sketch cardinality plugin module

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/ast/card_decl_plugin.cpp

@@ -0,0 +1,72 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    card_decl_plugin.cpp
+
+Abstract:
+
+    Cardinality Constraints plugin
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2013-05-11
+
+Revision History:
+
+--*/
+
+#include "card_decl_plugin.h"
+
+card_decl_plugin::card_decl_plugin():
+    m_at_most_sym("at_most")
+{}
+
+func_decl * card_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters, parameter const * parameters, 
+                                           unsigned arity, sort * const * domain, sort * range) {
+    SASSERT(m_manager);
+    ast_manager& m = *m_manager;
+    for (unsigned i = 0; i < arity; ++i) {
+        if (!m.is_bool(domain[i])) {
+            m.raise_exception("invalid non-Boolean sort applied to 'at_most_k'");
+        }
+    }
+    if (num_parameters != 1 || !parameters[0].is_int() || parameters[0].get_int() < 0) {
+        m.raise_exception("function 'at_most_k' expects one non-negative integer parameter");
+    }
+    func_decl_info info(m_family_id, OP_AT_MOST_K, 1, parameters);
+    return m.mk_func_decl(m_at_most_sym, arity, domain, m.mk_bool_sort(), info);
+}
+
+void card_decl_plugin::get_op_names(svector<builtin_name> & op_names, symbol const & logic) {
+    if (logic == symbol::null) {
+        op_names.push_back(builtin_name("at-most-k", OP_AT_MOST_K));
+    }
+}
+
+
+app * card_util::mk_at_most_k(unsigned num_args, expr * const * args, unsigned k) {
+    parameter param(1);
+    return m.mk_app(m_fid, OP_AT_MOST_K, 1, &param, num_args, args, m.mk_bool_sort());
+}
+
+bool card_util::is_at_most_k(app *a) const {
+    return is_app_of(a, m_fid, OP_AT_MOST_K);
+}
+
+bool card_util::is_at_most_k(app *a, unsigned& k) const {
+    if (is_at_most_k(a)) {
+        k = get_k(a);
+        return true;
+    }
+    else {
+        return false;
+    }
+}
+
+unsigned card_util::get_k(app *a) const {
+    SASSERT(is_at_most_k(a));
+    return static_cast<unsigned>(a->get_decl()->get_parameter(0).get_int());
+}
+

src/ast/card_decl_plugin.h

@@ -0,0 +1,83 @@
+/*++
+Copyright (c) 2013 Microsoft Corporation
+
+Module Name:
+
+    card_decl_plugin.h
+
+Abstract:
+
+    Cardinality Constraints plugin
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2013-05-11
+
+Notes:
+
+
+  (at-most-k x1 .... x_n) means x1 + ... + x_n <= k
+ 
+hence:
+
+  (not (at-most-k x1 .... x_n)) means x1 + ... + x_n >= k + 1
+
+
+--*/
+#ifndef _CARD_DECL_PLUGIN_H_
+#define _CARD_DECL_PLUGIN_H_
+
+#include"ast.h"
+
+
+ 
+enum card_op_kind {
+    OP_AT_MOST_K,
+    LAST_CARD_OP
+};
+
+
+class card_decl_plugin : public decl_plugin {
+    symbol m_at_most_sym;
+    func_decl * mk_at_most(unsigned arity, unsigned k);
+public:
+    card_decl_plugin();
+    virtual ~card_decl_plugin() {}
+
+    virtual sort * mk_sort(decl_kind k, unsigned num_parameters, parameter const * parameters) {
+        UNREACHABLE();
+        return 0;
+    }
+
+    virtual decl_plugin * mk_fresh() {
+        return alloc(card_decl_plugin);
+    }
+    
+    //
+    // Contract for func_decl:
+    //   parameters[0] - integer (at most k elements)
+    //   all sorts are Booleans
+    virtual func_decl * mk_func_decl(decl_kind k, unsigned num_parameters, parameter const * parameters, 
+                                     unsigned arity, sort * const * domain, sort * range);
+    virtual void get_op_names(svector<builtin_name> & op_names, symbol const & logic);
+    virtual void get_sort_names(svector<builtin_name> & sort_names, symbol const & logic);
+    virtual expr * get_some_value(sort * s);
+    virtual bool is_fully_interp(sort const * s) const;
+};
+
+
+class card_util {
+    ast_manager & m;
+    family_id     m_fid;
+public:
+    card_util(ast_manager& m):m(m), m_fid(m.mk_family_id("card")) {}
+    ast_manager & get_manager() const { return m; }
+    app * mk_at_most_k(unsigned num_args, expr * const * args, unsigned k);
+    bool is_at_most_k(app *a) const;
+    bool is_at_most_k(app *a, unsigned& k) const;
+    unsigned get_k(app *a) const;
+};
+
+
+#endif /* _CARD_DECL_PLUGIN_H_ */
+