element-vir/dist/util/lit-template.js

Heroic. Reactive. Declarative. Type safe. Web components without compromise.

import { check } from '@augment-vir/assert';
import { collapseWhiteSpace } from '@augment-vir/common';
/**
 * Converts an HTML or SVG template into a raw string.
 *
 * @category Util
 */
export function convertTemplateToString(template) {
    if ('templateString' in template) {
        return template.templateString;
    }
    const { strings, values } = template;
    if (!strings?.length && !values?.length) {
        return '';
    }
    const valueList = [
        ...(values || []),
        '', // this last empty string is so it's easier to deal with indexes
    ];
    const stringsList = strings?.length ? strings : [''];
    const all = stringsList.map((stringValue, index) => {
        const value = extractValue(stringValue, valueList[index]);
        return `${stringValue}${value}`;
    });
    return collapseWhiteSpace(all.join(''));
}
function extractValue(previousString, value) {
    if (value == undefined) {
        /** Lit renders nothing for nullish child values and an empty attribute value. */
        return previousString.endsWith('=') ? '""' : '';
    }
    else if (check.isObject(value) &&
        ('templateString' in value ||
            value._$litType$ != undefined ||
            value._$litDirective$ != undefined)) {
        // nested templates
        return convertTemplateToString(value);
    }
    else if (Array.isArray(value)) {
        /** Each entry gets the same treatment a top level value would, as lit does. */
        return value.map((innerValue) => extractValue('', innerValue)).join('');
    }
    else if (previousString.endsWith('=')) {
        return `"${value}"`;
    }
    else {
        return String(value);
    }
}