From 808c9d678e7b1a05713387b7c12def5a60a1ada2 Mon Sep 17 00:00:00 2001
From: Chris Dams <Chris.Dams@mi.infn.it>
Date: Fri, 23 Jun 2006 12:56:39 +0000
Subject: [PATCH] Added calchash and compare_same_type for symmetries.
 Necessary for archiving.

---
 ginac/symmetry.cpp | 62 ++++++++++++++++++++++++++++++++++++++++++++--
 ginac/symmetry.h   |  1 +
 2 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/ginac/symmetry.cpp b/ginac/symmetry.cpp
index 96225e74..9cee0ffb 100644
--- a/ginac/symmetry.cpp
+++ b/ginac/symmetry.cpp
@@ -142,11 +142,69 @@ int symmetry::compare_same_type(const basic & other) const
 {
 	GINAC_ASSERT(is_a<symmetry>(other));
 
-	// All symmetry trees are equal. They are not supposed to appear in
-	// ordinary expressions anyway...
+	// For archiving purposes we need to have an ordering of symmetries.
+	const symmetry &othersymm = ex_to<symmetry>(other);
+
+	// Compare type.
+	if (type > othersymm.type)
+		return 1;
+	if (type < othersymm.type)
+		return -1;
+
+	// Compare the index set.
+	size_t this_size = indices.size();
+	size_t that_size = othersymm.indices.size();
+	if (this_size > that_size)
+		return 1;
+	if (this_size < that_size)
+		return -1;
+	typedef std::set<unsigned>::iterator set_it;
+	set_it end = indices.end();
+	for (set_it i=indices.begin(),j=othersymm.indices.begin(); i!=end; ++i,++j) {
+		if(*i < *j)
+			return 1;
+		if(*i > *j)
+			return -1;
+	}
+
+	// Compare the children.
+	if (children.size() > othersymm.children.size())
+		return 1;
+	if (children.size() < othersymm.children.size())
+		return -1;
+	for (size_t i=0; i<children.size(); ++i) {
+		int cmpval = ex_to<symmetry>(children[i])
+			.compare_same_type(ex_to<symmetry>(othersymm.children[i]));
+		if (cmpval)
+			return cmpval;
+	}
+
 	return 0;
 }
 
+unsigned symmetry::calchash() const
+{
+	unsigned v = golden_ratio_hash((p_int)tinfo());
+
+	if (type == none) {
+		v = rotate_left(v);
+		v ^= *(indices.begin());
+	} else {
+		for (exvector::const_iterator i=children.begin(); i!=children.end(); ++i)
+		{
+			v = rotate_left(v);
+			v ^= i->gethash();
+		}
+	}
+
+	if (flags & status_flags::evaluated) {
+		setflag(status_flags::hash_calculated);
+		hashvalue = v;
+	}
+
+	return v;
+}
+
 void symmetry::do_print(const print_context & c, unsigned level) const
 {
 	if (children.empty()) {
diff --git a/ginac/symmetry.h b/ginac/symmetry.h
index 3720ee72..4168013e 100644
--- a/ginac/symmetry.h
+++ b/ginac/symmetry.h
@@ -84,6 +84,7 @@ public:
 protected:
 	void do_print(const print_context & c, unsigned level) const;
 	void do_print_tree(const print_tree & c, unsigned level) const;
+	unsigned calchash() const;
 
 	// member variables
 private:
-- 
2.44.0