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