extend getters on C API

cpp/include/cuopt/mathematical_optimization/constants.h

@@ -225,4 +225,36 @@
 #define CUOPT_BARRIER_ITERATIVE_REFINEMENT_OFF 0
 #define CUOPT_BARRIER_ITERATIVE_REFINEMENT_ON  1
 
+/* @brief Scalar problem attribute selectors
+ * Passed as cuopt_int_t; the valid set depends on the accessor's value type. */
+#define CUOPT_ATTR_NUM_VARIABLES             0
+#define CUOPT_ATTR_NUM_CONSTRAINTS           1
+#define CUOPT_ATTR_NUM_NONZEROS              2
+#define CUOPT_ATTR_NUM_INTEGERS              3
+#define CUOPT_ATTR_OBJECTIVE_SENSE           4
+#define CUOPT_ATTR_OBJECTIVE_OFFSET          5
+#define CUOPT_ATTR_OBJECTIVE_SCALING_FACTOR  6
+#define CUOPT_ATTR_PROBLEM_CATEGORY          7
+#define CUOPT_ATTR_IS_MIP                    8
+#define CUOPT_ATTR_HAS_QUADRATIC_OBJECTIVE   9
+#define CUOPT_ATTR_HAS_QUADRATIC_CONSTRAINTS 10
+
+/* @brief Numeric/char array problem attribute selectors
+ * (see cuOptGetProblem{Float,Char}ArrayAttribute; sized by num_variables / num_constraints).
+ * Passed as cuopt_int_t. Numbered in a separate range from the scalar selectors for safety.
+ */
+#define CUOPT_ARRAY_ATTR_OBJECTIVE_COEFFICIENTS  100
+#define CUOPT_ARRAY_ATTR_VARIABLE_LOWER_BOUNDS   101
+#define CUOPT_ARRAY_ATTR_VARIABLE_UPPER_BOUNDS   102
+#define CUOPT_ARRAY_ATTR_CONSTRAINT_LOWER_BOUNDS 103
+#define CUOPT_ARRAY_ATTR_CONSTRAINT_UPPER_BOUNDS 104
+#define CUOPT_ARRAY_ATTR_CONSTRAINT_RHS          105
+#define CUOPT_ARRAY_ATTR_CONSTRAINT_SENSE        106
+#define CUOPT_ARRAY_ATTR_VARIABLE_TYPES          107
+
+/* @brief String-array problem attribute selectors (see cuOptGetProblemStringArrayAttribute).
+ * Passed as cuopt_int_t; numbered in a separate range from the scalar and array selectors. */
+#define CUOPT_STRING_ARRAY_VARIABLE_NAMES 200
+#define CUOPT_STRING_ARRAY_ROW_NAMES      201
+
 #endif  // CUOPT_CONSTANTS_H

cpp/include/cuopt/mathematical_optimization/cuopt_c.h

@@ -563,7 +563,10 @@ cuopt_int_t cuOptGetObjectiveCoefficients(cuOptOptimizationProblem problem,
  */
 cuopt_int_t cuOptGetNumNonZeros(cuOptOptimizationProblem problem, cuopt_int_t* num_non_zeros_ptr);
 
-/** @brief Get the constraint matrix of an optimization problem in compressed sparse row format.
+/** @brief Get the linear constraint matrix of an optimization problem in compressed sparse row
+ * format. This is the matrix of the linear constraints only.
+ *
+ * @note **Deprecated:** Use ``cuOptGetConstraintMatrixCSR``.
  *
  * @param[in] problem - The optimization problem.
  *
@@ -586,6 +589,53 @@ cuopt_int_t cuOptGetConstraintMatrix(cuOptOptimizationProblem problem,
                                      cuopt_int_t* constraint_matrix_column_indices_ptr,
                                      cuopt_float_t* constraint_matrix_coefficients_ptr);
 
+/** @brief Get the linear constraint matrix of an optimization problem in compressed sparse row
+ * format. This is the matrix of the linear constraints only.
+ *
+ * @param[in] problem - The optimization problem.
+ *
+ * @param[out] constraint_matrix_row_offsets_ptr - A pointer to an array of type cuopt_int_t of size
+ *  num_constraints + 1 that on output will contain the row offsets of the constraint matrix.
+ *
+ * @param[out] constraint_matrix_column_indices_ptr - A pointer to an array of type cuopt_int_t of
+ *  size equal to the number of nonzeros that on output will contain the column indices of the
+ *  non-zero entries of the constraint matrix.
+ *
+ * @param[out] constraint_matrix_coefficients_ptr - A pointer to an array of type cuopt_float_t of
+ *  size equal to the number of nonzeros that on output will contain the coefficients of the
+ *  non-zero entries of the constraint matrix.
+ *
+ * @return A status code indicating success or failure.
+ */
+cuopt_int_t cuOptGetConstraintMatrixCSR(cuOptOptimizationProblem problem,
+                                        cuopt_int_t* constraint_matrix_row_offsets_ptr,
+                                        cuopt_int_t* constraint_matrix_column_indices_ptr,
+                                        cuopt_float_t* constraint_matrix_coefficients_ptr);
+
+/** @brief Get the linear constraint matrix of an optimization problem in compressed sparse column
+ * format. This is the matrix of the linear constraints only.
+ *
+ * @param[in] problem - The optimization problem.
+ *
+ * @param[out] constraint_matrix_column_offsets_ptr - A pointer to an array of type cuopt_int_t of
+ *  size num_variables + 1 (see cuOptGetProblemIntAttribute) that on output will contain the column
+ * offsets of the constraint matrix.
+ *
+ * @param[out] constraint_matrix_row_indices_ptr - A pointer to an array of type cuopt_int_t of size
+ *  equal to the number of nonzeros (see cuOptGetNumNonZeros) that on output will contain the row
+ *  indices of the non-zero entries of the constraint matrix.
+ *
+ * @param[out] constraint_matrix_coefficients_ptr - A pointer to an array of type cuopt_float_t of
+ *  size equal to the number of nonzeros that on output will contain the coefficients of the
+ *  non-zero entries of the constraint matrix.
+ *
+ * @return A status code indicating success or failure.
+ */
+cuopt_int_t cuOptGetConstraintMatrixCSC(cuOptOptimizationProblem problem,
+                                        cuopt_int_t* constraint_matrix_column_offsets_ptr,
+                                        cuopt_int_t* constraint_matrix_row_indices_ptr,
+                                        cuopt_float_t* constraint_matrix_coefficients_ptr);
+
 /** @brief Get the constraint sense of an optimization problem.
  *
  * @param[in] problem - The optimization problem.
@@ -1055,6 +1105,64 @@ cuopt_int_t cuOptGetDualObjectiveValue(cuOptSolution solution,
  */
 cuopt_int_t cuOptGetReducedCosts(cuOptSolution solution, cuopt_float_t* reduced_cost_ptr);
 
+/* -------------------------------------------------------------------------- */
+/* Generic problem attributes                                                 */
+/* -------------------------------------------------------------------------- */
+
+/*
+ * Attribute selectors are the CUOPT_ATTR_*, CUOPT_ARRAY_ATTR_*, and
+ * CUOPT_STRING_ARRAY_* integer constants defined in constants.h, passed as cuopt_int_t.
+ *
+ * These accessors use copy-out semantics: the caller allocates the output buffer and cuOpt copies
+ * values into it. Array attributes are sized by the problem dimensions: variable-indexed arrays
+ * have num_variables entries and constraint-indexed arrays have num_constraints entries (see
+ * cuOptGetProblemIntAttribute). The sole exception to copy-out is the
+ * string-array getter, which fills a caller-provided array of pointers with borrowed pointers into
+ * cuOpt-owned string storage; those pointers are valid until the problem is modified or destroyed
+ * and must not be freed.
+ *
+ * The constraint matrix is retrieved via cuOptGetConstraintMatrix (CSR) /
+ * cuOptGetConstraintMatrixCSC.
+ *
+ * TODO: there is no getter for the quadratic objective matrix (Q)
+ * or the quadratic constraint rows.
+ */
+
+/** @brief Get a scalar integer problem attribute (a CUOPT_ATTR_* with an integer value). */
+cuopt_int_t cuOptGetProblemIntAttribute(cuOptOptimizationProblem problem,
+                                        cuopt_int_t attribute,
+                                        cuopt_int_t* value_out);
+
+/** @brief Get a scalar floating-point problem attribute (objective offset / scaling factor). */
+cuopt_int_t cuOptGetProblemFloatAttribute(cuOptOptimizationProblem problem,
+                                          cuopt_int_t attribute,
+                                          cuopt_float_t* value_out);
+
+/** @brief Copy a floating-point array attribute into out. count must equal num_variables for
+ * variable-indexed attributes or num_constraints for constraint-indexed attributes (see
+ * cuOptGetProblemIntAttribute). */
+cuopt_int_t cuOptGetProblemFloatArrayAttribute(cuOptOptimizationProblem problem,
+                                               cuopt_int_t attribute,
+                                               cuopt_float_t* out,
+                                               cuopt_int_t count);
+
+/** @brief Copy a char array attribute (constraint sense or variable types) into out. count must
+ * equal num_constraints (constraint sense) or num_variables (variable types) (see
+ * cuOptGetProblemIntAttribute). */
+cuopt_int_t cuOptGetProblemCharArrayAttribute(cuOptOptimizationProblem problem,
+                                              cuopt_int_t attribute,
+                                              char* out,
+                                              cuopt_int_t count);
+
+/** @brief Fill a caller-provided array of `count` pointers with borrowed pointers to cuOpt-owned
+ * strings (CUOPT_STRING_ARRAY_VARIABLE_NAMES or _ROW_NAMES). count must equal
+ * num_variables or num_constraints respectively. The returned pointers are valid until the problem
+ * is modified or destroyed; do not free them. */
+cuopt_int_t cuOptGetProblemStringArrayAttribute(cuOptOptimizationProblem problem,
+                                                cuopt_int_t attribute,
+                                                const char** strings_out,
+                                                cuopt_int_t count);
+
 #ifdef __cplusplus
 }
 #endif