From fce1c18103f208857af477ca47af9aa908bd69b6 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Mon, 23 Mar 2020 22:02:40 +0100
Subject: Helper functions for grammer

---
 grammer.h | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

(limited to 'grammer.h')

diff --git a/grammer.h b/grammer.h
index ee2897d..e5c2f11 100644
--- a/grammer.h
+++ b/grammer.h
@@ -4,8 +4,11 @@
 #include "minicc.h"
 
 #include <cstdint>
+#include <unordered_set>
 #include <utility>
 
+class GrammerTest;
+
 namespace Gram {
 
 // TreeNodes are only intermediate. Terminal symbols don't get of TreeNodes
@@ -23,7 +26,6 @@ struct TreeNode {
 
 class Compiler
 {
-
 private:
  // The result
  index_t root_node_id{};
@@ -36,7 +38,7 @@ private:
  index_t tokens_used{0}; // number of tokens used, this is also the next token index to use
 
  BNF &bnf; // not const for access via operator[]
- const std::string& Top;
+ const std::string m_top;
 
  std::unordered_map<std::string, std::set<std::string>> ReverseBNF; // possible parent types of a given type; unused now: remove?
  std::unordered_map<std::string, std::set<std::string>> reversedFirst; // possible parent types of first childs of a given type
@@ -67,10 +69,19 @@ private:
  void AddPath(const std::vector<std::string>& path, index_t current_index);
  bool FillTree();
 
+ // top-down algorithm
+ std::unordered_map<std::string, size_t> m_min; // cache
+ size_t minimumSymbolsNeeded(std::string symbol);
+ size_t minimumSymbolsNeeded(std::vector<std::string> symbol_list);
+ bool match(std::string symbol, size_t begin, size_t end);
+ bool match(std::vector<std::string> symbol_list, size_t begin, size_t end);
+
 public:
- Compiler(BNF& bnf, const std::string& Top);
- std::pair<index_t, std::vector<TreeNode>> compile(std::vector<Token> Tokens);
+ Compiler(BNF& bnf, const std::string& top);
+ std::pair<index_t, std::vector<TreeNode>> compile(std::vector<Token> p_tokens);
  void DumpTree();
+
+ friend class ::GrammerTest;
 };
 
 bool ChildIdIsToken(int32_t child_id);
-- 
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