From 39716aa1907e975f6e37adafe42d72d643223a98 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Fri, 17 Jan 2020 23:05:21 +0100
Subject: Separated out CheckCandidates

---
 minicc.cpp | 86 +++++++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 60 insertions(+), 26 deletions(-)

(limited to 'minicc.cpp')

diff --git a/minicc.cpp b/minicc.cpp
index e9bc918..b609477 100644
--- a/minicc.cpp
+++ b/minicc.cpp
@@ -21,7 +21,7 @@ std::vector<std::string> split(std::string s)
  std::vector<std::string> result;
  boost::algorithm::split(result, s, boost::algorithm::is_any_of(s), boost::algorithm::token_compress_on);
  while (result.size() > 0 && result.back() == ""s)
-   result.pop_back();
+  result.pop_back();
  return result;
 }
 
@@ -43,12 +43,43 @@ struct TreeNode {
  std::string name;
 };
 
-using Tree = std::map<index_t, TreeNode>;
+struct Tree {
+ std::map<index_t, TreeNode> nodes; // index 0 = non existing; index starting at 1
+ index_t node_num{};
+ index_t root{};
+ index_t last{};
 
-bool ValidTree(const Tree& tree) {
- // Start symbol?
- // All terminal symbols?
- return true; // TODO
+ bool Valid() const {
+  // Start symbol?
+  // All terminal symbols?
+  return true; // TODO
+ }
+
+  bool Add(char c) {
+   // TODO
+   //node_num ++;
+   //nodes.emplace(node_num, {});
+   return false;
+  }
+
+};
+
+void CheckCandidates(std::deque<Tree>& candidates, std::string& token, std::vector<std::string>& result)
+{
+ bool valid{false};
+ for (const auto& ct : candidates) {
+  if (ct.Valid()) {
+   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();
 }
 
 std::vector<std::string> Lex(std::string s, std::string Top, BNF bnf)
@@ -68,38 +99,41 @@ std::vector<std::string> Lex(std::string s, std::string Top, BNF bnf)
     if (!token.empty())
      throw std::runtime_error("Expected empty token, got "s + token);
    } else { // check candidates
-    bool valid{false};
-    for (const auto& ct : candidates) {
-     if (ValidTree(ct)) {
-      if (valid)
-       throw std::runtime_error("Found ambigous token");
-      result.push_back(token);
-      token.clear();
-      valid = true;
-     }
-    }
-    if (!valid)
-     throw std::runtime_error("Invalid token: "s + token);
-
-    candidates.clear();
+    CheckCandidates(candidates, token, result);
    }
   } else { // no whitespace: try to add to tree
-   for (auto& ct : candidates) {
-    EraseList;
-    if (!Add(ct, c)) {
-     EraseList.add(ct); // no candidate anymore
+   std::deque<index_t> EraseList;
+   int i = 0;
+   for (auto ct = candidates.begin(); ct != candidates.end(); ct++, i++) {
+    if (!ct->Add(c)) {
+     EraseList.push_front(i); // no candidate anymore
     }
    }
+   // new candidate: starting with c
+   auto element {ReverseBNF.find(std::string(1, c))};
+   if (element != ReverseBNF.end()) {
+    candidates.emplace_back();
+    candidates.back().Add(c);
+   }
 
    if (candidates.size() - EraseList.size() > 0) { // Added to some candidates: Continue growing token
     token.push_back(c);
-    candidates.erase(EraseList);
+    for (const auto& i : EraseList)
+     candidates.erase(candidates.begin() + i);
    } else { // no candidates left: new tree
-    // TODO: same as above "check candidates"
+    CheckCandidates(candidates, token, result);
    }
   }
  }
 
+ // Final evaluation
+ if (candidates.empty()) { // skip
+  if (!token.empty())
+   throw std::runtime_error("Expected empty token at end of input, got "s + token);
+ } else { // check candidates
+  CheckCandidates(candidates, token, result);
+ }
+
  return result;
 }
 
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