1 files changed, 78 insertions, 0 deletions
diff --git a/packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts b/packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts
new file mode 100644
index 000000000..2e371c505
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts
@@ -0,0 +1,78 @@
+import { DataItem, SolidityTypes } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { DataTypeFactory } from '../abstract_data_types/interfaces';
+import { AbstractBlobDataType } from '../abstract_data_types/types/blob';
+import { RawCalldata } from '../calldata/raw_calldata';
+import { constants } from '../utils/constants';
+
+export class StaticBytesDataType extends AbstractBlobDataType {
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
+    private static readonly _MATCHER = RegExp(
+        '^(byte|bytes(1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31|32))$',
+    );
+    private static readonly _DEFAULT_WIDTH = 1;
+    private readonly _width: number;
+
+    public static matchType(type: string): boolean {
+        return StaticBytesDataType._MATCHER.test(type);
+    }
+
+    private static _decodeWidthFromType(type: string): number {
+        const matches = StaticBytesDataType._MATCHER.exec(type);
+        const width =
+            !_.isNull(matches) && matches.length === 3 && !_.isUndefined(matches[2])
+                ? parseInt(matches[2], constants.DEC_BASE)
+                : StaticBytesDataType._DEFAULT_WIDTH;
+        return width;
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, StaticBytesDataType._SIZE_KNOWN_AT_COMPILE_TIME);
+        if (!StaticBytesDataType.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate Static Bytes with bad input: ${dataItem}`);
+        }
+        this._width = StaticBytesDataType._decodeWidthFromType(dataItem.type);
+    }
+
+    public getSignature(): string {
+        // Note that `byte` reduces to `bytes1`
+        return `${SolidityTypes.Bytes}${this._width}`;
+    }
+
+    public encodeValue(value: string | Buffer): Buffer {
+        // 1/2 Convert value into a buffer and do bounds checking
+        this._sanityCheckValue(value);
+        const valueBuf = ethUtil.toBuffer(value);
+        // 2/2 Store value as hex
+        const valuePadded = ethUtil.setLengthRight(valueBuf, constants.EVM_WORD_WIDTH_IN_BYTES);
+        return valuePadded;
+    }
+
+    public decodeValue(calldata: RawCalldata): string {
+        const valueBufPadded = calldata.popWord();
+        const valueBuf = valueBufPadded.slice(0, this._width);
+        const value = ethUtil.bufferToHex(valueBuf);
+        this._sanityCheckValue(value);
+        return value;
+    }
+
+    private _sanityCheckValue(value: string | Buffer): void {
+        if (typeof value === 'string') {
+            if (!_.startsWith(value, '0x')) {
+                throw new Error(`Tried to encode non-hex value. Value must inlcude '0x' prefix.`);
+            } else if (value.length % 2 !== 0) {
+                throw new Error(`Tried to assign ${value}, which is contains a half-byte. Use full bytes only.`);
+            }
+        }
+        const valueBuf = ethUtil.toBuffer(value);
+        if (valueBuf.byteLength > this._width) {
+            throw new Error(
+                `Tried to assign ${value} (${
+                    valueBuf.byteLength
+                } bytes), which exceeds max bytes that can be stored in a ${this.getSignature()}`,
+            );
+        }
+    }
+}