Speed up: implement MultiRE

include/Lexesis/re.h

@@ -45,6 +45,17 @@ namespace lxs {
             char c;
     };
 
+    class MultiRE : public RE
+    {
+        public:
+            MultiRE(std::vector<char> chars) : chars(std::move(chars)) {}
+            ~MultiRE() {}
+            virtual State toENFA(ENFA& enfa, State attach);
+            virtual std::string toRe();
+
+            std::vector<char> chars;
+    };
+
     class ConcatRE : public RE
     {
         public:

src/re.cpp

@@ -48,6 +48,23 @@ namespace lxs {
         return attach + 1;
     }
 
+    string MultiRE::toRe()
+    {
+        //FIXME: this does not consider characters that need escaping
+        return "[" + string(chars.begin(), chars.end()) + "]";
+    }
+
+    State MultiRE::toENFA(ENFA& enfa, State attach)
+    {
+        enfa.numStates = std::max(attach + 1, enfa.numStates);
+        enfa.accepting.clear();
+        enfa.accepting.insert(attach + 1);
+        for (char c : chars) {
+            enfa.delta[attach][c].insert(attach + 1);
+        }
+        return attach + 1;
+    }
+
     string ConcatRE::toRe()
     {
         return e->toRe() + f->toRe();
@@ -158,22 +175,9 @@ namespace lxs {
             return c;
         }
 
-        void sumREs(std::vector<std::shared_ptr<RE> >& res)
-        {
-            for (std::size_t step = 1; step < res.size(); step <<= 1)
-            {
-                for (std::size_t i = 0; i < res.size(); i += step * 2)
-                {
-                    if (i + step < res.size())
-                        res[i] = std::make_shared<PlusRE>(res[i], res[i + step]);
-                }
-            }
-        }
-
         std::shared_ptr<RE> parseCharacterClass(const string& input, size_t& idx) {
             if (idx >= input.size())
                 throw SyntaxError("Unclosed character class");
-            std::vector<std::shared_ptr<RE> > chars;
             std::set<char> used_chars;
 
             bool invert = false;
@@ -243,24 +247,22 @@ namespace lxs {
             if (idx >= input.size())
                 throw SyntaxError("Unclosed character class");
 
+            std::vector<char> chars;
             for (int i = 0; i < 256; i++)
             {
                 if (invert ^ (used_chars.count((char) i) > 0))
-                    chars.push_back(std::make_shared<SingleRE>((char) i));
+                    chars.push_back((char) i);
             }
 
-            sumREs(chars);
-
-            return chars[0];
+            return std::make_shared<MultiRE>(chars);
         }
 
         std::shared_ptr<RE> dotChar() {
-            std::vector<std::shared_ptr<RE> > any;
+            std::vector<char> any;
             for (int i = 0; i < 256; i++)
                 if ((char) i != '\n') //Dot matches anything except newlines
-                    any.push_back(std::make_shared<SingleRE>((char) i));
-            sumREs(any);
-            return any[0];
+                    any.push_back((char) i);
+            return std::make_shared<MultiRE>(any);
         }
 
         std::shared_ptr<RE> parseRE(const string& input, size_t& idx)