forked from nikunjy/rules
/
evaluate.go
83 lines (70 loc) · 1.7 KB
/
evaluate.go
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package parser
import (
"fmt"
"github.com/antlr4-go/antlr/v4"
)
type Evaluator struct {
lastDebugErr error
rule string
tree antlr.ParseTree
testHookPanic func()
}
func NewEvaluator(rule string) (ret *Evaluator, retErr error) {
// antlr lib has panics for exceptions so we have to put a recover here
// in the unlikely case there is an exception
defer func() {
info := recover()
if info != nil {
retErr = fmt.Errorf("%q", info)
}
}()
input := antlr.NewInputStream(rule)
lex := NewJsonQueryLexer(input)
lex.RemoveErrorListeners()
tokens := antlr.NewCommonTokenStream(lex, antlr.TokenDefaultChannel)
p := NewJsonQueryParser(tokens)
// TODO: maybe log properly
p.RemoveErrorListeners()
tree := p.Query()
return &Evaluator{
rule: rule,
tree: tree,
}, nil
}
func (e *Evaluator) Reset() error {
e.lastDebugErr = nil
return nil
}
func (e *Evaluator) LastDebugErr() error {
return e.lastDebugErr
}
func (e *Evaluator) Process(items map[string]interface{}) (ret bool, retErr error) {
e.lastDebugErr = nil
// antlr lib has panics for exceptions so we have to put a recover here
// in the unlikely case there is an exception
defer func() {
info := recover()
if info != nil {
retErr = fmt.Errorf("%q", info)
ret = false
}
}()
visitor := NewJsonQueryVisitorImpl(items)
result := visitor.Visit(e.tree)
e.lastDebugErr = visitor.debugErr
if e.testHookPanic != nil {
defer e.testHookPanic()
}
if result == nil || visitor.err != nil {
return false, visitor.err
}
return result.(bool), visitor.err
}
func Evaluate(rule string, items map[string]interface{}) bool {
ev, err := NewEvaluator(rule)
if err != nil {
return false
}
result, _ := ev.Process(items)
return result
}