feat(packages/stdlib): add bit vector tool

packages/stdlib/src/bits/vector/index.ts

@@ -0,0 +1,61 @@
+export interface BitVector {
+  getBit(index: number): boolean;
+  setBit(index: number): void;
+  clearBit(index: number): void;
+  previousBit(index: number): number;
+}
+
+/**
+ * @name BitVector
+ * @category Bits
+ * @description A bit vector is a vector of bits that can be used to store a collection of bits
+ * 
+ * @since 0.0.3
+ */
+export class BitVector extends Uint8Array implements BitVector {
+  constructor(size: number) {
+    super(Math.ceil(size / 8));
+  }
+
+  getBit(index: number) {
+    const value = this[index >> 3]! & (1 << (index & 7));
+    return value !== 0;
+  }
+
+  setBit(index: number) {
+    this[index >> 3]! |= 1 << (index & 7);
+  }
+
+  clearBit(index: number): void {
+    this[index >> 3]! &= ~(1 << (index & 7));
+  }
+
+  previousBit(index: number): number {
+    while (index !== ((index >> 3) << 3)) {
+      --index;
+
+      if (this.getBit(index)) {
+        return index;
+      }
+    }
+
+    let byteIndex = (index >> 3) - 1;
+
+    while (byteIndex >= 0 && this[byteIndex] === 0)
+      --byteIndex;
+
+    if (byteIndex < 0)
+      return -1;
+
+    index = (byteIndex << 3) + 7;
+
+    while (index >= (byteIndex << 3)) {
+      if (this.getBit(index))
+        return index;
+
+      --index;
+    }
+
+    throw new RangeError('Unreachable value');
+  }
+}