From 71caf5006f0b2eb6c3ad77657ea6693dbe63df67 Mon Sep 17 00:00:00 2001
From: Jason Turner <jason@emptycrate.com>
Date: Sat, 23 Apr 2016 22:27:34 -0600
Subject: [PATCH] Pull constant folding optimizer out

---
 .../chaiscript/language/chaiscript_engine.hpp |  4 +--
 .../language/chaiscript_optimizer.hpp         | 27 ++++++++++++++--
 .../chaiscript/language/chaiscript_parser.hpp | 32 +------------------
 3 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/include/chaiscript/language/chaiscript_engine.hpp b/include/chaiscript/language/chaiscript_engine.hpp
index 27161273..1449b2ff 100644
--- a/include/chaiscript/language/chaiscript_engine.hpp
+++ b/include/chaiscript/language/chaiscript_engine.hpp
@@ -219,7 +219,7 @@ namespace chaiscript
                std::vector<std::string> t_modulepaths = std::vector<std::string>(),
                       std::vector<std::string> t_usepaths = std::vector<std::string>())
       : m_module_paths(std::move(t_modulepaths)), m_use_paths(std::move(t_usepaths)),
-        m_parser(std::make_unique<parser::ChaiScript_Parser<optimizer::Optimizer<optimizer::Return_Optimizer, optimizer::For_Loop_Optimizer>>>())
+        m_parser(std::make_unique<parser::ChaiScript_Parser<optimizer::Optimizer<optimizer::Constant_Fold, optimizer::Return, optimizer::For_Loop>>>())
     {
       if (m_module_paths.empty())
       {
@@ -244,7 +244,7 @@ namespace chaiscript
     ChaiScript( std::vector<std::string> t_modulepaths = std::vector<std::string>(),
                       std::vector<std::string> t_usepaths = std::vector<std::string>())
       : m_module_paths(std::move(t_modulepaths)), m_use_paths(std::move(t_usepaths)),
-        m_parser(std::make_unique<parser::ChaiScript_Parser<optimizer::Optimizer<optimizer::Return_Optimizer, optimizer::For_Loop_Optimizer>>>())
+        m_parser(std::make_unique<parser::ChaiScript_Parser<optimizer::Optimizer<optimizer::Constant_Fold, optimizer::Return, optimizer::For_Loop>>>())
     {
       if (m_module_paths.empty())
       {
diff --git a/include/chaiscript/language/chaiscript_optimizer.hpp b/include/chaiscript/language/chaiscript_optimizer.hpp
index 8fc10d83..3e82edd0 100644
--- a/include/chaiscript/language/chaiscript_optimizer.hpp
+++ b/include/chaiscript/language/chaiscript_optimizer.hpp
@@ -53,7 +53,7 @@ namespace chaiscript {
       }
 
 
-    struct Return_Optimizer {
+    struct Return {
       AST_NodePtr optimize(const AST_NodePtr &p)
       {
         if (p->identifier == AST_Node_Type::Def
@@ -74,8 +74,31 @@ namespace chaiscript {
       }
     };
 
+    struct Constant_Fold {
+      AST_NodePtr optimize(const AST_NodePtr &node) {
+        if (node->identifier == AST_Node_Type::Binary
+            && node->children.size() == 2
+            && node->children[0]->identifier == AST_Node_Type::Constant
+            && node->children[1]->identifier == AST_Node_Type::Constant)
+        {
+          const auto oper = node->text;
+          const auto parsed = Operators::to_operator(oper);
+          if (parsed != Operators::Opers::invalid) {
+            const auto lhs = std::dynamic_pointer_cast<eval::Constant_AST_Node>(node->children[0])->m_value;
+            const auto rhs = std::dynamic_pointer_cast<eval::Constant_AST_Node>(node->children[1])->m_value;
+            if (lhs.get_type_info().is_arithmetic() && rhs.get_type_info().is_arithmetic()) {
+              const auto val  = Boxed_Number::do_oper(parsed, lhs, rhs);
+              const auto match = node->children[0]->text + " " + oper + " " + node->children[1]->text;
+              return chaiscript::make_shared<AST_Node, eval::Constant_AST_Node>(std::move(match), node->location, std::move(val));
+            }
+          }
+        }
 
-    struct For_Loop_Optimizer {
+        return node;
+      }
+    };
+
+    struct For_Loop {
       AST_NodePtr optimize(const AST_NodePtr &for_node) {
 
         if (for_node->identifier != AST_Node_Type::For) {
diff --git a/include/chaiscript/language/chaiscript_parser.hpp b/include/chaiscript/language/chaiscript_parser.hpp
index 0b5af4ba..deae9410 100644
--- a/include/chaiscript/language/chaiscript_parser.hpp
+++ b/include/chaiscript/language/chaiscript_parser.hpp
@@ -2129,37 +2129,7 @@ namespace chaiscript
                 case(Operator_Precidence::Bitwise_Xor) :
                 case(Operator_Precidence::Bitwise_Or) :
                 case(Operator_Precidence::Comparison) :
-                  {
-                    bool folded = false;
-                    const auto size = m_match_stack.size();
-
-                    try {
-                      if (m_match_stack[size - 1]->identifier == AST_Node_Type::Constant
-                          && m_match_stack[size - 2]->identifier == AST_Node_Type::Constant) {
-                        const auto parsed = Operators::to_operator(oper);
-                        if (parsed != Operators::Opers::invalid) {
-                          const auto lhs = std::dynamic_pointer_cast<eval::Constant_AST_Node>(m_match_stack[size-2])->m_value;
-                          const auto rhs = std::dynamic_pointer_cast<eval::Constant_AST_Node>(m_match_stack[size-1])->m_value;
-                          if (lhs.get_type_info().is_arithmetic() && rhs.get_type_info().is_arithmetic()) {
-                            const auto val  = Boxed_Number::do_oper(parsed, lhs, rhs);
-                            const auto start = m_match_stack[size-2]->location;
-                            const auto match = m_match_stack[size-2]->text + " " + oper + " " + m_match_stack[size-1]->text;
-                            m_match_stack.resize(size-2);
-                            m_match_stack.push_back(
-                                make_node<eval::Constant_AST_Node>(std::move(match), start.start.line, start.start.column, std::move(val)));
-                            folded = true;
-                          }
-                        }
-                      }
-                    } catch (const std::exception &) {
-                      //failure to fold
-                    }
-
-                    if (!folded) {
-                      build_match<eval::Binary_Operator_AST_Node>(prev_stack_top, oper);
-                    }
-                  }
-
+                  build_match<eval::Binary_Operator_AST_Node>(prev_stack_top, oper);
                   break;
 
                 case(Operator_Precidence::Logical_And) :