package main import ( "go/format" "log" "sort" "strings" ) func (p CppParameter) RenderTypeGo() string { if p.Pointer && p.ParameterType == "char" { return "string" } if p.ParameterType == "QString" { return "string" } ret := "" if p.ByRef || p.Pointer { ret += "*" } ret += p.ParameterType return ret // ignore const } func emitParametersGo(params []CppParameter) string { tmp := make([]string, 0, len(params)) for _, p := range params { tmp = append(tmp, p.ParameterName+" "+p.RenderTypeGo()) } return strings.Join(tmp, ", ") } func emitParametersGo2CABIForwarding(m CppMethod) (preamble string, fowarding string) { tmp := make([]string, 0, len(m.Parameters)+2) tmp = append(tmp, "this.h") for _, p := range m.Parameters { if p.ParameterType == "QString" { // Go: convert string -> char* and len // CABI: convert char* and len -> real QString preamble += p.ParameterName + "_Cstring := C.CString(" + p.ParameterName + ")\n" preamble += "defer C.free(" + p.ParameterName + "_Cstring)\n" tmp = append(tmp, p.ParameterName+"_Cstring, len("+p.ParameterName+")") // TODO handle the return type as a pointer parameter } else if p.Pointer && p.ParameterType == "char" { // Single char* argument preamble += p.ParameterName + "_Cstring := C.CString(" + p.ParameterName + ")\n" preamble += "defer C.free(" + p.ParameterName + "_Cstring)\n" tmp = append(tmp, p.ParameterName+"_Cstring") } else if (p.Pointer || p.ByRef) && p.QtClassType() { // The C++ type is a pointer to Qt class // We want our functions to accept the Go wrapper type, and forward as cPointer() tmp = append(tmp, p.ParameterName+".cPointer()") } else { // Default tmp = append(tmp, p.ParameterName) } } if m.ReturnType.ParameterType == "QString" { tmp = append(tmp, "&_out, &_out_Strlen") } return preamble, strings.Join(tmp, ", ") } func emitGo(src *CppParsedHeader, headerName string) (string, error) { ret := strings.Builder{} ret.WriteString(`package miqt /* #cgo CFLAGS: -fPIC #cgo pkg-config: Qt5Widgets #include "gen_` + headerName + `" #include */ import "C" %%_IMPORTLIBS_%% `) imports := map[string]struct{}{} for _, c := range src.Classes { ret.WriteString(` type ` + c.ClassName + ` struct { h C.P` + c.ClassName + ` } func (this *` + c.ClassName + `) cPointer() C.P` + c.ClassName + ` { if this == nil { return nil } return this.h } `) for i, ctor := range c.Ctors { preamble, forwarding := emitParametersGo2CABIForwarding(ctor) ret.WriteString(` // New` + c.ClassName + maybeSuffix(i) + ` constructs a new ` + c.ClassName + ` object. func New` + c.ClassName + maybeSuffix(i) + `(` + emitParametersGo(ctor.Parameters) + `) { ` + preamble + ` ret := C.` + c.ClassName + `_new` + maybeSuffix(i) + `(` + forwarding + `) return &` + c.ClassName + `{h: ret} } `) } for _, m := range c.Methods { preamble, forwarding := emitParametersGo2CABIForwarding(m) shouldReturn := "return " afterword := "" returnTypeDecl := m.ReturnType.ParameterType // FIXME handle byRef/const here too if m.ReturnType.ParameterType == "void" && !m.ReturnType.Pointer { shouldReturn = "" returnTypeDecl = "" } else if m.ReturnType.ParameterType == "QString" { shouldReturn = "" returnTypeDecl = "string" preamble += "var _out *C.char = nil\n" preamble += "var _out_Strlen C.size_t = 0\n" afterword += "ret := C.GoStringN(_out, _out_Strlen)\n" afterword += "C.free(_out)\n" afterword += "return ret" } else if m.ReturnType.QtClassType() { // Construct our Go type based on this inner CABI type shouldReturn = "ret := " if m.ReturnType.Pointer { afterword = "return " + m.ReturnType.ParameterType + "{h: ret}" } else { // This is return by value, but CABI has new'd it into a // heap type for us // To preserve Qt's approximate semantics, add a runtime // finalizer to automatically Delete once the type goes out // of Go scope imports["runtime"] = struct{}{} afterword = "// Qt uses pass-by-value semantics for this type. Mimic with finalizer\n" afterword += "ret1 := &" + m.ReturnType.ParameterType + "{h: ret}\n" afterword += "runtime.SetFinalizer(ret1, func(ret2 *" + m.ReturnType.ParameterType + ") {\n" afterword += "ret2.Delete()\n" afterword += "runtime.KeepAlive(ret2.h)\n" afterword += "})\n" afterword += "return ret1" } } ret.WriteString(` func (this *` + c.ClassName + `) ` + m.SafeMethodName() + `(` + emitParametersGo(m.Parameters) + `) ` + returnTypeDecl + ` { ` + preamble + shouldReturn + ` C.` + c.ClassName + `_` + m.SafeMethodName() + `(` + forwarding + `) ` + afterword + `} `) } ret.WriteString(` func (this *` + c.ClassName + `) Delete() { C.` + c.ClassName + `_Delete(this.h) } `) } goSrc := ret.String() // Fixup imports if len(imports) > 0 { allImports := make([]string, 0, len(imports)) for k, _ := range imports { allImports = append(allImports, `"`+k+`"`) } sort.Strings(allImports) goSrc = strings.Replace(goSrc, `%%_IMPORTLIBS_%%`, "import (\n\t"+strings.Join(allImports, "\n\t")+"\n)", 1) } else { goSrc = strings.Replace(goSrc, `%%_IMPORTLIBS_%%`, "", 1) } // Run gofmt over the result formattedSrc, err := format.Source([]byte(goSrc)) if err != nil { log.Printf("gofmt failure: %v", err) formattedSrc = []byte(ret.String()) } return string(formattedSrc), nil }