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..189841989
--- /dev/null
+++ b/packages/utils/src/abi_encoder/calldata/raw_calldata.ts
@@ -0,0 +1,82 @@
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { constants } from '../utils/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;
+
+    public constructor(value: string | Buffer, hasSelector: boolean = true) {
+        // Sanity check
+        if (typeof value === 'string' && !_.startsWith(value, '0x')) {
+            throw new Error(`Expected raw calldata to start with '0x'`);
+        }
+        // Construct initial values
+        this._value = ethUtil.toBuffer(value);
+        this._selector = '0x';
+        this._scopes = new Queue<number>();
+        this._scopes.pushBack(RawCalldata._INITIAL_OFFSET);
+        this._offset = RawCalldata._INITIAL_OFFSET;
+        // If there's a selector then slice it
+        if (hasSelector) {
+            const selectorBuf = this._value.slice(constants.HEX_SELECTOR_LENGTH_IN_BYTES);
+            this._value = this._value.slice(constants.HEX_SELECTOR_LENGTH_IN_BYTES);
+            this._selector = ethUtil.bufferToHex(selectorBuf);
+        }
+    }
+
+    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.popFront();
+    }
+
+    public getOffset(): number {
+        return this._offset;
+    }
+
+    public toAbsoluteOffset(relativeOffset: number): number {
+        const scopeOffset = this._scopes.peekFront();
+        if (_.isUndefined(scopeOffset)) {
+            throw new Error(`Tried to access undefined scope.`);
+        }
+        const absoluteOffset = relativeOffset + scopeOffset;
+        return absoluteOffset;
+    }
+
+    public getSelector(): string {
+        return this._selector;
+    }
+}