From cd6c436cb70c4323c7d14ebd74f89bb0914649f2 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Tue, 31 Mar 2020 18:46:49 +0200
Subject: Optimization: Replace head recursion by tail recursion in matching

---
 lexer.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'lexer.cpp')

diff --git a/lexer.cpp b/lexer.cpp
index 0944738..a9cda32 100644
--- a/lexer.cpp
+++ b/lexer.cpp
@@ -85,14 +85,14 @@ void Lexer::addRule(const std::vector<std::string>& list, size_t list_index_from
  for (size_t i = list_index_from; i < list_index_to - 1; i++) {
   std::string symbol{list[i]};
   if (symbol == rule_symbol)
-   throw std::runtime_error("Recursion found but not allowed");
+   throw std::runtime_error("Recursion found but not allowed. Only head recursion allowed for lexer.");
 
   size_t state{newState()};
   addPathOrTransition(previousState, state, symbol);
   previousState = state;
  }
  if (list.back() == rule_symbol)
-  throw std::runtime_error("Recursion found but not allowed");
+  throw std::runtime_error("Tail recursion found but not allowed. Only head recursion allowed for lexer.");
 
  // last transition
  addPathOrTransition(previousState, state1, list.back());
-- 
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