[Implement] rest of buffer.from functions per dcode

AssemblyScript · jtenner · Jul 19, 2019 · Jul 20, 2019 · Jul 20, 2019 · Jul 23, 2019
commit 45a61c5599ebd5a80743f51501f4e111e389c51c
diff --git a/assembly/buffer/index.ts b/assembly/buffer/index.ts
@@ -2,6 +2,9 @@ import { BLOCK_MAXSIZE, BLOCK, BLOCK_OVERHEAD } from "rt/common";
 import { E_INVALIDLENGTH, E_INDEXOUTOFRANGE } from "util/error";
 import { Uint8Array } from "typedarray";
 import { ArrayBufferView } from "arraybuffer";
+import { Array } from "array";
+
+
 
 export class Buffer extends Uint8Array {
   constructor(size: i32) {
@@ -24,18 +27,85 @@ export class Buffer extends Uint8Array {
     return result;
   }
 
+  public static fromArrayBuffer(buffer: ArrayBuffer, byteOffset: i32 = 0, length: i32 = -1): Buffer {
+    length = select(buffer.byteLength, length, length < 0);
+    if (i32(byteOffset < 0) | i32(byteOffset > buffer.byteLength - length)) throw new RangeError(E_INDEXOUTOFRANGE);
+    if (length == 0) return new Buffer(0);
+    let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>()));
+    result.data = buffer; // retains
+    result.dataStart = changetype<usize>(buffer) + <usize>byteOffset;
+    result.dataLength = <usize>length;
+    return result;
+  }
+
+  public static fromString(value: string, encoding: string = "utf8"): Buffer {
+    let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>())); // retains
+    let buffer: ArrayBuffer;
+    if (encoding == "utf8" || encoding == "utf-8") {
+      buffer = String.UTF8.encode(value);
+    } else if (encoding == "utf16le") {
+      buffer = String.UTF16.encode(value);
+    } else if (encoding == "hex") {
+      buffer = Buffer.HEX.encode(value);
+      // TODO: add ascii encoding
+    } else {
+      throw new TypeError("Invalid string encoding.");
+    }
+
+    result.data = buffer; // retains
+    result.dataStart = changetype<usize>(buffer);
+    result.dataLength = buffer.byteLength;
+    return result;
+  }
+
+  public static fromArray<T extends ArrayBufferView>(value: T, offset: i32 = 0, length: i32 = -1): Buffer {
+    length = select(value.length, length, length < 0);
+    if (i32(offset < 0) | i32(offset > value.length)) throw new RangeError(E_INDEXOUTOFRANGE);
+    if (length > value.length - offset) throw new RangeError(E_INVALIDLENGTH);
+    if (length == 0) return new Buffer(0);
+    let abv = __alloc(offsetof<Buffer>(), idof<Buffer>());
+    let buffer = __alloc(length, idof<ArrayBuffer>());
+    if (value instanceof Array<String>) {
+      for (let i = 0; i < length; i++) {
+        let index = i + offset;
+        let byteValue = parseFloat(unchecked(value[index]));
+        store<u8>(buffer + <usize>i, <u8>select(0, <u8>byteValue, isNaN(byteValue)));
+      }
+    } else {
+      for (let i = 0; i < length; i++) {
+        let index = i + offset;
+        store<u8>(buffer + <usize>i, <u8>unchecked(value[index]));
+      }
+    }
+    let result = changetype<Buffer>(abv); // retains
+    result.data = changetype<ArrayBuffer>(buffer); // retains
+    result.dataStart = buffer;
+    result.dataLength = length;
+    return result;
+  }
+
+  public static fromBuffer(source: Buffer): Buffer {
+    let length = source.dataLength;
+    let data = changetype<ArrayBuffer>(__alloc(length, idof<ArrayBuffer>())); // retains
+    memory.copy(changetype<usize>(data), source.dataStart, length);
+    let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>())); // retains
+    result.data = data;
+    result.dataStart = changetype<usize>(data);
+    result.dataLength = length;
+    return result;
+  }
+
   // @ts-ignore: Buffer returns on all valid branches
-  public static from<T extends ArrayBufferView>(value: T): Buffer {
+  public static from<T>(value: T): Buffer {
     // @ts-ignore: AssemblyScript treats this statement correctly
-    if (value instanceof String[]) {
+    if (value instanceof Array<String>) {
       let length = <usize>value.length;
       let buffer = __alloc(length, idof<ArrayBuffer>());
       let sourceStart = value.dataStart;
       for (let i: usize = 0; i < length; i++) {
         let str = changetype<string>(load<usize>(sourceStart + (<usize>i << alignof<usize>())));
         let value = parseFloat(str); // parseFloat is still naive
-        trace("float values", 2, value, u8(value));
-        store<u8>(buffer + i, isFinite(value) ? u8(value) : u8(0));
+        store<u8>(buffer + i, <u8>select(value, 0.0, isFinite(value)));
       }
       let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>()));
       result.data = changetype<ArrayBuffer>(buffer);
@@ -57,20 +127,20 @@ export class Buffer extends Uint8Array {
       result.dataLength = buffer.byteLength;
       return result;
     } else if (value instanceof Buffer) {
-      let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>()));
+      let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>())); // retains
       result.data = value.buffer;
       result.dataStart = value.dataStart;
       result.dataLength = value.dataLength;
       return result;
     } else if (value instanceof ArrayBufferView) {
-      let length = value.length;
+      let length = <usize>value.length;
       let buffer = __alloc(length, idof<ArrayBuffer>());
-      let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>()));
+      let result = changetype<Buffer>(__alloc(offsetof<Buffer>(), idof<Buffer>())); // retains
       // @ts-ignore: value[i] is implied to work
-      for (let i = 0; i < length; i++) store<u8>(buffer + usize(i), u8(unchecked(value[i])));
-      result.data = changetype<ArrayBuffer>(buffer);
+      for (let i = <usize>0; i < length; i++) store<u8>(buffer + i, <u8>unchecked(value[i]));
+      result.data = changetype<ArrayBuffer>(buffer); // retains
       result.dataStart = buffer;
-      result.dataLength = u32(length);
+      result.dataLength = <u32>length;
       return result;
     }
     ERROR("Cannot call Buffer.from<T>() where T is not a string, Buffer, ArrayBuffer, Array, or Array-like Object.");

diff --git a/assembly/node.d.ts b/assembly/node.d.ts
@@ -5,6 +5,14 @@ declare class Buffer extends Uint8Array {
   static allocUnsafe(size: i32): Buffer;
   /** This method creates a Buffer from the given reference. This method is naive and defaults to utf8 encoding for strings. */
   static from<T>(value: T): Buffer;
+  /** This method creates a buffer from a given string. This method defaults to utf8 encoding. */
+  public static fromString(value: string, encoding?: string): Buffer;
+  /** This method creates a buffer that uses the given ArrayBuffer as an underlying value. */
+  public static fromArrayBuffer(buffer: ArrayBuffer, byteOffset?: i32 , length?: i32): Buffer;
+  /** This method creates a copy of the buffer using memory.copy(). */
+  public static fromBuffer(source: Buffer): Buffer;
+  /** This method creates a new Buffer by copying the underlying values to a new ArrayBuffer and coercing each one to an 8 bit integer value. */
+  public static fromArray<T extends ArrayBufferView<number | string>>(value: T, offset?: i32, length?: i32): Buffer;
   /** This method asserts a value is a Buffer object via `value instanceof Buffer`. */
   static isBuffer<T>(value: T): bool;
   /** Reads a signed integer at the designated offset. */

diff --git a/tests/buffer.spec.ts b/tests/buffer.spec.ts
@@ -21,7 +21,7 @@ function create<T>(values: valueof<T>[]): T {
 }
 
 describe("buffer", () => {
-  test("#constructor", () => {
+  test(".constructor", () => {
     expect<Buffer>(new Buffer(0)).toBeTruthy();
     expect<Buffer>(new Buffer(10)).toHaveLength(10);
     let myBuffer = new Buffer(10);
@@ -31,7 +31,7 @@ describe("buffer", () => {
     // TODO: expectFn(() => { new Buffer(BLOCK_MAXSIZE + 1); }).toThrow();
   });
 
-  test("#alloc", () => {
+  test(".alloc", () => {
     expect<Buffer>(Buffer.alloc(10)).toBeTruthy();
     expect<Buffer>(Buffer.alloc(10)).toHaveLength(10);
     let buff = Buffer.alloc(100);
@@ -42,7 +42,7 @@ describe("buffer", () => {
     // TODO: expectFn(() => { Buffer.alloc(BLOCK_MAXSIZE + 1); }).toThrow();
   });
 
-  test("#allocUnsafe", () => {
+  test(".allocUnsafe", () => {
     expect<Buffer>(Buffer.allocUnsafe(10)).toBeTruthy();
     expect<Buffer>(Buffer.allocUnsafe(10)).toHaveLength(10);
     let buff = Buffer.allocUnsafe(100);
@@ -92,6 +92,70 @@ describe("buffer", () => {
     expect<Buffer>(strArrayActual).toStrictEqual(strArrayExpected, "Array Of Strings");
   });
 
+  test(".fromString", () => {
+    // public static fromString(value: string, encoding: string = "utf8"): Buffer {
+    // default encoding is utf8
+    let expected = create<Buffer>([0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x61, 0x20, 0x74, 0xc3, 0xa9, 0x73, 0x74])
+    expect<Buffer>(Buffer.from('this is a tést'))
+      .toStrictEqual(expected);
+
+    expect<Buffer>(Buffer.fromString('7468697320697320612074c3a97374', 'hex'))
+      .toStrictEqual(expected);
+  });
+
+  test(".fromArrayBuffer", () => {
+    const arr = new Uint16Array(2);
+
+    arr[0] = 5000;
+    arr[1] = 4000;
+
+    // Shares memory with `arr`.
+    const buf = Buffer.fromArrayBuffer(arr.buffer);
+
+
+    expect<Buffer>(buf).toStrictEqual(create<Buffer>([0x88, 0x13, 0xa0, 0x0f]));
+
+    // Changing the original Uint16Array changes the Buffer also.
+    arr[1] = 6000;
+    expect<Buffer>(buf).toStrictEqual(create<Buffer>([0x88, 0x13, 0x70, 0x17]));
+
+    // test optional parameters
+    expect<Buffer>(Buffer.fromArrayBuffer(arr.buffer, 1, 2)).toStrictEqual(create<Buffer>([0x13, 0x70]));
+
+    // TODO:
+    // expectFn(() => {
+    //   let value = create<Uint16Array>([5000, 4000]); // 4 bytes
+    //   Buffer.fromArrayBuffer(value.buffer, 5);
+    // }).toThrow("offset out of bounds should throw");
+    // expectFn(() => {
+    //   let value = create<Uint16Array>([5000, 4000]); // 4 bytes
+    //   Buffer.fromArrayBuffer(value.buffer, 2, 3);
+    // }).toThrow("length out of bounds should throw");
+  });
+
+  test(".fromBuffer", () => {
+    let buff1 = create<Buffer>([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+    let buff2 = Buffer.fromBuffer(buff1);
+
+    expect<Buffer>(buff1).not.toBe(buff2);
+    expect<ArrayBuffer>(buff1.buffer).not.toBe(buff2.buffer);
+    expect<Buffer>(buff1).toStrictEqual(buff2);
+  });
+
+  test(".fromArray", () => {
+    let buff1 = create<Uint16Array>([3, 6, 9, 12, 15, 18, 21]);
+    let buff2 = Buffer.fromArray(buff1, 2, 4);
+    let expected = create<Buffer>([9, 12, 15, 18]);
+    expect<Buffer>(buff2).toStrictEqual(expected);
+
+    // test string values
+    buff2 = Buffer.fromArray<string[]>(["9.2", "12.1", "15.3", "18.8"]);
+    expect<Buffer>(buff2).toStrictEqual(expected);
+  });
+
+  // todo: fromArray
+  // todo: fromBuffer
+
   test("#isBuffer", () => {
     let a = "";
     let b = new Uint8Array(0);