Add redeclaration checks for functions and locals

Closes #1.

1 files changed, 28 insertions, 0 deletions

diff --git a/decl.go b/decl.go
new file mode 100644
index 0000000..179acb2
--- /dev/null
+++ b/decl.go
@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2024 Himbeer <himbeer@disroot.org>
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package main
+
+var funcs = map[string]struct{}{}
+var localConsts = map[string]map[string]string{}
+var localMuts = map[string]map[string]struct{}{}
+
+func isDeclared(name string, toplevel bool) bool {
+	if toplevel {
+		return isDeclaredToplevel(name)
+	}
+
+	return isDeclaredLocal(currentFunc, name)
+}
+
+func isDeclaredToplevel(name string) bool {
+	_, ok := funcs[name]
+	return ok
+}
+
+func isDeclaredLocal(function string, local string) bool {
+	_, constant := localConsts[function][local]
+	_, mutable := localMuts[function][local]
+	return constant || mutable
+}