feat: pointers (#17)

Co-authored-by: Elias Sjögreen <[email protected]>

.gitignore

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+/.vscode

types/ffi/mod.ts

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+export * from "./pointer_value.ts";
+export * from "./pointer_view.ts";
+export * from "./pointer.ts";

types/ffi/pointer.ts

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+import type { AlignedType, SizedType } from "../types.ts";
+import { pointerView } from "./pointer_view.ts";
+
+export class Pointer<T> implements AlignedType<T> {
+  byteLength: number;
+  byteAlign: number;
+  type: SizedType<T>;
+  pointerType: AlignedType<Deno.UnsafePointerView>;
+
+  constructor(
+    type: SizedType<T>,
+    pointerType: AlignedType<Deno.UnsafePointerView> = pointerView,
+  ) {
+    this.byteAlign = pointerType.byteAlign;
+    this.byteLength = pointerType.byteLength;
+    this.type = type;
+    this.pointerType = pointerType;
+  }
+
+  read(dataView: DataView, byteOffset = 0): T {
+    return this.type.read(
+      new DataView(
+        this.pointerType.read(dataView, byteOffset).getArrayBuffer(
+          this.type.byteLength,
+        ),
+      ),
+    );
+  }
+
+  write(value: T, dataView: DataView, byteOffset = 0) {
+    const buffer = new ArrayBuffer(this.type.byteLength);
+    this.type.write(value, new DataView(buffer));
+    const pointerView = new Deno.UnsafePointerView(
+      Deno.UnsafePointer.of(buffer)!,
+    );
+    this.pointerType.write(pointerView, dataView, byteOffset);
+  }
+}

types/ffi/pointer_value.ts

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+import type { AlignedType } from "../types.ts";
+import { u64 } from "../mod.ts";
+
+export class PointerValue implements AlignedType<Deno.PointerValue> {
+  byteLength: number;
+  byteAlign: number;
+  pointerType: AlignedType<number | bigint>;
+
+  constructor(
+    pointerType: AlignedType<number | bigint> = u64,
+  ) {
+    this.byteAlign = pointerType.byteAlign;
+    this.byteLength = pointerType.byteLength;
+    this.pointerType = pointerType;
+  }
+
+  read(dataView: DataView, byteOffset = 0): Deno.PointerValue {
+    return Deno.UnsafePointer.create(
+      this.pointerType.read(dataView, byteOffset),
+    );
+  }
+
+  write(value: Deno.PointerValue, dataView: DataView, byteOffset = 0) {
+    this.pointerType.write(
+      Deno.UnsafePointer.value(value),
+      dataView,
+      byteOffset,
+    );
+  }
+}
+
+export const pointerValue = new PointerValue();

types/ffi/pointer_view.ts

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+import type { AlignedType } from "../types.ts";
+import { pointerValue } from "./pointer_value.ts";
+
+export class PointerView implements AlignedType<Deno.UnsafePointerView> {
+  byteLength: number;
+  byteAlign: number;
+  pointerType: AlignedType<Deno.PointerValue>;
+
+  constructor(
+    pointerType: AlignedType<Deno.PointerValue> = pointerValue,
+  ) {
+    this.byteAlign = pointerType.byteAlign;
+    this.byteLength = pointerType.byteLength;
+    this.pointerType = pointerType;
+  }
+
+  read(dataView: DataView, byteOffset = 0): Deno.UnsafePointerView {
+    return new Deno.UnsafePointerView(
+      this.pointerType.read(dataView, byteOffset)!,
+    );
+  }
+
+  write(value: Deno.UnsafePointerView, dataView: DataView, byteOffset = 0) {
+    this.pointerType.write(value.pointer, dataView, byteOffset);
+  }
+}
+
+export const pointerView = new PointerView();