From fd332f979c4216a560925639ae99f2155ab56044 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Fri, 10 Dec 2010 18:28:49 +0000
Subject: Simplify if into nested 2-branch (scheme style) ifs at simplify
 stage.

git-svn-id: http://svn.drobilla.net/resp/resp@346 ad02d1e2-f140-0410-9f75-f8b11f17cedd
---
 src/simplify.cpp | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

(limited to 'src/simplify.cpp')

diff --git a/src/simplify.cpp b/src/simplify.cpp
index 31eb83a..35178ac 100644
--- a/src/simplify.cpp
+++ b/src/simplify.cpp
@@ -25,6 +25,34 @@
 
 using namespace std;
 
+static const AST*
+simplify_if(CEnv& cenv, const ATuple* aif) throw()
+{
+	List<ATuple, const AST> copy(aif->loc, cenv.penv.sym("if"), NULL);
+	copy.push_back(aif->list_ref(1));
+	copy.push_back(aif->list_ref(2));
+	
+	ATuple* tail = copy.tail;
+	ATuple::const_iterator i = aif->iter_at(3);
+	for (; ; ++i) {
+		ATuple::const_iterator next = i;
+		if (++next == aif->end())
+			break;
+
+		List<ATuple, const AST> inner_if((*i)->loc, cenv.penv.sym("if"), *i, *next, NULL);
+		tail->last(new ATuple(inner_if.head, NULL, Cursor()));
+		tail = inner_if.tail;
+
+		cenv.setTypeSameAs(inner_if, aif);
+
+		i = next; // jump 2 elements (to the next predicate)
+	}
+
+	tail->last(new ATuple(*i, NULL, Cursor()));
+	cenv.setTypeSameAs(copy, aif);
+	return copy;
+}
+
 static const AST*
 simplify_match(CEnv& cenv, const ATuple* match) throw()
 {
@@ -57,9 +85,8 @@ simplify_match(CEnv& cenv, const ATuple* match) throw()
 		copyIf.push_back(resp_simplify(cenv, body));
 	}
 	copyIf.push_back(cenv.penv.sym("__unreachable"));
-	copy.push_back(copyIf);
-
 	cenv.setTypeSameAs(copyIf, match);
+	copy.push_back(simplify_if(cenv, copyIf));
 	cenv.setTypeSameAs(copy, match);
 
 	return copy;
@@ -89,6 +116,8 @@ resp_simplify(CEnv& cenv, const AST* ast) throw()
 
 	if (form == "match")
 		return simplify_match(cenv, list);
+	else if (form == "if")
+		return simplify_if(cenv, list);
 	else
 		return simplify_list(cenv, list);
 }
-- 
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