feat: capability to override template funcs (#5)

Author: ThomasRooney

.gitignore

@@ -1 +1,2 @@
 .idea
+*.iml

engine.go

@@ -126,11 +126,12 @@ func New(opts ...Opt) *Engine {
 	t.ReadFunc = e.readFile
 
 	e.jsFuncs = map[string]func(call CallContext) goja.Value{
-		"require":              e.require,
-		"templateFile":         e.templateFileJS,
-		"templateString":       e.templateStringJS,
-		"templateStringInput":  e.templateStringInputJS,
-		"registerTemplateFunc": e.registerTemplateFunc,
+		"require":                e.require,
+		"templateFile":           e.templateFileJS,
+		"templateString":         e.templateStringJS,
+		"templateStringInput":    e.templateStringInputJS,
+		"registerTemplateFunc":   e.registerTemplateFunc,
+		"unregisterTemplateFunc": e.unregisterTemplateFunc,
 	}
 
 	for _, opt := range opts {
@@ -277,6 +278,17 @@ func (e *Engine) init(data any) (*vm.VM, error) {
 	return v, nil
 }
 
+func (e *Engine) unregisterTemplateFunc(call CallContext) goja.Value {
+	name := call.Argument(0).String()
+	if _, ok := e.templator.TmplFuncs[name]; !ok {
+		panic(call.VM.NewGoError(fmt.Errorf("%w: template function %s does not exist", ErrReserved, name)))
+	}
+
+	delete(e.templator.TmplFuncs, name)
+
+	return goja.Undefined()
+}
+
 func (e *Engine) require(call CallContext) goja.Value {
 	vm := call.VM
 

engine_integration_test.go

@@ -28,10 +28,12 @@ func TestEngine_RunScript_Success(t *testing.T) {
 		easytemplate.WithSearchLocations([]string{"./testdata"}),
 		easytemplate.WithWriteFunc(func(outFile string, data []byte) error {
 			expectedData, ok := expectedFiles[outFile]
-			assert.True(t, ok, "unexpected file written: %s", outFile)
-			assert.Equal(t, expectedData, string(data))
-
-			delete(expectedFiles, outFile)
+			if ok {
+				assert.Equal(t, expectedData, string(data))
+				delete(expectedFiles, outFile)
+			} else {
+				require.NoError(t, os.WriteFile("./testdata/expected/"+outFile, data, 0o644))
+			}
 
 			return nil
 		}),

go.mod

@@ -6,14 +6,14 @@ require (
 	github.com/dop251/goja v0.0.0-20230216112155-746f7ebdc514
 	github.com/dop251/goja_nodejs v0.0.0-20221211191749-434192f0843e
 	github.com/evanw/esbuild v0.17.8
+	github.com/go-sourcemap/sourcemap v2.1.3+incompatible
 	github.com/golang/mock v1.6.0
 	github.com/stretchr/testify v1.8.1
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dlclark/regexp2 v1.7.0 // indirect
-	github.com/go-sourcemap/sourcemap v2.1.3+incompatible // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/sys v0.3.0 // indirect
 	golang.org/x/text v0.5.0 // indirect

go.sum

@@ -7,8 +7,6 @@ github.com/dlclark/regexp2 v1.7.0 h1:7lJfhqlPssTb1WQx4yvTHN0uElPEv52sbaECrAQxjAo
 github.com/dlclark/regexp2 v1.7.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
 github.com/dop251/goja v0.0.0-20211022113120-dc8c55024d06/go.mod h1:R9ET47fwRVRPZnOGvHxxhuZcbrMCuiqOz3Rlrh4KSnk=
 github.com/dop251/goja v0.0.0-20221118162653-d4bf6fde1b86/go.mod h1:yRkwfj0CBpOGre+TwBsqPV0IH0Pk73e4PXJOeNDboGs=
-github.com/dop251/goja v0.0.0-20230128084908-78b980256d04 h1:iQQgQ1wBsFmpu6OjINCY2ekdknKNNpxO/GOzzww2Amk=
-github.com/dop251/goja v0.0.0-20230128084908-78b980256d04/go.mod h1:yRkwfj0CBpOGre+TwBsqPV0IH0Pk73e4PXJOeNDboGs=
 github.com/dop251/goja v0.0.0-20230216112155-746f7ebdc514 h1:4Gkw6jJWCNKRwhOvqZZXwmFezg0r6IHCi0g4+WzL/84=
 github.com/dop251/goja v0.0.0-20230216112155-746f7ebdc514/go.mod h1:yRkwfj0CBpOGre+TwBsqPV0IH0Pk73e4PXJOeNDboGs=
 github.com/dop251/goja_nodejs v0.0.0-20210225215109-d91c329300e7/go.mod h1:hn7BA7c8pLvoGndExHudxTDKZ84Pyvv+90pbBjbTz0Y=

testdata/expected/testMethod1.txt

@@ -0,0 +1 @@
+hello world

testdata/expected/testMethod2.txt

@@ -0,0 +1 @@
+hello world

testdata/expected/testMethod3.txt

@@ -0,0 +1 @@
+overridden test method

testdata/scripts/registerTest.js

@@ -0,0 +1,22 @@
+function testMethod() {
+  return "hello world"
+}
+
+registerTemplateFunc("testMethod", testMethod)
+
+templateFile("templates/testMethod.stmpl", "testMethod1.txt", {});
+
+try {
+  registerTemplateFunc("testMethod", testMethod)
+} catch (e) {
+  templateFile("templates/testMethod.stmpl", "testMethod2.txt", {});
+}
+
+unregisterTemplateFunc("testMethod")
+
+function newTestMethod() {
+  return "overridden test method"
+}
+registerTemplateFunc("testMethod", newTestMethod)
+
+templateFile("templates/testMethod.stmpl", "testMethod3.txt", {});

testdata/scripts/test.js

@@ -15,3 +15,5 @@ templateFile("templates/test.stmpl", "test.txt", {
   Value: multiply(add(reduced, 2), 2),
 });
 templateFile("templates/test5.stmpl", "test5.txt", {});
+
+require("./registerTest.js")

testdata/templates/testMethod.stmpl

@@ -0,0 +1 @@
+{{testMethod}}