inlined ex::swap() and provided versions of iter_swap() for ex and expair

[ginac.git] / ginac / ex.h

diff --git a/ginac/ex.h b/ginac/ex.h
index c76290ff1ceb0a04a2dbdc21597d1e49ecffa8ca..f59cd7aea21b5486a3aee142067b0350d3487467 100644 (file)
--- a/ginac/ex.h
+++ b/ginac/ex.h
@@ -3,7 +3,7 @@
  *  Interface to GiNaC's light-weight expression handles. */
 
 /*
- *  GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2002 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -23,11 +23,12 @@
 #ifndef __GINAC_EX_H__
 #define __GINAC_EX_H__
 
+#include <iosfwd>
+#include <functional>
+
 #include "basic.h"
 #include "operators.h"
 
-#include <functional>
-
 namespace GiNaC {
 
 /** Helper class to initialize the library.  There must be one static object
@@ -96,7 +97,19 @@ public:
        
        // non-virtual functions in this class
 public:
-       void swap(ex & other);
+       /** Efficiently swap the contents of two expressions. */
+       void swap(ex & other)
+       {
+               GINAC_ASSERT(bp!=0);
+               GINAC_ASSERT(bp->flags & status_flags::dynallocated);
+               GINAC_ASSERT(other.bp!=0);
+               GINAC_ASSERT(other.bp->flags & status_flags::dynallocated);
+       
+               basic * tmpbp = bp;
+               bp = other.bp;
+               other.bp = tmpbp;
+       }
+
        void print(const print_context & c, unsigned level = 0) const;
        void printtree(std::ostream & os) const;
        void dbgprint(void) const;
@@ -343,6 +356,11 @@ bool ex::is_equal(const ex & other) const
 
 
 // utility functions
+
+/** Compare two objects of class quickly without doing a deep tree traversal.
+ *  @return "true" if they are equal
+ *          "false" if equality cannot be established quickly (e1 and e2 may
+ *          still be equal, in this case. */
 inline bool are_ex_trivially_equal(const ex &e1, const ex &e2)
 {
        return e1.bp == e2.bp;
@@ -451,6 +469,10 @@ inline bool is_zero(const ex & thisex)
 inline void swap(ex & e1, ex & e2)
 { e1.swap(e2); }
 
+// This makes STL algorithms use the more efficient swap operation for ex objects
+inline void iter_swap(std::vector<ex>::iterator i1, std::vector<ex>::iterator i2)
+{ i1->swap(*i2); }
+
 
 /* Function objects for STL sort() etc. */
 struct ex_is_less : public std::binary_function<ex, ex, bool> {