fix assignment and adding IfStatement

inc/AST/IfStatement.h

@@ -0,0 +1,23 @@
+#ifndef IFSTATEMENT_H
+#define IFSTATEMENT_H
+
+#include "AST/Expression.h"
+#include "AST/Statement.h"
+
+class IfStatement : public Statement
+{
+public:
+    IfStatement(Expression* cond, Statement* stmt);
+    virtual ~IfStatement();
+
+    virtual void accept(ASTVisitor *visitor);
+
+    Expression* getCond();
+    Statement* getStmt();
+private:
+    Expression* cond_;
+    Statement* stmt_;
+
+};
+
+#endif // IFSTATEMENT_H