status-go/vendor/github.com/hashicorp/go-bexpr/bexpr.go

52 lines
1.8 KiB
Go

// bexpr is an implementation of a generic boolean expression evaluator.
// The general goal is to be able to evaluate some expression against some
// arbitrary data and get back a boolean of whether or not the data
// was matched by the expression
package bexpr
//go:generate pigeon -o grammar/grammar.go -optimize-parser grammar/grammar.peg
//go:generate goimports -w grammar/grammar.go
import (
"github.com/hashicorp/go-bexpr/grammar"
"github.com/mitchellh/pointerstructure"
)
// HookFn provides a way to translate one reflect.Value to another during
// evaluation by bexpr. This facilitates making Go structures appear in a way
// that matches the expected JSON Pointers used for evaluation. This is
// helpful, for example, when working with protocol buffers' well-known types.
type ValueTransformationHookFn = pointerstructure.ValueTransformationHookFn
type Evaluator struct {
// The syntax tree
ast grammar.Expression
tagName string
valueTransformationHook ValueTransformationHookFn
}
func CreateEvaluator(expression string, opts ...Option) (*Evaluator, error) {
parsedOpts := getOpts(opts...)
var parserOpts []grammar.Option
if parsedOpts.withMaxExpressions != 0 {
parserOpts = append(parserOpts, grammar.MaxExpressions(parsedOpts.withMaxExpressions))
}
ast, err := grammar.Parse("", []byte(expression), parserOpts...)
if err != nil {
return nil, err
}
eval := &Evaluator{
ast: ast.(grammar.Expression),
tagName: parsedOpts.withTagName,
valueTransformationHook: parsedOpts.withHookFn,
}
return eval, nil
}
func (eval *Evaluator) Evaluate(datum interface{}) (bool, error) {
return evaluate(eval.ast, datum, WithTagName(eval.tagName), WithHookFn(eval.valueTransformationHook))
}