1 files changed, 82 insertions, 0 deletions
diff --git a/packages/utils/src/abi_encoder/calldata/raw_calldata.ts b/packages/utils/src/abi_encoder/calldata/raw_calldata.ts
new file mode 100644
index 000000000..8b946ee4b
--- /dev/null
+++ b/packages/utils/src/abi_encoder/calldata/raw_calldata.ts
@@ -0,0 +1,82 @@
+import * as ethUtil from 'ethereumjs-util';
+
+import * as Constants from '../constants';
+import { Queue } from '../utils/queue';
+
+export class RawCalldata {
+    private static readonly _INITIAL_OFFSET = 0;
+    private readonly _value: Buffer;
+    private readonly _selector: string;
+    private readonly _scopes: Queue<number>;
+    private _offset: number; // tracks current offset into raw calldata; used for parsing
+
+    constructor(value: string | Buffer, hasSelectorPrefix: boolean = true) {
+        if (typeof value === 'string' && !value.startsWith('0x')) {
+            throw new Error(`Expected raw calldata to start with '0x'`);
+        }
+        const valueBuf = ethUtil.toBuffer(value);
+        if (hasSelectorPrefix) {
+            this._selector = ethUtil.bufferToHex(
+                valueBuf.slice(Constants.HEX_SELECTOR_BYTE_OFFSET_IN_CALLDATA, Constants.HEX_SELECTOR_LENGTH_IN_BYTES),
+            );
+            this._value = valueBuf.slice(Constants.HEX_SELECTOR_LENGTH_IN_BYTES); // disregard selector
+        } else {
+            this._selector = '0x';
+            this._value = valueBuf;
+        }
+
+        this._scopes = new Queue<number>();
+        this._scopes.push(RawCalldata._INITIAL_OFFSET);
+        this._offset = RawCalldata._INITIAL_OFFSET;
+    }
+
+    public popBytes(lengthInBytes: number): Buffer {
+        const value = this._value.slice(this._offset, this._offset + lengthInBytes);
+        this.setOffset(this._offset + lengthInBytes);
+        return value;
+    }
+
+    public popWord(): Buffer {
+        const wordInBytes = 32;
+        return this.popBytes(wordInBytes);
+    }
+
+    public popWords(length: number): Buffer {
+        const wordInBytes = 32;
+        return this.popBytes(length * wordInBytes);
+    }
+
+    public readBytes(from: number, to: number): Buffer {
+        const value = this._value.slice(from, to);
+        return value;
+    }
+
+    public setOffset(offsetInBytes: number): void {
+        this._offset = offsetInBytes;
+    }
+
+    public startScope(): void {
+        this._scopes.pushFront(this._offset);
+    }
+
+    public endScope(): void {
+        this._scopes.pop();
+    }
+
+    public getOffset(): number {
+        return this._offset;
+    }
+
+    public toAbsoluteOffset(relativeOffset: number): number {
+        const scopeOffset = this._scopes.peek();
+        if (scopeOffset === undefined) {
+            throw new Error(`Tried to access undefined scope.`);
+        }
+        const absoluteOffset = relativeOffset + scopeOffset;
+        return absoluteOffset;
+    }
+
+    public getSelector(): string {
+        return this._selector;
+    }
+}
+\ No newline at end of file