jintr/dist/nodes/UnaryExpression.js

A tiny JavaScript interpreter written in TypeScript.

import BaseJSNode from './BaseJSNode.js';
export default class UnaryExpression extends BaseJSNode {
    static isValidOperator(operator) {
        return operator in UnaryExpression.operatorMap;
    }
    run() {
        const { operator, argument } = this.node;
        if (!UnaryExpression.isValidOperator(operator)) {
            console.warn('Unhandled unary operator:', operator);
            return undefined;
        }
        return UnaryExpression.operatorMap[operator](this.visitor, argument);
    }
}
UnaryExpression.operatorMap = {
    // Arithmetic operators
    '-': (visitor, argument) => -visitor.visitNode(argument),
    '+': (visitor, argument) => +visitor.visitNode(argument),
    // Logical/Bitwise operators
    '!': (visitor, argument) => !visitor.visitNode(argument),
    '~': (visitor, argument) => ~visitor.visitNode(argument),
    // Type/Value operators
    'void': (visitor, argument) => {
        visitor.visitNode(argument);
        return undefined;
    },
    'typeof': (visitor, argument) => {
        const arg = visitor.visitNode(argument);
        if (argument.type === 'Identifier' && arg === 'undefined')
            return 'undefined';
        return typeof visitor.visitNode(argument);
    },
    // Property/Variable deletion
    'delete': (visitor, argument) => {
        if (argument.type === 'MemberExpression') {
            const obj = visitor.visitNode(argument.object);
            const prop = argument.computed
                ? visitor.visitNode(argument.property)
                : visitor.getName(argument.property);
            return delete obj[prop];
        }
        if (argument.type === 'Identifier' && visitor.scope.has(argument.name)) {
            return visitor.scope.delete(argument.name);
        }
        return true;
    }
};