packages/instant/src/util/big_number.ts


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import { BigNumber } from '@0x/utils';
import * as _ from 'lodash';

/**
 *  A BigNumber extension that is more flexible about decimal strings.
 *  Such as allowing:
 *  new BigNumberInput(0.) => 0
 *  new BigNumberInput(1.) => 1
 *  new BigNumberInput(1..) => still throws
 */
export class BigNumberInput extends BigNumber {
    private readonly _hasDecimalPeriod: boolean;
    constructor(bigNumberString: string) {
        const hasDecimalPeriod = _.endsWith(bigNumberString, '.');
        let internalString = bigNumberString;
        if (hasDecimalPeriod) {
            internalString = bigNumberString.slice(0, bigNumberString.length - 1);
        }
        super(internalString);
        this._hasDecimalPeriod = hasDecimalPeriod;
    }
    public toString(): string {
        const internalString = super.toString();
        if (this._hasDecimalPeriod) {
            return `${internalString}.`;
        }
        return internalString;
    }
}