evolved.EXCLUDES`
 
+### `evolved.REQUIRES`
+
 ### `evolved.ON_SET`
 
 ### `evolved.ON_ASSIGN`
@@ -1638,6 +1742,14 @@ function evolved.builder_mt:include(...) end
 function evolved.builder_mt:exclude(...) end
 ```
 
+### `evolved.builder_mt:require`
+
+```lua
+---@param ... evolved.fragment fragments
+---@return evolved.builder builder
+function evolved.builder_mt:require(...) end
+```
+
 #### `evolved.builder_mt:on_set`
 
 ```lua
@@ -1717,5 +1829,3 @@ function evolved.builder_mt:epilogue(epilogue) end
 ---@return evolved.builder builder
 function evolved.builder_mt:destruction_policy(destruction_policy) end
 ```
-
-## [License (MIT)](./LICENSE.md)

ROADMAP.md

@@ -7,6 +7,5 @@
 - cached queries
 - observers and events
 - add INDEX fragment trait
-- add REQUIRES fragment trait
 - use compact prefix-tree for chunks
 - optional ffi component storages

develop/all.lua

@@ -1,6 +1,10 @@
 require 'develop.example'
-require 'develop.unbench'
 require 'develop.untests'
+
+require 'develop.testing.requires_fragment_tests'
+require 'develop.testing.system_as_query_tests'
+
+require 'develop.unbench'
 require 'develop.usbench'
 
 local basics = require 'develop.basics'
@@ -12,4 +16,8 @@ basics.describe_fuzz 'develop.fuzzing.batch_destroy_fuzz'
 print '----------------------------------------'
 basics.describe_fuzz 'develop.fuzzing.explicit_fuzz'
 print '----------------------------------------'
+basics.describe_fuzz 'develop.fuzzing.pack_unpack_fuzz'
+print '----------------------------------------'
+basics.describe_fuzz 'develop.fuzzing.requires_fuzz'
+print '----------------------------------------'
 basics.describe_fuzz 'develop.fuzzing.unique_fuzz'

develop/fuzzing/pack_unpack_fuzz.lua

@@ -0,0 +1,20 @@
+local evo = require 'evolved'
+
+evo.debug_mode(true)
+
+---
+---
+---
+---
+---
+
+for _ = 1, 1000 do
+    local initial_index = math.random(1, 0xFFFFF)
+    local initial_version = math.random(1, 0xFFFFF)
+
+    local packed_id = evo.pack(initial_index, initial_version)
+    local unpacked_index, unpacked_version = evo.unpack(packed_id)
+
+    assert(initial_index == unpacked_index)
+    assert(initial_version == unpacked_version)
+end

develop/fuzzing/requires_fuzz.lua

@@ -0,0 +1,113 @@
+local evo = require 'evolved'
+
+evo.debug_mode(true)
+
+---
+---
+---
+---
+---
+
+local __table_unpack = (function()
+    ---@diagnostic disable-next-line: deprecated
+    return table.unpack or unpack
+end)()
+
+---
+---
+---
+---
+---
+
+local all_fragment_list = {} ---@type evolved.fragment[]
+
+for i = 1, math.random(1, 10) do
+    local fragment = evo.builder()
+        :default(42)
+        :spawn()
+    all_fragment_list[i] = fragment
+end
+
+for _, fragment in ipairs(all_fragment_list) do
+    if math.random(1, 2) == 1 then
+        for _ = 0, math.random(0, #all_fragment_list) do
+            local require_list = evo.get(fragment, evo.REQUIRES) or {}
+            require_list[#require_list + 1] = all_fragment_list[math.random(1, #all_fragment_list)]
+            evo.set(fragment, evo.REQUIRES, require_list)
+        end
+    end
+end
+
+local all_entity_list = {} ---@type evolved.entity[]
+
+for i = 1, math.random(1, 10) do
+    local entity = evo.id()
+    all_entity_list[i] = entity
+
+    for _ = 0, math.random(0, #all_fragment_list) do
+        local fragment = all_fragment_list[math.random(1, #all_fragment_list)]
+
+        if math.random(1, 2) == 1 then
+            evo.set(entity, fragment, 42)
+        else
+            local query = evo.builder()
+                :include(all_fragment_list[math.random(1, #all_fragment_list)])
+                :spawn()
+            evo.batch_set(query, fragment, 42)
+            evo.destroy(query)
+        end
+    end
+end
+
+for _ = 1, math.random(1, #all_entity_list) do
+    local components = {}
+    for _ = 1, math.random(1, #all_fragment_list) do
+        local fragment = all_fragment_list[math.random(1, #all_fragment_list)]
+        components[fragment] = 42
+    end
+    all_entity_list[#all_entity_list + 1] = evo.spawn(components)
+end
+
+for _ = 1, math.random(1, #all_entity_list) do
+    local prefab = all_entity_list[math.random(1, #all_entity_list)]
+    all_entity_list[#all_entity_list + 1] = evo.clone(prefab)
+end
+
+---
+---
+---
+---
+---
+
+local function collect_required_fragments_for(fragment, req_fragment_set, req_fragment_list)
+    local fragment_requires = evo.get(fragment, evo.REQUIRES) or {}
+    for _, required_fragment in ipairs(fragment_requires) do
+        if not req_fragment_set[required_fragment] then
+            req_fragment_set[required_fragment] = true
+            req_fragment_list[#req_fragment_list + 1] = required_fragment
+            collect_required_fragments_for(required_fragment, req_fragment_set, req_fragment_list)
+        end
+    end
+end
+
+for _, entity in ipairs(all_entity_list) do
+    for fragment in evo.each(entity) do
+        local req_fragment_list = {}
+        collect_required_fragments_for(fragment, {}, req_fragment_list)
+        for _, required_fragment in ipairs(req_fragment_list) do
+            assert(evo.has(entity, required_fragment))
+            local required_component = evo.get(entity, required_fragment)
+            assert(required_component == 42)
+        end
+    end
+end
+
+---
+---
+---
+---
+---
+
+evo.destroy(__table_unpack(all_entity_list))
+evo.destroy(__table_unpack(all_fragment_list))
+evo.collect_garbage()

develop/testing/requires_fragment_tests.lua

@@ -0,0 +1,245 @@
+local evo = require 'evolved'
+
+do
+    local f1, f2 = evo.id(2)
+    evo.set(f1, evo.REQUIRES)
+    evo.set(f2, evo.REQUIRES, evo.get(f1, evo.REQUIRES))
+    local f1_rs = evo.get(f1, evo.REQUIRES)
+    local f2_rs = evo.get(f2, evo.REQUIRES)
+    assert(f1_rs and f2_rs and #f1_rs == 0 and #f2_rs == 0 and f1_rs ~= f2_rs)
+end
+
+do
+    local f1, f2 = evo.id(2)
+    local f3 = evo.builder():require(f1):require(f2):spawn()
+    local f3_rs = evo.get(f3, evo.REQUIRES)
+    assert(f3_rs and #f3_rs == 2 and f3_rs[1] == f1 and f3_rs[2] == f2)
+end
+
+do
+    local f1, f2 = evo.id(2)
+    local f3 = evo.builder():require(f1, f2):spawn()
+    local f3_rs = evo.get(f3, evo.REQUIRES)
+    assert(f3_rs and #f3_rs == 2 and f3_rs[1] == f1 and f3_rs[2] == f2)
+end
+
+do
+    local f1, f2, f3 = evo.id(3)
+    evo.set(f1, evo.REQUIRES, { f2 })
+    evo.set(f3, evo.REQUIRES, { f1, f2 })
+
+    do
+        local e = evo.id()
+        evo.set(e, f1)
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == true)
+    end
+
+    do
+        local e = evo.builder():set(f1):spawn()
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == true)
+    end
+
+    do
+        local e = evo.spawn { [f1] = true }
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == true)
+
+        evo.remove(e, f2)
+        assert(not evo.has(e, f2))
+
+        local e2 = evo.clone(e)
+        assert(evo.has(e2, f2))
+        assert(evo.get(e2, f2) == true)
+
+        local e3 = evo.clone(e, { [f3] = true })
+        assert(evo.has(e3, f2))
+        assert(evo.get(e3, f2) == true)
+    end
+
+    do
+        local f0 = evo.id()
+        local q0 = evo.builder():include(f0):spawn()
+
+        local e1 = evo.builder():set(f0):spawn()
+        local e2 = evo.builder():set(f0):spawn()
+        local e3 = evo.builder():set(f0):set(f2, false):spawn()
+
+        evo.batch_set(q0, f1)
+
+        assert(evo.has(e1, f2) and evo.get(e1, f2) == true)
+        assert(evo.has(e2, f2) and evo.get(e2, f2) == true)
+        assert(evo.has(e3, f2) and evo.get(e3, f2) == false)
+    end
+end
+
+do
+    local f1, f2, f3 = evo.id(3)
+    evo.set(f1, evo.REQUIRES, { f2 })
+    evo.set(f2, evo.DEFAULT, 42)
+    evo.set(f3, evo.REQUIRES, { f1, f2 })
+
+    do
+        local e = evo.id()
+        evo.set(e, f1)
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == 42)
+    end
+
+    do
+        local e = evo.builder():set(f1):spawn()
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == 42)
+    end
+
+    do
+        local e = evo.spawn { [f1] = true, }
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == 42)
+
+        evo.remove(e, f2)
+        assert(not evo.has(e, f2))
+
+        local e2 = evo.clone(e)
+        assert(evo.has(e2, f2))
+        assert(evo.get(e2, f2) == 42)
+
+        local e3 = evo.clone(e, { [f3] = true })
+        assert(evo.has(e3, f2))
+        assert(evo.get(e3, f2) == 42)
+    end
+
+    do
+        local f0 = evo.id()
+        local q0 = evo.builder():include(f0):spawn()
+
+        local e1 = evo.builder():set(f0):spawn()
+        local e2 = evo.builder():set(f0):spawn()
+        local e3 = evo.builder():set(f0):set(f2, 21):spawn()
+
+        evo.batch_set(q0, f1)
+
+        assert(evo.has(e1, f2) and evo.get(e1, f2) == 42)
+        assert(evo.has(e2, f2) and evo.get(e2, f2) == 42)
+        assert(evo.has(e3, f2) and evo.get(e3, f2) == 21)
+    end
+end
+
+do
+    local f1, f2, f3 = evo.id(3)
+    evo.set(f1, evo.REQUIRES, { f2 })
+    evo.set(f2, evo.REQUIRES, { f3 })
+    evo.set(f3, evo.DEFAULT, 42)
+    evo.set(f3, evo.REQUIRES, { f1, f2 })
+
+    do
+        local e = evo.id()
+        evo.set(e, f1)
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == true)
+        assert(evo.has(e, f3))
+        assert(evo.get(e, f3) == 42)
+    end
+
+    do
+        local e = evo.builder():set(f1):spawn()
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == true)
+        assert(evo.has(e, f3))
+        assert(evo.get(e, f3) == 42)
+    end
+
+    do
+        local e = evo.spawn { [f1] = true }
+        assert(evo.has(e, f2))
+        assert(evo.get(e, f2) == true)
+        assert(evo.has(e, f3))
+        assert(evo.get(e, f3) == 42)
+
+        evo.remove(e, f2, f3)
+        assert(not evo.has(e, f2))
+        assert(not evo.has(e, f3))
+
+        local e2 = evo.clone(e, { [f1] = 21 })
+        assert(evo.has(e2, f1) and evo.get(e2, f1) == 21)
+        assert(evo.has(e2, f2) and evo.get(e2, f2) == true)
+        assert(evo.has(e2, f3) and evo.get(e2, f3) == 42)
+
+        local e3 = evo.clone(e, { [f3] = 21 })
+        assert(evo.has(e3, f1) and evo.get(e3, f1) == true)
+        assert(evo.has(e3, f2) and evo.get(e3, f2) == true)
+        assert(evo.has(e3, f3) and evo.get(e3, f3) == 21)
+    end
+end
+
+do
+    local f1, f2, f3 = evo.id(3)
+    evo.set(f1, evo.REQUIRES, { f2 })
+    evo.set(f2, evo.REQUIRES, { f3 })
+    evo.set(f3, evo.REQUIRES, { f1, f2, f3 })
+
+    do
+        local e = evo.id()
+        evo.set(e, f1, 42)
+        assert(evo.has(e, f1) and evo.get(e, f1) == 42)
+        assert(evo.has(e, f2) and evo.get(e, f2) == true)
+        assert(evo.has(e, f3) and evo.get(e, f3) == true)
+    end
+
+    do
+        local e = evo.builder():set(f1, 42):spawn()
+        assert(evo.has(e, f1) and evo.get(e, f1) == 42)
+        assert(evo.has(e, f2) and evo.get(e, f2) == true)
+        assert(evo.has(e, f3) and evo.get(e, f3) == true)
+    end
+
+    do
+        local e = evo.spawn { [f1] = 42 }
+        assert(evo.has(e, f1) and evo.get(e, f1) == 42)
+        assert(evo.has(e, f2) and evo.get(e, f2) == true)
+        assert(evo.has(e, f3) and evo.get(e, f3) == true)
+
+        evo.remove(e, f2, f3)
+        assert(not evo.has(e, f2))
+        assert(not evo.has(e, f3))
+
+        local e2 = evo.clone(e, { [f1] = 21 })
+        assert(evo.has(e2, f1) and evo.get(e2, f1) == 21)
+        assert(evo.has(e2, f2) and evo.get(e2, f2) == true)
+        assert(evo.has(e2, f3) and evo.get(e2, f3) == true)
+
+        local e3 = evo.clone(e, { [f3] = 21 })
+        assert(evo.has(e3, f1) and evo.get(e3, f1) == 42)
+        assert(evo.has(e3, f2) and evo.get(e3, f2) == true)
+        assert(evo.has(e3, f3) and evo.get(e3, f3) == 21)
+    end
+end
+
+do
+    local f1, f2, f3, f4 = evo.id(4)
+
+    do
+        evo.set(f1, evo.REQUIRES, { f2 })
+        do
+            local e = evo.id()
+            evo.set(e, f1)
+            assert(evo.has(e, f2) and evo.get(e, f2) == true)
+        end
+        evo.set(f1, evo.REQUIRES, { f2, f3 })
+        do
+            local e = evo.id()
+            evo.set(e, f1)
+            assert(evo.has(e, f2) and evo.get(e, f2) == true)
+            assert(evo.has(e, f3) and evo.get(e, f3) == true)
+        end
+        evo.set(f3, evo.REQUIRES, { f4 })
+        do
+            local e = evo.id()
+            evo.set(e, f1)
+            assert(evo.has(e, f2) and evo.get(e, f2) == true)
+            assert(evo.has(e, f3) and evo.get(e, f3) == true)
+            assert(evo.has(e, f4) and evo.get(e, f4) == true)
+        end
+    end
+end

develop/testing/system_as_query_tests.lua

@@ -0,0 +1,128 @@
+local evo = require 'evolved'
+
+do
+    local f1, f2, f3 = evo.id(3)
+
+    local q1e3 = evo.builder():include(f1):exclude(f3):spawn()
+    local q2e3 = evo.builder():include(f2):exclude(f3):spawn()
+
+    local e1 = evo.builder():set(f1, 1):spawn()
+    local e12 = evo.builder():set(f1, 11):set(f2, 12):spawn()
+    local e2 = evo.builder():set(f2, 2):spawn()
+    local e23 = evo.builder():set(f2, 23):set(f3, 3):spawn()
+
+    local c1 = evo.chunk(f1)
+    local c12 = evo.chunk(f1, f2)
+    local c2 = evo.chunk(f2)
+
+    do
+        local _, entity_list, entity_count = evo.chunk(f2, f3)
+        assert(entity_count == 1 and entity_list[1] == e23)
+    end
+
+    do
+        local entity_sum = 0
+
+        local s = evo.builder()
+            :query(q1e3)
+            :execute(function(chunk, entity_list, entity_count)
+                for i = 1, entity_count do
+                    entity_sum = entity_sum + entity_list[i]
+                end
+
+                if chunk == c1 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e1)
+                elseif chunk == c12 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e12)
+                else
+                    assert(false, "Unexpected chunk: " .. tostring(chunk))
+                end
+            end):spawn()
+
+        evo.process(s)
+
+        assert(entity_sum == e1 + e12)
+    end
+
+    do
+        local entity_sum = 0
+
+        local s = evo.builder()
+            :query(q2e3)
+            :execute(function(chunk, entity_list, entity_count)
+                for i = 1, entity_count do
+                    entity_sum = entity_sum + entity_list[i]
+                end
+
+                if chunk == c12 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e12)
+                elseif chunk == c2 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e2)
+                else
+                    assert(false, "Unexpected chunk: " .. tostring(chunk))
+                end
+            end):spawn()
+
+        evo.process(s)
+
+        assert(entity_sum == e12 + e2)
+    end
+
+    do
+        local entity_sum = 0
+
+        local s = evo.builder()
+            :include(f1)
+            :exclude(f3)
+            :execute(function(chunk, entity_list, entity_count)
+                for i = 1, entity_count do
+                    entity_sum = entity_sum + entity_list[i]
+                end
+
+                if chunk == c1 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e1)
+                elseif chunk == c12 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e12)
+                else
+                    assert(false, "Unexpected chunk: " .. tostring(chunk))
+                end
+            end):spawn()
+
+        evo.process(s)
+
+        assert(entity_sum == e1 + e12)
+    end
+
+    do
+        local entity_sum = 0
+
+        local s = evo.builder()
+            :include(f2)
+            :exclude(f3)
+            :execute(function(chunk, entity_list, entity_count)
+                for i = 1, entity_count do
+                    entity_sum = entity_sum + entity_list[i]
+                end
+
+                if chunk == c12 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e12)
+                elseif chunk == c2 then
+                    assert(entity_count == 1)
+                    assert(entity_list[1] == e2)
+                else
+                    assert(false, "Unexpected chunk: " .. tostring(chunk))
+                end
+            end):spawn()
+
+        evo.process(s)
+
+        assert(entity_sum == e12 + e2)
+    end
+end

develop/unbench.lua

@@ -7,6 +7,11 @@ local N = 1000
 local B = evo.builder()
 local F1, F2, F3, F4, F5 = evo.id(5)
 local Q1 = evo.builder():include(F1):spawn()
+local R1 = evo.builder():require(F1):spawn()
+local R2 = evo.builder():require(F1, F2):spawn()
+local R3 = evo.builder():require(F1, F2, F3):spawn()
+local R4 = evo.builder():require(F1, F2, F3, F4):spawn()
+local R5 = evo.builder():require(F1, F2, F3, F4, F5):spawn()
 
 print '----------------------------------------'
 
@@ -610,7 +615,6 @@ basics.describe_bench(string.format('create and destroy %d entities with 5 compo
 
 print '----------------------------------------'
 
-
 basics.describe_bench(string.format('create and destroy %d entities with 1 components / clone', N),
     ---@param entities evolved.id[]
     function(entities)
@@ -690,3 +694,167 @@ basics.describe_bench(string.format('create and destroy %d entities with 5 compo
     end, function()
         return {}
     end)
+
+print '----------------------------------------'
+
+basics.describe_bench(string.format('create and destroy %d entities with 1 requires / spawn', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local spawn = evo.spawn
+
+        local components = { [R1] = true }
+
+        for i = 1, N do
+            entities[i] = spawn(components)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 2 requires / spawn', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local spawn = evo.spawn
+
+        local components = { [R2] = true }
+
+        for i = 1, N do
+            entities[i] = spawn(components)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 3 requires / spawn', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local spawn = evo.spawn
+
+        local components = { [R3] = true }
+
+        for i = 1, N do
+            entities[i] = spawn(components)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 4 requires / spawn', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local spawn = evo.spawn
+
+        local components = { [R4] = true }
+
+        for i = 1, N do
+            entities[i] = spawn(components)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 5 requires / spawn', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local spawn = evo.spawn
+
+        local components = { [R5] = true }
+
+        for i = 1, N do
+            entities[i] = spawn(components)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+print '----------------------------------------'
+
+basics.describe_bench(string.format('create and destroy %d entities with 1 requires / clone', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local clone = evo.clone
+
+        local prefab = evo.spawn({ [R1] = true })
+
+        for i = 1, N do
+            entities[i] = clone(prefab)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 2 requires / clone', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local clone = evo.clone
+
+        local prefab = evo.spawn({ [R2] = true })
+
+        for i = 1, N do
+            entities[i] = clone(prefab)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 3 requires / clone', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local clone = evo.clone
+
+        local prefab = evo.spawn({ [R3] = true })
+
+        for i = 1, N do
+            entities[i] = clone(prefab)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 4 requires / clone', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local clone = evo.clone
+
+        local prefab = evo.spawn({ [R4] = true })
+
+        for i = 1, N do
+            entities[i] = clone(prefab)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)
+
+basics.describe_bench(string.format('create and destroy %d entities with 5 requires / clone', N),
+    ---@param entities evolved.id[]
+    function(entities)
+        local clone = evo.clone
+
+        local prefab = evo.spawn({ [R5] = true })
+
+        for i = 1, N do
+            entities[i] = clone(prefab)
+        end
+
+        evo.batch_destroy(Q1)
+    end, function()
+        return {}
+    end)

evolved.lua

@@ -1,7 +1,7 @@
 local evolved = {
     __HOMEPAGE = 'https://github.com/BlackMATov/evolved.lua',
     __DESCRIPTION = 'Evolved ECS (Entity-Component-System) for Lua',
-    __VERSION = '1.0.0',
+    __VERSION = '1.1.0',
     __LICENSE = [[
         MIT License
 
@@ -117,10 +117,11 @@ local __entity_places = {} ---@type table<integer, integer>
 
 local __structural_changes = 0 ---@type integer
 
-local __group_subsystems = {} ---@type table<evolved.system, evolved.assoc_list>
+local __sorted_includes = {} ---@type table<evolved.query, evolved.assoc_list>
+local __sorted_excludes = {} ---@type table<evolved.query, evolved.assoc_list>
+local __sorted_requires = {} ---@type table<evolved.fragment, evolved.assoc_list>
 
-local __query_sorted_includes = {} ---@type table<evolved.query, evolved.assoc_list>
-local __query_sorted_excludes = {} ---@type table<evolved.query, evolved.assoc_list>
+local __group_subsystems = {} ---@type table<evolved.system, evolved.assoc_list>
 
 ---
 ---
@@ -156,6 +157,7 @@ local __query_sorted_excludes = {} ---@type table<evolved.query, evolved.assoc_l
 ---@field package __has_explicit_major boolean
 ---@field package __has_explicit_minors boolean
 ---@field package __has_explicit_fragments boolean
+---@field package __has_required_fragments boolean
 local __chunk_mt = {}
 __chunk_mt.__index = __chunk_mt
 
@@ -701,6 +703,7 @@ local __DISABLED = __acquire_id()
 
 local __INCLUDES = __acquire_id()
 local __EXCLUDES = __acquire_id()
+local __REQUIRES = __acquire_id()
 
 local __ON_SET = __acquire_id()
 local __ON_ASSIGN = __acquire_id()
@@ -1019,6 +1022,7 @@ function __new_chunk(chunk_parent, chunk_fragment)
         __has_explicit_major = false,
         __has_explicit_minors = false,
         __has_explicit_fragments = false,
+        __has_required_fragments = false,
     }, __chunk_mt)
 
     if chunk_parent then
@@ -1156,6 +1160,9 @@ function __update_chunk_flags(chunk)
     local has_explicit_minors = chunk_parent ~= nil and chunk_parent.__has_explicit_fragments
     local has_explicit_fragments = has_explicit_major or has_explicit_minors
 
+    local has_required_fragments = (chunk_parent ~= nil and chunk_parent.__has_required_fragments)
+        or __evolved_has(chunk_fragment, __REQUIRES)
+
     chunk.__has_setup_hooks = has_setup_hooks
     chunk.__has_assign_hooks = has_assign_hooks
     chunk.__has_insert_hooks = has_insert_hooks
@@ -1168,6 +1175,8 @@ function __update_chunk_flags(chunk)
     chunk.__has_explicit_major = has_explicit_major
     chunk.__has_explicit_minors = has_explicit_minors
     chunk.__has_explicit_fragments = has_explicit_fragments
+
+    chunk.__has_required_fragments = has_required_fragments
 end
 
 ---@param major evolved.fragment
@@ -1609,6 +1618,112 @@ end
 ---
 ---
 
+---@param chunk evolved.chunk
+---@param req_fragment_set table<evolved.fragment, integer>
+---@param req_fragment_list evolved.fragment[]
+---@param req_fragment_count integer
+---@return integer
+---@nodiscard
+local function __chunk_required_fragments(chunk, req_fragment_set, req_fragment_list, req_fragment_count)
+    ---@type evolved.fragment[]
+    local fragment_stack = __acquire_table(__table_pool_tag.fragment_list)
+    local fragment_stack_size = 0
+
+    do
+        local chunk_fragment_list = chunk.__fragment_list
+        local chunk_fragment_count = chunk.__fragment_count
+
+        __lua_table_move(
+            chunk_fragment_list, 1, chunk_fragment_count,
+            fragment_stack_size + 1, fragment_stack)
+
+        fragment_stack_size = fragment_stack_size + chunk_fragment_count
+    end
+
+    while fragment_stack_size > 0 do
+        local stack_fragment = fragment_stack[fragment_stack_size]
+
+        fragment_stack[fragment_stack_size] = nil
+        fragment_stack_size = fragment_stack_size - 1
+
+        local fragment_requires = __sorted_requires[stack_fragment]
+        local fragment_require_list = fragment_requires and fragment_requires.__item_list
+        local fragment_require_count = fragment_requires and fragment_requires.__item_count or 0
+
+        for fragment_require_index = 1, fragment_require_count do
+            ---@cast fragment_require_list -?
+            local required_fragment = fragment_require_list[fragment_require_index]
+
+            if req_fragment_set[required_fragment] then
+                -- this fragment has already been gathered
+            else
+                req_fragment_count = req_fragment_count + 1
+                req_fragment_set[required_fragment] = req_fragment_count
+                req_fragment_list[req_fragment_count] = required_fragment
+
+                fragment_stack_size = fragment_stack_size + 1
+                fragment_stack[fragment_stack_size] = required_fragment
+            end
+        end
+    end
+
+    __release_table(__table_pool_tag.fragment_list, fragment_stack, true)
+    return req_fragment_count
+end
+
+---@param fragment evolved.fragment
+---@param req_fragment_set table<evolved.fragment, integer>
+---@param req_fragment_list evolved.fragment[]
+---@param req_fragment_count integer
+---@return integer
+---@nodiscard
+local function __fragment_required_fragments(fragment, req_fragment_set, req_fragment_list, req_fragment_count)
+    ---@type evolved.fragment[]
+    local fragment_stack = __acquire_table(__table_pool_tag.fragment_list)
+    local fragment_stack_size = 0
+
+    do
+        fragment_stack_size = fragment_stack_size + 1
+        fragment_stack[fragment_stack_size] = fragment
+    end
+
+    while fragment_stack_size > 0 do
+        local stack_fragment = fragment_stack[fragment_stack_size]
+
+        fragment_stack[fragment_stack_size] = nil
+        fragment_stack_size = fragment_stack_size - 1
+
+        local fragment_requires = __sorted_requires[stack_fragment]
+        local fragment_require_list = fragment_requires and fragment_requires.__item_list
+        local fragment_require_count = fragment_requires and fragment_requires.__item_count or 0
+
+        for fragment_require_index = 1, fragment_require_count do
+            ---@cast fragment_require_list -?
+            local required_fragment = fragment_require_list[fragment_require_index]
+
+            if req_fragment_set[required_fragment] then
+                -- this fragment has already been gathered
+            else
+                req_fragment_count = req_fragment_count + 1
+                req_fragment_set[required_fragment] = req_fragment_count
+                req_fragment_list[req_fragment_count] = required_fragment
+
+                fragment_stack_size = fragment_stack_size + 1
+                fragment_stack[fragment_stack_size] = required_fragment
+            end
+        end
+    end
+
+    __release_table(__table_pool_tag.fragment_list, fragment_stack, true)
+    return req_fragment_count
+end
+
+---
+---
+---
+---
+---
+
 local __defer_set
 local __defer_remove
 local __defer_clear
@@ -1694,6 +1809,29 @@ local function __spawn_entity(entity, components)
         return
     end
 
+    local req_fragment_set
+    local req_fragment_list
+    local req_fragment_count = 0
+
+    local ini_chunk = chunk
+    local ini_fragment_set = ini_chunk.__fragment_set
+
+    if chunk.__has_required_fragments then
+        ---@type table<evolved.fragment, integer>
+        req_fragment_set = __acquire_table(__table_pool_tag.fragment_set)
+
+        ---@type evolved.fragment[]
+        req_fragment_list = __acquire_table(__table_pool_tag.fragment_list)
+
+        req_fragment_count = __chunk_required_fragments(ini_chunk,
+            req_fragment_set, req_fragment_list, req_fragment_count)
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+            chunk = __chunk_with_fragment(chunk, req_fragment)
+        end
+    end
+
     local chunk_entity_list = chunk.__entity_list
     local chunk_entity_count = chunk.__entity_count
 
@@ -1738,6 +1876,36 @@ local function __spawn_entity(entity, components)
                 component_storage[place] = new_component
             end
         end
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+
+            if ini_fragment_set[req_fragment] then
+                -- this fragment has already been initialized
+            else
+                local req_component_index = chunk_component_indices[req_fragment]
+
+                if req_component_index then
+                    ---@type evolved.default?, evolved.duplicate?
+                    local req_fragment_default, req_fragment_duplicate =
+                        __evolved_get(req_fragment, __DEFAULT, __DUPLICATE)
+
+                    local req_component = req_fragment_default
+
+                    if req_component ~= nil and req_fragment_duplicate then
+                        req_component = req_fragment_duplicate(req_component)
+                    end
+
+                    if req_component == nil then
+                        req_component = true
+                    end
+
+                    local req_component_storage = chunk_component_storages[req_component_index]
+
+                    req_component_storage[place] = req_component
+                end
+            end
+        end
     else
         for fragment, component in __lua_next, components do
             local component_index = chunk_component_indices[fragment]
@@ -1750,6 +1918,24 @@ local function __spawn_entity(entity, components)
                 component_storage[place] = new_component
             end
         end
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+
+            if ini_fragment_set[req_fragment] then
+                -- this fragment has already been initialized
+            else
+                local req_component_index = chunk_component_indices[req_fragment]
+
+                if req_component_index then
+                    local req_component = true
+
+                    local req_component_storage = chunk_component_storages[req_component_index]
+
+                    req_component_storage[place] = req_component
+                end
+            end
+        end
     end
 
     if chunk.__has_insert_hooks then
@@ -1788,6 +1974,14 @@ local function __spawn_entity(entity, components)
             end
         end
     end
+
+    if req_fragment_set then
+        __release_table(__table_pool_tag.fragment_set, req_fragment_set)
+    end
+
+    if req_fragment_list then
+        __release_table(__table_pool_tag.fragment_list, req_fragment_list)
+    end
 end
 
 ---@param entity evolved.entity
@@ -1810,6 +2004,29 @@ local function __clone_entity(entity, prefab, components)
         return
     end
 
+    local req_fragment_set
+    local req_fragment_list
+    local req_fragment_count = 0
+
+    local ini_chunk = chunk
+    local ini_fragment_set = ini_chunk.__fragment_set
+
+    if chunk.__has_required_fragments then
+        ---@type table<evolved.fragment, integer>
+        req_fragment_set = __acquire_table(__table_pool_tag.fragment_set)
+
+        ---@type evolved.fragment[]
+        req_fragment_list = __acquire_table(__table_pool_tag.fragment_list)
+
+        req_fragment_count = __chunk_required_fragments(ini_chunk,
+            req_fragment_set, req_fragment_list, req_fragment_count)
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+            chunk = __chunk_with_fragment(chunk, req_fragment)
+        end
+    end
+
     local chunk_entity_list = chunk.__entity_list
     local chunk_entity_count = chunk.__entity_count
 
@@ -1910,6 +2127,36 @@ local function __clone_entity(entity, prefab, components)
                 component_storage[place] = new_component
             end
         end
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+
+            if ini_fragment_set[req_fragment] then
+                -- this fragment has already been initialized
+            else
+                local req_component_index = chunk_component_indices[req_fragment]
+
+                if req_component_index then
+                    ---@type evolved.default?, evolved.duplicate?
+                    local req_fragment_default, req_fragment_duplicate =
+                        __evolved_get(req_fragment, __DEFAULT, __DUPLICATE)
+
+                    local req_component = req_fragment_default
+
+                    if req_component ~= nil and req_fragment_duplicate then
+                        req_component = req_fragment_duplicate(req_component)
+                    end
+
+                    if req_component == nil then
+                        req_component = true
+                    end
+
+                    local req_component_storage = chunk_component_storages[req_component_index]
+
+                    req_component_storage[place] = req_component
+                end
+            end
+        end
     else
         for fragment, component in __lua_next, components do
             local component_index = chunk_component_indices[fragment]
@@ -1922,6 +2169,24 @@ local function __clone_entity(entity, prefab, components)
                 component_storage[place] = new_component
             end
         end
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+
+            if ini_fragment_set[req_fragment] then
+                -- this fragment has already been initialized
+            else
+                local req_component_index = chunk_component_indices[req_fragment]
+
+                if req_component_index then
+                    local req_component = true
+
+                    local req_component_storage = chunk_component_storages[req_component_index]
+
+                    req_component_storage[place] = req_component
+                end
+            end
+        end
     end
 
     if chunk.__has_insert_hooks then
@@ -1960,6 +2225,14 @@ local function __clone_entity(entity, prefab, components)
             end
         end
     end
+
+    if req_fragment_set then
+        __release_table(__table_pool_tag.fragment_set, req_fragment_set)
+    end
+
+    if req_fragment_list then
+        __release_table(__table_pool_tag.fragment_list, req_fragment_list)
+    end
 end
 
 ---
@@ -2372,6 +2645,29 @@ function __chunk_set(old_chunk, fragment, component)
             end
         end
     else
+        local req_fragment_set
+        local req_fragment_list
+        local req_fragment_count = 0
+
+        local ini_new_chunk = new_chunk
+        local ini_fragment_set = ini_new_chunk.__fragment_set
+
+        if new_chunk.__has_required_fragments then
+            ---@type table<evolved.fragment, integer>
+            req_fragment_set = __acquire_table(__table_pool_tag.fragment_set)
+
+            ---@type evolved.fragment[]
+            req_fragment_list = __acquire_table(__table_pool_tag.fragment_list)
+
+            req_fragment_count = __fragment_required_fragments(fragment,
+                req_fragment_set, req_fragment_list, req_fragment_count)
+
+            for i = 1, req_fragment_count do
+                local req_fragment = req_fragment_list[i]
+                new_chunk = __chunk_with_fragment(new_chunk, req_fragment)
+            end
+        end
+
         local new_entity_list = new_chunk.__entity_list
         local new_entity_count = new_chunk.__entity_count
 
@@ -2518,6 +2814,110 @@ function __chunk_set(old_chunk, fragment, component)
             end
         end
 
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+
+            if ini_fragment_set[req_fragment] then
+                -- this fragment has already been initialized
+            else
+                ---@type evolved.default?, evolved.duplicate?, evolved.set_hook?, evolved.insert_hook?
+                local req_fragment_default, req_fragment_duplicate, req_fragment_on_set, req_fragment_on_insert
+
+                if new_chunk_has_setup_hooks or new_chunk_has_insert_hooks then
+                    req_fragment_default, req_fragment_duplicate, req_fragment_on_set, req_fragment_on_insert =
+                        __evolved_get(req_fragment, __DEFAULT, __DUPLICATE, __ON_SET, __ON_INSERT)
+                end
+
+                if req_fragment_on_set or req_fragment_on_insert then
+                    local req_component_index = new_component_indices[req_fragment]
+
+                    if req_component_index then
+                        local req_component_storage = new_component_storages[req_component_index]
+
+                        if req_fragment_duplicate then
+                            for new_place = new_entity_count + 1, new_entity_count + old_entity_count do
+                                local entity = new_entity_list[new_place]
+
+                                local req_component = req_fragment_default
+                                if req_component ~= nil then req_component = req_fragment_duplicate(req_component) end
+                                if req_component == nil then req_component = true end
+
+                                req_component_storage[new_place] = req_component
+
+                                if req_fragment_on_set then
+                                    __defer_call_hook(req_fragment_on_set, entity, req_fragment, req_component)
+                                end
+
+                                if req_fragment_on_insert then
+                                    __defer_call_hook(req_fragment_on_insert, entity, req_fragment, req_component)
+                                end
+                            end
+                        else
+                            local req_component = req_fragment_default
+                            if req_component == nil then req_component = true end
+
+                            for new_place = new_entity_count + 1, new_entity_count + old_entity_count do
+                                local entity = new_entity_list[new_place]
+
+                                req_component_storage[new_place] = req_component
+
+                                if req_fragment_on_set then
+                                    __defer_call_hook(req_fragment_on_set, entity, req_fragment, req_component)
+                                end
+
+                                if req_fragment_on_insert then
+                                    __defer_call_hook(req_fragment_on_insert, entity, req_fragment, req_component)
+                                end
+                            end
+                        end
+                    else
+                        for new_place = new_entity_count + 1, new_entity_count + old_entity_count do
+                            local entity = new_entity_list[new_place]
+
+                            if req_fragment_on_set then
+                                __defer_call_hook(req_fragment_on_set, entity, req_fragment)
+                            end
+
+                            if req_fragment_on_insert then
+                                __defer_call_hook(req_fragment_on_insert, entity, req_fragment)
+                            end
+                        end
+                    end
+                else
+                    local req_component_index = new_component_indices[req_fragment]
+
+                    if req_component_index then
+                        local req_component_storage = new_component_storages[req_component_index]
+
+                        if req_fragment_duplicate then
+                            for new_place = new_entity_count + 1, new_entity_count + old_entity_count do
+                                local req_component = req_fragment_default
+                                if req_component ~= nil then req_component = req_fragment_duplicate(req_component) end
+                                if req_component == nil then req_component = true end
+                                req_component_storage[new_place] = req_component
+                            end
+                        else
+                            local req_component = req_fragment_default
+                            if req_component == nil then req_component = true end
+                            for new_place = new_entity_count + 1, new_entity_count + old_entity_count do
+                                req_component_storage[new_place] = req_component
+                            end
+                        end
+                    else
+                        -- nothing
+                    end
+                end
+            end
+        end
+
+        if req_fragment_set then
+            __release_table(__table_pool_tag.fragment_set, req_fragment_set)
+        end
+
+        if req_fragment_list then
+            __release_table(__table_pool_tag.fragment_list, req_fragment_list)
+        end
+
         __structural_changes = __structural_changes + 1
     end
 end
@@ -2727,6 +3127,7 @@ end
 
 ---@param system evolved.system
 local function __system_process(system)
+    ---@type evolved.query?, evolved.execute?, evolved.prologue?, evolved.epilogue?
     local query, execute, prologue, epilogue = __evolved_get(system,
         __QUERY, __EXECUTE, __PROLOGUE, __EPILOGUE)
 
@@ -2738,16 +3139,14 @@ local function __system_process(system)
         end
     end
 
-    if query and execute then
+    if execute then
         __evolved_defer()
-        do
-            for chunk, entity_list, entity_count in __evolved_execute(query) do
-                local success, result = __lua_pcall(execute, chunk, entity_list, entity_count)
+        for chunk, entity_list, entity_count in __evolved_execute(query or system) do
+            local success, result = __lua_pcall(execute, chunk, entity_list, entity_count)
 
-                if not success then
-                    __evolved_commit()
-                    __error_fmt('system execution failed: %s', result)
-                end
+            if not success then
+                __evolved_commit()
+                __error_fmt('system execution failed: %s', result)
             end
         end
         __evolved_commit()
@@ -3875,6 +4274,29 @@ function __evolved_set(entity, fragment, component)
             end
         end
     else
+        local req_fragment_set
+        local req_fragment_list
+        local req_fragment_count = 0
+
+        local ini_new_chunk = new_chunk
+        local ini_fragment_set = ini_new_chunk.__fragment_set
+
+        if new_chunk.__has_required_fragments then
+            ---@type table<evolved.fragment, integer>
+            req_fragment_set = __acquire_table(__table_pool_tag.fragment_set)
+
+            ---@type evolved.fragment[]
+            req_fragment_list = __acquire_table(__table_pool_tag.fragment_list)
+
+            req_fragment_count = __fragment_required_fragments(fragment,
+                req_fragment_set, req_fragment_list, req_fragment_count)
+
+            for i = 1, req_fragment_count do
+                local req_fragment = req_fragment_list[i]
+                new_chunk = __chunk_with_fragment(new_chunk, req_fragment)
+            end
+        end
+
         local new_entity_list = new_chunk.__entity_list
         local new_entity_count = new_chunk.__entity_count
 
@@ -3950,6 +4372,64 @@ function __evolved_set(entity, fragment, component)
                 end
             end
         end
+
+        for i = 1, req_fragment_count do
+            local req_fragment = req_fragment_list[i]
+
+            if ini_fragment_set[req_fragment] then
+                -- this fragment has already been initialized
+            else
+                ---@type evolved.default?, evolved.duplicate?, evolved.set_hook?, evolved.insert_hook?
+                local req_fragment_default, req_fragment_duplicate, req_fragment_on_set, req_fragment_on_insert
+
+                if new_chunk_has_setup_hooks or new_chunk_has_insert_hooks then
+                    req_fragment_default, req_fragment_duplicate, req_fragment_on_set, req_fragment_on_insert =
+                        __evolved_get(req_fragment, __DEFAULT, __DUPLICATE, __ON_SET, __ON_INSERT)
+                end
+
+                local req_component_index = new_component_indices[req_fragment]
+
+                if req_component_index then
+                    local req_component_storage = new_component_storages[req_component_index]
+
+                    local req_component = req_fragment_default
+
+                    if req_component ~= nil and req_fragment_duplicate then
+                        req_component = req_fragment_duplicate(req_component)
+                    end
+
+                    if req_component == nil then
+                        req_component = true
+                    end
+
+                    req_component_storage[new_place] = req_component
+
+                    if req_fragment_on_set then
+                        __defer_call_hook(req_fragment_on_set, entity, req_fragment, req_component)
+                    end
+
+                    if req_fragment_on_insert then
+                        __defer_call_hook(req_fragment_on_insert, entity, req_fragment, req_component)
+                    end
+                else
+                    if req_fragment_on_set then
+                        __defer_call_hook(req_fragment_on_set, entity, req_fragment)
+                    end
+
+                    if req_fragment_on_insert then
+                        __defer_call_hook(req_fragment_on_insert, entity, req_fragment)
+                    end
+                end
+            end
+        end
+
+        if req_fragment_set then
+            __release_table(__table_pool_tag.fragment_set, req_fragment_set)
+        end
+
+        if req_fragment_list then
+            __release_table(__table_pool_tag.fragment_list, req_fragment_list)
+        end
     end
 
     __evolved_commit()
@@ -4438,12 +4918,12 @@ function __evolved_execute(query)
     local chunk_stack = __acquire_table(__table_pool_tag.chunk_list)
     local chunk_stack_size = 0
 
-    local query_includes = __query_sorted_includes[query]
+    local query_includes = __sorted_includes[query]
     local query_include_set = query_includes and query_includes.__item_set --[[@as table<evolved.fragment, integer>]]
     local query_include_list = query_includes and query_includes.__item_list --[=[@as evolved.fragment[]]=]
     local query_include_count = query_includes and query_includes.__item_count or 0 --[[@as integer]]
 
-    local query_excludes = __query_sorted_excludes[query]
+    local query_excludes = __sorted_excludes[query]
     local query_exclude_set = query_excludes and query_excludes.__item_set --[[@as table<evolved.fragment, integer>]]
     local query_exclude_list = query_excludes and query_excludes.__item_list --[=[@as evolved.fragment[]]=]
     local query_exclude_count = query_excludes and query_excludes.__item_count or 0 --[[@as integer]]
@@ -5116,6 +5596,31 @@ function __builder_mt:exclude(...)
     return self:set(__EXCLUDES, exclude_list)
 end
 
+---@param ... evolved.fragment fragments
+---@return evolved.builder builder
+function __builder_mt:require(...)
+    local argument_count = __lua_select('#', ...)
+
+    if argument_count == 0 then
+        return self
+    end
+
+    local require_list = self:get(__REQUIRES)
+    local require_count = require_list and #require_list or 0
+
+    if require_count == 0 then
+        require_list = __lua_table_new(argument_count, 0)
+    end
+
+    for i = 1, argument_count do
+        ---@type evolved.fragment
+        local fragment = __lua_select(i, ...)
+        require_list[require_count + i] = fragment
+    end
+
+    return self:set(__REQUIRES, require_list)
+end
+
 ---@param on_set evolved.set_hook
 ---@return evolved.builder builder
 function __builder_mt:on_set(on_set)
@@ -5213,6 +5718,9 @@ __evolved_set(__DEFAULT, __ON_REMOVE, __update_major_chunks_hook)
 __evolved_set(__DUPLICATE, __ON_INSERT, __update_major_chunks_hook)
 __evolved_set(__DUPLICATE, __ON_REMOVE, __update_major_chunks_hook)
 
+__evolved_set(__REQUIRES, __ON_INSERT, __update_major_chunks_hook)
+__evolved_set(__REQUIRES, __ON_REMOVE, __update_major_chunks_hook)
+
 ---
 ---
 ---
@@ -5233,6 +5741,7 @@ __evolved_set(__DISABLED, __NAME, 'DISABLED')
 
 __evolved_set(__INCLUDES, __NAME, 'INCLUDES')
 __evolved_set(__EXCLUDES, __NAME, 'EXCLUDES')
+__evolved_set(__REQUIRES, __NAME, 'REQUIRES')
 
 __evolved_set(__ON_SET, __NAME, 'ON_SET')
 __evolved_set(__ON_ASSIGN, __NAME, 'ON_ASSIGN')
@@ -5277,6 +5786,9 @@ __evolved_set(__INCLUDES, __DUPLICATE, __list_copy)
 __evolved_set(__EXCLUDES, __DEFAULT, {})
 __evolved_set(__EXCLUDES, __DUPLICATE, __list_copy)
 
+__evolved_set(__REQUIRES, __DEFAULT, {})
+__evolved_set(__REQUIRES, __DUPLICATE, __list_copy)
+
 __evolved_set(__ON_SET, __UNIQUE)
 __evolved_set(__ON_ASSIGN, __UNIQUE)
 __evolved_set(__ON_INSERT, __UNIQUE)
@@ -5294,7 +5806,7 @@ __evolved_set(__INCLUDES, __ON_SET, function(query, _, include_list)
     local include_count = #include_list
 
     if include_count == 0 then
-        __query_sorted_includes[query] = nil
+        __sorted_includes[query] = nil
         return
     end
 
@@ -5306,11 +5818,11 @@ __evolved_set(__INCLUDES, __ON_SET, function(query, _, include_list)
     end
 
     __assoc_list_sort(sorted_includes)
-    __query_sorted_includes[query] = sorted_includes
+    __sorted_includes[query] = sorted_includes
 end)
 
 __evolved_set(__INCLUDES, __ON_REMOVE, function(query)
-    __query_sorted_includes[query] = nil
+    __sorted_includes[query] = nil
 end)
 
 ---
@@ -5325,7 +5837,7 @@ __evolved_set(__EXCLUDES, __ON_SET, function(query, _, exclude_list)
     local exclude_count = #exclude_list
 
     if exclude_count == 0 then
-        __query_sorted_excludes[query] = nil
+        __sorted_excludes[query] = nil
         return
     end
 
@@ -5337,11 +5849,42 @@ __evolved_set(__EXCLUDES, __ON_SET, function(query, _, exclude_list)
     end
 
     __assoc_list_sort(sorted_excludes)
-    __query_sorted_excludes[query] = sorted_excludes
+    __sorted_excludes[query] = sorted_excludes
 end)
 
 __evolved_set(__EXCLUDES, __ON_REMOVE, function(query)
-    __query_sorted_excludes[query] = nil
+    __sorted_excludes[query] = nil
+end)
+
+---
+---
+---
+---
+---
+
+---@param fragment evolved.fragment
+---@param require_list evolved.fragment[]
+__evolved_set(__REQUIRES, __ON_SET, function(fragment, _, require_list)
+    local require_count = #require_list
+
+    if require_count == 0 then
+        __sorted_requires[fragment] = nil
+        return
+    end
+
+    local sorted_requires = __assoc_list_new(require_count)
+
+    for require_index = 1, require_count do
+        local require = require_list[require_index]
+        __assoc_list_insert(sorted_requires, require)
+    end
+
+    __assoc_list_sort(sorted_requires)
+    __sorted_requires[fragment] = sorted_requires
+end)
+
+__evolved_set(__REQUIRES, __ON_REMOVE, function(fragment)
+    __sorted_requires[fragment] = nil
 end)
 
 ---
@@ -5414,6 +5957,7 @@ evolved.DISABLED = __DISABLED
 
 evolved.INCLUDES = __INCLUDES
 evolved.EXCLUDES = __EXCLUDES
+evolved.REQUIRES = __REQUIRES
 
 evolved.ON_SET = __ON_SET
 evolved.ON_ASSIGN = __ON_ASSIGN

rockspecs/evolved.lua-1.1.0-0.rockspec

@@ -0,0 +1,34 @@
+rockspec_format = "3.0"
+package = "evolved.lua"
+version = "1.1.0-0"
+source = {
+   url = "git://github.com/BlackMATov/evolved.lua",
+   tag = "v1.1.0",
+}
+description = {
+   homepage = "https://github.com/BlackMATov/evolved.lua",
+   summary = "Evolved ECS (Entity-Component-System) for Lua",
+   detailed = [[
+      `evolved.lua` is a fast and flexible ECS (Entity-Component-System) library for Lua.
+      It is designed to be simple and easy to use, while providing all the features needed to create complex systems with blazing performance.
+   ]],
+   license = "MIT",
+   labels = {
+      "ecs",
+      "entity",
+      "entities",
+      "component",
+      "components",
+      "entity-component",
+      "entity-component-system",
+   },
+}
+dependencies = {
+   "lua >= 5.1",
+}
+build = {
+   type = "builtin",
+   modules = {
+      evolved = "evolved.lua",
+   }
+}