Split EVM data types and factory into separate files

13 files changed, 634 insertions, 0 deletions

diff --git a/packages/utils/src/abi_encoder/evm_data_types/address.ts b/packages/utils/src/abi_encoder/evm_data_types/address.ts
new file mode 100644
index 000000000..4bd992cab
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/address.ts
@@ -0,0 +1,51 @@
+/* tslint:disable prefer-function-over-method */
+import { DataItem } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataTypeFactory, PayloadDataType } from '../data_type';
+
+export class Address extends PayloadDataType {
+    public static ERROR_MESSAGE_ADDRESS_MUST_START_WITH_0X = "Address must start with '0x'";
+    public static ERROR_MESSAGE_ADDRESS_MUST_BE_20_BYTES = 'Address must be 20 bytes';
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
+    private static readonly _ADDRESS_SIZE_IN_BYTES = 20;
+    private static readonly _DECODED_ADDRESS_OFFSET_IN_BYTES = Constants.EVM_WORD_WIDTH_IN_BYTES -
+        Address._ADDRESS_SIZE_IN_BYTES;
+
+    public static matchType(type: string): boolean {
+        return type === 'address';
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, Address._SIZE_KNOWN_AT_COMPILE_TIME);
+        if (!Address.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate Address with bad input: ${dataItem}`);
+        }
+    }
+
+    public getSignature(): string {
+        return 'address';
+    }
+
+    public encodeValue(value: string): Buffer {
+        if (!value.startsWith('0x')) {
+            throw new Error(Address.ERROR_MESSAGE_ADDRESS_MUST_START_WITH_0X);
+        }
+        const valueAsBuffer = ethUtil.toBuffer(value);
+        if (valueAsBuffer.byteLength !== Address._ADDRESS_SIZE_IN_BYTES) {
+            throw new Error(Address.ERROR_MESSAGE_ADDRESS_MUST_BE_20_BYTES);
+        }
+        const encodedValueBuf = ethUtil.setLengthLeft(valueAsBuffer, Constants.EVM_WORD_WIDTH_IN_BYTES);
+        return encodedValueBuf;
+    }
+
+    public decodeValue(calldata: RawCalldata): string {
+        const paddedValueBuf = calldata.popWord();
+        const valueBuf = paddedValueBuf.slice(Address._DECODED_ADDRESS_OFFSET_IN_BYTES);
+        const value = ethUtil.bufferToHex(valueBuf);
+        return value;
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/array.ts b/packages/utils/src/abi_encoder/evm_data_types/array.ts
new file mode 100644
index 000000000..707af7c7e
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/array.ts
@@ -0,0 +1,55 @@
+import { DataItem } from 'ethereum-types';
+
+import * as Constants from '../constants';
+import { DataTypeFactory, MemberDataType } from '../data_type';
+
+export class Array extends MemberDataType {
+    private static readonly _matcher = RegExp('^(.+)\\[([0-9]*)\\]$');
+    private readonly _arraySignature: string;
+    private readonly _elementType: string;
+
+    public static matchType(type: string): boolean {
+        return Array._matcher.test(type);
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        // Sanity check
+        const matches = Array._matcher.exec(dataItem.type);
+        if (matches === null || matches.length !== 3) {
+            throw new Error(`Could not parse array: ${dataItem.type}`);
+        } else if (matches[1] === undefined) {
+            throw new Error(`Could not parse array type: ${dataItem.type}`);
+        } else if (matches[2] === undefined) {
+            throw new Error(`Could not parse array length: ${dataItem.type}`);
+        }
+
+        const isArray = true;
+        const arrayElementType = matches[1];
+        const arrayLength = matches[2] === '' ? undefined : parseInt(matches[2], Constants.DEC_BASE);
+        super(dataItem, dataTypeFactory, isArray, arrayLength, arrayElementType);
+        this._elementType = arrayElementType;
+        this._arraySignature = this._computeSignature();
+    }
+
+    public getSignature(): string {
+        return this._arraySignature;
+    }
+
+    private _computeSignature(): string {
+        const dataItem: DataItem = {
+            type: this._elementType,
+            name: 'N/A',
+        };
+        const components = this.getDataItem().components;
+        if (components !== undefined) {
+            dataItem.components = components;
+        }
+        const elementDataType = this.getFactory().mapDataItemToDataType(dataItem);
+        const type = elementDataType.getSignature();
+        if (this._arrayLength === undefined) {
+            return `${type}[]`;
+        } else {
+            return `${type}[${this._arrayLength}]`;
+        }
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/bool.ts b/packages/utils/src/abi_encoder/evm_data_types/bool.ts
new file mode 100644
index 000000000..aee2727c7
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/bool.ts
@@ -0,0 +1,50 @@
+/* tslint:disable prefer-function-over-method */
+import { DataItem } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { BigNumber } from '../../configured_bignumber';
+import { RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataTypeFactory, PayloadDataType } from '../data_type';
+
+export class Bool extends PayloadDataType {
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
+
+    public static matchType(type: string): boolean {
+        return type === 'bool';
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, Bool._SIZE_KNOWN_AT_COMPILE_TIME);
+        if (!Bool.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate Bool with bad input: ${dataItem}`);
+        }
+    }
+
+    public getSignature(): string {
+        return 'bool';
+    }
+
+    public encodeValue(value: boolean): Buffer {
+        const encodedValue = value ? '0x1' : '0x0';
+        const encodedValueBuf = ethUtil.setLengthLeft(
+            ethUtil.toBuffer(encodedValue),
+            Constants.EVM_WORD_WIDTH_IN_BYTES,
+        );
+        return encodedValueBuf;
+    }
+
+    public decodeValue(calldata: RawCalldata): boolean {
+        const valueBuf = calldata.popWord();
+        const valueHex = ethUtil.bufferToHex(valueBuf);
+        const valueNumber = new BigNumber(valueHex, Constants.HEX_BASE);
+        if (!(valueNumber.equals(0) || valueNumber.equals(1))) {
+            throw new Error(`Failed to decode boolean. Expected 0x0 or 0x1, got ${valueHex}`);
+        }
+        /* tslint:disable boolean-naming */
+        const value: boolean = valueNumber.equals(0) ? false : true;
+        /* tslint:enable boolean-naming */
+        return value;
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts b/packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts
new file mode 100644
index 000000000..51165881a
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/dynamic_bytes.ts
@@ -0,0 +1,58 @@
+/* tslint:disable prefer-function-over-method */
+import { DataItem } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataTypeFactory, PayloadDataType } from '../data_type';
+
+export class DynamicBytes extends PayloadDataType {
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = false;
+
+    public static matchType(type: string): boolean {
+        return type === 'bytes';
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, DynamicBytes._SIZE_KNOWN_AT_COMPILE_TIME);
+        if (!DynamicBytes.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate DynamicBytes with bad input: ${dataItem}`);
+        }
+    }
+
+    public encodeValue(value: string | Buffer): Buffer {
+        if (typeof value === 'string' && !value.startsWith('0x')) {
+            throw new Error(`Tried to encode non-hex value. Value must inlcude '0x' prefix. Got '${value}'`);
+        }
+        const valueBuf = ethUtil.toBuffer(value);
+        if (value.length % 2 !== 0) {
+            throw new Error(`Tried to assign ${value}, which is contains a half-byte. Use full bytes only.`);
+        }
+
+        const wordsForValue = Math.ceil(valueBuf.byteLength / Constants.EVM_WORD_WIDTH_IN_BYTES);
+        const paddedDynamicBytesForValue = wordsForValue * Constants.EVM_WORD_WIDTH_IN_BYTES;
+        const paddedValueBuf = ethUtil.setLengthRight(valueBuf, paddedDynamicBytesForValue);
+        const paddedLengthBuf = ethUtil.setLengthLeft(
+            ethUtil.toBuffer(valueBuf.byteLength),
+            Constants.EVM_WORD_WIDTH_IN_BYTES,
+        );
+        const encodedValueBuf = Buffer.concat([paddedLengthBuf, paddedValueBuf]);
+        return encodedValueBuf;
+    }
+
+    public decodeValue(calldata: RawCalldata): string {
+        const lengthBuf = calldata.popWord();
+        const lengthHex = ethUtil.bufferToHex(lengthBuf);
+        const length = parseInt(lengthHex, Constants.HEX_BASE);
+        const wordsForValue = Math.ceil(length / Constants.EVM_WORD_WIDTH_IN_BYTES);
+        const paddedValueBuf = calldata.popWords(wordsForValue);
+        const valueBuf = paddedValueBuf.slice(0, length);
+        const decodedValue = ethUtil.bufferToHex(valueBuf);
+        return decodedValue;
+    }
+
+    public getSignature(): string {
+        return 'bytes';
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/index.ts b/packages/utils/src/abi_encoder/evm_data_types/index.ts
new file mode 100644
index 000000000..fc0edabf1
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/index.ts
@@ -0,0 +1,11 @@
+export * from './address';
+export * from './bool';
+export * from './int';
+export * from './uint';
+export * from './static_bytes';
+export * from './dynamic_bytes';
+export * from './string';
+export * from './pointer';
+export * from './tuple';
+export * from './array';
+export * from './method';
diff --git a/packages/utils/src/abi_encoder/evm_data_types/int.ts b/packages/utils/src/abi_encoder/evm_data_types/int.ts
new file mode 100644
index 000000000..ba5b4cac9
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/int.ts
@@ -0,0 +1,33 @@
+/* tslint:disable prefer-function-over-method */
+import { DataItem } from 'ethereum-types';
+
+import { BigNumber } from '../../configured_bignumber';
+import { DataTypeFactory } from '../data_type';
+
+import { Number } from './number';
+
+export class Int extends Number {
+    private static readonly _matcher = RegExp(
+        '^int(8|16|24|32|40|48|56|64|72|88|96|104|112|120|128|136|144|152|160|168|176|184|192|200|208|216|224|232|240|248|256){0,1}$',
+    );
+
+    public static matchType(type: string): boolean {
+        return Int._matcher.test(type);
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, Int._matcher, dataTypeFactory);
+    }
+
+    public getMaxValue(): BigNumber {
+        return new BigNumber(2).toPower(this._width - 1).sub(1);
+    }
+
+    public getMinValue(): BigNumber {
+        return new BigNumber(2).toPower(this._width - 1).times(-1);
+    }
+
+    public getSignature(): string {
+        return `int${this._width}`;
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/method.ts b/packages/utils/src/abi_encoder/evm_data_types/method.ts
new file mode 100644
index 000000000..e8e717bf1
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/method.ts
@@ -0,0 +1,90 @@
+import { DataItem, MethodAbi } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { DecodingRules, EncodingRules, RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataType, DataTypeFactory, MemberDataType } from '../data_type';
+
+import { StaticBytes } from './static_bytes';
+import { Tuple } from './tuple';
+
+export class Method extends MemberDataType {
+    // TMP
+    public selector: string;
+
+    private readonly _methodSignature: string;
+    private readonly _methodSelector: string;
+    private readonly _returnDataTypes: DataType[];
+    private readonly _returnDataItem: DataItem;
+
+    public constructor(abi: MethodAbi, dataTypeFactory: DataTypeFactory) {
+        super({ type: 'method', name: abi.name, components: abi.inputs }, dataTypeFactory);
+        this._methodSignature = this._computeSignature();
+        this.selector = this._methodSelector = this._computeSelector();
+        this._returnDataTypes = [];
+        this._returnDataItem = { type: 'tuple', name: abi.name, components: abi.outputs };
+        const dummy = new StaticBytes({ type: 'byte', name: 'DUMMY' }, dataTypeFactory); // @TODO TMP
+        _.each(abi.outputs, (dataItem: DataItem) => {
+            this._returnDataTypes.push(this.getFactory().create(dataItem, dummy));
+        });
+    }
+
+    public encode(value: any, rules?: EncodingRules): string {
+        const calldata = super.encode(value, rules, this.selector);
+        return calldata;
+    }
+
+    public decode(calldata: string, rules?: DecodingRules): any[] | object {
+        if (!calldata.startsWith(this.selector)) {
+            throw new Error(
+                `Tried to decode calldata, but it was missing the function selector. Expected '${this.selector}'.`,
+            );
+        }
+        const hasSelector = true;
+        const value = super.decode(calldata, rules, hasSelector);
+        return value;
+    }
+
+    public encodeReturnValues(value: any, rules?: EncodingRules): string {
+        const returnDataType = new Tuple(this._returnDataItem, this.getFactory());
+        const returndata = returnDataType.encode(value, rules);
+        return returndata;
+    }
+
+    public decodeReturnValues(returndata: string, rules?: DecodingRules): any {
+        const returnValues: any[] = [];
+        const rules_: DecodingRules = rules ? rules : { structsAsObjects: false };
+        const rawReturnData = new RawCalldata(returndata, false);
+        _.each(this._returnDataTypes, (dataType: DataType) => {
+            returnValues.push(dataType.generateValue(rawReturnData, rules_));
+        });
+        return returnValues;
+    }
+
+    public getSignature(): string {
+        return this._methodSignature;
+    }
+
+    public getSelector(): string {
+        return this._methodSelector;
+    }
+
+    private _computeSignature(): string {
+        const memberSignature = this._computeSignatureOfMembers();
+        const methodSignature = `${this.getDataItem().name}${memberSignature}`;
+        return methodSignature;
+    }
+
+    private _computeSelector(): string {
+        const signature = this._computeSignature();
+        const selector = ethUtil.bufferToHex(
+            ethUtil.toBuffer(
+                ethUtil
+                    .sha3(signature)
+                    .slice(Constants.HEX_SELECTOR_BYTE_OFFSET_IN_CALLDATA, Constants.HEX_SELECTOR_LENGTH_IN_BYTES),
+            ),
+        );
+        return selector;
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/number.ts b/packages/utils/src/abi_encoder/evm_data_types/number.ts
new file mode 100644
index 000000000..17201362e
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/number.ts
@@ -0,0 +1,100 @@
+import { DataItem } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { BigNumber } from '../../configured_bignumber';
+import { RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataTypeFactory, PayloadDataType } from '../data_type';
+
+export abstract class Number extends PayloadDataType {
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
+    private static readonly _MAX_WIDTH: number = 256;
+    private static readonly _DEFAULT_WIDTH: number = Number._MAX_WIDTH;
+    protected _width: number;
+
+    constructor(dataItem: DataItem, matcher: RegExp, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, Number._SIZE_KNOWN_AT_COMPILE_TIME);
+        const matches = matcher.exec(dataItem.type);
+        if (matches === null) {
+            throw new Error(`Tried to instantiate Number with bad input: ${dataItem}`);
+        }
+        this._width =
+            matches !== null && matches.length === 2 && matches[1] !== undefined
+                ? parseInt(matches[1], Constants.DEC_BASE)
+                : (this._width = Number._DEFAULT_WIDTH);
+    }
+
+    public encodeValue(value_: BigNumber | string | number): Buffer {
+        const value = new BigNumber(value_, 10);
+        if (value.greaterThan(this.getMaxValue())) {
+            throw new Error(`Tried to assign value of ${value}, which exceeds max value of ${this.getMaxValue()}`);
+        } else if (value.lessThan(this.getMinValue())) {
+            throw new Error(`Tried to assign value of ${value}, which exceeds min value of ${this.getMinValue()}`);
+        }
+
+        let valueBuf: Buffer;
+        if (value.greaterThanOrEqualTo(0)) {
+            valueBuf = ethUtil.setLengthLeft(
+                ethUtil.toBuffer(`0x${value.toString(Constants.HEX_BASE)}`),
+                Constants.EVM_WORD_WIDTH_IN_BYTES,
+            );
+        } else {
+            // BigNumber can't write a negative hex value, so we use twos-complement conversion to do it ourselves.
+            // Step 1/3: Convert value to positive binary string
+            const binBase = 2;
+            const valueBin = value.times(-1).toString(binBase);
+
+            // Step 2/3: Invert binary value
+            let invertedValueBin = '1'.repeat(Constants.EVM_WORD_WIDTH_IN_BITS - valueBin.length);
+            _.each(valueBin, (bit: string) => {
+                invertedValueBin += bit === '1' ? '0' : '1';
+            });
+            const invertedValue = new BigNumber(invertedValueBin, binBase);
+
+            // Step 3/3: Add 1 to inverted value
+            // The result is the two's-complement represent of the input value.
+            const negativeValue = invertedValue.plus(1);
+
+            // Convert the negated value to a hex string
+            valueBuf = ethUtil.setLengthLeft(
+                ethUtil.toBuffer(`0x${negativeValue.toString(Constants.HEX_BASE)}`),
+                Constants.EVM_WORD_WIDTH_IN_BYTES,
+            );
+        }
+
+        return valueBuf;
+    }
+
+    public decodeValue(calldata: RawCalldata): BigNumber {
+        const paddedValueBuf = calldata.popWord();
+        const paddedValueHex = ethUtil.bufferToHex(paddedValueBuf);
+        let value = new BigNumber(paddedValueHex, 16);
+        if (this.getMinValue().lessThan(0)) {
+            // Check if we're negative
+            const valueBin = value.toString(Constants.BIN_BASE);
+            if (valueBin.length === Constants.EVM_WORD_WIDTH_IN_BITS && valueBin[0].startsWith('1')) {
+                // Negative
+                // Step 1/3: Invert binary value
+                let invertedValueBin = '';
+                _.each(valueBin, (bit: string) => {
+                    invertedValueBin += bit === '1' ? '0' : '1';
+                });
+                const invertedValue = new BigNumber(invertedValueBin, Constants.BIN_BASE);
+
+                // Step 2/3: Add 1 to inverted value
+                // The result is the two's-complement represent of the input value.
+                const positiveValue = invertedValue.plus(1);
+
+                // Step 3/3: Invert positive value
+                const negativeValue = positiveValue.times(-1);
+                value = negativeValue;
+            }
+        }
+
+        return value;
+    }
+
+    public abstract getMaxValue(): BigNumber;
+    public abstract getMinValue(): BigNumber;
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/pointer.ts b/packages/utils/src/abi_encoder/evm_data_types/pointer.ts
new file mode 100644
index 000000000..e0bd3509c
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/pointer.ts
@@ -0,0 +1,15 @@
+import { DataItem } from 'ethereum-types';
+
+import { DataType, DataTypeFactory, DependentDataType } from '../data_type';
+
+export class Pointer extends DependentDataType {
+    constructor(destDataType: DataType, parentDataType: DataType, dataTypeFactory: DataTypeFactory) {
+        const destDataItem = destDataType.getDataItem();
+        const dataItem: DataItem = { name: `ptr<${destDataItem.name}>`, type: `ptr<${destDataItem.type}>` };
+        super(dataItem, dataTypeFactory, destDataType, parentDataType);
+    }
+
+    public getSignature(): string {
+        return this._dependency.getSignature();
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts b/packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts
new file mode 100644
index 000000000..309dca234
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/static_bytes.ts
@@ -0,0 +1,68 @@
+import { DataItem } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataTypeFactory, PayloadDataType } from '../data_type';
+
+export class StaticBytes extends PayloadDataType {
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = true;
+    private static readonly _matcher = RegExp(
+        '^(byte|bytes(1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31|32))$',
+    );
+
+    private static readonly _DEFAULT_WIDTH = 1;
+    private readonly _width: number;
+
+    public static matchType(type: string): boolean {
+        return StaticBytes._matcher.test(type);
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, StaticBytes._SIZE_KNOWN_AT_COMPILE_TIME);
+        const matches = StaticBytes._matcher.exec(dataItem.type);
+        if (!StaticBytes.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate Byte with bad input: ${dataItem}`);
+        }
+        this._width =
+            matches !== null && matches.length === 3 && matches[2] !== undefined
+                ? parseInt(matches[2], Constants.DEC_BASE)
+                : StaticBytes._DEFAULT_WIDTH;
+    }
+
+    public getSignature(): string {
+        // Note that `byte` reduces to `bytes1`
+        return `bytes${this._width}`;
+    }
+
+    public encodeValue(value: string | Buffer): Buffer {
+        // Sanity check if string
+        if (typeof value === 'string' && !value.startsWith('0x')) {
+            throw new Error(`Tried to encode non-hex value. Value must inlcude '0x' prefix.`);
+        }
+        // Convert value into a buffer and do bounds checking
+        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()}`,
+            );
+        } else if (value.length % 2 !== 0) {
+            throw new Error(`Tried to assign ${value}, which is contains a half-byte. Use full bytes only.`);
+        }
+
+        // Store value as hex
+        const evmWordWidth = 32;
+        const paddedValue = ethUtil.setLengthRight(valueBuf, evmWordWidth);
+        return paddedValue;
+    }
+
+    public decodeValue(calldata: RawCalldata): string {
+        const paddedValueBuf = calldata.popWord();
+        const valueBuf = paddedValueBuf.slice(0, this._width);
+        const value = ethUtil.bufferToHex(valueBuf);
+        return value;
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/string.ts b/packages/utils/src/abi_encoder/evm_data_types/string.ts
new file mode 100644
index 000000000..96b36e735
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/string.ts
@@ -0,0 +1,47 @@
+/* tslint:disable prefer-function-over-method */
+import { DataItem } from 'ethereum-types';
+import * as ethUtil from 'ethereumjs-util';
+import * as _ from 'lodash';
+
+import { RawCalldata } from '../calldata';
+import * as Constants from '../constants';
+import { DataTypeFactory, PayloadDataType } from '../data_type';
+
+export class String extends PayloadDataType {
+    private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = false;
+
+    public static matchType(type: string): boolean {
+        return type === 'string';
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory, String._SIZE_KNOWN_AT_COMPILE_TIME);
+        if (!String.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate String with bad input: ${dataItem}`);
+        }
+    }
+
+    public encodeValue(value: string): Buffer {
+        const wordsForValue = Math.ceil(value.length / Constants.EVM_WORD_WIDTH_IN_BYTES);
+        const paddedDynamicBytesForValue = wordsForValue * Constants.EVM_WORD_WIDTH_IN_BYTES;
+        const valueBuf = ethUtil.setLengthRight(new Buffer(value), paddedDynamicBytesForValue);
+        const lengthBuf = ethUtil.setLengthLeft(ethUtil.toBuffer(value.length), Constants.EVM_WORD_WIDTH_IN_BYTES);
+        const encodedValueBuf = Buffer.concat([lengthBuf, valueBuf]);
+        return encodedValueBuf;
+    }
+
+    public decodeValue(calldata: RawCalldata): string {
+        const lengthBuf = calldata.popWord();
+        const lengthHex = ethUtil.bufferToHex(lengthBuf);
+        const length = parseInt(lengthHex, Constants.HEX_BASE);
+        const wordsForValue = Math.ceil(length / Constants.EVM_WORD_WIDTH_IN_BYTES);
+        const paddedValueBuf = calldata.popWords(wordsForValue);
+        const valueBuf = paddedValueBuf.slice(0, length);
+        const value = valueBuf.toString('ascii');
+        return value;
+    }
+
+    public getSignature(): string {
+        return 'string';
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/tuple.ts b/packages/utils/src/abi_encoder/evm_data_types/tuple.ts
new file mode 100644
index 000000000..0db29c1eb
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/tuple.ts
@@ -0,0 +1,23 @@
+import { DataItem } from 'ethereum-types';
+
+import { DataTypeFactory, MemberDataType } from '../data_type';
+
+export class Tuple extends MemberDataType {
+    private readonly _tupleSignature: string;
+
+    public static matchType(type: string): boolean {
+        return type === 'tuple';
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, dataTypeFactory);
+        if (!Tuple.matchType(dataItem.type)) {
+            throw new Error(`Tried to instantiate Tuple with bad input: ${dataItem}`);
+        }
+        this._tupleSignature = this._computeSignatureOfMembers();
+    }
+
+    public getSignature(): string {
+        return this._tupleSignature;
+    }
+}
diff --git a/packages/utils/src/abi_encoder/evm_data_types/uint.ts b/packages/utils/src/abi_encoder/evm_data_types/uint.ts
new file mode 100644
index 000000000..86b31ab4c
--- /dev/null
+++ b/packages/utils/src/abi_encoder/evm_data_types/uint.ts
@@ -0,0 +1,33 @@
+/* tslint:disable prefer-function-over-method */
+import { DataItem } from 'ethereum-types';
+
+import { BigNumber } from '../../configured_bignumber';
+import { DataTypeFactory } from '../data_type';
+
+import { Number } from './number';
+
+export class UInt extends Number {
+    private static readonly _matcher = RegExp(
+        '^uint(8|16|24|32|40|48|56|64|72|88|96|104|112|120|128|136|144|152|160|168|176|184|192|200|208|216|224|232|240|248|256){0,1}$',
+    );
+
+    public static matchType(type: string): boolean {
+        return UInt._matcher.test(type);
+    }
+
+    public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
+        super(dataItem, UInt._matcher, dataTypeFactory);
+    }
+
+    public getMaxValue(): BigNumber {
+        return new BigNumber(2).toPower(this._width).sub(1);
+    }
+
+    public getMinValue(): BigNumber {
+        return new BigNumber(0);
+    }
+
+    public getSignature(): string {
+        return `uint${this._width}`;
+    }
+}