[TS/JS] BigInt implementation (#6998)

* BigInt implementation

* Unit test reading long from existing bytebuffer

* Code review

6 files changed, 29 insertions, 72 deletions

diff --git a/ts/builder.ts b/ts/builder.ts
index 7aad15e2..9e7a67e7 100644
--- a/ts/builder.ts
+++ b/ts/builder.ts
@@ -1,7 +1,6 @@
 import { ByteBuffer } from "./byte-buffer"
 import { SIZEOF_SHORT, SIZE_PREFIX_LENGTH, SIZEOF_INT, FILE_IDENTIFIER_LENGTH } from "./constants"
 import { Offset, IGeneratedObject } from "./types"
-import { Long } from "./long"
 
 export class Builder {
     private bb: ByteBuffer
@@ -136,7 +135,7 @@ export class Builder {
       this.bb.writeInt32(this.space -= 4, value);
     }
   
-    writeInt64(value: Long): void {
+    writeInt64(value: bigint): void {
       this.bb.writeInt64(this.space -= 8, value);
     }
   
@@ -179,7 +178,7 @@ export class Builder {
      * Add an `int64` to the buffer, properly aligned, and grows the buffer (if necessary).
      * @param value The `int64` to add the the buffer.
      */
-    addInt64(value: Long): void {
+    addInt64(value: bigint): void {
       this.prep(8, 0);
       this.writeInt64(value);
     }
@@ -223,8 +222,8 @@ export class Builder {
       }
     }
   
-    addFieldInt64(voffset: number, value: Long, defaultValue: Long): void {
-      if (this.force_defaults || !value.equals(defaultValue)) {
+    addFieldInt64(voffset: number, value: bigint, defaultValue: bigint): void {
+      if (this.force_defaults || value !== defaultValue) {
         this.addInt64(value);
         this.slot(voffset);
       }
@@ -575,13 +574,6 @@ export class Builder {
     }
   
     /**
-     * A helper function to avoid generated code depending on this file directly.
-     */
-    createLong(low: number, high: number): Long {
-      return Long.create(low, high);
-    }
-  
-    /**
      * A helper function to pack an object
      * 
      * @returns offset of obj
diff --git a/ts/byte-buffer.ts b/ts/byte-buffer.ts
index f802548a..2e07573d 100644
--- a/ts/byte-buffer.ts
+++ b/ts/byte-buffer.ts
@@ -1,5 +1,4 @@
 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";
 import { Encoding } from "./encoding";
@@ -75,12 +74,12 @@ export class ByteBuffer {
       return this.readInt32(offset) >>> 0;
     }
   
-    readInt64(offset: number): Long {
-      return new Long(this.readInt32(offset), this.readInt32(offset + 4));
+    readInt64(offset: number): bigint {
+      return BigInt.asIntN(64, BigInt(this.readUint32(offset)) + (BigInt(this.readUint32(offset + 4)) << BigInt(32)));
     }
   
-    readUint64(offset: number): Long {
-      return new Long(this.readUint32(offset), this.readUint32(offset + 4));
+    readUint64(offset: number): bigint {
+      return BigInt.asUintN(64, BigInt(this.readUint32(offset)) + (BigInt(this.readUint32(offset + 4)) << BigInt(32)));
     }
   
     readFloat32(offset: number): number {
@@ -108,8 +107,8 @@ export class ByteBuffer {
     }
   
     writeUint16(offset: number, value: number): void {
-        this.bytes_[offset] = value;
-        this.bytes_[offset + 1] = value >> 8;
+      this.bytes_[offset] = value;
+      this.bytes_[offset + 1] = value >> 8;
     }
   
     writeInt32(offset: number, value: number): void {
@@ -120,20 +119,20 @@ export class ByteBuffer {
     }
   
     writeUint32(offset: number, value: number): void {
-        this.bytes_[offset] = value;
-        this.bytes_[offset + 1] = value >> 8;
-        this.bytes_[offset + 2] = value >> 16;
-        this.bytes_[offset + 3] = value >> 24;
+      this.bytes_[offset] = value;
+      this.bytes_[offset + 1] = value >> 8;
+      this.bytes_[offset + 2] = value >> 16;
+      this.bytes_[offset + 3] = value >> 24;
     }
   
-    writeInt64(offset: number, value: Long): void {
-      this.writeInt32(offset, value.low);
-      this.writeInt32(offset + 4, value.high);
+    writeInt64(offset: number, value: bigint): void {
+      this.writeInt32(offset, Number(BigInt.asIntN(32, value)));
+      this.writeInt32(offset + 4, Number(BigInt.asIntN(32, value >> BigInt(32))));
     }
   
-    writeUint64(offset: number, value: Long): void {
-        this.writeUint32(offset, value.low);
-        this.writeUint32(offset + 4, value.high);
+    writeUint64(offset: number, value: bigint): void {
+      this.writeUint32(offset, Number(BigInt.asUintN(32, value)));
+      this.writeUint32(offset + 4, Number(BigInt.asUintN(32, value >> BigInt(32))));
     }
   
     writeFloat32(offset: number, value: number): void {
@@ -301,14 +300,7 @@ export class ByteBuffer {
       }
       return true;
     }
-  
-    /**
-     * A helper function to avoid generated code depending on this file directly.
-     */
-    createLong(low: number, high: number): Long {
-      return Long.create(low, high);
-    }
-  
+
     /**
      * A helper function for generating list for obj api
      */
@@ -341,4 +333,4 @@ export class ByteBuffer {
       return ret;
     }
   
-  }
\ No newline at end of file
+  }
diff --git a/ts/flatbuffers.ts b/ts/flatbuffers.ts
index e7b0729b..4246109c 100644
--- a/ts/flatbuffers.ts
+++ b/ts/flatbuffers.ts
@@ -7,7 +7,6 @@ export { Table, Offset } from './types'
 
 export { int32, float32, float64, isLittleEndian } from './utils'
 
-export { Long, createLong } from './long'
 export { Encoding } from './encoding'
 export { Builder } from './builder'
 export { ByteBuffer } from './byte-buffer'
diff --git a/ts/flexbuffers/reference-util.ts b/ts/flexbuffers/reference-util.ts
index a5eb48d9..7e833678 100644
--- a/ts/flexbuffers/reference-util.ts
+++ b/ts/flexbuffers/reference-util.ts
@@ -3,15 +3,13 @@ import { toByteWidth, fromByteWidth } from './bit-width-util'
 import { toUTF8Array, fromUTF8Array } from './flexbuffers-util'
 import { Reference } from './reference'
 
-import { Long } from '../long'
-
 export function validateOffset(dataView: DataView, offset: number, width: number): void {
   if (dataView.byteLength <= offset + width || (offset & (toByteWidth(width) - 1)) !== 0) {
     throw "Bad offset: " + offset + ", width: " + width;
   }
 }
 
-export function readInt(dataView: DataView, offset: number, width: number): number | Long | bigint {
+export function readInt(dataView: DataView, offset: number, width: number): number | bigint {
   if (width < 2) {
     if (width < 1) {
       return dataView.getInt8(offset);
@@ -23,14 +21,14 @@ export function readInt(dataView: DataView, offset: number, width: number): numb
       return dataView.getInt32(offset, true)
     } else {
       if (dataView.setBigInt64 === undefined) {
-        return new Long(dataView.getUint32(offset, true), dataView.getUint32(offset + 4, true))
+        return BigInt(dataView.getUint32(offset, true)) + (BigInt(dataView.getUint32(offset + 4, true)) << BigInt(32));
       }
       return dataView.getBigInt64(offset, true)
     }
   }
 }
 
-export function readUInt(dataView: DataView, offset: number, width: number): number | Long | bigint {
+export function readUInt(dataView: DataView, offset: number, width: number): number | bigint {
   if (width < 2) {
     if (width < 1) {
       return dataView.getUint8(offset);
@@ -42,7 +40,7 @@ export function readUInt(dataView: DataView, offset: number, width: number): num
       return dataView.getUint32(offset, true)
     } else {
       if (dataView.getBigUint64 === undefined) {
-        return new Long(dataView.getUint32(offset, true), dataView.getUint32(offset + 4, true))
+        return BigInt(dataView.getUint32(offset, true)) + (BigInt(dataView.getUint32(offset + 4, true)) << BigInt(32));
       }
       return dataView.getBigUint64(offset, true)
     }
@@ -116,4 +114,4 @@ export function keyForIndex(index: number, dataView: DataView, offset: number, p
     length++;
   }
   return fromUTF8Array(new Uint8Array(dataView.buffer, keyIndirectOffset, length));
-}
\ No newline at end of file
+}
diff --git a/ts/flexbuffers/reference.ts b/ts/flexbuffers/reference.ts
index bfcd927c..9a3f5f7f 100644
--- a/ts/flexbuffers/reference.ts
+++ b/ts/flexbuffers/reference.ts
@@ -2,7 +2,6 @@ import { fromByteWidth } from './bit-width-util'
 import { ValueType } from './value-type'
 import { isNumber, isIndirectNumber, isAVector, fixedTypedVectorElementSize, isFixedTypedVector, isTypedVector, typedVectorElementType, packedType, fixedTypedVectorElementType } from './value-type-util'
 import { indirect, keyForIndex, keyIndex, readFloat, readInt, readUInt, valueForIndexWithKey } from './reference-util'
-import { Long } from '../long';
 import { fromUTF8Array } from './flexbuffers-util';
 import { BitWidth } from './bit-width';
 
@@ -48,7 +47,7 @@ export class Reference {
     return null;
   }
 
-  intValue(): number | Long | bigint | null {
+  intValue(): number | bigint | null {
     if (this.valueType === ValueType.INT) {
       return readInt(this.dataView, this.offset, this.parentWidth);
     }
@@ -74,7 +73,7 @@ export class Reference {
     return null;
   }
 
-  numericValue(): number | Long | bigint | null { return this.floatValue() || this.intValue()}
+  numericValue(): number | bigint | null { return this.floatValue() || this.intValue()}
 
   stringValue(): string | null {
     if (this.valueType === ValueType.STRING || this.valueType === ValueType.KEY) {
diff --git a/ts/long.ts b/ts/long.ts
deleted file mode 100644
index 50a3ea87..00000000
--- a/ts/long.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-export function createLong(low: number, high: number): Long {
-    return Long.create(low, high);
-}
-  
-export class Long {
-    static readonly ZERO = new Long(0, 0)
-    low: number
-    high: number
-    constructor(low: number, high: number) {
-        this.low = low | 0;
-        this.high = high | 0;
-    }
-    static create(low: number, high: number): Long {
-        // Special-case zero to avoid GC overhead for default values
-        return low == 0 && high == 0 ? Long.ZERO : new Long(low, high);
-    }
-    toFloat64(): number {
-        return (this.low >>> 0) + this.high * 0x100000000;
-    }
-    equals(other: Long): boolean {
-        return this.low == other.low && this.high == other.high;
-    }
-}
\ No newline at end of file