* of any interest to the user of the library. */
/*
- * GiNaC Copyright (C) 1999-2008 Johannes Gutenberg University Mainz, Germany
+ * GiNaC Copyright (C) 1999-2019 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
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
-#ifndef __GINAC_UTILS_H__
-#define __GINAC_UTILS_H__
+#ifndef GINAC_UTILS_H
+#define GINAC_UTILS_H
-#include "config.h"
+#include "assertion.h"
-#include <string>
#include <functional>
-
-#include "assertion.h"
+#include <cstdint> // for uintptr_t
+#include <string>
namespace GiNaC {
unsigned log2(unsigned n);
/** Rotate bits of unsigned value by one bit to the left.
- * This can be necesary if the user wants to define its own hashes. */
+ * This can be necessary if the user wants to define its own hashes. */
inline unsigned rotate_left(unsigned n)
{
return (n & 0x80000000U) ? (n << 1 | 0x00000001U) : (n << 1);
return 0;
}
-#if SIZEOF_VOID_P == SIZEOF_INT
-typedef unsigned int p_int;
-#elif SIZEOF_VOID_P == SIZEOF_LONG
-typedef unsigned long p_int;
-#elif SIZEOF_VOID_P == SIZEOF_LONG_LONG
-typedef unsigned long long p_int;
-#else
-typedef unsigned long p_int;
-#endif
-
/** Truncated multiplication with golden ratio, for computing hash values. */
-inline unsigned golden_ratio_hash(p_int n)
+inline unsigned golden_ratio_hash(uintptr_t n)
{
- // This function works much better when fast arithmetic with at
- // least 64 significant bits is available.
-#if SIZEOF_LONG >= 8
- // So 'long' has 64 bits. Excellent! We prefer it because it might be
- // more efficient than 'long long'.
- unsigned long l = n * 0x4f1bbcddUL;
- return (unsigned)l;
-#elif SIZEOF_LONG_LONG >= 8
- // This requires 'long long' (or an equivalent 64 bit type)---which is,
- // unfortunately, not ANSI-C++-compliant.
- // (Yet C99 demands it, which is reason for hope.)
- unsigned long long l = n * 0x4f1bbcddULL;
- return (unsigned)l;
-#else
- // Without a type with 64 significant bits do the multiplication manually
- // by splitting n up into the lower and upper two bytes.
- const unsigned n0 = (n & 0x0000ffffU);
- const unsigned n1 = (n & 0xffff0000U) >> 16;
- return (n0 * 0x0000bcddU) + ((n1 * 0x0000bcddU + n0 * 0x00004f1bU) << 16);
-#endif
+ return n * UINT64_C(0x4f1bbcdd);
}
/* Compute the sign of a permutation of a container, with and without an
template <class It>
int permutation_sign(It first, It last)
{
+ using std::swap;
if (first == last)
return 0;
--last;
bool swapped = false;
while (i != first) {
if (*i < *other) {
- std::iter_swap(other, i);
+ swap(*other, *i);
flag = other;
swapped = true;
sign = -sign;
} else if (!(*other < *i))
return 0;
- --i; --other;
+ --i;
+ if (i != first)
+ --other;
}
if (!swapped)
return sign;
swapped = false;
while (i != last) {
if (*other < *i) {
- std::iter_swap(i, other);
+ swap(*i, *other);
flag = other;
swapped = true;
sign = -sign;
} else if (!(*i < *other))
return 0;
- ++i; ++other;
+ ++i;
+ if (i != last)
+ ++other;
}
if (!swapped)
return sign;
sign = -sign;
} else if (!comp(*other, *i))
return 0;
- --i; --other;
+ --i;
+ if (i != first)
+ --other;
}
if (!swapped)
return sign;
sign = -sign;
} else if (!comp(*i, *other))
return 0;
- ++i; ++other;
+ ++i;
+ if (i != last)
+ ++other;
}
if (!swapped)
return sign;
flag = other;
swapped = true;
}
- --i; --other;
+ --i;
+ if (i != first)
+ --other;
}
if (!swapped)
return;
flag = other;
swapped = true;
}
- ++i; ++other;
+ ++i;
+ if (i != last)
+ ++other;
}
if (!swapped)
return;
}
}
+/** Base class for generating all bounded combinatorial partitions of an integer
+ * n with exactly m parts in non-decreasing order.
+ */
+class basic_partition_generator {
+protected:
+ // Partitions n into m parts, not including zero parts.
+ // (Cf. OEIS sequence A008284; implementation adapted from Jörg Arndt's
+ // FXT library)
+ struct mpartition2
+ {
+ // partition: x[1] + x[2] + ... + x[m] = n and sentinel x[0] == 0
+ std::vector<unsigned> x;
+ unsigned n; // n>0
+ unsigned m; // 0<m<=n
+ mpartition2(unsigned n_, unsigned m_)
+ : x(m_+1), n(n_), m(m_)
+ {
+ for (unsigned k=1; k<m; ++k)
+ x[k] = 1;
+ x[m] = n - m + 1;
+ }
+ bool next_partition()
+ {
+ unsigned u = x[m]; // last element
+ unsigned k = m;
+ unsigned s = u;
+ while (--k) {
+ s += x[k];
+ if (x[k] + 2 <= u)
+ break;
+ }
+ if (k==0)
+ return false; // current is last
+ unsigned f = x[k] + 1;
+ while (k < m) {
+ x[k] = f;
+ s -= f;
+ ++k;
+ }
+ x[m] = s;
+ return true;
+ }
+ };
+ mpartition2 mpgen;
+ basic_partition_generator(unsigned n_, unsigned m_)
+ : mpgen(n_, m_)
+ { }
+};
+
+/** Generate all bounded combinatorial partitions of an integer n with exactly
+ * m parts (including zero parts) in non-decreasing order.
+ */
+class partition_with_zero_parts_generator : public basic_partition_generator {
+private:
+ unsigned m; // number of parts 0<m
+ mutable std::vector<unsigned> partition; // current partition
+ mutable bool current_updated; // whether partition vector has been updated
+public:
+ partition_with_zero_parts_generator(unsigned n_, unsigned m_)
+ : basic_partition_generator(n_, 1), m(m_), partition(m_), current_updated(false)
+ { }
+ // returns current partition in non-decreasing order, padded with zeros
+ const std::vector<unsigned>& get() const
+ {
+ if (!current_updated) {
+ for (unsigned i = 0; i < m - mpgen.m; ++i)
+ partition[i] = 0; // pad with zeros
+
+ for (unsigned i = m - mpgen.m; i < m; ++i)
+ partition[i] = mpgen.x[i - m + mpgen.m + 1];
+
+ current_updated = true;
+ }
+ return partition;
+ }
+ bool next()
+ {
+ current_updated = false;
+ if (!mpgen.next_partition()) {
+ if (mpgen.m == m || mpgen.m == mpgen.n)
+ return false; // current is last
+ // increment number of parts
+ mpgen = mpartition2(mpgen.n, mpgen.m + 1);
+ }
+ return true;
+ }
+};
+
+/** Generate all bounded combinatorial partitions of an integer n with exactly
+ * m parts (not including zero parts) in non-decreasing order.
+ */
+class partition_generator : public basic_partition_generator {
+private:
+ mutable std::vector<unsigned> partition; // current partition
+ mutable bool current_updated; // whether partition vector has been updated
+public:
+ partition_generator(unsigned n_, unsigned m_)
+ : basic_partition_generator(n_, m_), partition(m_), current_updated(false)
+ { }
+ // returns current partition in non-decreasing order, padded with zeros
+ const std::vector<unsigned>& get() const
+ {
+ if (!current_updated) {
+ for (unsigned i = 0; i < mpgen.m; ++i)
+ partition[i] = mpgen.x[i + 1];
+
+ current_updated = true;
+ }
+ return partition;
+ }
+ bool next()
+ {
+ current_updated = false;
+ return mpgen.next_partition();
+ }
+};
+
+/** Generate all compositions of a partition of an integer n, starting with the
+ * compositions which has non-decreasing order.
+ */
+class composition_generator {
+private:
+ // Generates all distinct permutations of a multiset.
+ // (Based on Aaron Williams' algorithm 1 from "Loopless Generation of
+ // Multiset Permutations using a Constant Number of Variables by Prefix
+ // Shifts." <http://webhome.csc.uvic.ca/~haron/CoolMulti.pdf>)
+ struct coolmulti {
+ // element of singly linked list
+ struct element {
+ unsigned value;
+ element* next;
+ element(unsigned val, element* n)
+ : value(val), next(n) {}
+ ~element()
+ { // recurses down to the end of the singly linked list
+ delete next;
+ }
+ };
+ element *head, *i, *after_i;
+ // NB: Partition must be sorted in non-decreasing order.
+ explicit coolmulti(const std::vector<unsigned>& partition)
+ : head(nullptr), i(nullptr), after_i(nullptr)
+ {
+ for (unsigned n = 0; n < partition.size(); ++n) {
+ head = new element(partition[n], head);
+ if (n <= 1)
+ i = head;
+ }
+ after_i = i->next;
+ }
+ ~coolmulti()
+ { // deletes singly linked list
+ delete head;
+ }
+ void next_permutation()
+ {
+ element *before_k;
+ if (after_i->next != nullptr && i->value >= after_i->next->value)
+ before_k = after_i;
+ else
+ before_k = i;
+ element *k = before_k->next;
+ before_k->next = k->next;
+ k->next = head;
+ if (k->value < head->value)
+ i = k;
+ after_i = i->next;
+ head = k;
+ }
+ bool finished() const
+ {
+ return after_i->next == nullptr && after_i->value >= head->value;
+ }
+ } cmgen;
+ bool atend; // needed for simplifying iteration over permutations
+ bool trivial; // likewise, true if all elements are equal
+ mutable std::vector<unsigned> composition; // current compositions
+ mutable bool current_updated; // whether composition vector has been updated
+public:
+ explicit composition_generator(const std::vector<unsigned>& partition)
+ : cmgen(partition), atend(false), trivial(true), composition(partition.size()), current_updated(false)
+ {
+ for (unsigned i=1; i<partition.size(); ++i)
+ trivial = trivial && (partition[0] == partition[i]);
+ }
+ const std::vector<unsigned>& get() const
+ {
+ if (!current_updated) {
+ coolmulti::element* it = cmgen.head;
+ size_t i = 0;
+ while (it != nullptr) {
+ composition[i] = it->value;
+ it = it->next;
+ ++i;
+ }
+ current_updated = true;
+ }
+ return composition;
+ }
+ bool next()
+ {
+ // This ugly contortion is needed because the original coolmulti
+ // algorithm requires code duplication of the payload procedure,
+ // one before the loop and one inside it.
+ if (trivial || atend)
+ return false;
+ cmgen.next_permutation();
+ current_updated = false;
+ atend = cmgen.finished();
+ return true;
+ }
+};
+
+/** Compute the multinomial coefficient n!/(p1!*p2!*...*pk!) where
+ * n = p1+p2+...+pk, i.e. p is a partition of n.
+ */
+const numeric
+multinomial_coefficient(const std::vector<unsigned> & p);
+
// Collection of `construct on first use' wrappers for safely avoiding
// internal object replication without running into the `static
// Helper macros for class implementations (mostly useful for trivial classes)
#define DEFAULT_CTOR(classname) \
-classname::classname() : inherited(&classname::tinfo_static) { setflag(status_flags::evaluated | status_flags::expanded); }
-
-#define DEFAULT_UNARCHIVE(classname) \
-ex classname::unarchive(const archive_node &n, lst &sym_lst) \
-{ \
- return (new classname(n, sym_lst))->setflag(status_flags::dynallocated); \
-}
-
-#define DEFAULT_ARCHIVING(classname) \
-classname::classname(const archive_node &n, lst &sym_lst) : inherited(n, sym_lst) {} \
-DEFAULT_UNARCHIVE(classname) \
-void classname::archive(archive_node &n) const \
-{ \
- inherited::archive(n); \
-}
+classname::classname() { setflag(status_flags::evaluated | status_flags::expanded); }
#define DEFAULT_COMPARE(classname) \
int classname::compare_same_type(const basic & other) const \
} // namespace GiNaC
-
-#endif // ndef __GINAC_UTILS_H__
+#endif // ndef GINAC_UTILS_H
git://www.ginac.de / ginac.git / blobdiff