Add support for default value in Module Interface

demo/basic/generated/kotlin/IHtmlApi.kt

@@ -33,6 +33,7 @@ interface IHtmlApiBridge {
     fun getName(callback: Callback<IHtmlApiGetNameReturnType>)
     fun getAge(gender: IHtmlApiGetAgeGender, callback: Callback<IHtmlApiGetAgeReturnType>)
     fun testDictionaryWithAnyKey(dict: Map<String, String>)
+    fun testDefaultValue(bool: Boolean? = null, bool2: Boolean?, bool3: Boolean = true, num: Float = 1, string: String = "hello")
 }
 
 open class IHtmlApiBridge(editor: WebEditor, gson: Gson) : JsBridge(editor, gson, "htmlApi"), IHtmlApiBridge {
@@ -86,6 +87,16 @@ open class IHtmlApiBridge(editor: WebEditor, gson: Gson) : JsBridge(editor, gson
             "dict" to dict
         ))
     }
+
+    override fun testDefaultValue(bool: Boolean? = null, bool2: Boolean?, bool3: Boolean = true, num: Float = 1, string: String = "hello") {
+        executeJs("testDefaultValue", mapOf(
+            "bool" to bool
+            "bool2" to bool2
+            "bool3" to bool3
+            "num" to num
+            "string" to string
+        ))
+    }
 }
 
 data class JSBaseSize(

demo/basic/generated/swift/IHtmlApi.swift

@@ -85,6 +85,24 @@ public class IHtmlApi {
     )
     jsExecutor.execute(with: "htmlApi", feature: "testDictionaryWithAnyKey", args: args, completion: completion)
   }
+
+  public func testDefaultValue(bool: Bool? = nil, bool2: Bool?, bool3: Bool = true, num: Double = 1, string: String = "hello", completion: BridgeJSExecutor.Completion? = nil) {
+    struct Args: Encodable {
+      let bool: Bool?
+      let bool2: Bool?
+      let bool3: Bool
+      let num: Double
+      let string: String
+    }
+    let args = Args(
+      bool: bool,
+      bool2: bool2,
+      bool3: bool3,
+      num: num,
+      string: string
+    )
+    jsExecutor.execute(with: "htmlApi", feature: "testDefaultValue", args: args, completion: completion)
+  }
 }
 
 public struct BaseSize: Codable {

demo/basic/interfaces.ts

@@ -76,6 +76,26 @@ export interface IHtmlApi {
   getName(): 'A2' | 'B2';
   getAge({ gender }: { gender: 'Male' | 'Female' }): 21 | 22;
   testDictionaryWithAnyKey({ dict }: { dict: DictionaryWithAnyKey }): void;
+
+  testDefaultValue(options: {
+    /**
+     * @default null
+     */
+    bool?: boolean;
+    bool2?: boolean;
+    /**
+     * @default true
+     */
+    bool3: boolean;
+    /**
+     * @default 1
+     */
+    num: number;
+    /**
+     * @default "hello"
+     */
+    string: string;
+  }): void;
 }
 
 /**

documentation/interface-guide.md

@@ -216,6 +216,7 @@ ts-gyb parses tags in [JSDoc](https://jsdoc.app) documentation.
 - `@shouldExport`: Specify whether an `interface` should be exported. Set it to `true` to export.
 - `@overrideModuleName`: Change the name of the interface for ts-gyb. This is helpful for dropping the `I` prefix in TypeScript interface name.
 - `@overrideTypeName`: Similar to `@overrideModuleName`, this is used to override the name of custom types used in method parameters or return values.
+- `@default`: default value for Module Interface's function parameter, 
 
 ```typescript
 /**
@@ -225,6 +226,18 @@ ts-gyb parses tags in [JSDoc](https://jsdoc.app) documentation.
 interface InterfaceWithTags {
   // The name of the module would be `ProperNamedInterface` in generated code
   ...
+
+  foo(bar: {
+    /**
+     * @default null
+     */
+    bool?: boolean;
+    bool2?: boolean;
+    /**
+     * @default 1
+     */
+    num: number;
+  }): void;
 }
 ```
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ts-gyb",
-  "version": "0.10.1",
+  "version": "0.11.0",
   "description": "Generate Native API based on TS interface",
   "repository": {
     "type": "git",

src/parser/ValueParser.ts

@@ -145,6 +145,7 @@ export class ValueParser {
     const documentation = ts.displayPartsToString(symbol?.getDocumentationComment(this.checker));
 
     const staticValue = this.parseLiteralNode(node.type);
+
     if (staticValue !== null) {
       return { name, type: staticValue.type, staticValue: staticValue.value, documentation };
     }
@@ -155,11 +156,32 @@ export class ValueParser {
 
     const valueType = this.valueTypeFromNode(node);
 
-    return {
+    const jsDocTags = symbol?.getJsDocTags(this.checker);
+    let defaultValue: string | undefined;
+    jsDocTags?.forEach((tag) => {
+      if (tag.name === 'default') {
+        if (tag.text?.length !== 1 || tag.text[0].kind !== 'text' || tag.text[0].text.length === 0) {
+          throw new ValueParserError(
+            `Invalid default value for ${name}`,
+            'Default value must be a single value, like `@default 0` or `@default "hello"`'
+          );
+        }
+        defaultValue = tag.text[0].text;
+      }
+    });
+
+    const field: Field = {
       name,
       type: valueType,
-      documentation,
+      documentation
     };
+
+    if (defaultValue != null) {
+      // to fix test fail
+      field.defaultValue = defaultValue;
+    }
+
+    return field;
   }
 
   private parseTypeLiteralNode(typeNode: ts.TypeNode): TupleType | DictionaryType | null {

src/renderer/renderer.ts

@@ -8,5 +8,7 @@ export function renderCode<View>(templatePath: string, view: View): string {
   return Mustache.render(template, view, (partialName) => {
     const partialPath = path.join(directory, `${partialName}.mustache`);
     return fs.readFileSync(partialPath).toString();
+  }, {
+    escape: (value: string) => value,
   });
 }

src/renderer/value-transformer/KotlinValueTransformer.ts

@@ -133,4 +133,8 @@ export class KotlinValueTransformer implements ValueTransformer {
   convertTypeNameFromCustomMap(name: string): string {
     return this.typeNameMap[name] ?? name;
   }
+
+  null(): string {
+    return 'null';
+  }
 }

src/renderer/value-transformer/SwiftValueTransformer.ts

@@ -144,4 +144,8 @@ export class SwiftValueTransformer implements ValueTransformer {
   convertTypeNameFromCustomMap(name: string): string {
     return this.typeNameMap[name] ?? name;
   }
+
+  null(): string {
+    return 'nil';
+  }
 }

src/renderer/value-transformer/ValueTransformer.ts

@@ -6,4 +6,5 @@ export interface ValueTransformer {
   convertValue(value: Value, type: ValueType): string;
   convertEnumKey(text: string): string;
   convertTypeNameFromCustomMap(name: string): string;
+  null(): string;
 }

src/renderer/views/MethodView.ts

@@ -10,13 +10,23 @@ export class MethodView {
   }
 
   get parametersDeclaration(): string {
-    return this.parameters.map((parameter) => `${parameter.name}: ${parameter.type}`).join(', ');
+    return this.parameters.map((parameter) => {
+      let { defaultValue } = parameter;
+      if (defaultValue == null) {
+        return `${parameter.name}: ${parameter.type}`;
+      }
+      if (defaultValue === 'null') {
+        defaultValue = this.valueTransformer.null();
+      }
+      return `${parameter.name}: ${parameter.type} = ${defaultValue}`;
+    }).join(', ');
   }
 
-  get parameters(): { name: string; type: string; last: boolean }[] {
+  get parameters(): { name: string; type: string; defaultValue?: string; last: boolean }[] {
     return this.method.parameters.map((parameter, index) => ({
       name: parameter.name,
       type: this.valueTransformer.convertValueType(parameter.type),
+      defaultValue: parameter.defaultValue,
       last: index === this.method.parameters.length - 1,
     }));
   }

src/types.ts

@@ -20,6 +20,7 @@ export interface Field {
   type: ValueType;
   staticValue?: Value;
   documentation: string;
+  defaultValue?: string;
 }
 
 export type ValueType = NonEmptyType | OptionalType;