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{"version":3,"file":"class-map.js","sources":["../../src/directives/class-map.ts"],"sourcesContent":["/**\n * @license\n * Copyright 2018 Google LLC\n * SPDX-License-Identifier: BSD-3-Clause\n */\n\nimport {AttributePart, noChange} from '../lit-html.js';\nimport {\n directive,\n Directive,\n DirectiveParameters,\n PartInfo,\n PartType,\n} from '../directive.js';\n\n/**\n * A key-value set of class names to truthy values.\n */\nexport interface ClassInfo {\n readonly [name: string]: string | boolean | number;\n}\n\nclass ClassMapDirective extends Directive {\n /**\n * Stores the ClassInfo object applied to a given AttributePart.\n * Used to unset existing values when a new ClassInfo object is applied.\n */\n private _previousClasses?: Set<string>;\n private _staticClasses?: Set<string>;\n\n constructor(partInfo: PartInfo) {\n super(partInfo);\n if (\n partInfo.type !== PartType.ATTRIBUTE ||\n partInfo.name !== 'class' ||\n (partInfo.strings?.length as number) > 2\n ) {\n throw new Error(\n '`classMap()` can only be used in the `class` attribute ' +\n 'and must be the only part in the attribute.'\n );\n }\n }\n\n render(classInfo: ClassInfo) {\n // Add spaces to ensure separation from static classes\n return (\n ' ' +\n Object.keys(classInfo)\n .filter((key) => classInfo[key])\n .join(' ') +\n ' '\n );\n }\n\n override update(part: AttributePart, [classInfo]: DirectiveParameters<this>) {\n // Remember dynamic classes on the first render\n if (this._previousClasses === undefined) {\n this._previousClasses = new Set();\n if (part.strings !== undefined) {\n this._staticClasses = new Set(\n part.strings\n .join(' ')\n .split(/\\s/)\n .filter((s) => s !== '')\n );\n }\n for (const name in classInfo) {\n if (classInfo[name] && !this._staticClasses?.has(name)) {\n this._previousClasses.add(name);\n }\n }\n return this.render(classInfo);\n }\n\n const classList = part.element.classList;\n\n // Remove old classes that no longer apply\n // We use forEach() instead of for-of so that we don't require down-level\n // iteration.\n this._previousClasses.forEach((name) => {\n if (!(name in classInfo)) {\n classList.remove(name);\n this._previousClasses!.delete(name);\n }\n });\n\n // Add or remove classes based on their classMap value\n for (const name in classInfo) {\n // We explicitly want a loose truthy check of `value` because it seems\n // more convenient that '' and 0 are skipped.\n const value = !!classInfo[name];\n if (\n value !== this._previousClasses.has(name) &&\n !this._staticClasses?.has(name)\n ) {\n if (value) {\n classList.add(name);\n this._previousClasses.add(name);\n } else {\n classList.remove(name);\n this._previousClasses.delete(name);\n }\n }\n }\n return noChange;\n }\n}\n\n/**\n * A directive that applies dynamic CSS classes.\n *\n * This must be used in the `class` attribute and must be the only part used in\n * the attribute. It takes each property in the `classInfo` argument and adds\n * the property name to the element's `classList` if the property value is\n * truthy; if the property value is falsey, the property name is removed from\n * the element's `class`.\n *\n * For example `{foo: bar}` applies the class `foo` if the value of `bar` is\n * truthy.\n *\n * @param classInfo\n */\nexport const classMap = directive(ClassMapDirective);\n\n/**\n * The type of the class that powers this directive. Necessary for naming the\n * directive's return type.\n */\nexport type {ClassMapDirective};\n"],"names":["classMap","directive","Directive","constructor","partInfo","super","type","PartType","ATTRIBUTE","name","_a","strings","length","Error","render","classInfo","Object","keys","filter","key","join","update","part","undefined","this","_p
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