From de4b97f096e38f78952b5f49de4ab4f141bc6ba5 Mon Sep 17 00:00:00 2001
From: Valentin Ochs <a@0au.de>
Date: Sun, 9 Feb 2020 23:06:14 +0100
Subject: [PATCH] Sort & comment

---
 markov.hpp | 118 +++++++++++++++++++++++++++--------------------------
 1 file changed, 60 insertions(+), 58 deletions(-)

diff --git a/markov.hpp b/markov.hpp
index 8f6ad98..aadad13 100644
--- a/markov.hpp
+++ b/markov.hpp
@@ -63,60 +63,6 @@ public:
     return false;
   }
 
-  template <typename IT, typename Generator>
-  T gen(IT iter, size_t size, Generator &g) const {
-    while (size > order()) {
-      iter++;
-      size--;
-    }
-
-    if (size == 0) {
-      return random_child(g);
-    }
-
-    return gen_impl(iter, size, g, std::bool_constant<(ORDER > 0)>{});
-  }
-
-protected:
-  template <typename IT, typename Generator>
-  T gen_impl(IT iter, size_t size, Generator &g,
-             std::bool_constant<true>) const {
-    auto child = children.find(*iter);
-    if (child == children.end()) {
-      return random_child(g);
-    }
-
-    return child->second.gen(iter + 1, size - 1, g);
-  }
-  template <typename IT, typename Generator>
-  T gen_impl(IT iter, size_t size, Generator &g,
-             std::bool_constant<false>) const {
-    return random_child(g);
-  }
-
-  /* Finds the key or adds it */
-  typename Children::iterator find(const T &key) {
-    return children.try_emplace(key).first;
-  }
-
-public:
-  /* Probability of finding the first order() items (but at most size) in the
-     sequence */
-  template <typename IT> double probability(IT iter, size_t size) const {
-    if (size == 0) {
-      return 1.;
-    }
-
-    auto child = children.find(*iter);
-    if (child != children.cend()) {
-      auto &val = child->second;
-      return (double(val.total) / double(total)) *
-             val.probability(iter + 1, size - 1);
-    } else {
-      return 0.5 / double(total);
-    }
-  }
-
   /* Probability of finding the last item (but at most the order+1st) in the
      model, given the previous sequence */
   template <typename IT> double final_probability(IT iter, size_t size) const {
@@ -136,6 +82,40 @@ public:
     }
   }
 
+  /* Generate one single item that can appear after the prefix given by iter and
+  size, using the RNG g */
+  template <typename IT, typename Generator>
+  T gen(IT iter, size_t size, Generator &g) const {
+    while (size > order()) {
+      iter++;
+      size--;
+    }
+
+    if (size == 0) {
+      return random_child(g);
+    }
+
+    return gen_impl(iter, size, g, std::bool_constant<(ORDER > 0)>{});
+  }
+
+  /* Probability of finding the first order() items (but at most size) in the
+     sequence */
+  template <typename IT> double probability(IT iter, size_t size) const {
+    if (size == 0) {
+      return 1.;
+    }
+
+    auto child = children.find(*iter);
+    if (child != children.cend()) {
+      auto &val = child->second;
+      return (double(val.total) / double(total)) *
+             val.probability(iter + 1, size - 1);
+    } else {
+      return 0.5 / double(total);
+    }
+  }
+
+  /* Returns a random item, weighted by the probability of child nodes */
   template <typename Generator> T random_child(Generator &g) const {
     std::uniform_int_distribution<size_t> dist(0u, total - 1);
     auto val = dist(g);
@@ -148,6 +128,31 @@ public:
     }
     return T{};
   }
+
+protected:
+  /* Finds the key or adds it */
+  typename Children::iterator find(const T &key) {
+    return children.try_emplace(key).first;
+  }
+
+  /* Generate an item for Markov chains of order 0 */
+  template <typename IT, typename Generator>
+  T gen_impl(IT iter, size_t size, Generator &g,
+             std::bool_constant<false>) const {
+    return random_child(g);
+  }
+
+  /* Generate an item for longer chains, using the prefix */
+  template <typename IT, typename Generator>
+  T gen_impl(IT iter, size_t size, Generator &g,
+             std::bool_constant<true>) const {
+    auto child = children.find(*iter);
+    if (child == children.end()) {
+      return random_child(g);
+    }
+
+    return child->second.gen(iter + 1, size - 1, g);
+  }
 };
 
 /* Leaf of the recursion with just a count */
@@ -159,15 +164,12 @@ public:
   constexpr size_t order() const { return 0; }
 
   template <typename IT> void add(IT, size_t) { total++; }
-
   template <typename IT> bool dec(IT, size_t) {
     total--;
     return true;
   }
-
-  template <typename IT> double probability(IT, size_t) const { return 1.; }
-
   template <typename IT> double final_probability(IT, size_t) const {
     return 1.;
   }
+  template <typename IT> double probability(IT, size_t) const { return 1.; }
 };