0xweb/dequanto/src/evm/opcodes/iszero.ts

Contract package manager and other web3 tools

import { EvmBytecode } from '../EvmBytecode';
import Opcode from '../interfaces/IOpcode';
import { LT } from './lt';
import { GT } from './gt';
import stringify from '../utils/stringify';
import { $is } from '@dequanto/utils/$is';

export class ISZERO {
    readonly name: string;
    readonly type?: string;
    readonly wrapped: boolean;
    readonly item: any;

    constructor(item: any) {
        this.name = 'ISZERO';
        this.wrapped = true;
        this.item = item;
    }

    toString() {
        return stringify(this.item) + ' == 0';
    }
}

export default (opcode: Opcode, state: EvmBytecode): void => {
    const item = state.stack.pop();
    if ($is.BigInt(item)) {
        state.stack.push(item === 0n ? 1n : 0n);
    } else if (item.name === 'LT') {
        if (item.equal) {
            state.stack.push(new GT(item.left, item.right));
        } else {
            state.stack.push(new GT(item.left, item.right, true));
        }
    } else if (item.name === 'GT') {
        if (item.equal) {
            state.stack.push(new LT(item.left, item.right));
        } else {
            state.stack.push(new LT(item.left, item.right, true));
        }
    } else if (item instanceof ISZERO) {
        state.stack.push(item.item);
    } else {
        state.stack.push(new ISZERO(item));
    }
    /* == -> != */
    /* != -> == */
};