/* Part of the generic incremental SAT API called 'ipasir'.
 * See 'LICENSE' for rights to use this software.
 */
#ifndef ipasir_h_INCLUDED
#define ipasir_h_INCLUDED

/*
 * In this header, the macro IPASIR_API is defined as follows:
 * - if IPASIR_SHARED_LIB is not defined, then IPASIR_API is defined, but empty.
 * - if IPASIR_SHARED_LIB is defined...
 *    - ...and if BUILDING_IPASIR_SHARED_LIB is not defined, IPASIR_API is
 *      defined to contain symbol visibility attributes for importing symbols
 *      of a DSO (including the __declspec rsp. __attribute__ keywords).
 *    - ...and if BUILDING_IPASIR_SHARED_LIB is defined, IPASIR_API is defined
 *      to contain symbol visibility attributes for exporting symbols from a
 *      DSO (including the __declspec rsp. __attribute__ keywords).
 */

#if defined(IPASIR_SHARED_LIB)
    #if defined(_WIN32) || defined(__CYGWIN__)
        #if defined(BUILDING_IPASIR_SHARED_LIB)
            #if defined(__GNUC__)
                #define IPASIR_API __attribute__((dllexport))
            #elif defined(_MSC_VER)
                #define IPASIR_API __declspec(dllexport)
            #endif
        #else
            #if defined(__GNUC__)
                #define IPASIR_API __attribute__((dllimport))
            #elif defined(_MSC_VER)
                #define IPASIR_API __declspec(dllimport)
            #endif
        #endif
    #elif defined(__GNUC__)
        #define IPASIR_API __attribute__((visibility("default")))
    #endif

    #if !defined(IPASIR_API)
        #if !defined(IPASIR_SUPPRESS_WARNINGS)
            #warning "Unknown compiler. Not adding visibility information to IPASIR symbols."
            #warning "Define IPASIR_SUPPRESS_WARNINGS to suppress this warning."
        #endif
        #define IPASIR_API
    #endif
#else
    #define IPASIR_API
#endif

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Return the name and the version of the incremental SAT
 * solving library.
 */
IPASIR_API const char * ipasir_signature ();

/**
 * Construct a new solver and return a pointer to it.
 * Use the returned pointer as the first parameter in each
 * of the following functions.
 *
 * Required state: N/A
 * State after: INPUT
 */
IPASIR_API void * ipasir_init ();

/**
 * Release the solver, i.e., all its resoruces and
 * allocated memory (destructor). The solver pointer
 * cannot be used for any purposes after this call.
 *
 * Required state: INPUT or SAT or UNSAT
 * State after: undefined
 */
IPASIR_API void ipasir_release (void * solver);

/**
 * Add the given literal into the currently added clause
 * or finalize the clause with a 0.  Clauses added this way
 * cannot be removed. The addition of removable clauses
 * can be simulated using activation literals and assumptions.
 *
 * Required state: INPUT or SAT or UNSAT
 * State after: INPUT
 *
 * Literals are encoded as (non-zero) integers as in the
 * DIMACS formats.  They have to be smaller or equal to
 * INT_MAX and strictly larger than INT_MIN (to avoid
 * negation overflow).  This applies to all the literal
 * arguments in API functions.
 */
IPASIR_API void ipasir_add (void * solver, int lit_or_zero);

/**
 * Add an assumption for the next SAT search (the next call
 * of ipasir_solve). After calling ipasir_solve all the
 * previously added assumptions are cleared.
 *
 * Required state: INPUT or SAT or UNSAT
 * State after: INPUT
 */
IPASIR_API void ipasir_assume (void * solver, int lit);

/**
 * Solve the formula with specified clauses under the specified assumptions.
 * If the formula is satisfiable the function returns 10 and the state of the solver is changed to SAT.
 * If the formula is unsatisfiable the function returns 20 and the state of the solver is changed to UNSAT.
 * If the search is interrupted (see ipasir_set_terminate) the function returns 0 and the state of the solver is changed to INPUT.
 * This function can be called in any defined state of the solver. 
 * Note that the state of the solver _during_ execution of 'ipasir_solve' is undefined. 
 *
 * Required state: INPUT or SAT or UNSAT
 * State after: INPUT or SAT or UNSAT
 */
IPASIR_API int ipasir_solve (void * solver);

/**
 * Get the truth value of the given literal in the found satisfying
 * assignment. Return 'lit' if True, '-lit' if False; 
 * 'ipasir_val(lit)' may return '0' if the found assignment is satisfying for both valuations of lit. 
 * Each solution that agrees with all non-zero values of ipasir_val() is a model of the formula. 
 * 
 * This function can only be used if ipasir_solve has returned 10
 * and no 'ipasir_add' nor 'ipasir_assume' has been called
 * since then, i.e., the state of the solver is SAT.
 *
 * Required state: SAT
 * State after: SAT
 */
IPASIR_API int ipasir_val (void * solver, int lit);

/**
 * Check if the given assumption literal was used to prove the
 * unsatisfiability of the formula under the assumptions
 * used for the last SAT search. Return 1 if so, 0 otherwise.
 * 
 * The formula remains unsatisfiable even just under assumption literals for which ipasir_failed() returns 1. 
 * Note that for literals 'lit' which are not assumption literals, the behavior of 'ipasir_failed(lit)' is not specified. 
 * 
 * This function can only be used if ipasir_solve has returned 20 and
 * no ipasir_add or ipasir_assume has been called since then, i.e.,
 * the state of the solver is UNSAT.
 *
 * Required state: UNSAT
 * State after: UNSAT
 */
IPASIR_API int ipasir_failed (void * solver, int lit);

/**
 * Set a callback function used to indicate a termination requirement to the
 * solver. The solver will periodically call this function and check its return
 * value during the search. The ipasir_set_terminate function can be called in any
 * state of the solver, the state remains unchanged after the call.
 * The callback function is of the form "int terminate(void * data)"
 *   - it returns a non-zero value if the solver should terminate.
 *   - the solver calls the callback function with the parameter "data"
 *     having the value passed in the ipasir_set_terminate function (2nd parameter).
 *
 * Required state: INPUT or SAT or UNSAT
 * State after: INPUT or SAT or UNSAT
 */
IPASIR_API void ipasir_set_terminate (void * solver, void * data, int (*terminate)(void * data));

/**
 * Set a callback function used to extract learned clauses up to a given length from the
 * solver. The solver will call this function for each learned clause that satisfies
 * the maximum length (literal count) condition. The ipasir_set_learn function can be called in any
 * state of the solver, the state remains unchanged after the call.
 * The callback function is of the form "void learn(void * data, int * clause)"
 *   - the solver calls the callback function with the parameter "data"
 *     having the value passed in the ipasir_set_learn function (2nd parameter).
 *   - the argument "clause" is a pointer to a null terminated integer array containing the learned clause.
 *     the solver can change the data at the memory location that "clause" points to after the function call.
 *
 * Required state: INPUT or SAT or UNSAT
 * State after: INPUT or SAT or UNSAT
 */
IPASIR_API void ipasir_set_learn (void * solver, void * data, int max_length, void (*learn)(void * data, int * clause));

#ifdef __cplusplus
} // closing extern "C"
#endif

#endif