From 38d34a7cbc12e5fe934471f627a9ea7ef2941052 Mon Sep 17 00:00:00 2001
From: nitrix <me@nitrix.one>
Date: Mon, 11 Nov 2019 22:27:27 +0100
Subject: [PATCH] implement else if nesting

---
 src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4  |  2 +-
 .../de/hsrm/compiler/Klang/ContextAnalysis.java  | 13 ++++++++-----
 .../Klang/nodes/statements/IfStatement.java      | 16 +++++++++++++++-
 .../compiler/Klang/visitors/EvalVisitor.java     |  6 +++++-
 .../Klang/visitors/PrettyPrintVisitor.java       |  3 +++
 5 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4 b/src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4
index 6127283..d4249ea 100644
--- a/src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4
+++ b/src/main/antlr4/de/hsrm/compiler/Klang/Klang.g4
@@ -22,7 +22,7 @@ print
   ;
 
 if_statement
-  : IF OPAR expression CPAR braced_block (ELSE braced_block)?
+  : IF OPAR cond = expression CPAR then = braced_block (ELSE (alt = braced_block | elif = if_statement) )?
   ;  
 
 expression
diff --git a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
index 72e4974..328ff76 100644
--- a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
+++ b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
@@ -42,14 +42,17 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitIf_statement(KlangParser.If_statementContext ctx) {
-    Node condition = this.visit(ctx.expression());
-    Node thenBlock = this.visit(ctx.braced_block(0));
+    Node condition = this.visit(ctx.cond);
+    Node thenBlock = this.visit(ctx.then);
 
-    if (ctx.braced_block().size() > 1) {
-      Node elseBlock = this.visit(ctx.braced_block(1));
+    if (ctx.alt != null) {
+      Node elseBlock = this.visit(ctx.alt);
       return new IfStatement((Expression) condition, (Block) thenBlock, (Block) elseBlock);
+    } else if(ctx.elif != null) {
+      Node elif = this.visit(ctx.elif);
+      return new IfStatement((Expression) condition, (Block) thenBlock, (IfStatement) elif);
     } else {
-      return new IfStatement((Expression) condition, (Block) thenBlock, null);
+      return new IfStatement((Expression) condition, (Block) thenBlock);
     }
   }
 
diff --git a/src/main/java/de/hsrm/compiler/Klang/nodes/statements/IfStatement.java b/src/main/java/de/hsrm/compiler/Klang/nodes/statements/IfStatement.java
index 02eb480..87e4f54 100644
--- a/src/main/java/de/hsrm/compiler/Klang/nodes/statements/IfStatement.java
+++ b/src/main/java/de/hsrm/compiler/Klang/nodes/statements/IfStatement.java
@@ -9,11 +9,25 @@ public class IfStatement extends Statement {
     public Expression cond;
     public Block then;
     public Block alt;
+    public IfStatement elif;
 
-    public IfStatement(Expression cond, Block then, Block alt) {
+    public IfStatement(Expression cond, Block then, Block alt, IfStatement elif) {
         this.cond = cond;
         this.then = then;
         this.alt = alt;
+        this.elif = elif;
+    }
+
+    public IfStatement(Expression cond, Block then, Block alt) {
+        this(cond, then, alt, null);
+    }
+
+    public IfStatement(Expression cond, Block then, IfStatement elif) {
+        this(cond, then, null, elif);
+    }
+
+    public IfStatement(Expression cond, Block then) {
+        this(cond, then, null, null);
     }
 
     @Override
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 fbc06eb..52fca42 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/EvalVisitor.java
@@ -49,6 +49,8 @@ public class EvalVisitor implements Visitor<Value> {
             e.then.welcome(this);
         } else if (e.alt != null) {
             e.alt.welcome(this);
+        } else if (e.elif != null) {
+            e.elif.welcome(this);
         }
 
         return null;
@@ -66,7 +68,9 @@ public class EvalVisitor implements Visitor<Value> {
 
     @Override
     public Value visit(Block e) {
-        // TODO Auto-generated method stub
+        for (var stmt: e.statements) {
+            stmt.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 fd73577..ada0573 100644
--- a/src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java
+++ b/src/main/java/de/hsrm/compiler/Klang/visitors/PrettyPrintVisitor.java
@@ -99,6 +99,9 @@ public class PrettyPrintVisitor implements Visitor<Void> {
         if (e.alt != null) {
             ex.write(" else ");
             e.alt.welcome(this);
+        } else if (e.elif != null) {
+            ex.write(" else ");
+            e.elif.welcome(this);
         }
         return null;
     }