main repo

node_modules/motion-dom/dist/es/value/transform-value.mjs

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+import { collectMotionValues, motionValue } from './index.mjs';
+import { subscribeValue } from './subscribe-value.mjs';
+
+/**
+ * Create a `MotionValue` that transforms the output of other `MotionValue`s by
+ * passing their latest values through a transform function.
+ *
+ * Whenever a `MotionValue` referred to in the provided function is updated,
+ * it will be re-evaluated.
+ *
+ * ```jsx
+ * const x = motionValue(0)
+ * const y = transformValue(() => x.get() * 2) // double x
+ * ```
+ *
+ * @param transformer - A transform function. This function must be pure with no side-effects or conditional statements.
+ * @returns `MotionValue`
+ *
+ * @public
+ */
+function transformValue(transform) {
+    const collectedValues = [];
+    /**
+     * Open session of collectMotionValues. Any MotionValue that calls get()
+     * inside transform will be saved into this array.
+     */
+    collectMotionValues.current = collectedValues;
+    const initialValue = transform();
+    collectMotionValues.current = undefined;
+    const value = motionValue(initialValue);
+    subscribeValue(collectedValues, value, transform);
+    return value;
+}
+
+export { transformValue };