Creating normalizers.Prepend (To be used instead of Metaspace). (#1194)

* Creating `normalizers.Prepend` (To be used instead of `Metaspace`).

* Linting + stub.

* Fixing pickling/unpickling by setting a default.

* Black.

bindings/node/lib/bindings/normalizers.d.ts

@@ -78,6 +78,12 @@ export function lowercaseNormalizer(): Normalizer;
  */
 export function stripNormalizer(left?: boolean, right?: boolean): Normalizer;
 
+/**
+ *  Returns a new Prepend Normalizer
+ * @param [prepend] The string to prepend
+ */
+export function prependNormalizer(prepend: string): Normalizer;
+
 /**
  *  Returns a new StripAccents Normalizer
  */

bindings/node/lib/bindings/normalizers.js

@@ -9,6 +9,7 @@ module.exports = {
   sequenceNormalizer: native.normalizers_Sequence,
   lowercaseNormalizer: native.normalizers_Lowercase,
   stripNormalizer: native.normalizers_Strip,
+  prependNormalizer: native.normalizers_Prepend,
   stripAccentsNormalizer: native.normalizers_StripAccents,
   nmtNormalizer: native.normalizers_Nmt,
   precompiledNormalizer: native.normalizers_Precompiled,

bindings/node/lib/bindings/normalizers.test.ts

@@ -1,4 +1,8 @@
-import { stripAccentsNormalizer, stripNormalizer } from "./normalizers";
+import {
+  prependNormalizer,
+  stripAccentsNormalizer,
+  stripNormalizer,
+} from "./normalizers";
 
 describe("stripNormalizer", () => {
   it("instantiates with no parameters", () => {
@@ -24,6 +28,12 @@ describe("stripNormalizer", () => {
     expect(normalizer.constructor.name).toEqual("Normalizer");
   });
 
+  it("prepend instantiates with one parameter", () => {
+    const normalizer = prependNormalizer("_");
+    expect(normalizer.constructor.name).toEqual("Normalizer");
+    expect(normalizer.normalizeString("Hello")).toEqual("_Hello");
+  });
+
   it("can normalize strings", () => {
     const normalizer = stripNormalizer();
     expect(normalizer.normalizeString("     Hello there   ")).toEqual("Hello there");

bindings/node/native/src/normalizers.rs

@@ -175,6 +175,18 @@ fn strip(mut cx: FunctionContext) -> JsResult<JsNormalizer> {
 
     Ok(normalizer)
 }
+
+/// prepend(prepend: string)
+fn prepend(mut cx: FunctionContext) -> JsResult<JsNormalizer> {
+    let prepend: String = cx.extract::<String>(0)?;
+
+    let mut normalizer = JsNormalizer::new::<_, JsNormalizer, _>(&mut cx, vec![])?;
+    let guard = cx.lock();
+    normalizer.borrow_mut(&guard).normalizer =
+        Some(tk::normalizers::prepend::Prepend::new(prepend).into());
+
+    Ok(normalizer)
+}
 /// strip_accents()
 fn strip_accents(mut cx: FunctionContext) -> JsResult<JsNormalizer> {
     let mut normalizer = JsNormalizer::new::<_, JsNormalizer, _>(&mut cx, vec![])?;
@@ -267,6 +279,7 @@ pub fn register(m: &mut ModuleContext, prefix: &str) -> NeonResult<()> {
     m.export_function(&format!("{}_Sequence", prefix), sequence)?;
     m.export_function(&format!("{}_Lowercase", prefix), lowercase)?;
     m.export_function(&format!("{}_Strip", prefix), strip)?;
+    m.export_function(&format!("{}_Prepend", prefix), prepend)?;
     m.export_function(&format!("{}_StripAccents", prefix), strip_accents)?;
     m.export_function(&format!("{}_Nmt", prefix), nmt)?;
     m.export_function(&format!("{}_Precompiled", prefix), precompiled)?;