From 903b44695404990c56304c7b0d829514ef9a41c2 Mon Sep 17 00:00:00 2001
From: Ben Cohen <ben_cohen@apple.com>
Date: Thu, 31 Oct 2024 11:16:32 -0700
Subject: [PATCH] Adopt experimental version of fixed-size Vector type

---
 Examples/SwiftBreak/Sources/FixedArray.swift  | 71 ++++++++++++-------
 Examples/SwiftBreak/Sources/Game.swift        |  7 +-
 Examples/SwiftBreak/Sources/Sprite+Game.swift |  2 +-
 Examples/SwiftBreak/Sources/Vector.swift      | 10 +--
 Examples/swift.mk                             |  4 ++
 5 files changed, 57 insertions(+), 37 deletions(-)

diff --git a/Examples/SwiftBreak/Sources/FixedArray.swift b/Examples/SwiftBreak/Sources/FixedArray.swift
index 18dba0d..ab7e982 100644
--- a/Examples/SwiftBreak/Sources/FixedArray.swift
+++ b/Examples/SwiftBreak/Sources/FixedArray.swift
@@ -1,35 +1,52 @@
-struct FixedArray<Element: ~Copyable>: ~Copyable {
-  let count: Int
-  private let _buffer: UnsafeMutablePointer<Element>
+import Builtin
 
-  init(count: Int, first: consuming Element, rest: (borrowing Element) -> Element) {
-    precondition(count > 0)
-    self.count = count
-    _buffer = .allocate(capacity: count)
-    for i in 1..<count {
-      (_buffer + i).initialize(to: rest(first))
-    }
-    _buffer.initialize(to: first)
-  }
+@frozen
+public struct Vector<let Count: Int, Element: ~Copyable>: ~Copyable {
+    private var storage: Builtin.FixedArray<Count, Element>
+}
 
-  deinit {
-    _buffer.deinitialize(count: count)
-    _buffer.deallocate()
-  }
+extension Vector where Element: ~Copyable {
+    init(first: @autoclosure ()->Element, rest valueForIndex: (borrowing Element) -> Element) {
+        storage = Builtin.emplace { rawPointer in
+            let first = first()
+            let base = UnsafeMutablePointer<Element>(rawPointer)
+            for i in 1..<Count {
+                (base + i).initialize(to: valueForIndex(first))
+            }
+            base.initialize(to: first)
+        }
+    }
 }
 
-extension FixedArray where Element: ~Copyable {
-  func forEach(_ body: (borrowing Element) -> Void) {
-    for i in 0..<self.count {
-      body((self._buffer + i).pointee)
+extension Vector where Element: ~Copyable {
+    public subscript(i: Int) -> Element {
+        _read {
+            assert(i >= 0 && i < Count)
+            let rawPointer = Builtin.addressOfBorrow(self)
+            let base = UnsafePointer<Element>(rawPointer)
+            yield ((base + i).pointee)
+        }
+        
+        _modify {
+            assert(i >= 0 && i < Count)
+            let rawPointer = Builtin.addressof(&self)
+            let base = UnsafeMutablePointer<Element>(rawPointer)
+            yield (&(base + i).pointee)
+        }
+    }
+    
+    func forEach(_ body: (borrowing Element) -> Void) {
+      for i in 0..<Count {
+        body(self[i])
+      }
     }
-  }
 
-  func enumerated(_ body: (Int, borrowing Element) -> Void) {
-    var i = 0
-    self.forEach {
-      body(i, $0)
-      i += 1
+    func enumerated(_ body: (Int, borrowing Element) -> Void) {
+      for i in 0..<Count {
+        body(i,self[i])
+      }
     }
-  }
+    
+    var count: Int { Count }
 }
+
diff --git a/Examples/SwiftBreak/Sources/Game.swift b/Examples/SwiftBreak/Sources/Game.swift
index 9b936ba..6a1405c 100644
--- a/Examples/SwiftBreak/Sources/Game.swift
+++ b/Examples/SwiftBreak/Sources/Game.swift
@@ -13,12 +13,12 @@ struct Sprites: ~Copyable {
   var ball: Sprite
   var paddle: Sprite
   var gameOver: Sprite
-  var bricks: FixedArray<Sprite>
+  var bricks: Vector<40,Sprite>
 }
 
 struct ActiveGame {
   var score: Int
-  var ballVelocity: Vector
+  var ballVelocity: Vec2
   var bricksRemaining: Int
 }
 
@@ -36,7 +36,6 @@ struct Game: ~Copyable {
     Sprite.setupWalls()
 
     // Start in loading state with 4 x 10 bricks.
-    let brick = Sprite.brick()
     let splash = Sprite.splash()
     splash.addSprite()
     self.sprites =
@@ -46,7 +45,7 @@ struct Game: ~Copyable {
         ball: .ball(),
         paddle: .paddle(),
         gameOver: .gameOver(),
-        bricks: .init(count: 40, first: brick) { $0.copy() })
+        bricks: .init(first: Sprite.brick()) { $0.copy() })
     Sprite.drawSprites()
     self.state = .loading
   }
diff --git a/Examples/SwiftBreak/Sources/Sprite+Game.swift b/Examples/SwiftBreak/Sources/Sprite+Game.swift
index ce48e6e..83bffaa 100644
--- a/Examples/SwiftBreak/Sources/Sprite+Game.swift
+++ b/Examples/SwiftBreak/Sources/Sprite+Game.swift
@@ -83,7 +83,7 @@ extension Sprite {
             activeGame.bricksRemaining -= 1
           }
 
-          var normal = Vector(collision.normal)
+          var normal = Vec2(collision.normal)
 
           if otherSprite.tag == .paddle {
             // compute placement of ball on paddle in domain -1 to 1.
diff --git a/Examples/SwiftBreak/Sources/Vector.swift b/Examples/SwiftBreak/Sources/Vector.swift
index a6684c8..db065fd 100644
--- a/Examples/SwiftBreak/Sources/Vector.swift
+++ b/Examples/SwiftBreak/Sources/Vector.swift
@@ -1,8 +1,8 @@
 import Playdate
 
-typealias Vector = SIMD2<Float32>
+typealias Vec2 = SIMD2<Float32>
 
-extension Vector {
+extension Vec2 {
   init(_ collisionVector: CollisionVector) {
     self = .init(Float32(collisionVector.x), Float32(collisionVector.y))
   }
@@ -12,7 +12,7 @@ extension Vector {
   }
 }
 
-extension Vector {
+extension Vec2 {
   func reflected(along normal: Self) -> Self {
     self - (2 * (self • normal)) * normal
   }
@@ -22,7 +22,7 @@ extension Vector {
   }
 }
 
-extension Vector {
+extension Vec2 {
   func rotated(by theta: Float32) -> Self {
     .init(
       x: self.x * cosf(theta) + self.y * -sinf(theta),
@@ -35,7 +35,7 @@ extension Vector {
 }
 
 infix operator • : MultiplicationPrecedence
-extension Vector {
+extension Vec2 {
   static func • (lhs: Self, rhs: Self) -> Float {
     (lhs.x * rhs.x) + (lhs.y * rhs.y)
   }
diff --git a/Examples/swift.mk b/Examples/swift.mk
index d3fc471..9c0c69d 100644
--- a/Examples/swift.mk
+++ b/Examples/swift.mk
@@ -42,8 +42,12 @@ SWIFT_FLAGS := \
 	-O \
 	-wmo -enable-experimental-feature Embedded \
 	-enable-experimental-feature NoncopyableGenerics \
+	-enable-experimental-feature ValueGenerics \
+	-enable-experimental-feature BuiltinModule \
 	-Xfrontend -disable-stack-protector \
 	-Xfrontend -function-sections \
+	-Xfrontend -disable-availability-checking \
+	-disable-experimental-parser-round-trip \
 	-swift-version 6 \
 	-Xcc -DTARGET_EXTENSION \
 	-module-cache-path build/module-cache \