From 1c686fb0ea6787b8dde239acf6f81c93cd80d2e4 Mon Sep 17 00:00:00 2001
From: nitrix <me@nitrix.one>
Date: Mon, 16 Dec 2019 22:41:58 +0100
Subject: [PATCH] Implement variable declaration

---
 .../de/hsrm/compiler/Klang/visitors/EvalVisitor.java | 11 +++++++++++
 .../java/de/hsrm/compiler/Klang/visitors/GenASM.java | 12 ++++++++++++
 .../de/hsrm/compiler/Klang/visitors/GetVars.java     |  7 ++++++-
 .../compiler/Klang/visitors/PrettyPrintVisitor.java  | 12 ++++++++++++
 .../de/hsrm/compiler/Klang/visitors/Visitor.java     |  1 +
 5 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java b/src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java
index 7142326..09d870a 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java
@@ -101,6 +101,17 @@ public class EvalVisitor implements Visitor<Value> {
     return null;
   }
 
+  @Override
+  public Value visit(VariableDeclaration e) {
+    Value initialValue = null;
+    if (e.expression != null) {
+      initialValue = e.expression.welcome(this);
+    }
+
+    this.env.put(e.name, initialValue);
+    return null;
+  }
+
   @Override
   public Value visit(VariableAssignment e) {
     Value result = e.expression.welcome(this);
diff --git a/src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java b/src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java
index cc01a65..38e62f4 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java
@@ -162,6 +162,18 @@ public class GenASM implements Visitor<Void> {
     throw new RuntimeException("Das machen wir mal nicht, ne?!");
   }
 
+  @Override
+  public Void visit(VariableDeclaration e) {
+    // If there is an initialization present,
+    // push it to the location of the local var
+    if (e.expression != null) {
+      e.expression.welcome(this);
+      int offset = this.env.get(e.name);
+      this.ex.write("    movq %rax, " + offset + "(%rbp)\n");
+    }
+    return null;
+  }
+
   @Override
   public Void visit(VariableAssignment e) {
     e.expression.welcome(this);
diff --git a/src/main/java/de/hsrm/compiler/Klang/visitors/GetVars.java b/src/main/java/de/hsrm/compiler/Klang/visitors/GetVars.java
index 8c7444d..1bef69b 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/GetVars.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/GetVars.java
@@ -84,8 +84,13 @@ class GetVars implements Visitor<Void> {
   }
 
   @Override
-  public Void visit(VariableAssignment e) {
+  public Void visit(VariableDeclaration e) {
     vars.add(e.name);
+    return null;
+  }
+
+  @Override
+  public Void visit(VariableAssignment e) {
     e.expression.welcome(this);
     return null;
   }
diff --git a/src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java b/src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java
index 0e74dc0..009c74c 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java
@@ -153,6 +153,18 @@ public class PrettyPrintVisitor implements Visitor<Void> {
         return null;
     }
 
+    @Override
+    public Void visit(VariableDeclaration e) {
+        ex.write("let " + e.name);
+
+        if (e.expression != null) {
+            ex.write(" = " + e.expression.welcome(this));
+        }
+
+        ex.write(";");
+        return null;
+    }
+
     @Override
     public Void visit(VariableAssignment e) {
         ex.write(e.name + " = ");
diff --git a/src/main/java/de/hsrm/compiler/Klang/visitors/Visitor.java b/src/main/java/de/hsrm/compiler/Klang/visitors/Visitor.java
index 662500d..6b944d7 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/Visitor.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/Visitor.java
@@ -17,6 +17,7 @@ public interface Visitor<R> {
     R visit(NegateExpression e);
     R visit(IfStatement e);
     R visit(PrintStatement e);
+    R visit(VariableDeclaration e);
     R visit(VariableAssignment e);
     R visit(ReturnStatement e);
     R visit(Block e);