1 files changed, 39 insertions, 1 deletions
diff --git a/submit/ast/If.java b/submit/ast/If.java
index a516c94..0c47ce9 100644
--- a/submit/ast/If.java
+++ b/submit/ast/If.java
@@ -4,6 +4,10 @@
  */
 package submit.ast;
 
+import submit.MIPSResult;
+import submit.RegisterAllocator;
+import submit.SymbolTable;
+
 /**
  *
  * @author edwajohn
@@ -14,7 +18,8 @@ public class If extends AbstractNode implements Statement {
   private final Statement trueStatement;
   private final Statement falseStatement;
 
-  public If(Expression expression, Statement trueStatement, Statement falseStatement) {
+  public If(Expression expression, Statement trueStatement,
+            Statement falseStatement) {
     this.expression = expression;
     this.trueStatement = trueStatement;
     this.falseStatement = falseStatement;
@@ -41,4 +46,37 @@ public class If extends AbstractNode implements Statement {
     }
     // builder.append(prefix).append("}");
   }
+
+  @Override
+  public MIPSResult toMIPS(StringBuilder code, StringBuilder data,
+                           SymbolTable symbolTable,
+                           RegisterAllocator regAllocator) {
+    String continueLabel = "if_" + SymbolTable.nextId();
+    String elseLabel = "else_" + SymbolTable.nextId();
+
+    MIPSResult expressionTruthiness =
+        expression.toMIPS(code, data, symbolTable, regAllocator);
+
+    code.append(String.format("bne %s $zero %s\n",
+                              expressionTruthiness.getRegister(), elseLabel));
+    regAllocator.clear(expressionTruthiness.getRegister());
+
+    MIPSResult trueRes =
+        trueStatement.toMIPS(code, data, symbolTable, regAllocator);
+    regAllocator.clear(trueRes.getRegister());
+
+    code.append(String.format("j %s\n", continueLabel))
+        .append(String.format("%s:\n", elseLabel));
+
+    regAllocator.clear(expressionTruthiness.getRegister());
+
+    if (falseStatement != null) {
+      MIPSResult falseRes =
+          falseStatement.toMIPS(code, data, symbolTable, regAllocator);
+      regAllocator.clear(falseRes.getRegister());
+    }
+    code.append(String.format("%s:\n", continueLabel));
+
+    return MIPSResult.createVoidResult();
+  }
 }