From a4dbf3d1957c7bd6cfde28290b6649ba5d3bd126 Mon Sep 17 00:00:00 2001
From: Robin Jadoul <robin.jadoul@gmail.com>
Date: Thu, 26 May 2016 17:13:20 +0200
Subject: [PATCH] Compress the tables in c++ backend, fixes #2

---
 src/backends/cpp.cpp | 33 +++++++++++++++++++++++++++------
 src/main.cpp         |  1 +
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/backends/cpp.cpp b/src/backends/cpp.cpp
index d592d70..8d194ac 100644
--- a/src/backends/cpp.cpp
+++ b/src/backends/cpp.cpp
@@ -117,12 +117,33 @@ namespace lxs { namespace backends {
         return templ::make_array(tokenList);
     }
 
-    std::pair<std::vector<unsigned char>, int> CppBackend::buildTransitionIndices(const DFA& /* dfa */) const {
-        //FIXME: this is not really optimal ;-)
-        std::vector<unsigned char> transition_idx;
-        for (int i = 0; i < 256; i++)
-            transition_idx.push_back(i);
-        return std::make_pair(transition_idx, 256);
+    std::pair<std::vector<unsigned char>, int> CppBackend::buildTransitionIndices(const DFA& dfa) const {
+        std::vector<unsigned char> transition_idx(256);
+        int count = 0;
+        for (int i = 0; i < 256; i++) {
+            int found = i;
+            for (int j = 0; j < i; j++) {
+                bool differ = false;
+                for (State s = 0; s < dfa.numStates; s++) {
+                    if (dfa.delta.find(s)->second.find(i)->second != dfa.delta.find(s)->second.find(j)->second) {
+                        differ = true;
+                        break;
+                    }
+                }
+                if (!differ) {
+                    found = j;
+                    break;
+                }
+            }
+            if (found != i)
+            {
+                transition_idx[i] = transition_idx[found];
+            } else {
+                transition_idx[i] = count++;
+            }
+        }
+
+        return std::make_pair(transition_idx, count);
     }
 
     templ::TemplateContext CppBackend::transformTransitionIndices(const std::vector<unsigned char>& transition_indices) const {
diff --git a/src/main.cpp b/src/main.cpp
index 458aa53..0e0c834 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -30,6 +30,7 @@ int main(int argc, char** argv) {
     }
 
     std::string lexername = options["lexername"];
+    //FIXME: this really needs some more work...
     if (!lexername.length()) {
         if (args[0].length() >= 4 && args[0].substr(args[0].length() - 4, 4) == ".lxs") {
             lexername = args[0].substr(0, args[0].length() - 4); //Drop the .lxs