wip: use cel2db to CEL -> SQL conversion

.gitignore

@@ -1,2 +1,4 @@
 main
 terraform-provider-bookstore
+# libcel2db should be compiled and added.
+example/service/libcel2db.a

DEVELOPMENT.md

@@ -27,4 +27,17 @@ go install github.com/aep-dev/api-linter/cmd/api-linter@latest
 The standard GoLang toolchain is used, with the addition of protobuf for
 compiling the resource definition.
 1. `./scripts/regenerate-all.sh`
-2. `go build main.go`
+2. `go build main.go`
+
+## Importing cel2db
+
+Today, the CEL <-> SQL translation in the example service requireds [cel2db](https://github.com/aep-dev/cel2db), written in Rust and therefore not compatible with the standard `go get` approach to managing dependencies.
+
+This will be streamlined in the future, but for now, do the following (bazel and rust build tooling is required):
+
+```bash
+git clone git@github.com:aep-dev/cel2db.git
+cd ./cel2db
+bazel build //cel2db:cel2db_static
+cp bazel-bin/cel2db/libcel2db.a ${AEPC_REPO}/example/service/
+```

example/service/cel.go

@@ -1,11 +1,27 @@
 package service
 
+// required for cel2db.
+
+// extern char *cel_to_sql(const char *cel_expr, const char *sql_dialect);
+// #cgo LDFLAGS: -L ${SRCDIR} -lcel2db
+import "C"
+
 import (
+	"errors"
+
 	"github.com/aep-dev/aepc/pkg/cel2ansisql"
 	"github.com/google/cel-go/cel"
 )
 
 func convertCELToSQL(expr string) (string, error) {
+	condition := C.cel_to_sql(C.CString(expr), C.CString("sqlite"))
+	if condition == nil {
+		return "", errors.New("failed to convert CEL to SQL")
+	}
+	return C.GoString(condition), nil
+}
+
+func convertCELToSQL2(expr string) (string, error) {
 	if expr == "" {
 		return "", nil
 	}

example/service/cel_test.go

@@ -15,6 +15,11 @@ func TestCELToSQL(t *testing.T) {
 			input:    "description.startsWith('tomorrow')",
 			expected: "description LIKE CONCAT('tomorrow', '%')",
 		},
+		{
+			name:     "arithemtic",
+			input:    "1 + 2",
+			expected: "1 + 2",
+		},
 		{
 			name:     "empty",
 			input:    "",