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32 lines
706 B
Go
32 lines
706 B
Go
package expression
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type expressionWrapper struct {
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fn func(ctx Context) (interface{}, error)
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}
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func (w expressionWrapper) Evaluate(ctx Context) (interface{}, error) {
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return w.fn(ctx)
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}
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// Constant creates an expression that returns a constant value.
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func Constant(k interface{}) Expression {
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return expressionWrapper{
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func(_ Context) (interface{}, error) {
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return k, nil
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},
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}
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}
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// Not creates an expression that returns ! of the wrapped expression.
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func Not(e Expression) Expression {
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return expressionWrapper{
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func(ctx Context) (interface{}, error) {
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value, err := e.Evaluate(ctx)
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if err != nil {
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return nil, err
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}
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return (value == nil || value == false), nil
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},
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}
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}
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