EvaluateBool usability function

Author: pjdufour

dfl/EvaluateBool.go

@@ -0,0 +1,25 @@
+package dfl
+
+import (
+  "fmt"
+	"reflect"
+)
+
+import (
+	"github.com/pkg/errors"
+)
+
+// EvaluateBool returns the boolean value of a node given a context.  If the result is not a bool, then returns an error.
+func EvaluateBool(n Node, ctx Context, funcs FunctionMap) (bool, error) {
+  result, err := n.Evaluate(ctx, funcs)
+  if err != nil {
+    return false, errors.Wrap(err, "Error evaluating expression")
+  }
+
+  switch result.(type) {
+  case bool:
+    return result.(bool), nil
+  }
+
+  return false, errors.New("Evaluation returned a "+fmt.Sprint(reflect.TypeOf(result))+" instead of bool")
+}