From e40d45d3bbeda09cc1f42b4d8abfa4e75c55ade9 Mon Sep 17 00:00:00 2001
From: Chris Dams <Chris.Dams@mi.infn.it>
Date: Thu, 1 Mar 2007 14:43:33 +0000
Subject: [PATCH] Faster archiving by adding a map from strings to idices in
 the atoms vector.

---
 ginac/archive.cpp | 19 ++++++++++---------
 ginac/archive.h   |  5 +++++
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/ginac/archive.cpp b/ginac/archive.cpp
index 8280e429..e08aaafb 100644
--- a/ginac/archive.cpp
+++ b/ginac/archive.cpp
@@ -272,8 +272,10 @@ std::istream &operator>>(std::istream &is, archive &ar)
 	// Read atoms
 	unsigned num_atoms = read_unsigned(is);
 	ar.atoms.resize(num_atoms);
-	for (unsigned i=0; i<num_atoms; i++)
+	for (unsigned i=0; i<num_atoms; i++) {
 		getline(is, ar.atoms[i], '\0');
+		ar.inverse_atoms[ar.atoms[i]] = i;
+	}
 
 	// Read expressions
 	unsigned num_exprs = read_unsigned(is);
@@ -297,17 +299,15 @@ std::istream &operator>>(std::istream &is, archive &ar)
  *  represents the string). */
 archive_atom archive::atomize(const std::string &s) const
 {
-	// Search for string in atoms vector
-	std::vector<std::string>::const_iterator i = atoms.begin(), iend = atoms.end();
-	archive_atom id = 0;
-	while (i != iend) {
-		if (*i == s)
-			return id;
-		i++; id++;
-	}
+	// Search for string in inverse_atoms map.
+	inv_at_cit i = inverse_atoms.find(s);
+	if (i!=inverse_atoms.end())
+		return i->second;
 
 	// Not found, add to atoms vector
+	archive_atom id = atoms.size();
 	atoms.push_back(s);
+	inverse_atoms[s] = id;
 	return id;
 }
 
@@ -540,6 +540,7 @@ ex archive_node::unarchive(lst &sym_lst) const
 void archive::clear()
 {
 	atoms.clear();
+	inverse_atoms.clear();
 	exprs.clear();
 	nodes.clear();
 	exprtable.clear();
diff --git a/ginac/archive.h b/ginac/archive.h
index dafbb38c..1d60f531 100644
--- a/ginac/archive.h
+++ b/ginac/archive.h
@@ -242,6 +242,11 @@ public:
 private:
 	/** Vector of atomized strings (using a vector allows faster unarchiving). */
 	mutable std::vector<std::string> atoms;
+	/** The map of from strings to indices of the atoms vectors allows for
+	 *  faster archiving.
+	 */
+	typedef std::map<std::string, archive_atom>::const_iterator inv_at_cit;
+	mutable std::map<std::string, archive_atom> inverse_atoms;
 
 	/** Map of stored expressions to nodes for faster archiving */
 	typedef std::map<ex, archive_node_id, ex_is_less>::iterator mapit;
-- 
2.44.0