From 0dde43edac6817c3f0a237d25c2054c0ee75926c Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Mon, 23 Feb 2015 19:03:16 +0100
Subject: Added binary incrementer state table to Turing machine example *
 reintroduced `BLANK` as the _BLANK_ symbol * fixed implicit tape expansion in
 `tape::readSymbol`

---
 example/turing/src/tape.h | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

(limited to 'example/turing/src/tape.h')

diff --git a/example/turing/src/tape.h b/example/turing/src/tape.h
index 39814d8..4f79bd9 100644
--- a/example/turing/src/tape.h
+++ b/example/turing/src/tape.h
@@ -10,6 +10,12 @@ namespace machine {
 
 namespace tape {
 
+struct BLANK {
+	typedef BLANK type;
+
+	static constexpr char value{'\0'};
+};
+
 // (define (readSymbol position tape)
 //   (if (= (length tape) position)
 //       '()
@@ -18,11 +24,11 @@ template <
 	typename Position,
 	typename Tape
 >
-using readSymbol = tav::If<
-	tav::IsEqualValue<tav::Length<Tape>, Position>,
-	void,
-	tav::Nth<Position, Tape>
->;
+using readSymbol = tav::Eval<tav::If<
+	tav::LowerThan<Position, tav::Length<Tape>>,
+	tav::utility::defer_eval<tav::Nth, Position, Tape>,
+	BLANK
+>>;
 
 // (define (writeSymbol position symbol tape)
 //   (if (= (length tape) position)
-- 
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