first commit

internal/codegen/config.go

@@ -0,0 +1,41 @@
+package codegen
+
+import (
+	"fmt"
+)
+
+// Config is the configuration for the code generation.
+type Config struct {
+	Debug         bool
+	Class         string
+	ValidateOnly  bool
+	methodFilters []string
+}
+
+// NewConfig returns a new Config with default values.
+func NewConfig() *Config {
+	return &Config{}
+}
+
+// AddMethodFilter adds a method to the list of methodFilters to generate.
+func (cfg *Config) AddMethodFilter(methodFilter string) {
+	cfg.methodFilters = append(cfg.methodFilters, methodFilter)
+}
+
+// MethodFilter creates and returns a new method filter for the current config.
+func (cfg *Config) MethodFilter() *MethodFilter {
+	return NewMethodFilter(cfg.methodFilters)
+}
+
+// Validate validates the Config and returns an error if there's any problem.
+func (cfg *Config) Validate() error {
+	if cfg == nil {
+		return fmt.Errorf("config is nil")
+	}
+
+	if cfg.Class == "" {
+		return fmt.Errorf("generated classes may not be empty")
+	}
+
+	return nil
+}

internal/codegen/methodfilter.go

@@ -0,0 +1,28 @@
+package codegen
+
+// MethodFilter is a filter for methods to be generated.
+type MethodFilter struct {
+	filters []string
+}
+
+// NewMethodFilter creates a new MethodFilter.
+func NewMethodFilter(filters []string) *MethodFilter {
+	return &MethodFilter{filters}
+}
+
+// Filter returns true if the method matches one of the filters.
+// In case no filter matches the method, the method is allowed.
+func (md *MethodFilter) Filter(method string) bool {
+	for _, filter := range md.filters {
+		result := true
+		if filter[0] == '!' {
+			filter = filter[1:]
+			result = false
+		}
+
+		if filter == "*" || filter == method {
+			return result
+		}
+	}
+	return true // everything matches by default
+}

internal/codegen/templates.go

@@ -0,0 +1,311 @@
+package codegen
+
+import (
+	"embed"
+	"strings"
+	"text/template"
+
+	"github.com/saltosystems/winrt-go/internal/winmd"
+)
+
+type genDataFile struct {
+	Filename string
+	Data     genData
+}
+
+type genData struct {
+	Package    string
+	Imports    []string
+	Classes    []*genClass
+	Enums      []*genEnum
+	Interfaces []*genInterface
+	Structs    []*genStruct
+	Delegates  []*genDelegate
+}
+
+func (g *genData) ComputeImports(typeDef *winmd.TypeDef) {
+	// gather all imports
+	imports := make([]*genImport, 0)
+	if g.Classes != nil {
+		for _, c := range g.Classes {
+			imports = append(imports, c.GetRequiredImports()...)
+		}
+	}
+	if g.Interfaces != nil {
+		for _, i := range g.Interfaces {
+			imports = append(imports, i.GetRequiredImports()...)
+		}
+	}
+
+	for _, i := range imports {
+		if typeDef.TypeNamespace != i.Namespace {
+			g.Imports = append(g.Imports, i.ToGoImport())
+		}
+	}
+}
+
+type genInterface struct {
+	Name      string
+	GUID      string
+	Signature string
+	Funcs     []*genFunc
+}
+
+func (g *genInterface) GetRequiredImports() []*genImport {
+	imports := make([]*genImport, 0)
+	for _, f := range g.Funcs {
+		imports = append(imports, f.RequiresImports...)
+	}
+	return imports
+}
+
+type genClass struct {
+	Name                string
+	Signature           string
+	RequiresImports     []*genImport
+	FullyQualifiedName  string
+	ImplInterfaces      []*genInterface
+	ExclusiveInterfaces []*genInterface
+	HasEmptyConstructor bool
+	IsAbstract          bool
+}
+
+func (g *genClass) GetRequiredImports() []*genImport {
+	imports := make([]*genImport, 0)
+	if g.RequiresImports != nil {
+		imports = append(imports, g.RequiresImports...)
+	}
+	if g.ExclusiveInterfaces != nil {
+		for _, i := range g.ExclusiveInterfaces {
+			imports = append(imports, i.GetRequiredImports()...)
+		}
+	}
+
+	return imports
+}
+
+type genDelegate struct {
+	Name        string
+	GUID        string
+	Signature   string
+	InParams    []*genParam
+	ReturnParam *genParam // this may be nil
+}
+
+type genEnum struct {
+	Name      string
+	Type      string
+	Signature string
+	Values    []*genEnumValue
+}
+type genEnumValue struct {
+	Name  string
+	Value string
+}
+
+type genFunc struct {
+	Name            string
+	RequiresImports []*genImport
+	Implement       bool
+	FuncOwner       string
+	InParams        []*genParam
+	ReturnParams    []*genParam // this may be empty
+
+	// ExclusiveTo is the name of the class that this function is exclusive to.
+	// The funcion will be called statically using the RoGetActivationFactory function.
+	ExclusiveTo        string
+	RequiresActivation bool
+
+	InheritedFrom winmd.QualifiedID
+}
+
+type genImport struct {
+	Namespace, Name string
+}
+
+func (i genImport) ToGoImport() string {
+	if !strings.Contains(i.Namespace, ".") && i.Namespace != "Windows" {
+		// This is probably a built-in package
+		return i.Namespace
+	}
+
+	folder := typeToFolder(i.Namespace, i.Name)
+	return "github.com/saltosystems/winrt-go/" + folder
+}
+
+// some of the variables are not public to avoid using them
+// by mistake in the code.
+type genDefaultValue struct {
+	value       string
+	isPrimitive bool
+}
+
+// some of the variables are not public to avoid using them
+// by mistake in the code.
+type genParamType struct {
+	namespace string
+	name      string
+
+	IsPointer          bool
+	IsGeneric          bool
+	IsArray            bool
+	IsPrimitive        bool
+	IsEnum             bool
+	UnderlyingEnumType string
+
+	defaultValue genDefaultValue
+}
+
+// some of the variables are not public to avoid using them
+// by mistake in the code.
+type genParam struct {
+	callerPackage string
+
+	varName string
+
+	Type *genParamType
+
+	IsOut bool
+}
+
+func (g *genParam) GoVarName() string {
+	return typeNameToGoName(g.varName, true) // assume all are public
+}
+
+func (g *genParam) GoTypeName() string {
+	if g.Type.IsPrimitive {
+		return g.Type.name
+	}
+
+	name := typeNameToGoName(g.Type.name, true) // assume all are public
+
+	pkg := typePackage(g.Type.namespace, g.Type.name)
+	if g.callerPackage != pkg {
+		name = pkg + "." + name
+	}
+
+	return name
+}
+
+func (g *genParam) GoDefaultValue() string {
+	if g.Type.defaultValue.isPrimitive {
+		return g.Type.defaultValue.value
+	}
+
+	pkg := typePackage(g.Type.namespace, g.Type.name)
+	if g.callerPackage != pkg {
+		return pkg + "." + g.Type.defaultValue.value
+	}
+
+	return g.Type.defaultValue.value
+}
+
+type genStruct struct {
+	Name      string
+	Signature string
+	Fields    []*genParam
+}
+
+//go:embed templates/*
+var templatesFS embed.FS
+
+func getTemplates() (*template.Template, error) {
+	return template.New("").
+		Funcs(funcs()).
+		ParseFS(templatesFS, "templates/*")
+}
+
+func funcs() template.FuncMap {
+	return template.FuncMap{
+		"funcName": funcName,
+		"concat": func(a, b []*genParam) []*genParam {
+			return append(a, b...)
+		},
+		"toLower": func(s string) string {
+			return strings.ToLower(s[:1]) + s[1:]
+		},
+	}
+}
+
+// funcName is used to generate the name of a function.
+func funcName(m genFunc) string {
+	// There are some special prefixes applied to methods that we need to replace
+	replacer := strings.NewReplacer(
+		"get_", "Get",
+		"put_", "Set",
+		"add_", "Add",
+		"remove_", "Remove",
+	)
+	name := replacer.Replace(m.Name)
+
+	// Add a prefix to static methods to include the owner class of the method.
+	// This is necessary to avoid conflicts with method names within the same package.
+	// Static methods are those that are exclusive to a class and require activation.
+	prefix := ""
+	if m.ExclusiveTo != "" && m.RequiresActivation {
+		nsAndName := strings.Split(m.ExclusiveTo, ".")
+		prefix = typeNameToGoName(nsAndName[len(nsAndName)-1], true)
+	}
+
+	return prefix + name
+}
+
+func typeToFolder(ns, name string) string {
+	fullName := ns
+	return strings.ToLower(strings.Replace(fullName, ".", "/", -1))
+}
+
+func typePackage(ns, name string) string {
+	sns := strings.Split(ns, ".")
+	return strings.ToLower(sns[len(sns)-1])
+}
+
+func enumName(typeName string, enumName string) string {
+	return typeName + enumName
+}
+
+func typeDefGoName(typeName string, public bool) string {
+	name := typeName
+
+	if isParameterizedName(typeName) {
+		name = strings.Split(name, "`")[0]
+	}
+
+	if !public {
+		name = strings.ToLower(name[0:1]) + name[1:]
+	}
+	return name
+}
+
+func isParameterizedName(typeName string) bool {
+	// parameterized types contain a '`' followed by the amount of generic parameters in their name.
+	return strings.Contains(typeName, "`")
+}
+
+func typeFilename(typeName string) string {
+	// public boolean is not relevant, we are going to lower everything
+	goname := typeDefGoName(typeName, true)
+	return strings.ToLower(goname)
+}
+
+// removes Go reserved words from param names
+func cleanReservedWords(name string) string {
+	switch name {
+	case "type":
+		return "mType"
+	}
+	return name
+}
+
+func typeNameToGoName(typeName string, public bool) string {
+	name := typeName
+
+	if isParameterizedName(typeName) {
+		name = strings.Split(name, "`")[0]
+	}
+
+	if !public {
+		name = strings.ToLower(name[0:1]) + name[1:]
+	}
+	return name
+}

internal/codegen/templates/class.tmpl

@@ -0,0 +1,60 @@
+{{if not .IsAbstract}}
+const Signature{{.Name}} string = "{{.Signature}}"
+
+type {{.Name}} struct {
+    ole.IUnknown
+}
+
+{{if .HasEmptyConstructor}}
+func New{{.Name}}() (*{{.Name}}, error) {
+    inspectable, err := ole.RoActivateInstance("{{.FullyQualifiedName}}")
+    if err != nil {
+        return nil, err
+    }
+    return (*{{.Name}})(unsafe.Pointer(inspectable)), nil
+}
+{{end}}
+{{end}}
+
+{{$owner := .Name}}
+{{range .ImplInterfaces}}
+    {{range .Funcs}}
+        {{if not .Implement}}{{continue}}{{end}}
+        func (impl *{{$owner}}) {{funcName .}} (
+            {{- range .InParams -}}
+                {{/*do not include out parameters, they are used as return values*/ -}}
+                {{ if .IsOut }}{{continue}}{{ end -}}
+                {{.GoVarName}} {{template "variabletype.tmpl" . }},
+            {{- end -}}
+        )
+
+        {{- /* return params */ -}}
+
+        ( {{range .InParams -}}
+            {{ if not .IsOut }}{{continue}}{{ end -}}
+            {{template "variabletype.tmpl" . }},{{end -}}
+        {{range .ReturnParams}}{{template "variabletype.tmpl" . }},{{end}} error )
+
+        {{- /* method body */ -}}
+
+        {
+            itf := impl.MustQueryInterface(ole.NewGUID({{if .InheritedFrom.Namespace}}{{.InheritedFrom.Namespace}}.{{end}}GUID{{.InheritedFrom.Name}}))
+            defer itf.Release()
+            v := (*{{if .InheritedFrom.Namespace}}{{.InheritedFrom.Namespace}}.{{end}}{{.InheritedFrom.Name}})(unsafe.Pointer(itf))
+            return v.{{funcName . -}}
+            (
+                {{- range .InParams -}}
+                    {{if .IsOut -}}
+                        {{continue -}}
+                    {{end -}}
+                    {{.GoVarName -}}
+                    ,
+                {{- end -}}
+            )
+        }
+    {{end}}
+{{end}}
+
+{{range .ExclusiveInterfaces}}
+    {{ template "interface.tmpl" .}}
+{{end}}

internal/codegen/templates/delegate.tmpl

@@ -0,0 +1,204 @@
+
+const GUID{{.Name}} string = "{{.GUID}}"
+const Signature{{.Name}} string = "{{.Signature}}"
+
+type {{.Name}} struct {
+	ole.IUnknown
+	sync.Mutex
+	refs uintptr
+	IID  ole.GUID
+}
+
+type {{.Name}}Vtbl struct {
+	ole.IUnknownVtbl
+	Invoke uintptr
+}
+
+type {{.Name}}Callback func(instance *{{.Name}},{{- range .InParams -}}
+	{{.GoVarName}} {{template "variabletype.tmpl" . }},
+{{- end -}})
+
+var callbacks{{.Name}} = &{{.Name | toLower}}Callbacks {
+	mu:        &sync.Mutex{},
+	callbacks: make(map[unsafe.Pointer]{{.Name}}Callback),
+}
+
+var releaseChannels{{.Name}} = &{{.Name | toLower}}ReleaseChannels {
+	mu:        &sync.Mutex{},
+	chans: make(map[unsafe.Pointer]chan struct{}),
+}
+
+func New{{.Name}}(iid *ole.GUID, callback {{.Name}}Callback) *{{.Name}} {
+	// create type instance
+	size := unsafe.Sizeof(*(*{{.Name}})(nil))
+	instPtr := kernel32.Malloc(size)
+	inst := (*{{.Name}})(instPtr)
+	
+	// get the callbacks for the VTable
+	callbacks := delegate.RegisterCallbacks(instPtr, inst)
+
+	// the VTable should also be allocated in the heap
+	sizeVTable := unsafe.Sizeof(*(*{{.Name}}Vtbl)(nil))
+	vTablePtr := kernel32.Malloc(sizeVTable)
+
+	inst.RawVTable = (*interface{})(vTablePtr)
+	
+	vTable := (*{{.Name}}Vtbl)(vTablePtr)
+	vTable.IUnknownVtbl = ole.IUnknownVtbl{
+			QueryInterface: callbacks.QueryInterface,
+			AddRef:         callbacks.AddRef,
+			Release:        callbacks.Release,
+	}
+	vTable.Invoke = callbacks.Invoke
+
+	// Initialize all properties: the malloc may contain garbage
+	inst.IID = *iid // copy contents
+	inst.Mutex = sync.Mutex{}
+	inst.refs = 0
+
+	callbacks{{.Name}}.add(unsafe.Pointer(inst), callback)
+
+	// See the docs in the releaseChannels{{.Name}} struct
+	releaseChannels{{.Name}}.acquire(unsafe.Pointer(inst))
+
+	inst.addRef()
+	return inst
+}
+
+func (r *{{.Name}}) GetIID() *ole.GUID {
+	return &r.IID
+}
+
+// addRef increments the reference counter by one
+func (r *{{.Name}}) addRef() uintptr {
+	r.Lock()
+	defer r.Unlock()
+	r.refs++
+	return r.refs
+}
+
+// removeRef decrements the reference counter by one. If it was already zero, it will just return zero.
+func (r *{{.Name}}) removeRef() uintptr {
+	r.Lock()
+	defer r.Unlock()
+
+	if r.refs > 0 {
+		r.refs--
+	}
+
+	return r.refs
+}
+
+func (instance *{{.Name}}) Invoke(instancePtr, rawArgs0, rawArgs1, rawArgs2, rawArgs3, rawArgs4, rawArgs5, rawArgs6, rawArgs7, rawArgs8 unsafe.Pointer) uintptr {
+	{{range $i, $arg := .InParams -}}
+			{{- if $arg.Type.IsEnum -}}
+					{{$arg.GoVarName}}Raw := ({{$arg.Type.UnderlyingEnumType}})(uintptr(rawArgs{{$i}}))
+			{{- else -}}
+					{{$arg.GoVarName}}Ptr := rawArgs{{$i}}
+			{{- end}}
+	{{end}} 
+
+	// See the quote above.
+	{{range .InParams -}}
+			{{if .Type.IsEnum -}}
+					{{.GoVarName}} := ({{template "variabletype.tmpl" . }})({{.GoVarName}}Raw)
+			{{else -}}
+					{{.GoVarName}} := ({{template "variabletype.tmpl" . }})({{.GoVarName}}Ptr)
+			{{end -}}
+	{{end -}}
+	if callback, ok := callbacks{{.Name}}.get(instancePtr); ok {
+		callback(instance, {{range .InParams}}{{.GoVarName}},{{end}})
+	}
+	return ole.S_OK
+}
+
+func (instance *{{.Name}}) AddRef() uintptr {
+	return instance.addRef()
+}
+
+func (instance *{{.Name}}) Release() uintptr {
+	rem := instance.removeRef()
+	if rem == 0 {
+		// We're done.
+		instancePtr := unsafe.Pointer(instance)
+		callbacks{{.Name}}.delete(instancePtr)
+
+		// stop release channels used to avoid
+		// https://github.com/golang/go/issues/55015
+		releaseChannels{{.Name}}.release(instancePtr)
+
+		kernel32.Free(unsafe.Pointer(instance.RawVTable))
+		kernel32.Free(instancePtr)
+	}
+	return rem
+}
+
+type {{.Name | toLower}}Callbacks struct {
+	mu        *sync.Mutex
+	callbacks map[unsafe.Pointer]{{.Name}}Callback
+}
+
+func (m *{{.Name | toLower}}Callbacks) add(p unsafe.Pointer, v {{.Name}}Callback) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	m.callbacks[p] = v
+}
+
+func (m *{{.Name | toLower}}Callbacks) get(p unsafe.Pointer) ({{.Name}}Callback, bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	v, ok := m.callbacks[p]
+	return v, ok
+}
+
+func (m *{{.Name | toLower}}Callbacks) delete(p unsafe.Pointer) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	delete(m.callbacks, p)
+}
+
+// typedEventHandlerReleaseChannels keeps a map with channels
+// used to keep a goroutine alive during the lifecycle of this object.
+// This is required to avoid causing a deadlock error.
+// See this: https://github.com/golang/go/issues/55015
+type {{.Name | toLower}}ReleaseChannels struct {
+	mu        *sync.Mutex
+	chans map[unsafe.Pointer]chan struct{}
+}
+
+func (m *{{.Name | toLower}}ReleaseChannels) acquire(p unsafe.Pointer) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	c := make(chan struct{})
+	m.chans[p] = c
+
+	go func() {
+		// we need a timer to trick the go runtime into
+		// thinking there's still something going on here
+		// but we are only really interested in <-c
+		t := time.NewTimer(time.Minute)
+		for {
+			select {
+			case <-t.C:
+				t.Reset(time.Minute)
+			case <-c:
+				t.Stop()
+				return
+			}
+		}
+	}()
+}
+
+func (m *{{.Name | toLower}}ReleaseChannels) release(p unsafe.Pointer) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if c, ok := m.chans[p]; ok {
+		close(c)
+		delete(m.chans, p)
+	}
+}

internal/codegen/templates/enum.tmpl

@@ -0,0 +1,6 @@
+type {{.Name}} {{.Type}}
+const Signature{{.Name}} string = "{{.Signature}}"
+
+const ({{range .Values}}
+    {{.Name}} {{$.Name}} = {{.Value}}{{end}}
+)

internal/codegen/templates/file.tmpl

@@ -0,0 +1,36 @@
+// Code generated by winrt-go-gen. DO NOT EDIT.
+
+//go:build windows
+
+//nolint:all
+package {{.Package}}
+
+import (
+	"syscall"
+	"unsafe"
+	"github.com/go-ole/go-ole"
+	"github.com/saltosystems/winrt-go"
+	"github.com/saltosystems/winrt-go/internal/kernel32"
+	{{range .Imports}}"{{.}}"
+	{{end}}
+)
+
+{{range .Interfaces}}
+	{{template "interface.tmpl" .}}
+{{end}}
+
+{{range .Classes}}
+	{{template "class.tmpl" .}}
+{{end}}
+
+{{range .Enums}}
+	{{template "enum.tmpl" .}}
+{{end}}
+
+{{range .Structs}}
+	{{template "struct.tmpl" .}}
+{{end}}
+
+{{range .Delegates}}
+	{{template "delegate.tmpl" .}}
+{{end}}

internal/codegen/templates/func.tmpl

@@ -0,0 +1,30 @@
+{{if .Implement}}
+    func {{if and .FuncOwner (not .RequiresActivation)}}
+        (v *{{.FuncOwner}})
+    {{- end -}}
+
+    {{funcName .}} 
+    
+    {{- /* in params */ -}}
+
+    ( 
+    {{- range .InParams -}}
+        {{/*do not include out parameters, they are used as return values*/ -}}
+        {{ if .IsOut }}{{continue}}{{ end -}}
+        {{.GoVarName}} {{template "variabletype.tmpl" . }},
+    {{- end -}}
+    )
+
+    {{- /* return params */ -}}
+
+    ( {{range .InParams -}}
+        {{ if not .IsOut }}{{continue}}{{ end -}}
+        {{template "variabletype.tmpl" . }},{{end -}}
+    {{range .ReturnParams}}{{template "variabletype.tmpl" . }},{{end}} error )
+
+    {{- /* method body */ -}}
+
+    {
+    {{template "funcimpl.tmpl" .}}
+    }
+{{end}}

internal/codegen/templates/funcimpl.tmpl

@@ -0,0 +1,86 @@
+{{if .RequiresActivation}}{{/*Activate class*/ -}}
+inspectable, err := ole.RoGetActivationFactory("{{.ExclusiveTo}}", ole.NewGUID(GUID{{.FuncOwner}}))
+if err != nil {
+    return {{range .ReturnParams -}}
+        {{.GoDefaultValue}}, {{end}}err
+}
+v := (*{{.FuncOwner}})(unsafe.Pointer(inspectable))
+
+{{end -}}
+
+{{- /* Declare out variables*/ -}}
+
+{{range (concat .InParams .ReturnParams) -}}
+    {{ if not .IsOut}}{{continue}}{{end -}}
+    {{if eq .GoTypeName "string" -}}
+        var {{.GoVarName}}HStr ole.HString
+    {{ else -}}
+        var {{.GoVarName}} {{template "variabletype.tmpl" . -}}
+        {{if .Type.IsArray}} = make({{template "variabletype.tmpl" . -}}, {{.GoVarName}}Size){{end}}
+    {{ end -}}
+{{ end -}}
+
+{{- /* Convert in variables to winrt types */ -}}
+
+{{range .InParams -}}
+    {{ if .IsOut}}{{continue}}{{end -}}
+    {{if eq .GoTypeName "string" -}}
+        {{.GoVarName}}HStr, err := ole.NewHString({{.GoVarName}})
+        if err != nil{
+            return {{range $.InParams}}{{if .IsOut}}{{.GoDefaultValue}}, {{end}}{{end -}}
+                {{range $.ReturnParams }}{{.GoDefaultValue}}, {{end}}err
+        }
+    {{ end -}}
+{{ end -}}
+hr, _, _ := syscall.SyscallN(
+    v.VTable().{{funcName .}},
+    uintptr(unsafe.Pointer(v)), // this
+    {{range (concat .InParams .ReturnParams) -}}
+        {{if .Type.IsArray -}}
+            {{/* Arrays need to pass a pointer to their first element */ -}}
+            uintptr(unsafe.Pointer(&{{.GoVarName}}[0])),   // {{if .IsOut}}out{{else}}in{{end}} {{.GoTypeName}}
+        {{else if .IsOut -}}
+            {{if (or .Type.IsPrimitive .Type.IsEnum) -}}
+                {{if eq .GoTypeName "string" -}}
+                    uintptr(unsafe.Pointer(&{{.GoVarName}}HStr)),   // out {{.GoTypeName}}
+                {{else -}}
+                    uintptr(unsafe.Pointer(&{{.GoVarName}})),   // out {{.GoTypeName}}
+                {{end -}}
+            {{else -}}
+                uintptr(unsafe.Pointer(&{{.GoVarName}})),   // out {{.GoTypeName}}
+            {{end -}}
+        {{else if .Type.IsPointer -}}
+            uintptr(unsafe.Pointer({{.GoVarName}})),   // in {{.GoTypeName}}
+        {{else if (or .Type.IsPrimitive .Type.IsEnum) -}}
+            {{ if eq .GoTypeName "bool" -}}
+                uintptr(*(*byte)(unsafe.Pointer(&{{.GoVarName}}))),   // in {{.GoTypeName}}
+            {{ else if eq .GoTypeName "string" -}}
+                uintptr({{.GoVarName}}HStr),   // in {{.GoTypeName}}
+            {{else -}}
+                uintptr({{.GoVarName}}),   // in {{.GoTypeName}}
+            {{end -}}
+        {{else if .Type.IsGeneric -}}
+            uintptr({{.GoVarName}}),   // in {{.GoTypeName}}
+        {{else -}}
+            uintptr(unsafe.Pointer(&{{.GoVarName}})),   // in {{.GoTypeName}}
+        {{end -}}
+    {{end -}}
+)
+
+if hr != 0 {
+    return {{range .InParams}}{{if .IsOut}}{{.GoDefaultValue}}, {{end}}{{end -}}
+        {{range .ReturnParams }}{{.GoDefaultValue}}, {{end}}ole.NewError(hr)
+}
+
+{{range (concat .InParams .ReturnParams) -}}
+    {{ if not .IsOut}}{{continue}}{{end -}}
+    {{if eq .GoTypeName "string" -}}
+        {{.GoVarName}} := {{.GoVarName}}HStr.String()
+        ole.DeleteHString({{.GoVarName}}HStr)
+    {{ end -}}
+{{ end -}}
+
+
+return {{range .InParams}}{{if .IsOut}}{{.GoVarName}}, {{end}}{{end -}}
+    {{range .ReturnParams }}{{.GoVarName}},{{end}} nil
+{{- /* remove trailing white space*/ -}}

internal/codegen/templates/interface.tmpl

@@ -0,0 +1,22 @@
+const GUID{{.Name}} string = "{{.GUID}}"
+const Signature{{.Name}} string = "{{.Signature}}"
+
+type {{.Name}} struct {
+    ole.IInspectable
+}
+
+type {{.Name}}Vtbl struct {
+    ole.IInspectableVtbl
+
+    {{range .Funcs}}
+        {{funcName .}} uintptr
+    {{- end}}
+}
+
+func (v *{{.Name}}) VTable() *{{.Name}}Vtbl {
+	return (*{{.Name}}Vtbl)(unsafe.Pointer(v.RawVTable))
+}
+
+{{range .Funcs}}
+{{template "func.tmpl" .}}
+{{end}}

internal/codegen/templates/struct.tmpl

@@ -0,0 +1,7 @@
+const Signature{{.Name}} string = "{{.Signature}}"
+
+type {{.Name}} struct {
+    {{range .Fields}}
+        {{.GoVarName}} {{.GoTypeName}}
+    {{end}}
+}

internal/codegen/templates/variabletype.tmpl

@@ -0,0 +1,5 @@
+{{if .Type.IsArray}}[]{{end -}}
+{{if .Type.IsPointer}}*{{end -}}
+{{.GoTypeName -}}
+
+{{- /*remove trailing whitespace*/ -}}