[Assembly Script] Add basic Assembly Script support

as/byte-buffer.ts

@@ -0,0 +1,365 @@
+import { FILE_IDENTIFIER_LENGTH, SIZEOF_INT } from './constants';
+import { Long } from './long';
+import { int32, isLittleEndian, float32, float64 } from './utils';
+import { Offset, Table, IGeneratedObject } from './types';
+
+export class ByteBuffer {
+  private position_: i32 = 0;
+
+  /**
+   * Create a new ByteBuffer with a given array of bytes (`Uint8Array`)
+   */
+  constructor(private bytes_: Uint8Array) {}
+
+  /**
+   * Create and allocate a new ByteBuffer with a given size.
+   */
+  static allocate(byte_size: i32): ByteBuffer {
+    return new ByteBuffer(new Uint8Array(byte_size));
+  }
+
+  clear(): void {
+    this.position_ = 0;
+  }
+
+  /**
+   * Get the underlying `Uint8Array`.
+   */
+  bytes(): Uint8Array {
+    return this.bytes_;
+  }
+
+  /**
+   * Get the buffer's position.
+   */
+  position(): i32 {
+    return this.position_;
+  }
+
+  /**
+   * Set the buffer's position.
+   */
+  setPosition(position: i32): void {
+    this.position_ = position;
+  }
+
+  /**
+   * Get the buffer's capacity.
+   */
+  capacity(): i32 {
+    return this.bytes_.length;
+  }
+
+  readInt8(offset: i32): i32 {
+    return (i32(this.readUint8(offset)) << 24) >> 24;
+  }
+
+  readUint8(offset: i32): i32 {
+    return this.bytes_[offset];
+  }
+
+  readInt16(offset: i32): i32 {
+    return (i32(this.readUint16(offset)) << 16) >> 16;
+  }
+
+  readUint16(offset: i32): i32 {
+    return i32(this.bytes_[offset]) | (i32(this.bytes_[offset + 1]) << 8);
+  }
+
+  readInt32(offset: i32): i32 {
+    return (
+      i32(this.bytes_[offset]) |
+      (i32(this.bytes_[offset + 1]) << 8) |
+      (i32(this.bytes_[offset + 2]) << 16) |
+      (i32(this.bytes_[offset + 3]) << 24)
+    );
+  }
+
+  readUint32(offset: i32): i32 {
+    return this.readInt32(offset) >>> 0;
+  }
+
+  readInt64(offset: i32): Long {
+    return new Long(this.readInt32(offset), this.readInt32(offset + 4));
+  }
+
+  readUint64(offset: i32): Long {
+    return new Long(this.readUint32(offset), this.readUint32(offset + 4));
+  }
+
+  readFloat32(offset: i32): f32 {
+    int32[0] = this.readInt32(offset);
+    return float32[0];
+  }
+
+  readFloat64(offset: i32): f64 {
+    int32[isLittleEndian ? 0 : 1] = this.readInt32(offset);
+    int32[isLittleEndian ? 1 : 0] = this.readInt32(offset + 4);
+    return float64[0];
+  }
+
+  writeInt8(offset: i32, value: i32): void {
+    this.bytes_[offset] = value;
+  }
+
+  writeUint8(offset: i32, value: i32): void {
+    this.bytes_[offset] = value;
+  }
+
+  writeInt16(offset: i32, value: i32): void {
+    this.bytes_[offset] = value;
+    this.bytes_[offset + 1] = value >> 8;
+  }
+
+  writeUint16(offset: i32, value: i32): void {
+    this.bytes_[offset] = value;
+    this.bytes_[offset + 1] = value >> 8;
+  }
+
+  writeInt32(offset: i32, value: i32): void {
+    this.bytes_[offset] = value;
+    this.bytes_[offset + 1] = value >> 8;
+    this.bytes_[offset + 2] = value >> 16;
+    this.bytes_[offset + 3] = value >> 24;
+  }
+
+  writeUint32(offset: i32, value: i32): void {
+    this.bytes_[offset] = value;
+    this.bytes_[offset + 1] = value >> 8;
+    this.bytes_[offset + 2] = value >> 16;
+    this.bytes_[offset + 3] = value >> 24;
+  }
+
+  writeInt64(offset: i32, value: Long): void {
+    this.writeInt32(offset, value.low);
+    this.writeInt32(offset + 4, value.high);
+  }
+
+  writeUint64(offset: i32, value: Long): void {
+    this.writeUint32(offset, value.low);
+    this.writeUint32(offset + 4, value.high);
+  }
+
+  writeFloat32(offset: i32, value: f32): void {
+    float32[0] = value;
+    this.writeInt32(offset, int32[0]);
+  }
+
+  writeFloat64(offset: i32, value: f64): void {
+    float64[0] = value;
+    this.writeInt32(offset, int32[isLittleEndian ? 0 : 1]);
+    this.writeInt32(offset + 4, int32[isLittleEndian ? 1 : 0]);
+  }
+
+  /**
+   * Return the file identifier.   Behavior is undefined for FlatBuffers whose
+   * schema does not include a file_identifier (likely points at padding or the
+   * start of a the root vtable).
+   */
+  getBufferIdentifier(): string {
+    if (
+      this.bytes_.length <
+      this.position_ + SIZEOF_INT + FILE_IDENTIFIER_LENGTH
+    ) {
+      throw new Error(
+        'FlatBuffers: ByteBuffer is too short to contain an identifier.'
+      );
+    }
+    let result = '';
+    for (let i = 0; i < FILE_IDENTIFIER_LENGTH; i++) {
+      result += String.fromCharCode(
+        this.readInt8(this.position_ + SIZEOF_INT + i)
+      );
+    }
+    return result;
+  }
+
+  /**
+   * Look up a field in the vtable, return an offset into the object, or 0 if the
+   * field is not present.
+   */
+  __offset(bb_pos: i32, vtable_offset: i32): Offset {
+    const vtable = bb_pos - this.readInt32(bb_pos);
+    return vtable_offset < this.readInt16(vtable)
+      ? this.readInt16(vtable + vtable_offset)
+      : 0;
+  }
+
+  /**
+   * Initialize any Table-derived type to point to the union at the given offset.
+   */
+  __union(t: Table, offset: i32): Table {
+    t.bb_pos = offset + this.readInt32(offset);
+    t.bb = this;
+    return t;
+  }
+
+  /**
+   * Create a JavaScript string from UTF-8 data stored inside the FlatBuffer.
+   * This allocates a new string and converts to wide chars upon each access.
+   *
+   * To avoid the conversion to UTF-16, pass Encoding.UTF8_BYTES as
+   * the "optionalEncoding" argument. This is useful for avoiding conversion to
+   * and from UTF-16 when the data will just be packaged back up in another
+   * FlatBuffer later on.
+   *
+   * @param offset
+   * @param opt_encoding Defaults to UTF16_STRING
+   */
+  __string(offset: i32): string {
+    offset += this.readInt32(offset);
+
+    const length = this.readInt32(offset);
+    let result = '';
+    let i = 0;
+
+    offset += SIZEOF_INT;
+
+    while (i < length) {
+      let codePoint: i32;
+
+      // Decode UTF-8
+      const a = this.readUint8(offset + i++);
+      if (a < 0xc0) {
+        codePoint = a;
+      } else {
+        const b = this.readUint8(offset + i++);
+        if (a < 0xe0) {
+          codePoint = ((a & 0x1f) << 6) | (b & 0x3f);
+        } else {
+          const c = this.readUint8(offset + i++);
+          if (a < 0xf0) {
+            codePoint = ((a & 0x0f) << 12) | ((b & 0x3f) << 6) | (c & 0x3f);
+          } else {
+            const d = this.readUint8(offset + i++);
+            codePoint =
+              ((a & 0x07) << 18) |
+              ((b & 0x3f) << 12) |
+              ((c & 0x3f) << 6) |
+              (d & 0x3f);
+          }
+        }
+      }
+
+      // Encode UTF-16
+      if (codePoint < 0x10000) {
+        result += String.fromCharCode(codePoint);
+      } else {
+        codePoint -= 0x10000;
+        result += String.fromCharCode(
+          (codePoint >> 10) + 0xd800,
+          (codePoint & ((1 << 10) - 1)) + 0xdc00
+        );
+      }
+    }
+
+    return result;
+  }
+
+  /**
+   * Handle unions that can contain string as its member, if a Table-derived type then initialize it,
+   * if a string then return a new one
+   *
+   * WARNING: strings are immutable in JS so we can't change the string that the user gave us, this
+   * makes the behaviour of __union_with_string different compared to __union
+   */
+  __union_with_string(offset: i32): string {
+    return this.__string(offset) as string;
+  }
+
+  __union_with_table(o: Table, offset: i32): Table {
+    return this.__union(o, offset);
+  }
+
+  /**
+   * Retrieve the relative offset stored at "offset"
+   */
+  __indirect(offset: Offset): Offset {
+    return offset + this.readInt32(offset);
+  }
+
+  /**
+   * Get the start of data of a vector whose offset is stored at "offset" in this object.
+   */
+  __vector(offset: Offset): Offset {
+    return offset + this.readInt32(offset) + SIZEOF_INT; // data starts after the length
+  }
+
+  /**
+   * Get the length of a vector whose offset is stored at "offset" in this object.
+   */
+  __vector_len(offset: Offset): Offset {
+    return this.readInt32(offset + this.readInt32(offset));
+  }
+
+  __has_identifier(ident: string): boolean {
+    if (ident.length != FILE_IDENTIFIER_LENGTH) {
+      throw new Error(
+        'FlatBuffers: file identifier must be length ' + FILE_IDENTIFIER_LENGTH
+      );
+    }
+    for (let i = 0; i < FILE_IDENTIFIER_LENGTH; i++) {
+      if (
+        ident.charCodeAt(i) != this.readInt8(this.position() + SIZEOF_INT + i)
+      ) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
+   * A helper function to avoid generated code depending on this file directly.
+   */
+  createLong(low: i32, high: i32): Long {
+    return Long.create(low, high);
+  }
+
+  /**
+   * A helper function for generating list for obj api
+   */
+  createScalarList(
+    listAccessor: (i: i32) => unknown,
+    listLength: i32
+  ): unknown[] {
+    const ret: unknown[] = [];
+    for (let i = 0; i < listLength; ++i) {
+      if (listAccessor(i) !== null) {
+        ret.push(listAccessor(i));
+      }
+    }
+
+    return ret;
+  }
+
+  /**
+   * This function is here only to get around typescript type system
+   */
+  createStringList(
+    listAccessor: (i: i32) => unknown,
+    listLength: i32
+  ): unknown[] {
+    return this.createScalarList(listAccessor, listLength);
+  }
+
+  /**
+   * A helper function for generating list for obj api
+   * @param listAccessor function that accepts an index and return data at that index
+   * @param listLength listLength
+   * @param res result list
+   */
+  createObjList(
+    listAccessor: (i: i32) => IGeneratedObject,
+    listLength: i32
+  ): IGeneratedObject[] {
+    const ret: IGeneratedObject[] = [];
+    for (let i = 0; i < listLength; ++i) {
+      const val = listAccessor(i);
+      if (val !== null) {
+        ret.push(val.unpack());
+      }
+    }
+
+    return ret;
+  }
+}

as/constants.ts

@@ -0,0 +1,4 @@
+export const SIZEOF_SHORT = 2;
+export const SIZEOF_INT = 4;
+export const FILE_IDENTIFIER_LENGTH = 4;
+export const SIZE_PREFIX_LENGTH = 4;

as/encoding.ts

@@ -0,0 +1,4 @@
+export enum Encoding {
+  UTF8_BYTES = 1,
+  UTF16_STRING = 2,
+}