- implemented object fusion as proposed by Richy

[ginac.git] / ginac / ex.h

diff --git a/ginac/ex.h b/ginac/ex.h
index 38dcf732f29f23203c6b1de8be57e01aabbd1d93..ee891a2fb9c431e0c66f7440a00ad5bc74c6e654 100644 (file)
--- a/ginac/ex.h
+++ b/ginac/ex.h
@@ -304,11 +304,11 @@ public:
        ex numer_denom() const;
 
        // polynomial algorithms
-       ex unit(const symbol &x) const;
-       ex content(const symbol &x) const;
+       ex unit(const ex &x) const;
+       ex content(const ex &x) const;
        numeric integer_content() const;
-       ex primpart(const symbol &x) const;
-       ex primpart(const symbol &x, const ex &cont) const;
+       ex primpart(const ex &x) const;
+       ex primpart(const ex &x, const ex &cont) const;
        ex smod(const numeric &xi) const { return bp->smod(xi); }
        numeric max_coefficient() const;
 
@@ -345,6 +345,7 @@ private:
        static basic & construct_from_double(double d);
        static ptr<basic> construct_from_string_and_lst(const std::string &s, const ex &l);
        void makewriteable();
+       void share(const ex & other) const;
 
 #ifdef OBSCURE_CINT_HACK
 public:
@@ -368,7 +369,7 @@ protected:
 // member variables
 
 private:
-       ptr<basic> bp;      ///< pointer to basic object managed by this
+       mutable ptr<basic> bp;  ///< pointer to basic object managed by this
 
 #ifdef OBSCURE_CINT_HACK
 public:
@@ -481,7 +482,14 @@ int ex::compare(const ex & other) const
 {
        if (bp == other.bp)  // trivial case: both expressions point to same basic
                return 0;
-       return bp->compare(*other.bp);
+       const int cmpval = bp->compare(*other.bp);
+       if (cmpval == 0) {
+               // Expressions point to different, but equal, trees: conserve
+               // memory and make subsequent compare() operations faster by
+               // making both expression point to the same tree.
+               share(other);
+       }
+       return cmpval;
 }
 
 inline