From 6ea4e6b2b08cc73ae828d157b4475aa19e3dd030 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Sun, 27 Apr 2014 23:19:11 -0700
Subject: [PATCH] Give rules::Visitor a virtual destructor

---
 examples/grammars/helpers.cc  | 16 ++++++++--------
 examples/grammars/helpers.h   |  2 +-
 src/compiler/rules/visitor.cc |  4 +++-
 src/compiler/rules/visitor.h  |  1 +
 4 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/examples/grammars/helpers.cc b/examples/grammars/helpers.cc
index ffb52321..5176b970 100644
--- a/examples/grammars/helpers.cc
+++ b/examples/grammars/helpers.cc
@@ -2,38 +2,38 @@
 
 namespace tree_sitter_examples {
     using namespace tree_sitter::rules;
-    
+
     rule_ptr comma_sep1(rule_ptr element) {
         return seq({ element, repeat(seq({ str(","), element })) });
     }
-    
+
     rule_ptr comma_sep(rule_ptr element) {
         return choice({ comma_sep1(element), blank() });
     }
-    
+
     rule_ptr optional(rule_ptr rule) {
         return choice({ rule, blank() });
     }
-    
+
     rule_ptr in_parens(rule_ptr rule) {
         return seq({ str("("), rule, str(")") });
     }
-    
+
     rule_ptr in_braces(rule_ptr rule) {
         return seq({ str("{"), rule, str("}") });
     }
-    
+
     rule_ptr in_brackets(rule_ptr rule) {
         return seq({ str("["), rule, str("]") });
     }
-    
+
     rule_ptr infix(int precedence, std::string op) {
         return prec(precedence, seq({
             sym("expression"),
             str(op),
             sym("expression") }));
     }
-    
+
     rule_ptr prefix(int precedence, std::string op) {
         return prec(precedence, seq({
             str(op),
diff --git a/examples/grammars/helpers.h b/examples/grammars/helpers.h
index e4b7e60a..f41d118e 100644
--- a/examples/grammars/helpers.h
+++ b/examples/grammars/helpers.h
@@ -5,7 +5,7 @@
 
 namespace tree_sitter_examples {
     using namespace tree_sitter::rules;
-    
+
     rule_ptr comma_sep1(rule_ptr element);
     rule_ptr comma_sep(rule_ptr element);
     rule_ptr optional(rule_ptr rule);
diff --git a/src/compiler/rules/visitor.cc b/src/compiler/rules/visitor.cc
index 4e74bc39..04cfc5e0 100644
--- a/src/compiler/rules/visitor.cc
+++ b/src/compiler/rules/visitor.cc
@@ -12,8 +12,10 @@
 
 namespace tree_sitter {
     using std::vector;
-    
+
     namespace rules {
+        Visitor::~Visitor() {}
+
         rule_ptr IdentityRuleFn::default_apply(const Rule *rule) {
             return rule->copy();
         }
diff --git a/src/compiler/rules/visitor.h b/src/compiler/rules/visitor.h
index 44a02d01..a7538958 100644
--- a/src/compiler/rules/visitor.h
+++ b/src/compiler/rules/visitor.h
@@ -28,6 +28,7 @@ namespace tree_sitter {
             virtual void visit(const String *rule) = 0;
             virtual void visit(const Symbol *rule) = 0;
             virtual void visit(const ISymbol *rule) = 0;
+            virtual ~Visitor();
         };
 
         template<typename T>