extend getters on C API

cpp/include/cuopt/mathematical_optimization/constants.h

@@ -214,4 +214,41 @@
 #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
+/* NOTE: HAS_QUADRATIC_OBJECTIVE / HAS_QUADRATIC_CONSTRAINTS report presence only. The quadratic
+ * objective matrix (Q) and quadratic constraint data are not currently retrievable through any
+ * getter */
+
+/* @brief Numeric/char array problem attribute selectors
+ * (see cuOptGetProblem{Float,Char}ArrayAttribute; sized by num_variables / num_constraints).
+ * The constraint matrix is retrieved via cuOptGetConstraintMatrix / cuOptGetConstraintMatrixCSC,
+ * not through these selectors. Passed as cuopt_int_t. Numbered in a separate range from the scalar
+ * selectors so a selector from the wrong family fails validation (there is no compile-time type).
+ */
+#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 +563,9 @@ 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; quadratic constraint terms (if any)
+ * are not included.
  *
  * @param[in] problem - The optimization problem.
  *
@@ -586,6 +588,31 @@ 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 column
+ * format. This is the matrix of the linear constraints only; quadratic constraint terms (if any)
+ * are not included.
+ *
+ * @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 cuOptGetNumVariables) 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 +1082,65 @@ 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
+ * cuOptGetNumVariables / cuOptGetNumConstraints). 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: quadratic data is not yet retrievable. CUOPT_ATTR_HAS_QUADRATIC_OBJECTIVE and
+ * CUOPT_ATTR_HAS_QUADRATIC_CONSTRAINTS report presence only; 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
+ * cuOptGetNumVariables / cuOptGetNumConstraints). */
+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
+ * cuOptGetNumConstraints / cuOptGetNumVariables). */
+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

cpp/src/pdlp/CMakeLists.txt

@@ -35,6 +35,7 @@ set(LP_CORE_FILES
 set(LP_ADAPTER_FILES
   ${CMAKE_CURRENT_SOURCE_DIR}/utilities/cython_solve.cu
   ${CMAKE_CURRENT_SOURCE_DIR}/cuopt_c.cpp
+  ${CMAKE_CURRENT_SOURCE_DIR}/cuopt_c_attributes.cpp
 )
 
 # Choose which files to include based on build mode