From 9a51af46ee4a35b3d1ce2fcdc6f561aa68307cf0 Mon Sep 17 00:00:00 2001
From: Greg Hysen <greg.hysen@gmail.com>
Date: Sun, 25 Nov 2018 18:24:46 -0800
Subject: Payload -> Blob, Dependent -> Pointer, Member -> Set

---
 .../src/abi_encoder/calldata/blocks/pointer.ts     | 59 ++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 packages/utils/src/abi_encoder/calldata/blocks/pointer.ts

(limited to 'packages/utils/src/abi_encoder/calldata/blocks/pointer.ts')

diff --git a/packages/utils/src/abi_encoder/calldata/blocks/pointer.ts b/packages/utils/src/abi_encoder/calldata/blocks/pointer.ts
new file mode 100644
index 000000000..1c49a8c6c
--- /dev/null
+++ b/packages/utils/src/abi_encoder/calldata/blocks/pointer.ts
@@ -0,0 +1,59 @@
+import * as ethUtil from 'ethereumjs-util';
+
+import * as Constants from '../../utils/constants';
+
+import { CalldataBlock } from '../calldata_block';
+
+export class Pointer extends CalldataBlock {
+    public static readonly RAW_DATA_START = new Buffer('<');
+    public static readonly RAW_DATA_END = new Buffer('>');
+    private static readonly _DEPENDENT_PAYLOAD_SIZE_IN_BYTES = 32;
+    private static readonly _EMPTY_HEADER_SIZE = 0;
+    private readonly _parent: CalldataBlock;
+    private readonly _dependency: CalldataBlock;
+    private _aliasFor: CalldataBlock | undefined;
+
+    constructor(name: string, signature: string, parentName: string, dependency: CalldataBlock, parent: CalldataBlock) {
+        const headerSizeInBytes = Pointer._EMPTY_HEADER_SIZE;
+        const bodySizeInBytes = Pointer._DEPENDENT_PAYLOAD_SIZE_IN_BYTES;
+        super(name, signature, parentName, headerSizeInBytes, bodySizeInBytes);
+        this._parent = parent;
+        this._dependency = dependency;
+        this._aliasFor = undefined;
+    }
+
+    public toBuffer(): Buffer {
+        const destinationOffset =
+            this._aliasFor !== undefined ? this._aliasFor.getOffsetInBytes() : this._dependency.getOffsetInBytes();
+        const parentOffset = this._parent.getOffsetInBytes();
+        const parentHeaderSize = this._parent.getHeaderSizeInBytes();
+        const pointer: number = destinationOffset - (parentOffset + parentHeaderSize);
+        const pointerHex = `0x${pointer.toString(Constants.HEX_BASE)}`;
+        const pointerBuf = ethUtil.toBuffer(pointerHex);
+        const pointerBufPadded = ethUtil.setLengthLeft(pointerBuf, Constants.EVM_WORD_WIDTH_IN_BYTES);
+        return pointerBufPadded;
+    }
+
+    public getDependency(): CalldataBlock {
+        return this._dependency;
+    }
+
+    public setAlias(block: CalldataBlock): void {
+        this._aliasFor = block;
+        this._setName(`${this.getName()} (alias for ${block.getName()})`);
+    }
+
+    public getAlias(): CalldataBlock | undefined {
+        return this._aliasFor;
+    }
+
+    public getRawData(): Buffer {
+        const dependencyRawData = this._dependency.getRawData();
+        const rawDataComponents: Buffer[] = [];
+        rawDataComponents.push(Pointer.RAW_DATA_START);
+        rawDataComponents.push(dependencyRawData);
+        rawDataComponents.push(Pointer.RAW_DATA_END);
+        const rawData = Buffer.concat(rawDataComponents);
+        return rawData;
+    }
+}
-- 
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