provisional implementation of the postfix ++ operator

operator-post-inc.go

@@ -0,0 +1,41 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-post-inc.go
+package expr
+
+// -------- post increment term
+
+func newPostIncTerm(tk *Token) *term {
+	return &term{
+		tk:       *tk,
+		parent:   nil,
+		children: make([]*term, 0, 1),
+		position: posPostfix,
+		priority: priPrePost,
+		evalFunc: evalPostInc,
+	}
+}
+
+func evalPostInc(ctx ExprContext, self *term) (v any, err error) {
+	var leftValue any
+	if leftValue, err = self.evalPrefix(ctx); err != nil {
+		return
+	}
+
+	if dc, ok := leftValue.(*dataCursor); ok {
+		v, err = dc.Next()
+	} else if isInteger(leftValue) && self.children[0].symbol() == SymIdentifier {
+		v = leftValue
+		i, _ := leftValue.(int64)
+		ctx.SetVar(self.children[0].source(), i+1)
+	} else {
+		self.errIncompatibleType(leftValue)
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymDoublePlus, newPostIncTerm)
+}