Refactored transpiling function bodies to its own function (#219)

Perryvw · web-flow · commit ad6fd3782a26 · 2018-10-07T21:10:18.000+02:00
diff --git a/src/Transpiler.ts b/src/Transpiler.ts
@@ -1497,29 +1497,9 @@ export abstract class LuaTranspiler {
         if (!node.body) { return ""; }
 
         let result = "";
-        const identifier = node.name;
-        const methodName = this.transpileIdentifier(identifier);
-        const parameters = node.parameters;
-        const body = node.body;
+        const methodName = this.transpileIdentifier(node.name);
 
-        // Build parameter string
-        const paramNames: string[] = [];
-
-        let spreadIdentifier = "";
-
-        // Only push parameter name to paramName array if it isn't a spread parameter
-        for (const param of parameters) {
-            const paramName = this.transpileIdentifier(param.name as ts.Identifier);
-
-            // This parameter is a spread parameter (...param)
-            if (!param.dotDotDotToken) {
-                paramNames.push(paramName);
-            } else {
-                spreadIdentifier = paramName;
-                // Push the spread operator into the paramNames array
-                paramNames.push("...");
-            }
-        }
+        const [paramNames, spreadIdentifier] = this.transpileParameters(node.parameters);
 
         let prefix = this.accessPrefix(node);
 
@@ -1531,13 +1511,7 @@ export abstract class LuaTranspiler {
         result += this.indent + prefix + `function ${methodName}(${paramNames.join(",")})\n`;
 
         this.pushIndent();
-
-        // Push spread operator here
-        if (spreadIdentifier !== "") {
-            result += this.indent + `local ${spreadIdentifier} = { ... }\n`;
-        }
-
-        result += this.transpileBlock(body);
+        result += this.transpileFunctionBody(node.parameters, node.body, spreadIdentifier);
         this.popIndent();
 
         // Close function block
@@ -1548,21 +1522,10 @@ export abstract class LuaTranspiler {
         return result;
     }
 
-    public transpileMethodDeclaration(node: ts.MethodDeclaration, callPath: string): string {
-        // Don't transpile methods without body (overload declarations)
-        if (!node.body) { return ""; }
-
-        let result = "";
-        const identifier = node.name as ts.Identifier;
-        let methodName = this.transpileIdentifier(identifier);
-        if (methodName === "toString") {
-            methodName = "__tostring";
-        }
-        const parameters = node.parameters;
-        const body = node.body;
-
+    // Transpile a list of parameters, returns a list of transpiled parameters and an optional spread identifier
+    public transpileParameters(parameters: ts.NodeArray<ts.ParameterDeclaration>): [string[], string] {
         // Build parameter string
-        const paramNames: string[] = ["self"];
+        const paramNames: string[] = [];
 
         let spreadIdentifier = "";
 
@@ -1579,21 +1542,49 @@ export abstract class LuaTranspiler {
                 paramNames.push("...");
             }
         }
-        // Parameters with default values
-        const defaultValueParams = node.parameters.filter(declaration => declaration.initializer !== undefined);
 
-        // Build function header
-        result += this.indent + `function ${callPath}${methodName}(${paramNames.join(",")})\n`;
+        return [paramNames, spreadIdentifier];
+    }
 
-        this.pushIndent();
+    public transpileFunctionBody(parameters: ts.NodeArray<ts.ParameterDeclaration>,
+                                 body: ts.Block,
+                                 spreadIdentifier: string = ""
+    ): string {
+        let result = "";
+
+        // Add default parameters
+        const defaultValueParams = parameters.filter(declaration => declaration.initializer !== undefined);
+        result += this.transpileParameterDefaultValues(defaultValueParams);
 
         // Push spread operator here
         if (spreadIdentifier !== "") {
             result += this.indent + `local ${spreadIdentifier} = { ... }\n`;
         }
 
-        result += this.transpileParameterDefaultValues(defaultValueParams);
         result += this.transpileBlock(body);
+
+        return result;
+    }
+
+    public transpileMethodDeclaration(node: ts.MethodDeclaration, callPath: string): string {
+        // Don't transpile methods without body (overload declarations)
+        if (!node.body) { return ""; }
+
+        let result = "";
+        let methodName = this.transpileIdentifier(node.name as ts.Identifier);
+        if (methodName === "toString") {
+            methodName = "__tostring";
+        }
+
+        const [paramNames, spreadIdentifier] = this.transpileParameters(node.parameters);
+
+        const selfParamNames = ["self"].concat(paramNames);
+
+        // Build function header
+        result += this.indent + `function ${callPath}${methodName}(${selfParamNames.join(",")})\n`;
+
+        this.pushIndent();
+        result += this.transpileFunctionBody(node.parameters, node.body, spreadIdentifier);
         this.popIndent();
 
         // Close function block
diff --git a/test/unit/functions.spec.ts b/test/unit/functions.spec.ts
@@ -97,6 +97,19 @@ export class FunctionTests {
         Expect(result).toBe(3);
     }
 
+    @Test("Function default parameter")
+    public functionDefaultParameter(): void {
+        // Transpile
+        const lua = util.transpileString(`function abc(defaultParam: string = "abc") { return defaultParam; }\n
+            return abc() + abc("def");`);
+
+        // Execute
+        const result = util.executeLua(lua);
+
+        // Assert
+        Expect(result).toBe("abcdef");
+    }
+
     @TestCase([], 7)
     @TestCase([5], 9)
     @TestCase([1, 2], 3)
