first commit

xterminal/source/history/index.ts

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+import { isArray } from "../helpers";
+import type { IHistory } from "./interface";
+
+/**
+ * History stack
+ */
+export default class XHistory implements IHistory {
+    private store;
+    private ptr;
+
+    constructor(initialState: string[] = []) {
+        this.store = isArray(initialState) ? initialState : [];
+        this.ptr = -1;
+    }
+
+    private get size(): number {
+        return this.store.length;
+    }
+
+    public get list(): string[] {
+        return [].slice.call(this.store).reverse();
+    }
+
+    add(input: string): void {
+        if (input && input !== this.store[0]) {
+            this.store.unshift(input);
+        }
+        this.ptr = -1;
+    }
+
+    previous(): string {
+        this.ptr++;
+        if (this.ptr >= this.size) this.ptr = this.size - 1;
+        return this.store[this.ptr] || "";
+    }
+
+    next(): string {
+        this.ptr--;
+        if (this.ptr <= -1) this.ptr = -1;
+        return this.store[this.ptr] || "";
+    }
+
+    clear(): void {
+        this.store.splice(0);
+    }
+}