snapshot of https://github.com/cortezaproject/corteza.git (2024.9.x, 2026-09-18; blobs > 131072B omitted)

server/pkg/expr/parser.go

@@ -0,0 +1,128 @@
+package expr
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/PaesslerAG/gval"
+)
+
+type (
+	Parsable interface {
+		Parse(string) (Evaluable, error)
+		ParseEvaluators(ee ...Evaluator) error
+	}
+
+	Evaluable interface {
+		Eval(context.Context, *Vars) (interface{}, error)
+		Test(context.Context, *Vars) (bool, error)
+	}
+
+	Evaluator interface {
+		GetExpr() string
+		SetEval(eval Evaluable)
+	}
+
+	gvalParser struct {
+		lang gval.Language
+	}
+
+	gvalEval struct {
+		evaluable gval.Evaluable
+	}
+)
+
+var (
+	parser      gval.Language
+	initialized = false
+)
+
+func Init(ext ...func() []gval.Language) {
+	aux := make([]gval.Language, 0, len(ext))
+
+	for _, e := range ext {
+		aux = append(aux, e()...)
+	}
+
+	initialized = true
+	parser = gval.Full(aux...)
+}
+
+// Parser returns global parser instance
+func Parser() gval.Language {
+	if !initialized {
+		Init(AllFunctions)
+	}
+	return parser
+}
+
+func NewParser() Parsable {
+	return NewGvalParser()
+}
+
+func NewGvalParser() *gvalParser {
+	return &gvalParser{lang: Parser()}
+}
+
+func (p *gvalParser) Parse(expr string) (Evaluable, error) {
+	var (
+		ge  = &gvalEval{}
+		err error
+	)
+
+	if ge.evaluable, err = p.lang.NewEvaluable(expr); err != nil {
+		return nil, err
+	}
+
+	return ge, err
+}
+
+func (p *gvalParser) ParseEvaluators(ee ...Evaluator) error {
+	for _, e := range ee {
+		evaluable, err := p.Parse(e.GetExpr())
+		if err != nil {
+			return err
+		}
+
+		e.SetEval(evaluable)
+	}
+
+	return nil
+}
+
+func (e *gvalEval) Eval(ctx context.Context, scope *Vars) (interface{}, error) {
+	return e.evaluable(ctx, scope)
+}
+
+func (e *gvalEval) Test(ctx context.Context, scope *Vars) (bool, error) {
+	r, err := e.evaluable(ctx, scope)
+	if err != nil {
+		return false, err
+	}
+
+	return !isEmpty(r), nil
+}
+
+func AllFunctions() []gval.Language {
+	ff := make([]gval.Language, 0, 100)
+
+	ff = append(ff, GenericFunctions()...)
+	ff = append(ff, StringFunctions()...)
+	ff = append(ff, JsonFunctions()...)
+	ff = append(ff, NumericFunctions()...)
+	ff = append(ff, TimeFunctions()...)
+	ff = append(ff, ArrayFunctions()...)
+	ff = append(ff, KvFunctions()...)
+
+	return ff
+}
+
+// utility function for examples
+func eval(e string, p interface{}) {
+	result, err := Parser().Evaluate(e, p)
+	if err != nil {
+		fmt.Printf("error: %v", err)
+	} else {
+		fmt.Printf("%+v", UntypedValue(result))
+	}
+}