From fd7f7c39bb68e3a79a4b36fca623770412aebe94 Mon Sep 17 00:00:00 2001
From: nitrix <me@nitrix.one>
Date: Tue, 4 Feb 2020 19:17:13 +0100
Subject: [PATCH] implement a visitor that collects the names of all structs
 that were defined

---
 .../de/hsrm/compiler/Klang/GetStructs.java    | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 src/main/java/de/hsrm/compiler/Klang/GetStructs.java

diff --git a/src/main/java/de/hsrm/compiler/Klang/GetStructs.java b/src/main/java/de/hsrm/compiler/Klang/GetStructs.java
new file mode 100644
index 0000000..b18c497
--- /dev/null
+++ b/src/main/java/de/hsrm/compiler/Klang/GetStructs.java
@@ -0,0 +1,38 @@
+package de.hsrm.compiler.Klang;
+
+import java.util.Set;
+
+import de.hsrm.compiler.Klang.helper.Helper;
+
+public class GetStructs extends KlangBaseVisitor<Void> {
+
+    private Set<String> structs;
+
+    public GetStructs(Set<String> structs) {
+        this.structs = structs;
+    }
+
+    @Override
+    public Void visitProgram(KlangParser.ProgramContext ctx) {
+        for (int i = 0; i < ctx.structDef().size(); i++) {
+            this.visit(ctx.structDef(i));
+        }
+
+        return null;
+    }
+
+    @Override
+    public Void visitStructDef(KlangParser.StructDefContext ctx) {
+        String name = ctx.structName.getText();
+        int line = ctx.start.getLine();
+        int col = ctx.start.getCharPositionInLine();
+
+        if (this.structs.contains(name)) {
+            String error = "Struct " + name + " defined multiple times.";
+            throw new Error(Helper.getErrorPrefix(line, col) + error);
+        }
+
+        this.structs.add(name);
+        return null;
+    }
+}
\ No newline at end of file