lasso/src/condition.js

Lasso.js is a build tool and runtime library for building and bundling all of the resources needed by a web application

exports.ifCondition = function(condition) {
    // This is a hack because we moved from "flags" to "extensions"
    // We create a function that introduces two scoped variables: flags, extensions
    const conditionFunc = eval('(function(flags, extensions) { return ' + condition + ';})');

    return function(flags) {
        return conditionFunc(flags, flags);
    };
};

exports.ifFlag = function(flag) {
    return function(flags) {
        return flags.contains(flag);
    };
};

exports.ifNotFlag = function(flag) {
    return function(flags) {
        return !flags.contains(flag);
    };
};

exports.fromObject = function(o) {
    let condition;

    if ((condition = o.if)) {
        return exports.ifCondition(condition);
    } else if ((condition = o['if-flag'] || o['if-extension'])) {
        return exports.ifFlag(condition);
    } else if ((condition = o['if-not-flag'] || o['if-not-extension'])) {
        return exports.ifNotFlag(condition);
    }

    return null;
};