feat: 🎸 implement control value transformer metadata decorator

projects/ngze/control-value-transformer/src/lib/metadata/control-value-transformer-metadata.interface.ts

@@ -0,0 +1,9 @@
+/**
+ * Interface that represents metadata related to control value transformer.
+ */
+export interface ControlValueTransformerMetadata {
+  /**
+   * Unique name for the control value transformer.
+   */
+  name: string;
+}

projects/ngze/control-value-transformer/src/lib/metadata/control-value-transformer-metadata.utils.ts

@@ -0,0 +1,45 @@
+import { Class } from 'utility-types';
+
+import { Transformer } from '../shared';
+
+import { ControlValueTransformerMetadata } from './control-value-transformer-metadata.interface';
+
+/**
+ * Unique symbol used as a key to define and read metadata related to control value transformers.
+ */
+const CONTROL_VALUE_TRANSFORMER_METADATA = Symbol('CONTROL_VALUE_TRANSFORMER_METADATA');
+
+/**
+ * Asserts the given transformer class is decorated with {@link Transformer}.
+ * @param transformer - Instance of control value transformer that should be decorated.
+ */
+const assertTransformerIsDecorated = (transformer: Transformer) => {
+  const hasMetadata = Reflect.hasMetadata(CONTROL_VALUE_TRANSFORMER_METADATA, transformer.constructor);
+
+  if (!hasMetadata) {
+    throw new TypeError(`"${transformer.constructor}" is not decorated with ControlValueTransformer.`);
+  }
+};
+
+/**
+ * Returns metadata associate with the given control value transformer.
+ * @param transformer - Instance of control value transformer.
+ * @returns Control value transformer metadata.
+ */
+export const getControlValueTransformerMetadata = (transformer: Transformer): ControlValueTransformerMetadata => {
+  assertTransformerIsDecorated(transformer);
+
+  return Reflect.getMetadata(CONTROL_VALUE_TRANSFORMER_METADATA, transformer.constructor);
+};
+
+/**
+ * Defines metadata on the given control value transformer class.
+ * @param transformerClass - Class that implements {@link Transformer}.
+ * @param metadata - Control value transformer metadata.
+ */
+export const definedControlValueTransformerMetadata = (
+  transformerClass: Class<Transformer>,
+  metadata: ControlValueTransformerMetadata
+) => {
+  return Reflect.defineMetadata(CONTROL_VALUE_TRANSFORMER_METADATA, metadata, transformerClass);
+};

projects/ngze/control-value-transformer/src/lib/metadata/control-value-transformer.decorator.ts

@@ -0,0 +1,17 @@
+import { Class } from 'utility-types';
+
+import { Transformer } from '../shared';
+
+import { ControlValueTransformerMetadata } from './control-value-transformer-metadata.interface';
+import { definedControlValueTransformerMetadata } from './control-value-transformer-metadata.utils';
+
+/**
+ * Decorator used to define required metadata on control value transformers.
+ * @param metadata - Control value transformer metadata.
+ */
+export const ControlValueTransformer = (metadata: ControlValueTransformerMetadata) => <T extends Transformer>(
+  transformerClass: Class<T>
+): Class<T> => {
+  definedControlValueTransformerMetadata(transformerClass, metadata);
+  return transformerClass;
+};

projects/ngze/control-value-transformer/src/lib/metadata/index.ts

@@ -0,0 +1,6 @@
+export { ControlValueTransformer } from './control-value-transformer.decorator';
+export { ControlValueTransformerMetadata } from './control-value-transformer-metadata.interface';
+export {
+  definedControlValueTransformerMetadata,
+  getControlValueTransformerMetadata,
+} from './control-value-transformer-metadata.utils';

projects/ngze/control-value-transformer/src/lib/shared/index.ts

@@ -0,0 +1 @@
+export { Transformer } from './transformer.interface';

projects/ngze/control-value-transformer/src/lib/shared/transformer.interface.ts

@@ -0,0 +1,16 @@
+/**
+ * Interface that represents value transformer.
+ * `S` - Source value type.
+ * `T` - Target value type.
+ */
+export interface Transformer<S = unknown, T = unknown> {
+  /**
+   * Transforms the given source value (`S`) to the target value type (`T`).
+   */
+  toTarget: (sourceValue: S) => T;
+
+  /**
+   * Transforms the given target value (`T`) to the source value type (`S`).
+   */
+  toSource: (targetValue: T, currentSourceValue: S) => S;
+}

projects/ngze/control-value-transformer/src/public-api.ts

@@ -1,3 +1,12 @@
 /*
  * Public API Surface of Control Value Transformer
  */
+
+import 'reflect-metadata';
+
+export {
+  ControlValueTransformer,
+  ControlValueTransformerMetadata,
+  getControlValueTransformerMetadata,
+} from './lib/metadata';
+export { Transformer } from './lib/shared';