added async search capability

diff --git a/src/util/AsyncSearch.js b/src/util/AsyncSearch.js
new file mode 100644 (file)
index 0000000..1751719
--- /dev/null
+++ b/src/util/AsyncSearch.js
@@ -0,0 +1,124 @@
+import EventEmitter from 'events';
+
+class AsyncSearch extends EventEmitter {
+  constructor() {
+    super();
+
+    this._reset();
+
+    this.RESULT_SENT = 'RESULT_SENT';
+  }
+
+  _reset() {
+    this.dataList = null;
+    this.term = null;
+    this.searchKeys = null;
+    this.isContain = false;
+    this.isCaseSensitive = false;
+    this.ignoreWhitespace = true;
+    this.limit = null;
+    this.findingList = [];
+
+    this.searchUptoIndex = 0;
+    this.sessionStartTimestamp = 0;
+  }
+
+  _softReset() {
+    this.term = null;
+    this.findingList = [];
+    this.searchUptoIndex = 0;
+    this.sessionStartTimestamp = 0;
+  }
+
+  /**
+   * Setup the search.
+   * opts.keys are required when dataList items are object.
+   *
+   * @param {[string | object]} dataList - A list to search in
+   * @param {object} opts - Options
+   * @param {string | [string]} [opts.keys=null]
+   * @param {boolean} [opts.isContain=false] - Add finding to result if it contain search term
+   * @param {boolean} [opts.isCaseSensitive=false]
+   * @param {boolean} [opts.ignoreWhitespace=true]
+   * @param {number} [opts.limit=null] - Stop search after limit
+   */
+  setup(dataList, opts) {
+    this._reset();
+    this.dataList = dataList;
+    this.searchKeys = opts?.keys || null;
+    this.isContain = opts?.isContain || false;
+    this.isCaseSensitive = opts?.isCaseSensitive || false;
+    this.ignoreWhitespace = opts?.ignoreWhitespace || true;
+    this.limit = opts?.limit || null;
+  }
+
+  search(term) {
+    this._softReset();
+
+    this.term = (this.isCaseSensitive) ? term : term.toLocaleLowerCase();
+    if (this.ignoreWhitespace) this.term = this.term.replace(' ', '');
+
+    this._find(this.sessionStartTimestamp, 0);
+  }
+
+  _find(sessionTimestamp, lastFindingCount) {
+    if (sessionTimestamp !== this.sessionStartTimestamp) return;
+    this.sessionStartTimestamp = window.performance.now();
+
+    for (
+      let searchIndex = this.searchUptoIndex;
+      searchIndex < this.dataList.length;
+      searchIndex += 1
+    ) {
+      if (this._match(this.dataList[searchIndex])) {
+        this.findingList.push(this.dataList[searchIndex]);
+        if (typeof this.limit === 'number' && this.findingList.length >= this.limit) break;
+      }
+
+      const calcFinishTime = window.performance.now();
+      if (calcFinishTime - this.sessionStartTimestamp > 8) {
+        const thisFindingCount = this.findingList.length;
+        const thisSessionTimestamp = this.sessionStartTimestamp;
+        if (lastFindingCount !== thisFindingCount) this._sendFindings();
+
+        this.searchUptoIndex = searchIndex + 1;
+        queueMicrotask(() => this._find(thisSessionTimestamp, thisFindingCount));
+        return;
+      }
+    }
+
+    if (lastFindingCount !== this.findingList.length
+      || lastFindingCount === 0) this._sendFindings();
+    this._softReset();
+  }
+
+  _match(item) {
+    if (typeof item === 'string') {
+      return this._compare(item);
+    }
+    if (typeof item === 'object') {
+      if (Array.isArray(this.searchKeys)) {
+        return !!this.searchKeys.find((key) => this._compare(item[key]));
+      }
+      if (typeof this.searchKeys === 'string') {
+        return this._compare(item[this.searchKeys]);
+      }
+    }
+    return false;
+  }
+
+  _compare(item) {
+    if (typeof item !== 'string') return false;
+    let myItem = (this.isCaseSensitive) ? item : item.toLocaleLowerCase();
+    if (this.ignoreWhitespace) myItem = myItem.replace(' ', '');
+
+    if (this.isContain) return myItem.indexOf(this.term) !== -1;
+    return myItem.startsWith(this.term);
+  }
+
+  _sendFindings() {
+    this.emit(this.RESULT_SENT, this.findingList);
+  }
+}
+
+export default AsyncSearch;