Make errors a little nicer

ph7.go

@@ -16,98 +16,125 @@ import (
 	"fmt"
 )
 
+type ResultCode int
+
+const (
+	ResultCodeOK         = ResultCode(C.PH7_OK)
+	ResultCodeNoMem      = ResultCode(C.PH7_NOMEM)
+	ResultCodeAbort      = ResultCode(C.PH7_ABORT)
+	ResultCodeIOErr      = ResultCode(C.PH7_IO_ERR)
+	ResultCodeLooked     = ResultCode(C.PH7_LOOKED)
+	ResultCodeCorrupt    = ResultCode(C.PH7_CORRUPT)
+	ResultCodeCompileErr = ResultCode(C.PH7_COMPILE_ERR)
+	ResultCodeVMErr      = ResultCode(C.PH7_VM_ERR)
+)
+
+func (r ResultCode) String() string {
+	switch r {
+	case ResultCodeOK:
+		return "PH7_OK"
+	case ResultCodeNoMem:
+		return "PH7_NOMEM"
+	case ResultCodeAbort:
+		return "PH7_ABORT"
+	case ResultCodeIOErr:
+		return "PH7_IO_ERR"
+	case ResultCodeLooked:
+		return "PH7_LOOKED"
+	case ResultCodeCorrupt:
+		return "PH7_CORRUPT"
+	case ResultCodeCompileErr:
+		return "PH7_COMPILE_ERR"
+	case ResultCodeVMErr:
+		return "PH7_VM_ERR"
+	default:
+		return "UNKNOWN"
+	}
+}
+
 type Error struct {
-	Value int
+	Code ResultCode
+}
+
+func newError(code C.int) error {
+	if code != C.PH7_OK {
+		return Error{
+			Code: ResultCode(code),
+		}
+	}
+	return nil
 }
 
 func (e Error) Error() string {
-	return fmt.Sprintf("ph7 error: %d", e.Value)
-}
-
-func newError(value C.int) Error {
-	return Error{
-		Value: int(value),
-	}
+	return fmt.Sprintf("ph7: %s", e.Code)
 }
 
 type Engine struct {
 	ptr *C.ph7
 }
 
-func NewEngine() (*Engine, error) {
-	engine := new(Engine)
+func NewEngine() (Engine, error) {
+	var engine Engine
 	result := C.ph7_init(&engine.ptr)
 	if result != C.PH7_OK {
-		return nil, newError(result)
+		return Engine{}, newError(result)
 	}
 
 	return engine, nil
 }
 
-func (e *Engine) ExtractErrLog() (string, error) {
+func (e Engine) ErrLog() (string, error) {
 	var s *C.char
 	var n C.int
 
-	result := C.engine_config_err_log(e.ptr, &s, &n)
-	if result != C.PH7_OK {
-		return "", newError(result)
+	err := newError(C.engine_config_err_log(e.ptr, &s, &n))
+	if err != nil {
+		return "", err
 	}
 
 	return C.GoStringN(s, n), nil
 }
 
-func (e *Engine) Compile(source []byte, phpOnly bool) (*VM, error) {
+func (e Engine) Compile(source []byte, phpOnly bool) (*VM, error) {
 	csource := C.CBytes(source)
 	vm := new(VM)
 	var flags C.int
 	if phpOnly {
 		flags |= C.PH7_PHP_ONLY
 	}
-	result := C.ph7_compile_v2(e.ptr, (*C.char)(csource), C.int(len(source)), &vm.ptr, flags)
-	if result != C.PH7_OK {
-		return nil, newError(result)
+	err := newError(C.ph7_compile_v2(e.ptr, (*C.char)(csource), C.int(len(source)), &vm.ptr, flags))
+	if err != nil {
+		return nil, err
 	}
 
 	// TODO free csource
 	return vm, nil
 }
 
-func (e *Engine) Close() error {
-	result := C.ph7_release(e.ptr)
-	if result != C.PH7_OK {
-		return newError(result)
-	}
-	return nil
+func (e Engine) Close() error {
+	return newError(C.ph7_release(e.ptr))
 }
 
 type VM struct {
 	ptr *C.ph7_vm
 }
 
-func (vm *VM) ExtractOutput() (string, error) {
+func (vm VM) ExtractOutput() (string, error) {
 	var s *C.char
 	var n C.int
 
-	result := C.vm_extract_output(vm.ptr, &s, &n)
-	if result != C.PH7_OK {
-		return "", newError(result)
+	err := newError(C.vm_extract_output(vm.ptr, &s, &n))
+	if err != nil {
+		return "", err
 	}
 
 	return C.GoStringN(s, n), nil
 }
 
-func (v *VM) Exec() error {
-	result := C.ph7_vm_exec(v.ptr, (*C.int)(nil))
-	if result != C.PH7_OK {
-		return newError(result)
-	}
-	return nil
+func (v VM) Exec() error {
+	return newError(C.ph7_vm_exec(v.ptr, (*C.int)(nil)))
 }
 
-func (v *VM) Close() error {
-	result := C.ph7_vm_release(v.ptr)
-	if result != C.PH7_OK {
-		return newError(result)
-	}
-	return nil
+func (v VM) Close() error {
+	return newError(C.ph7_vm_release(v.ptr))
 }

ph7_test.go

@@ -7,19 +7,28 @@ import (
 )
 
 func mustSucceed(t *testing.T, err error) {
+	t.Helper()
 	if err != nil {
 		t.Fatal(err.Error())
 	}
 }
 
+func mustFail(t *testing.T, err error) {
+	t.Helper()
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}
+
 func mustSucceedF(t *testing.T, f func() error) {
+	t.Helper()
 	err := f()
 	if err != nil {
 		t.Fatal(err.Error())
 	}
 }
 
-func TestDoStuff(t *testing.T) {
+func TestHelloWorld(t *testing.T) {
 	engine, err := ph7.NewEngine()
 	mustSucceed(t, err)
 	defer mustSucceedF(t, engine.Close)
@@ -36,3 +45,17 @@ func TestDoStuff(t *testing.T) {
 		t.Fatalf("unexpected output: %s", output)
 	}
 }
+
+func TestCompileError(t *testing.T) {
+	engine, err := ph7.NewEngine()
+	mustSucceed(t, err)
+	defer mustSucceedF(t, engine.Close)
+
+	_, err = engine.Compile([]byte("<?php 1234 echo 'Hello world!'; ?>"), false)
+	mustFail(t, err)
+	msg, err := engine.ErrLog()
+	mustSucceed(t, err)
+	if msg == "" {
+		t.Fatalf("expected error message, got nothing")
+	}
+}