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node_modules/lit-html/node/development/directives/async-append.js

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+import { directive, PartType } from '../directive.js';
+import { AsyncReplaceDirective } from './async-replace.js';
+import { clearPart, insertPart, setChildPartValue } from '../directive-helpers.js';
+
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+class AsyncAppendDirective extends AsyncReplaceDirective {
+    // Override AsyncReplace to narrow the allowed part type to ChildPart only
+    constructor(partInfo) {
+        super(partInfo);
+        if (partInfo.type !== PartType.CHILD) {
+            throw new Error('asyncAppend can only be used in child expressions');
+        }
+    }
+    // Override AsyncReplace to save the part since we need to append into it
+    update(part, params) {
+        this.__childPart = part;
+        return super.update(part, params);
+    }
+    // Override AsyncReplace to append rather than replace
+    commitValue(value, index) {
+        // When we get the first value, clear the part. This lets the
+        // previous value display until we can replace it.
+        if (index === 0) {
+            clearPart(this.__childPart);
+        }
+        // Create and insert a new part and set its value to the next value
+        const newPart = insertPart(this.__childPart);
+        setChildPartValue(newPart, value);
+    }
+}
+/**
+ * A directive that renders the items of an async iterable[1], appending new
+ * values after previous values, similar to the built-in support for iterables.
+ * This directive is usable only in child expressions.
+ *
+ * Async iterables are objects with a [Symbol.asyncIterator] method, which
+ * returns an iterator who's `next()` method returns a Promise. When a new
+ * value is available, the Promise resolves and the value is appended to the
+ * Part controlled by the directive. If another value other than this
+ * directive has been set on the Part, the iterable will no longer be listened
+ * to and new values won't be written to the Part.
+ *
+ * [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of
+ *
+ * @param value An async iterable
+ * @param mapper An optional function that maps from (value, index) to another
+ *     value. Useful for generating templates for each item in the iterable.
+ */
+const asyncAppend = directive(AsyncAppendDirective);
+
+export { asyncAppend };
+//# sourceMappingURL=async-append.js.map