lit-html/development/directive-helpers.js

/**
 * @license
 * Copyright 2020 Google LLC
 * SPDX-License-Identifier: BSD-3-Clause
 */
import { _$LH, } from './lit-html.js';
const { _ChildPart: ChildPart } = _$LH;
const ENABLE_SHADYDOM_NOPATCH = true;
const wrap = ENABLE_SHADYDOM_NOPATCH &&
    window.ShadyDOM?.inUse &&
    window.ShadyDOM?.noPatch === true
    ? window.ShadyDOM.wrap
    : (node) => node;
/**
 * Tests if a value is a primitive value.
 *
 * See https://tc39.github.io/ecma262/#sec-typeof-operator
 */
export const isPrimitive = (value) => value === null || (typeof value != 'object' && typeof value != 'function');
export const TemplateResultType = {
    HTML: 1,
    SVG: 2,
};
/**
 * Tests if a value is a TemplateResult or a CompiledTemplateResult.
 */
export const isTemplateResult = (value, type) => type === undefined
    ? // This property needs to remain unminified.
        value?.['_$litType$'] !== undefined
    : value?.['_$litType$'] === type;
/**
 * Tests if a value is a CompiledTemplateResult.
 */
export const isCompiledTemplateResult = (value) => {
    return value?.['_$litType$']?.h != null;
};
/**
 * Tests if a value is a DirectiveResult.
 */
export const isDirectiveResult = (value) => 
// This property needs to remain unminified.
value?.['_$litDirective$'] !== undefined;
/**
 * Retrieves the Directive class for a DirectiveResult
 */
export const getDirectiveClass = (value) => 
// This property needs to remain unminified.
value?.['_$litDirective$'];
/**
 * Tests whether a part has only a single-expression with no strings to
 * interpolate between.
 *
 * Only AttributePart and PropertyPart can have multiple expressions.
 * Multi-expression parts have a `strings` property and single-expression
 * parts do not.
 */
export const isSingleExpression = (part) => part.strings === undefined;
const createMarker = () => document.createComment('');
/**
 * Inserts a ChildPart into the given container ChildPart's DOM, either at the
 * end of the container ChildPart, or before the optional `refPart`.
 *
 * This does not add the part to the containerPart's committed value. That must
 * be done by callers.
 *
 * @param containerPart Part within which to add the new ChildPart
 * @param refPart Part before which to add the new ChildPart; when omitted the
 *     part added to the end of the `containerPart`
 * @param part Part to insert, or undefined to create a new part
 */
export const insertPart = (containerPart, refPart, part) => {
    const container = wrap(containerPart._$startNode).parentNode;
    const refNode = refPart === undefined ? containerPart._$endNode : refPart._$startNode;
    if (part === undefined) {
        const startNode = wrap(container).insertBefore(createMarker(), refNode);
        const endNode = wrap(container).insertBefore(createMarker(), refNode);
        part = new ChildPart(startNode, endNode, containerPart, containerPart.options);
    }
    else {
        const endNode = wrap(part._$endNode).nextSibling;
        const oldParent = part._$parent;
        const parentChanged = oldParent !== containerPart;
        if (parentChanged) {
            part._$reparentDisconnectables?.(containerPart);
            // Note that although `_$reparentDisconnectables` updates the part's
            // `_$parent` reference after unlinking from its current parent, that
            // method only exists if Disconnectables are present, so we need to
            // unconditionally set it here
            part._$parent = containerPart;
            // Since the _$isConnected getter is somewhat costly, only
            // read it once we know the subtree has directives that need
            // to be notified
            let newConnectionState;
            if (part._$notifyConnectionChanged !== undefined &&
                (newConnectionState = containerPart._$isConnected) !==
                    oldParent._$isConnected) {
                part._$notifyConnectionChanged(newConnectionState);
            }
        }
        if (endNode !== refNode || parentChanged) {
            let start = part._$startNode;
            while (start !== endNode) {
                const n = wrap(start).nextSibling;
                wrap(container).insertBefore(start, refNode);
                start = n;
            }
        }
    }
    return part;
};
/**
 * Sets the value of a Part.
 *
 * Note that this should only be used to set/update the value of user-created
 * parts (i.e. those created using `insertPart`); it should not be used
 * by directives to set the value of the directive's container part. Directives
 * should return a value from `update`/`render` to update their part state.
 *
 * For directives that require setting their part value asynchronously, they
 * should extend `AsyncDirective` and call `this.setValue()`.
 *
 * @param part Part to set
 * @param value Value to set
 * @param index For `AttributePart`s, the index to set
 * @param directiveParent Used internally; should not be set by user
 */
export const setChildPartValue = (part, value, directiveParent = part) => {
    part._$setValue(value, directiveParent);
    return part;
};
// A sentinel value that can never appear as a part value except when set by
// live(). Used to force a dirty-check to fail and cause a re-render.
const RESET_VALUE = {};
/**
 * Sets the committed value of a ChildPart directly without triggering the
 * commit stage of the part.
 *
 * This is useful in cases where a directive needs to update the part such
 * that the next update detects a value change or not. When value is omitted,
 * the next update will be guaranteed to be detected as a change.
 *
 * @param part
 * @param value
 */
export const setCommittedValue = (part, value = RESET_VALUE) => (part._$committedValue = value);
/**
 * Returns the committed value of a ChildPart.
 *
 * The committed value is used for change detection and efficient updates of
 * the part. It can differ from the value set by the template or directive in
 * cases where the template value is transformed before being committed.
 *
 * - `TemplateResult`s are committed as a `TemplateInstance`
 * - Iterables are committed as `Array<ChildPart>`
 * - All other types are committed as the template value or value returned or
 *   set by a directive.
 *
 * @param part
 */
export const getCommittedValue = (part) => part._$committedValue;
/**
 * Removes a ChildPart from the DOM, including any of its content.
 *
 * @param part The Part to remove
 */
export const removePart = (part) => {
    part._$notifyConnectionChanged?.(false, true);
    let start = part._$startNode;
    const end = wrap(part._$endNode).nextSibling;
    while (start !== end) {
        const n = wrap(start).nextSibling;
        wrap(start).remove();
        start = n;
    }
};
export const clearPart = (part) => {
    part._$clear();
};
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