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expression.go
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expression.go
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// Copyright 2017 Istio 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 compiled
import "istio.io/istio/mixer/pkg/attribute"
// Expression represents a precompiled expression that can be immediately evaluated.
// It holds no cache and does not listen to any events. If the configuration changes, the CompiledExpression needs
// to be discarded and created again.
type Expression interface {
// Evaluate evaluates this compiled expression against the attribute bag.
Evaluate(attributes attribute.Bag) (interface{}, error)
// EvaluateBoolean evaluates this compiled expression against the attribute bag and returns the result as boolean.
// panics if the expression does not return a boolean.
EvaluateBoolean(attributes attribute.Bag) (bool, error)
// EvaluateString evaluates this compiled expression against the attribute bag and returns the result as string.
// panics if the expression does not return a string.
EvaluateString(attributes attribute.Bag) (string, error)
// EvaluateDouble evaluates this compiled expression against the attribute bag and returns the result as float64.
// panics if the expression does not return a float64.
EvaluateDouble(attribute attribute.Bag) (float64, error)
// EvaluateInteger evaluates this compiled expression against the attribute bag and returns the result as int64.
// panics if the expression does not return a int64.
EvaluateInteger(attribute attribute.Bag) (int64, error)
}