Added 'stack' function to api

mapparatus · May 19, 2019 · 12832e4 · 12832e4
1 parent efef382
commit 12832e4
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diff --git a/README.md b/README.md
@@ -42,6 +42,7 @@ General methods
  - `errors` - list of current errors
  - `current` - the current immutable object
  - `history` - array of immutable objects
+ - `stack(idx)` - get a item from the history stack, supports negative index lookups to start from the end of history
  - `canUndo()` - is there anything to undo in the history stack
  - `undo()` - move backward in the history stack
  - `canRedo()` - is there anything to redo in the history stack

diff --git a/lib/index.js b/lib/index.js
@@ -343,6 +343,14 @@ class IcepickStyle extends EventEmitter {
 
 		return this;
 	}
+
+	stack(idx) {
+		if (idx > -1) {
+			return this.history[idx];
+		}
+
+		return this.history[this.history.length - 1 + idx];
+	}
 }
 
 module.exports = IcepickStyle;
diff --git a/test/ops.js b/test/ops.js
@@ -210,6 +210,27 @@ describe('ops', () => {
 		);
 	});
 
+	it('stack(idx)', () => {
+		const style = new IcepickStyle({
+			layers: [],
+			sources: {},
+			zoom: 10
+		});
+
+		style.modifyRoot('zoom', 11);
+		style.modifyRoot('zoom', 12);
+		style.modifyRoot('zoom', 13);
+
+		assert.strictEqual(style.stack(-1).style.zoom, 12);
+		assert.strictEqual(style.stack(-2).style.zoom, 11);
+		assert.strictEqual(style.stack(-3).style.zoom, 10);
+
+		assert.strictEqual(style.stack(0).style.zoom, 10);
+		assert.strictEqual(style.stack(1).style.zoom, 11);
+		assert.strictEqual(style.stack(2).style.zoom, 12);
+		assert.strictEqual(style.stack(3).style.zoom, 13);
+	});
+
 	it('replace()', () => {
 		const style = new IcepickStyle({
 			version: 8,