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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 DynamicBytesDataType extends AbstractBlobDataType {
private static readonly _SIZE_KNOWN_AT_COMPILE_TIME: boolean = false;
private static readonly _DEFAULT_VALUE = '0x';
public static matchType(type: string): boolean {
return type === SolidityTypes.Bytes;
}
private static _sanityCheckValue(value: string | Buffer): void {
if (typeof value !== 'string') {
return;
}
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.`);
}
}
public constructor(dataItem: DataItem, dataTypeFactory: DataTypeFactory) {
super(dataItem, dataTypeFactory, DynamicBytesDataType._SIZE_KNOWN_AT_COMPILE_TIME);
if (!DynamicBytesDataType.matchType(dataItem.type)) {
throw new Error(`Tried to instantiate Dynamic Bytes with bad input: ${dataItem}`);
}
}
// Disable prefer-function-over-method for inherited abstract methods.
/* tslint:disable prefer-function-over-method */
public encodeValue(value: string | Buffer): Buffer {
// Encoded value is of the form: <length><value>, with each field padded to be word-aligned.
// 1/3 Construct the length
const valueBuf = ethUtil.toBuffer(value);
const wordsToStoreValuePadded = Math.ceil(valueBuf.byteLength / constants.EVM_WORD_WIDTH_IN_BYTES);
const bytesToStoreValuePadded = wordsToStoreValuePadded * constants.EVM_WORD_WIDTH_IN_BYTES;
const lengthBuf = ethUtil.toBuffer(valueBuf.byteLength);
const lengthBufPadded = ethUtil.setLengthLeft(lengthBuf, constants.EVM_WORD_WIDTH_IN_BYTES);
// 2/3 Construct the value
DynamicBytesDataType._sanityCheckValue(value);
const valueBufPadded = ethUtil.setLengthRight(valueBuf, bytesToStoreValuePadded);
// 3/3 Combine length and value
const encodedValue = Buffer.concat([lengthBufPadded, valueBufPadded]);
return encodedValue;
}
public decodeValue(calldata: RawCalldata): string {
// Encoded value is of the form: <length><value>, with each field padded to be word-aligned.
// 1/2 Decode length
const lengthBuf = calldata.popWord();
const lengthHex = ethUtil.bufferToHex(lengthBuf);
const length = parseInt(lengthHex, constants.HEX_BASE);
// 2/2 Decode value
const wordsToStoreValuePadded = Math.ceil(length / constants.EVM_WORD_WIDTH_IN_BYTES);
const valueBufPadded = calldata.popWords(wordsToStoreValuePadded);
const valueBuf = valueBufPadded.slice(0, length);
const value = ethUtil.bufferToHex(valueBuf);
DynamicBytesDataType._sanityCheckValue(value);
return value;
}
public getDefaultValue(): string {
return DynamicBytesDataType._DEFAULT_VALUE;
}
public getSignatureType(): string {
return SolidityTypes.Bytes;
}
/* tslint:enable prefer-function-over-method */
}
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