wip

vendor/github.com/antonmedv/expr/optimizer/const_range.go

@@ -0,0 +1,33 @@
+package optimizer
+
+import (
+	. "github.com/antonmedv/expr/ast"
+)
+
+type constRange struct{}
+
+func (*constRange) Enter(*Node) {}
+func (*constRange) Exit(node *Node) {
+	switch n := (*node).(type) {
+	case *BinaryNode:
+		if n.Operator == ".." {
+			if min, ok := n.Left.(*IntegerNode); ok {
+				if max, ok := n.Right.(*IntegerNode); ok {
+					size := max.Value - min.Value + 1
+					// In this case array is too big. Skip generation,
+					// and wait for memory budget detection on runtime.
+					if size > 1e6 {
+						return
+					}
+					value := make([]int, size)
+					for i := range value {
+						value[i] = min.Value + i
+					}
+					Patch(node, &ConstantNode{
+						Value: value,
+					})
+				}
+			}
+		}
+	}
+}