From ff0c8036659ea31f60b6b3523b8e4e044a70ecf4 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Sun, 9 Feb 2020 15:34:46 +0100
Subject: Bugfixing

---
 grammer.cpp | 40 ++++++++++++++++++++++++++--------------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/grammer.cpp b/grammer.cpp
index 4118733..186a4bd 100644
--- a/grammer.cpp
+++ b/grammer.cpp
@@ -264,12 +264,13 @@ void Compiler::TrackBack()
  ChangeNodeType();
 }
 
-// return shortest path with variants
+// GetPath() + traverse(): return shortest path with variants
 // via first-entry-in-bnf-rule
 // excluding lower (already exists)
 // including upper (already determined to be included)
 
 // breadth-first search
+// return: node, child
 std::map<std::string, std::string> Compiler::traverse(lower, upper)
 {
  std::map<std::string, std::string> visited; // node, child
@@ -279,7 +280,8 @@ std::map<std::string, std::string> Compiler::traverse(lower, upper)
   auto& [current_node, current_child] = todo.front();
   todo.pop_front();
 
-  if (!visited[current_node]) {
+  auto it {visited.find(current_node)};
+  if (it == visited.end()) { // not visited, yet: visit now
    auto parents_it {reverseBNF.find(current_node)};
 
    if (parents_it != reverseBNF.end()) {
@@ -295,7 +297,7 @@ std::map<std::string, std::string> Compiler::traverse(lower, upper)
  return visited;
 }
 
-// returns list from lower (excluding) to upper (including)
+// returns list from upper (including) to lower (excluding)
 // returns empty list on fail
 std::vector<std::string> Compiler::GetPath(std::string upper, std::string lower)
 {
@@ -306,16 +308,20 @@ std::vector<std::string> Compiler::GetPath(std::string upper, std::string lower)
  
  auto current {upper};
  while (current != lower) {
-  auto& child = visited[current];
+  auto it {visited.find(current)};
+  if (it != visited.end()) {
+   auto& child{it->second};
 
-  result.push_back(current);
+   result.push_back(current);
 
-  current = child;
+   current = child;
+  } else
+   return {};
  }
  return result;
 }
 
-index_t Compiler::AddNode(const std::string& name, const std::string& child_type, index_t parent_index)
+index_t Compiler::AddNode(const std::string& child_type, index_t parent_index)
 {
  TreeNode& parent {nodes[parent_index]};
  index_t index = nodes.size();
@@ -325,9 +331,16 @@ index_t Compiler::AddNode(const std::string& name, const std::string& child_type
  std::deque<std::string> alternatives;
 
  const auto& lists { bnf[parent.type] };
+ bool found{false};
  for (int i = 0; i < lists.size(); i++) { // variants
-  if (lists[i].size() > 0 && lists[i][0] == child_type)
-   variant = i;
+  if (lists[i].size() > 0 && lists[i][0] == child_type) {
+   if (!found) { // use first match
+    variant = i;
+    found = true;
+   } else { // defer all others
+    alternatives.emplace_back(child_type, i);
+   }
+  }
  }
 
  nodes.emplace_back({parent_index, index, child_type, variant, alternatives, {}});
@@ -338,9 +351,8 @@ index_t Compiler::AddNode(const std::string& name, const std::string& child_type
 
 void Compiler::AddPath(const std::vector<std::string>& path, index_t current_index)
 {
- for (int i = path.size() - 1; i > 0; i--) {
-  std::string child_name = path[i - 1];
-  current_index = AddNode(path[i], child_name, current_index);
+ for (const std::string& child_type: path) {
+  current_index = AddNode(child_type, current_index);
  }
 
  nodes.back().child_ids.emplace_back(ChildIdFromTokenId(tokens_used));
@@ -352,18 +364,18 @@ bool Compiler::FillTree()
  if (nodes.size() == 0) // ignore empty tree, successfully
   return true;
 
- index_t to_fill;
+ index_t to_fill{};
 
  while (!subTreeIsComplete(root_node_id, to_fill)) {
   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;
   } else {
    return false;
   }
  }
+ return true;
 }
 
 Compiler::Compiler(const BNF& bnf, const std::string& Top): bnf(bnf), Top(Top), ReverseBNF{Reverse(bnf)}
-- 
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