[FEATURE] Introduce ReaderFilter

lib/AbstractReader.js

@@ -70,6 +70,16 @@ class AbstractReader {
 		});
 	}
 
+	filter({resourceTagCollection, matchMode, filters}) {
+		const ReaderFilter = require("./ReaderFilter");
+		return new ReaderFilter({
+			reader: this,
+			resourceTagCollection,
+			matchMode,
+			filters
+		});
+	}
+
 	/**
 	 * Locates resources by one or more glob patterns.
 	 *

lib/ReaderFilter.js

@@ -0,0 +1,104 @@
+const AbstractReader = require("./AbstractReader");
+
+/**
+ * Resource Locator ReaderCollection
+ *
+ * @public
+ * @memberof module:@ui5/fs
+ * @augments module:@ui5/fs.AbstractReader
+ */
+class ReaderFilter extends AbstractReader {
+	/**
+	 * The constructor.
+	 *
+	 * @param {object} parameters Parameters
+	 * @param {module:@ui5/fs.AbstractReader} parameters.reader A resource reader
+	 * @param {module:@ui5/fs.ResourceTagCollection} parameters.resourceTagCollection
+	 * 			Resource tag collection to apply filters onto
+	 * @param {object[]} parameters.filters Filters
+	 * @param {string} parameters.matchMode Whether to match "any", "all" or "none"
+	 */
+	constructor({reader, resourceTagCollection, filters, matchMode}) {
+		super();
+		if (!reader) {
+			throw new Error(`Missing parameter "reader"`);
+		}
+		if (!resourceTagCollection) {
+			throw new Error(`Missing parameter "resourceTagCollection"`);
+		}
+		if (!filters || !filters.length) {
+			throw new Error(`Missing parameter "filters"`);
+		}
+		if (!matchMode) {
+			throw new Error(`Missing parameter "matchMode"`);
+		}
+		this._reader = reader;
+		this._resourceTagCollection = resourceTagCollection;
+		this._filters = filters;
+
+		this._matchMode = matchMode;
+	}
+
+	/**
+	 * Locates resources by glob.
+	 *
+	 * @private
+	 * @param {string|string[]} pattern glob pattern as string or an array of
+	 *         glob patterns for virtual directory structure
+	 * @param {object} options glob options
+	 * @param {module:@ui5/fs.tracing.Trace} trace Trace instance
+	 * @returns {Promise<module:@ui5/fs.Resource[]>} Promise resolving to list of resources
+	 */
+	async _byGlob(pattern, options, trace) {
+		const result = await this._reader._byGlob(pattern, options, trace);
+		return result.filter(this._filterResource.bind(this));
+	}
+
+	/**
+	 * Locates resources by path.
+	 *
+	 * @private
+	 * @param {string} virPath Virtual path
+	 * @param {object} options Options
+	 * @param {module:@ui5/fs.tracing.Trace} trace Trace instance
+	 * @returns {Promise<module:@ui5/fs.Resource>} Promise resolving to a single resource
+	 */
+	async _byPath(virPath, options, trace) {
+		const result = await this._reader._byPath(virPath, options, trace);
+		if (result) {
+			if (!this._filterResource(result)) {
+				return null;
+			}
+		}
+		return result;
+	}
+
+	_filterResource(resource) {
+		let filterFunction;
+		let testEquality = true;
+		switch (this._matchMode) {
+		case "any":
+			filterFunction = "some";
+			break;
+		case "all":
+			filterFunction = "every";
+			break;
+		case "none":
+			filterFunction = "every";
+			testEquality = false;
+			break;
+		default:
+			throw Error(`Unknown match mode ${this._matchMode}`);
+		}
+		return this._filters[filterFunction](({tag, value: filterValue}) => {
+			const tagValue = this._resourceTagCollection.getTag(resource, tag);
+			if (testEquality) {
+				return tagValue === filterValue;
+			} else {
+				return tagValue !== filterValue;
+			}
+		});
+	}
+}
+
+module.exports = ReaderFilter;