| /* |
| * |
| * Copyright 2020 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| package engine |
| |
| import ( |
| "errors" |
| |
| expr "google.golang.org/genproto/googleapis/api/expr/v1alpha1" |
| "google.golang.org/protobuf/proto" |
| |
| "github.com/google/cel-go/cel" |
| "github.com/google/cel-go/checker/decls" |
| ) |
| |
| func compileCel(env *cel.Env, expr string) (*cel.Ast, error) { |
| ast, iss := env.Parse(expr) |
| // Report syntactic errors, if present. |
| if iss.Err() != nil { |
| return nil, iss.Err() |
| } |
| // Type-check the expression for correctness. |
| checked, iss := env.Check(ast) |
| if iss.Err() != nil { |
| return nil, iss.Err() |
| } |
| // Check the result type is a Boolean. |
| if !proto.Equal(checked.ResultType(), decls.Bool) { |
| return nil, errors.New("failed to compile CEL string: get non-bool value") |
| } |
| return checked, nil |
| } |
| |
| func compileStringToCheckedExpr(expr string, declarations []*expr.Decl) (*expr.CheckedExpr, error) { |
| env, err := cel.NewEnv(cel.Declarations(declarations...)) |
| if err != nil { |
| return nil, err |
| } |
| checked, err := compileCel(env, expr) |
| if err != nil { |
| return nil, err |
| } |
| checkedExpr, err := cel.AstToCheckedExpr(checked) |
| if err != nil { |
| return nil, err |
| } |
| return checkedExpr, nil |
| } |
| |
| func compileStringToExpr(expr string, declarations []*expr.Decl) *expr.Expr { |
| checkedExpr, err := compileStringToCheckedExpr(expr, declarations) |
| if err != nil { |
| logger.Fatalf("error encountered when compiling string to expression: %v", err) |
| } |
| return checkedExpr.Expr |
| } |