From 4e6fe47af1964c3efe50d0e244331d0dd4df51fc Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Sun, 19 Jan 2020 18:52:23 +0100
Subject: Remove candidate handling

---
 minicc.cpp | 71 +++++++++++++++++++-------------------------------------------
 1 file changed, 21 insertions(+), 50 deletions(-)

(limited to 'minicc.cpp')

diff --git a/minicc.cpp b/minicc.cpp
index b392195..37fc974 100644
--- a/minicc.cpp
+++ b/minicc.cpp
@@ -62,6 +62,13 @@ private:
  index_t last{};
 
 public:
+ void clear() {
+  nodes.clear();
+  root = 0;
+  last = 0;
+  node_num = 0;
+ }
+
  bool Valid(const std::string& Top) const {
   // A token is non empty
   if (node_num == 0)
@@ -298,38 +305,14 @@ private:
  std::map<std::string, std::set<std::string>> ReverseBNF;
 
  // to be called on token end
- void FinalizeCandidates(std::deque<Tree>& candidates, std::string& token, std::vector<std::string>& result)
+ void FinalizeTree(Tree& tree, std::string& token, std::vector<std::string>& result)
  {
-  if (candidates.empty()) { // skip
-   if (!token.empty())
-    throw std::runtime_error("Expected empty token, got "s + token);
-  } else { // check candidates
-   bool valid{false};
-   for (auto& ct : candidates) {
-    ct.Resolve(bnf, ReverseBNF);
-    if (ct.Valid(Top)) {
-     if (valid)
-      throw std::runtime_error("Found ambiguous token "s + token);
-     result.push_back(token);
-     token.clear();
-     valid = true;
-    }
-   }
-   if (!valid)
-    throw std::runtime_error("Invalid token: "s + token);
-
-   candidates.clear();
-  }
- }
-
- void AddCandidate(char c, std::deque<Tree>& candidates) {
-  // new candidate: starting with c
-  auto element {ReverseBNF.find(std::string(1, c))};
-  if (element != ReverseBNF.end()) {
-   Tree newTree;
-   if (newTree.Add(c, bnf, ReverseBNF))
-    candidates.push_back(newTree);
+  tree.Resolve(bnf, ReverseBNF);
+  if (tree.Valid(Top)) {
+   result.push_back(token);
+   token.clear();
   }
+  tree.clear();
  }
 
 public:
@@ -343,39 +326,27 @@ public:
   std::string token;
 
   std::string Whitespace{"\t \n\r"};
-  std::deque<Tree> candidates;
+  Tree tree;
 
   for (size_t pos{0}; pos < s.size(); pos++) {
    char c{s[pos]};
    std::cout << "Char: |" << c << "|" << std::endl;
    if (Whitespace.find(c) != std::string::npos) { // found whitespace character
     // evaluate token up to now and skip whitespace
-    FinalizeCandidates(candidates, token, result);
+    FinalizeTree(tree, token, result);
    } else { // no whitespace: try to add to tree
-    std::deque<index_t> EraseList;
-    int i = 0;
-    for (auto ct = candidates.begin(); ct != candidates.end(); ct++, i++) {
-     if (!ct->Add(c, bnf, ReverseBNF)) { // either add char or delete candidate
-      // push to front to get reversed order
-      EraseList.push_front(i); // no candidate anymore
-     }
-    }
-    
-    if (token.empty()) {
-     AddCandidate(c, candidates);
-    } else if (candidates.size() - EraseList.size() > 0) { // added to some candidates: Erase invalidated ones
-     for (const auto& i : EraseList)
-      candidates.erase(candidates.begin() + i);
-    } else { // no candidates left: new tree
-     FinalizeCandidates(candidates, token, result);
-     AddCandidate(c, candidates);
+    if (!tree.Add(c, bnf, ReverseBNF)) {
+     FinalizeTree(tree, token, result);
+     if (!tree.Add(c, bnf, ReverseBNF))
+      throw std::runtime_error("Parse error");
     }
+
     token.push_back(c);
    }
   }
 
   // Final evaluation of last token
-  FinalizeCandidates(candidates, token, result);
+  FinalizeTree(tree, token, result);
 
   return result;
  }
-- 
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