Bindings for C, C#, Golang (#124)

* FFI bindings

Generate C FFI as well as C# FFI

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* Regorus C binding

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* C# binding

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

* Golang binding

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

---------

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

bindings/go/pkg/regorus/mod.go

@@ -0,0 +1,117 @@
+package regorus
+
+// #cgo LDFLAGS: -L ../../../../target/release -lregorus_ffi
+// #include "../../../ffi/regorus.h"
+import "C"
+import (
+	"fmt"
+	"unsafe"
+)
+
+type Engine struct {
+	e *C.RegorusEngine
+}
+
+func NewEngine() *Engine {
+	e := new(Engine)
+	e.e = C.regorus_engine_new()
+	return e
+}
+
+func (e *Engine) Close() {
+	C.regorus_engine_drop(e.e)
+}
+
+func (e *Engine) Clone() *Engine {
+	c := new(Engine)
+	c.e = C.regorus_engine_clone(e.e)
+	return c
+}
+
+func (e *Engine) AddPolicy(path string, rego string) error {
+	path_c := C.CString(path)
+	defer C.free(unsafe.Pointer(path_c))
+
+	rego_c := C.CString(rego)
+	defer C.free(unsafe.Pointer(rego_c))
+
+	result := C.regorus_engine_add_policy(e.e, path_c, rego_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+	return nil
+}
+
+func (e *Engine) AddPolicyFromFile(path string) error {
+	path_c := C.CString(path)
+	defer C.free(unsafe.Pointer(path_c))
+
+	result := C.regorus_engine_add_policy_from_file(e.e, path_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+	return nil
+}
+
+func (e *Engine) AddDataJson(data string) error {
+	data_c := C.CString(data)
+	defer C.free(unsafe.Pointer(data_c))
+
+	result := C.regorus_engine_add_data_json(e.e, data_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+	return nil
+}
+
+func (e *Engine) AddDataFromJsonFile(path string) error {
+	path_c := C.CString(path)
+	defer C.free(unsafe.Pointer(path_c))
+
+	result := C.regorus_engine_add_data_from_json_file(e.e, path_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+	return nil
+}
+
+func (e *Engine) SetInputJson(input string) error {
+	input_c := C.CString(input)
+	defer C.free(unsafe.Pointer(input_c))
+
+	result := C.regorus_engine_set_input_json(e.e, input_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+	return nil
+}
+
+func (e *Engine) SetInputFromJsonFile(path string) error {
+	path_c := C.CString(path)
+	defer C.free(unsafe.Pointer(path_c))
+
+	result := C.regorus_engine_set_input_from_json_file(e.e, path_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+	return nil
+}
+
+func (e *Engine) EvalQuery(query string) (string, error) {
+	query_c := C.CString(query)
+	defer C.free(unsafe.Pointer(query_c))
+
+	result := C.regorus_engine_eval_query(e.e, query_c)
+	defer C.regorus_result_drop(result)
+	if result.status != C.RegorusStatusOk {
+		return "", fmt.Errorf("%s", C.GoString(result.error_message))
+	}
+
+	return C.GoString(result.output), nil
+}