From f1b23e34bee172e0c0ed8e65bcd7904baef9e857 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Wed, 5 Feb 2020 21:18:31 +0100
Subject: Fix GetPath

---
 grammer.cpp | 51 ++++++++++++++++++++-------------------------------
 1 file changed, 20 insertions(+), 31 deletions(-)

diff --git a/grammer.cpp b/grammer.cpp
index f7a370f..4bdf8f4 100644
--- a/grammer.cpp
+++ b/grammer.cpp
@@ -268,22 +268,26 @@ std::map<std::string, std::string> Compiler::traverse(lower, upper)
  std::deque<std::pair<std::string, std::string>> todo{{lower, ""}}; // node, child
  
  while (!todo.empty()) {
-  current = todo.front();
+  auto& [current_node, current_child] = todo.front();
   todo.pop_front();
 
-  if (!visited[current.first]) {
-   parents = reverseBNF[current.first];
-   
-   visited[current.first] = current.second;
-   
-   std::for_each(parents.begin(), parents.end(), [&](const auto&x) {todo.emplace_back(x, current.first);});
+  if (!visited[current_node]) {
+   auto parents_it {reverseBNF.find(current_node)};
+
+   if (parents_it != reverseBNF.end()) {
+    auto& parents {parents_it->second};
+    
+    visited[current_node] = current_child;
+    
+    std::for_each(parents.begin(), parents.end(), [&](const auto&x) {todo.emplace_back(x, current_node);});
+   }
   }
  }
  
  return visited;
 }
 
-// returns list from lower (including) to upper (excluding)
+// returns list from lower (excluding) to upper (including)
 // returns empty list on fail
 std::vector<std::string> Compiler::GetPath(std::string upper, std::string lower) {
  std::vector<std::string> result;
@@ -291,29 +295,13 @@ std::vector<std::string> Compiler::GetPath(std::string upper, std::string lower)
  // traverse bnf from lower to upper
  std::map<std::string, std::string> visited {traverse(lower, upper)};
  
- while (lower != upper) {
-  auto parents {ReverseBNF.find(lower)};
-  if (parents == ReverseBNF.end())
-   return {};
-
-  std::string new_lower;
-  bool hit{false};
-  for (const auto& parent : parents->second) {
-   for (const auto& list : bnf.at(parent)) {
-    if (list.size() > 0 && list[0] == lower) {
-     if (!hit) {
-      result.push_back(lower);
-      new_lower = parent;
-      hit = true;
-     } else
-      throw std::runtime_error("Double match for "s + lower + ": "s + parent + ", "s + new_lower); // TODO: also get alternatives at each step
-    }
-   }
-  }
+ auto current {upper};
+ while (current != lower) {
+  auto& child = visited[current];
+
+  result.push_back(current);
 
-  if (!hit)
-   throw std::runtime_error("GetPath error!"); // ICE
-  lower = new_lower;
+  current = child;
  }
  return result;
 }
@@ -357,7 +345,8 @@ bool Compiler::FillTree()
  index_t to_fill;
 
  while (!subTreeIsComplete(root_node_id, to_fill)) {
-  auto list = GetPath(nodes[to_fill].type, tokens[tokens_used]);
+  auto& node {nodes[to_fill]};
+  auto list = GetPath(bnf[node.type][node.variant][node.child_ids.size()], tokens[tokens_used]);
   if (list.size() > 0) {
    AddPath(list, to_fill);
    return true;
-- 
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