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{"version":3,"file":"async-directive.js","sources":["../src/async-directive.ts"],"sourcesContent":["/**\n * @license\n * Copyright 2017 Google LLC\n * SPDX-License-Identifier: BSD-3-Clause\n */\n\n/**\n * Overview:\n *\n * This module is designed to add support for an async `setValue` API and\n * `disconnected` callback to directives with the least impact on the core\n * runtime or payload when that feature is not used.\n *\n * The strategy is to introduce a `AsyncDirective` subclass of\n * `Directive` that climbs the \"parent\" tree in its constructor to note which\n * branches of lit-html's \"logical tree\" of data structures contain such\n * directives and thus need to be crawled when a subtree is being cleared (or\n * manually disconnected) in order to run the `disconnected` callback.\n *\n * The \"nodes\" of the logical tree include Parts, TemplateInstances (for when a\n * TemplateResult is committed to a value of a ChildPart), and Directives; these\n * all implement a common interface called `DisconnectableChild`. Each has a\n * `_$parent` reference which is set during construction in the core code, and a\n * `_$disconnectableChildren` field which is initially undefined.\n *\n * The sparse tree created by means of the `AsyncDirective` constructor\n * crawling up the `_$parent` tree and placing a `_$disconnectableChildren` Set\n * on each parent that includes each child that contains a\n * `AsyncDirective` directly or transitively via its children. In order to\n * notify connection state changes and disconnect (or reconnect) a tree, the\n * `_$notifyConnectionChanged` API is patched onto ChildParts as a directive\n * climbs the parent tree, which is called by the core when clearing a part if\n * it exists. When called, that method iterates over the sparse tree of\n * Set<DisconnectableChildren> built up by AsyncDirectives, and calls\n * `_$notifyDirectiveConnectionChanged` on any directives that are encountered\n * in that tree, running the required callbacks.\n *\n * A given \"logical tree\" of lit-html data-structures might look like this:\n *\n * ChildPart(N1) _$dC=[D2,T3]\n * ._directive\n * AsyncDirective(D2)\n * ._value // user value was TemplateResult\n * TemplateInstance(T3) _$dC=[A4,A6,N10,N12]\n * ._$parts[]\n * AttributePart(A4) _$dC=[D5]\n * ._directives[]\n * AsyncDirective(D5)\n * AttributePart(A6) _$dC=[D7,D8]\n * ._directives[]\n * AsyncDirective(D7)\n * Directive(D8) _$dC=[D9]\n * ._directive\n * AsyncDirective(D9)\n * ChildPart(N10) _$dC=[D11]\n * ._directive\n * AsyncDirective(D11)\n * ._value\n * string\n * ChildPart(N12) _$dC=[D13,N14,N16]\n * ._directive\n * AsyncDirective(D13)\n * ._value // user value was iterable\n * Array<ChildPart>\n * ChildPart(N14) _$dC=[D15]\n * ._value\n * string\n * ChildPart(N16) _$dC=[D17,T18]\n * ._directive\n * AsyncDirective(D17)\n * ._value // user value was TemplateResult\n * TemplateInstance(T18) _$dC=[A19,A21,N25]\n * ._$parts[]\n * AttributePart(A19) _$dC=[D20]\n * ._directives[]\n * AsyncDirective(D20)\n * AttributePart(A21) _$dC=[22,23]\n * ._directives[]\n * AsyncDirective(D22)\n * Directive(D23) _$dC=[D24]\n * ._directive\n * AsyncDirective(D24)\n * ChildPart(N25) _$dC=[D26]\n * ._directive\n * AsyncDirective(D26)\n * ._value\n * string\n *\n * Example 1: The directive in ChildPart(N12) updates and returns `nothing`. The\n * ChildPart will _clear() itself, and so we need to disconnect the \"value\" of\n * the ChildPart (but not its directive). In this case, when `_clear()
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