Add open variable lists

Makefile.in

@@ -323,7 +323,9 @@ INTSRC0 = \
 	int-set.cpp var-imp/int.cpp var-imp/bool.cpp var/int.cpp \
 	var/bool.cpp array.cpp bool.cpp bool/eqv.cpp \
 	extensional/dfa.cpp extensional/tuple-set.cpp \
-	extensional-regular.cpp extensional-tuple-set.cpp \
+	extensional-regular.cpp extensional-open-regular.cpp \
+	extensional-tuple-set.cpp \
+	open-var-list.cpp \
 	dom.cpp rel.cpp precede.cpp element.cpp count.cpp \
 	arithmetic.cpp exec.cpp \
 	exec/when.cpp element/pair.cpp \
@@ -348,6 +350,7 @@ INTSRC0 = \
 	exception.cpp
 
 INTHDR0 = \
+	open-var-list.hpp \
 	limits.hpp support-values.hh support-values.hpp \
 	idx-view.hh idx-view.hpp div.hh div.hpp \
 	exec.hh exec/when.hpp \
@@ -906,7 +909,7 @@ INTEXAMPLESRC0 =						\
 	word-square crossword open-shop car-sequencing sat      \
 	bin-packing knights tsp perfect-square schurs-lemma     \
 	dominating-queens colored-matrix multi-bin-packing	\
-	qcp job-shop
+	qcp job-shop open-route common-pattern fifteen-puzzle
 
 
 INTEXAMPLEHDR  = $(INTEXAMPLEHDR0:%=examples/%.hpp)
@@ -1119,7 +1122,7 @@ EXETARGETS = $(FLATZINCEXE) $(FLATZINCLAUNCHER)
 
 INTTESTSRC00 = \
 	channel arithmetic basic bool count dom distinct element extensional \
-	rel linear gcc sorted unshare exec sequence \
+	rel linear gcc sorted unshare exec sequence open-var-list \
 	mm-arithmetic mm-bool mm-lin mm-count mm-rel \
 	bin-packing order unary cumulative cumulatives circuit \
 	no-overlap precede nvalues member min-distance

changelog.in

@@ -73,6 +73,46 @@ Date: unreleased
 [DESCRIPTION]
 This is the development changelog for the next Gecode release.
 
+[ENTRY]
+Module: int
+What:   new
+Rank:   major
+[DESCRIPTION]
+Add OpenIntVarList and OpenBoolVarList for lists whose length is decided
+during propagation and search. OpenVarList supports other variable types
+through a factory. Constraints follow the growing prefix, including regular
+language constraints. Branching assigns prefix values before closing or
+extending the list, using standard variable and value selectors. Posting a
+brancher on the length first selects the length before list values. The
+common-pattern example demonstrates constrained frequent subsequence mining
+without padding, with support thresholds and integer database input;
+open-route provides a smaller introduction.
+Open-list factories and transitions run inside Space::NoGPI scopes by
+default, including transitions called by direct append. Callback-local
+Space::UseGPI scopes enable global information for selected postings;
+nested list construction starts its own NoGPI scope.
+
+[ENTRY]
+Module: kernel
+What:   new
+Rank:   minor
+[DESCRIPTION]
+Add Space::NoGPI for scoped posting without globally shared propagator
+information. Scoped propagators keep their identifiers and groups in the
+space, have zero AFC, and copy their information when cloned. Rewriting
+preserves the original propagator information. Space::UseGPI enables global
+information for selected posting calls inside a NoGPI scope. Both contexts
+restore the previous setting when they leave scope.
+
+[ENTRY]
+Module: int
+What:   bug
+Rank:   minor
+[DESCRIPTION]
+Fix iterator invalidation when counting-based search removes expired
+propagator cache entries. The invalid iterator could skip remaining entries
+and leave the brancher without a choice.
+
 [ENTRY]
 
 Module: int

cmake/GecodeSources.cmake

@@ -83,7 +83,9 @@ set(GECODE_INT_SOURCES
   gecode/int/exec.cpp
   gecode/int/exec/when.cpp
   gecode/int/extensional-regular.cpp
+  gecode/int/extensional-open-regular.cpp
   gecode/int/extensional-tuple-set.cpp
+  gecode/int/open-var-list.cpp
   gecode/int/extensional/dfa.cpp
   gecode/int/extensional/tuple-set.cpp
   gecode/int/gcc.cpp
@@ -426,6 +428,7 @@ set(GECODE_TEST_SOURCES
   test/int/no-overlap.cpp
   test/int/nvalues.cpp
   test/int/order.cpp
+  test/int/open-var-list.cpp
   test/int/precede.cpp
   test/int/rel.cpp
   test/int/sequence.cpp

examples/CMakeLists.txt

@@ -13,6 +13,7 @@ set(GECODE_EXAMPLE_SOURCES
   car-sequencing.cpp
   cartesian-heart.cpp
   colored-matrix.cpp
+  common-pattern.cpp
   crew.cpp
   crossword.cpp
   crowded-chess.cpp
@@ -22,6 +23,7 @@ set(GECODE_EXAMPLE_SOURCES
   donald.cpp
   efpa.cpp
   eq20.cpp
+  fifteen-puzzle.cpp
   golden-spiral.cpp
   golf.cpp
   golomb-ruler.cpp
@@ -40,6 +42,7 @@ set(GECODE_EXAMPLE_SOURCES
   money.cpp
   multi-bin-packing.cpp
   nonogram.cpp
+  open-route.cpp
   open-shop.cpp
   ortho-latin.cpp
   partition.cpp

examples/common-pattern.cpp

@@ -0,0 +1,251 @@
+/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
+/*
+ *  Main author:
+ *     Mikael Zayenz Lagerkvist <lagerkvist@gecode.dev>
+ *
+ *  Copyright:
+ *     Mikael Zayenz Lagerkvist, 2026
+ *
+ *  This file is part of Gecode, the generic constraint
+ *  development environment:
+ *     http://www.gecode.dev
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining
+ *  a copy of this software and associated documentation files (the
+ *  "Software"), to deal in the Software without restriction, including
+ *  without limitation the rights to use, copy, modify, merge, publish,
+ *  distribute, sublicense, and/or sell copies of the Software, and to
+ *  permit persons to whom the Software is furnished to do so, subject to
+ *  the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be
+ *  included in all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#include <gecode/driver.hh>
+
+#include "common-pattern.hh"
+
+#include <fstream>
+#include <memory>
+
+using namespace Gecode;
+
+/// Sequence database and restrictions on the patterns to mine
+class CommonPatternOptions : public Options {
+protected:
+  Driver::StringValueOption _sequences, _file, _support, _required;
+  Driver::StringOption _format, _language;
+  Driver::UnsignedIntOption _min_length;
+  Driver::BoolOption _motif;
+  std::unique_ptr<PatternMining::Database> input;
+  std::vector<int> required_items;
+  int threshold;
+public:
+  CommonPatternOptions(void)
+    : Options("CommonPattern"),
+      _sequences("sequences","comma-separated sequences over A..Z","ABCBC,BABC,ABDC"),
+      _file("file","sequence database; one sequence per line",""),
+      _support("support","minimum supporting sequences, as a percentage","100"),
+      _required("required","items that must occur, comma-separated letters or IDs",""),
+      _format("format","database format",PatternMining::LETTERS),
+      _language("language","pattern language",PatternMining::DEFAULT),
+      _min_length("min-length","minimum pattern length",1),
+      _motif("motif","default language starts with A and ends with C",true),
+      threshold(0) {
+    _format.add(PatternMining::LETTERS,"letters");
+    _format.add(PatternMining::INTEGERS,"integers");
+    _format.add(PatternMining::SPMF,"spmf");
+    _language.add(PatternMining::DEFAULT,"default","use -motif");
+    _language.add(PatternMining::NONE,"none");
+    _language.add(PatternMining::MOTIF,"motif");
+    _language.add(PatternMining::RE10,"re10");
+    _language.add(PatternMining::RE14,"re14");
+    _language.add(PatternMining::RE2,"re2");
+    add(_sequences); add(_file); add(_format); add(_support);
+    add(_min_length); add(_required); add(_language); add(_motif);
+  }
+
+  /// Validate external input before constructing a space
+  void read(void) {
+    if (_min_length.value() < 1 || _min_length.value() > Int::Limits::max)
+      throw std::invalid_argument("Minimum length must be a positive Gecode integer");
+    PatternMining::Sequences sequences;
+    const std::string filename(_file.value());
+    if (filename.empty()) {
+      if (_format.value() != PatternMining::LETTERS)
+        throw std::invalid_argument("Integer and SPMF formats require -file");
+      const std::string text(_sequences.value());
+      if (text.empty() || text.back() == ',')
+        throw std::invalid_argument("Expected comma-separated nonempty A..Z sequences");
+      std::istringstream stream(text);
+      std::string sequence;
+      while (std::getline(stream,sequence,','))
+        sequences.push_back(PatternMining::read_sequence(sequence,PatternMining::LETTERS));
+    } else {
+      std::ifstream stream(filename);
+      sequences = PatternMining::read_database(stream,
+        static_cast<PatternMining::Format>(_format.value()));
+    }
+    input.reset(new PatternMining::Database(sequences));
+    threshold = PatternMining::minimum_support(_support.value(),input->ends.size());
+    const std::string items(_required.value());
+    if (!items.empty()) {
+      if (items.back() == ',')
+        throw std::invalid_argument("Empty required item");
+      std::istringstream stream(items);
+      std::string item;
+      while (std::getline(stream,item,',')) {
+        const std::vector<int> parsed = PatternMining::read_sequence(item,
+          letters() ? PatternMining::LETTERS : PatternMining::INTEGERS);
+        if (parsed.size() != 1)
+          throw std::invalid_argument("Required items must be single letters or IDs");
+        required_items.push_back(parsed[0]);
+      }
+    }
+  }
+
+  const PatternMining::Database& database(void) const { return *input; }
+  const std::vector<int>& required(void) const { return required_items; }
+  int support(void) const { return threshold; }
+  int min_length(void) const { return static_cast<int>(_min_length.value()); }
+  bool letters(void) const { return _format.value() == PatternMining::LETTERS; }
+  PatternMining::Language language(void) const {
+    if (_language.value() == PatternMining::DEFAULT)
+      return _motif.value() ? PatternMining::MOTIF : PatternMining::NONE;
+    return static_cast<PatternMining::Language>(_language.value());
+  }
+};
+
+/**
+ * \brief %Example: constrained frequent subsequences of unknown length
+ *
+ * A pattern must occur in at least -support percent of the input sequences.
+ * Matching preserves order and may skip items; repeated items match distinct
+ * positions. Support counts records, including duplicate records, once each.
+ * By default the inputs ABCBC, BABC, ABDC must all support the pattern, which
+ * must start with A and end with C. AC and ABC are feasible; ABC is longest.
+ *
+ * The decision is an ordered list of items with unknown length. The frequency
+ * constraint requires sufficiently many records to contain that list as a
+ * subsequence. Ordinary length and regular constraints restrict the pattern:
+ * they do not restrict the matching positions in the input records. Default
+ * DFS enumerates every qualifying pattern; -search bab finds a longest one.
+ * These are different queries from closed, maximal, or top-k frequent mining.
+ *
+ * An OpenIntVarList constructs pattern positions as needed, without an end
+ * marker or unused suffix variables. Pattern languages therefore describe
+ * just the pattern, without padding transitions. The private frequency
+ * constraint maintains supporting suffixes after the assigned prefix and
+ * removes items with insufficient support. This prefix projection follows
+ * Kemmar et al., "PREFIX-PROJECTION Global Constraint for Sequential Pattern
+ * Mining", CP 2015, doi:10.1007/978-3-319-23219-5_17, with an additional
+ * remaining-suffix length bound. Projection is a filtering method, independent
+ * of the pattern's length, item and language restrictions. OpenRoute is the
+ * simpler introduction to open lists.
+ *
+ * The paper's Table 1 can be mined with:
+ * -sequences ABCBC,BABC,AB,BCD -support 50 -language none.
+ * -min-length and -required constrain length and item membership. -language
+ * also accepts motif (A, any items, C), re10, re14, re2 (comparison presets
+ * from the paper). Their letters mean item IDs A=1 through Z=26; integer data
+ * must use the corresponding mapping for these named expressions.
+ *
+ * -file reads one sequence per line in -format letters, integers, or spmf.
+ * Integer IDs are positive and preserved in output. SPMF records must have
+ * singleton itemsets: "1 -1 2 -1 3 -1 -2" is the sequence ABC. Multi-item
+ * itemsets are rejected because they define a different mining problem.
+ * No gap or time restrictions are supported. The comparison runner in
+ * misc/common-pattern/README.md uses identical mining queries across models.
+ *
+ * \ingroup Example
+ */
+class CommonPattern : public IntMaximizeScript {
+protected:
+  OpenIntVarList pattern;
+  IntVar frequency;
+  PatternMining::Database database;
+  bool letters;
+public:
+  enum { SEARCH_BAB, SEARCH_DFS };
+
+  CommonPattern(const CommonPatternOptions& opt)
+    : IntMaximizeScript(opt), database(opt.database()), letters(opt.letters()) {
+    pattern = OpenIntVarList(*this,database.domain(),database.max_length());
+    rel(*this,pattern.length(),IRT_GQ,opt.min_length());
+    frequency = PatternMining::frequent(*this,pattern,database,opt.support());
+    if (opt.language() != PatternMining::NONE)
+      extensional(*this,pattern,PatternMining::language(opt.language(),database));
+    if (!opt.required().empty()) {
+      REG alphabet(IntArgs(database.alphabet));
+      for (int item : opt.required())
+        extensional(*this,pattern,*alphabet + REG(item) + *alphabet);
+    }
+    branch(*this,pattern,INT_VAR_NONE(),INT_VAL_MIN());
+  }
+
+  virtual IntVar cost(void) const { return pattern.length(); }
+
+  CommonPattern(CommonPattern& s)
+    : IntMaximizeScript(s), database(s.database), letters(s.letters) {
+    pattern.update(*this,s.pattern);
+    frequency.update(*this,s.frequency);
+  }
+
+  virtual Space* copy(void) { return new CommonPattern(*this); }
+
+  virtual void print(std::ostream& os) const {
+    os << "\t";
+    for (int i=0; i<pattern.known_length(); i++) {
+      if (i && !letters)
+        os << ' ';
+      if (pattern[i].assigned()) {
+        const int item = pattern[i].val();
+        if (letters)
+          os << static_cast<char>('A'+item-1);
+        else
+          os << item;
+      } else {
+        os << pattern[i];
+      }
+    }
+    os << " (length " << pattern.length()
+       << ", support " << frequency << '/' << database.ends.size()
+       << ")" << std::endl;
+  }
+};
+
+/** \brief Main-function
+ *  \relates CommonPattern
+ */
+int
+main(int argc, char* argv[]) {
+  CommonPatternOptions opt;
+  opt.solutions(0);
+  opt.search(CommonPattern::SEARCH_DFS);
+  opt.search(CommonPattern::SEARCH_BAB,"bab","find a longest pattern");
+  opt.search(CommonPattern::SEARCH_DFS,"dfs","enumerate frequent patterns");
+  opt.parse(argc,argv);
+  try {
+    opt.read();
+  } catch (const std::invalid_argument& error) {
+    std::cerr << error.what() << std::endl;
+    return 1;
+  }
+  if (opt.search() == CommonPattern::SEARCH_DFS)
+    IntMaximizeScript::run<CommonPattern,DFS,CommonPatternOptions>(opt);
+  else
+    IntMaximizeScript::run<CommonPattern,BAB,CommonPatternOptions>(opt);
+  return 0;
+}
+
+// STATISTICS: example-any