nehan/dist/pseudo-class-selector.js

Html layout engine for paged-media written in Typescript

import { Utils, Selector, } from "./public-api";
export class PseudoClassSelector extends Selector {
    constructor(source) {
        super();
        this.src = source;
        this.specificity.b = 1;
    }
    toString() {
        return ":" + this.src;
    }
    testEven(element) {
        return (element.index + 1) % 2 === 0;
    }
    testOdd(element) {
        return this.testEven(element) === false;
    }
    getNthExpr(src) {
        return src.replace(/\s/g, "").replace(/^nth-child\((.+)\)/, "$1");
    }
    testNthFuncExpr(index, expr) {
        let match_a = expr.match(/\d+(?=n)/);
        if (!match_a) {
            console.error("invalid nth-child expr:%s", expr);
            return false;
        }
        let a = Utils.atoi(match_a[0]);
        let match_b = expr.replace(/\d+n/g, "").replace(/[+-]/g, "");
        let b = match_b ? Utils.atoi(match_b[0]) : 0;
        if (a === 0) {
            return index === b;
        }
        if (index < b) {
            return false;
        }
        return (index - b) % a === 0;
    }
    testNthExpr(index) {
        let expr = this.getNthExpr(this.src);
        if (/^\d+$/.test(expr)) {
            let nth = Utils.atoi(expr);
            return index + 1 === nth;
        }
        return this.testNthFuncExpr(index, expr);
    }
    testNthChild(element) {
        return this.testNthExpr(element.indexOfElement);
    }
    testMatch(element) {
        throw new Error("pseudo-class 'match' is not implemented yet");
    }
    test(element) {
        if (this.src === "first-child") {
            return element.isFirstElementChild();
        }
        if (this.src === "last-child") {
            return element.isLastElementChild();
        }
        if (this.src === "odd") {
            return this.testOdd(element);
        }
        if (this.src === "even") {
            return this.testEven(element);
        }
        if (this.src.indexOf("nth-child(") >= 0) {
            return this.testNthChild(element);
        }
        if (this.src.indexOf("match(") >= 0) {
            return this.testMatch(element);
        }
        return false;
    }
}
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