math-opt: add CPLEX solver backend

ortools/math_opt/BUILD.bazel

@@ -1,4 +1,4 @@
-# Copyright 2010-2025 Google LLC
+# Copyright 2010-2026 Google LLC
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
@@ -127,6 +127,7 @@ proto_library(
     srcs = ["parameters.proto"],
     deps = [
         "//ortools/glop:parameters_proto",
+        "//ortools/math_opt/solvers:cplex_proto",
         "//ortools/math_opt/solvers:glpk_proto",
         "//ortools/math_opt/solvers:gurobi_proto",
         "//ortools/math_opt/solvers:highs_proto",

ortools/math_opt/cpp/parameters.cc

@@ -1,4 +1,4 @@
-// Copyright 2010-2025 Google LLC
+// Copyright 2010-2026 Google LLC
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -88,6 +88,8 @@ std::optional<absl::string_view> Enum<SolverType>::ToOptString(
       return "santorini";
     case SolverType::kXpress:
       return "xpress";
+    case SolverType::kCplex:
+      return "cplex";
   }
   return std::nullopt;
 }
@@ -97,7 +99,7 @@ absl::Span<const SolverType> Enum<SolverType>::AllValues() {
       SolverType::kGscip,     SolverType::kGurobi, SolverType::kGlop,
       SolverType::kCpSat,     SolverType::kPdlp,   SolverType::kGlpk,
       SolverType::kEcos,      SolverType::kScs,    SolverType::kHighs,
-      SolverType::kSantorini, SolverType::kXpress,
+      SolverType::kSantorini, SolverType::kXpress, SolverType::kCplex,
   };
   return absl::MakeConstSpan(kSolverTypeValues);
 }
@@ -234,6 +236,59 @@ XpressParameters XpressParameters::FromProto(
   return result;
 }
 
+CplexParametersProto CplexParameters::Proto() const {
+  CplexParametersProto result;
+  for (const auto& [key, val] : param_double_values) {
+    auto* p = result.add_parameters()->mutable_parameter_double();
+    p->set_name(key);
+    p->set_value(val);
+  }
+  for (const auto& [key, val] : param_bool_values) {
+    auto* p = result.add_parameters()->mutable_parameter_bool();
+    p->set_name(key);
+    p->set_value(val);
+  }
+  for (const auto& [key, val] : param_int32_values) {
+    auto* p = result.add_parameters()->mutable_parameter_int32();
+    p->set_name(key);
+    p->set_value(val);
+  }
+  for (const auto& [key, val] : param_int64_values) {
+    auto* p = result.add_parameters()->mutable_parameter_int64();
+    p->set_name(key);
+    p->set_value(val);
+  }
+  for (const auto& [key, val] : param_string_values) {
+    auto* p = result.add_parameters()->mutable_parameter_string();
+    p->set_name(key);
+    p->set_value(val);
+  }
+  return result;
+}
+
+CplexParameters CplexParameters::FromProto(const CplexParametersProto& proto) {
+  CplexParameters result;
+  for (const CplexParametersProto::Parameter& p : proto.parameters()) {
+    if (p.has_parameter_double()) {
+      result.param_double_values[p.parameter_double().name()] =
+          p.parameter_double().value();
+    } else if (p.has_parameter_bool()) {
+      result.param_bool_values[p.parameter_bool().name()] =
+          p.parameter_bool().value();
+    } else if (p.has_parameter_int32()) {
+      result.param_int32_values[p.parameter_int32().name()] =
+          p.parameter_int32().value();
+    } else if (p.has_parameter_int64()) {
+      result.param_int64_values[p.parameter_int64().name()] =
+          p.parameter_int64().value();
+    } else if (p.has_parameter_string()) {
+      result.param_string_values[p.parameter_string().name()] =
+          p.parameter_string().value();
+    }
+  }
+  return result;
+}
+
 SolveParametersProto SolveParameters::Proto() const {
   SolveParametersProto result;
   result.set_enable_output(enable_output);
@@ -287,6 +342,7 @@ SolveParametersProto SolveParameters::Proto() const {
   *result.mutable_glpk() = glpk.Proto();
   *result.mutable_highs() = highs;
   *result.mutable_xpress() = xpress.Proto();
+  *result.mutable_cplex() = cplex.Proto();
   return result;
 }
 
@@ -347,6 +403,7 @@ absl::StatusOr<SolveParameters> SolveParameters::FromProto(
   result.glpk = GlpkParameters::FromProto(proto.glpk());
   result.highs = proto.highs();
   result.xpress = XpressParameters::FromProto(proto.xpress());
+  result.cplex = CplexParameters::FromProto(proto.cplex());
   return result;
 }
 

ortools/math_opt/cpp/parameters.h

@@ -1,4 +1,4 @@
-// Copyright 2010-2025 Google LLC
+// Copyright 2010-2026 Google LLC
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -28,6 +28,7 @@
 #include "ortools/glop/parameters.pb.h"  // IWYU pragma: export
 #include "ortools/math_opt/cpp/enums.h"  // IWYU pragma: export
 #include "ortools/math_opt/parameters.pb.h"
+#include "ortools/math_opt/solvers/cplex.pb.h"        // IWYU pragma: export
 #include "ortools/math_opt/solvers/gscip/gscip.pb.h"  // IWYU pragma: export
 #include "ortools/math_opt/solvers/gurobi.pb.h"       // IWYU pragma: export
 #include "ortools/math_opt/solvers/highs.pb.h"        // IWYU pragma: export
@@ -114,6 +115,12 @@ enum class SolverType {
   // Supports LP, MIP, and nonconvex integer quadratic problems.
   // A fast option, but has special licensing.
   kXpress = SOLVER_TYPE_XPRESS,
+
+  // IBM ILOG CPLEX solver (third party).
+  //
+  // Supports LP, MIP problems (other types are unimplemented).
+  // A fast option, but has special licensing.
+  kCplex = SOLVER_TYPE_CPLEX,
 };
 
 MATH_OPT_DEFINE_ENUM(SolverType, SOLVER_TYPE_UNSPECIFIED);
@@ -292,6 +299,23 @@ struct XpressParameters {
   bool empty() const { return param_values.empty(); }
 };
 
+struct CplexParameters {
+  absl::linked_hash_map<std::string, double> param_double_values;
+  absl::linked_hash_map<std::string, bool> param_bool_values;
+  absl::linked_hash_map<std::string, int32_t> param_int32_values;
+  absl::linked_hash_map<std::string, int64_t> param_int64_values;
+  absl::linked_hash_map<std::string, std::string> param_string_values;
+
+  CplexParametersProto Proto() const;
+  static CplexParameters FromProto(const CplexParametersProto& proto);
+
+  bool empty() const {
+    return param_double_values.empty() && param_bool_values.empty() &&
+           param_int32_values.empty() && param_int64_values.empty() &&
+           param_string_values.empty();
+  }
+};
+
 // Parameters to control a single solve.
 //
 // Contains both parameters common to all solvers, e.g. time_limit, and
@@ -466,6 +490,7 @@ struct SolveParameters {
   GlpkParameters glpk;
   HighsOptionsProto highs;
   XpressParameters xpress;
+  CplexParameters cplex;
 
   SolveParametersProto Proto() const;
   static absl::StatusOr<SolveParameters> FromProto(

ortools/math_opt/parameters.proto

@@ -1,4 +1,4 @@
-// Copyright 2010-2025 Google LLC
+// Copyright 2010-2026 Google LLC
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
@@ -19,6 +19,7 @@ package operations_research.math_opt;
 import "google/protobuf/duration.proto";
 import "ortools/pdlp/solvers.proto";
 import "ortools/glop/parameters.proto";
+import "ortools/math_opt/solvers/cplex.proto";
 import "ortools/math_opt/solvers/glpk.proto";
 import "ortools/math_opt/solvers/gscip/gscip.proto";
 import "ortools/math_opt/solvers/gurobi.proto";
@@ -115,6 +116,12 @@ enum SolverTypeProto {
   // Supports LP, MIP, and nonconvex integer quadratic problems.
   // A fast option, but has special licensing.
   SOLVER_TYPE_XPRESS = 13;
+
+  // IBM ILOG CPLEX solver (third party).
+  //
+  // Supports LP, MIP. (other problem-types are unimplemented)
+  // A fast option, but has special licensing.
+  SOLVER_TYPE_CPLEX = 14;
 }
 
 // Selects an algorithm for solving linear programs.
@@ -179,6 +186,7 @@ message SolverInitializerProto {
   GurobiInitializerProto gurobi = 1;
   reserved 2;
   XpressInitializerProto xpress = 3;
+  CplexInitializerProto cplex = 4;
 }
 
 // Parameters to control a single solve.
@@ -381,5 +389,7 @@ message SolveParametersProto {
 
   XpressParametersProto xpress = 28;
 
+  CplexParametersProto cplex = 29;
+
   reserved 11;  // Deleted
 }

ortools/math_opt/python/init_arguments.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright 2010-2025 Google LLC
+# Copyright 2010-2026 Google LLC
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
@@ -129,6 +129,11 @@ class StreamableHighsInitArguments:
     """Streamable Highs specific parameters for solver instantiation."""
 
 
+@dataclasses.dataclass
+class StreamableCplexInitArguments:
+    """Streamable Cplex specific parameters for solver instantiation."""
+
+
 @dataclasses.dataclass
 class StreamableSantoriniInitArguments:
     """Streamable Santorini specific parameters for solver instantiation."""
@@ -150,6 +155,7 @@ class StreamableSolverInitArguments:
       scs: Initialization parameters specific to SCS.
       highs: Initialization parameters specific to HiGHS.
       santorini: Initialization parameters specific to Santorini.
+      cplex: Initialization parameters specific to Cplex.
     """
 
     gscip: Optional[StreamableGScipInitArguments] = None
@@ -163,6 +169,7 @@ class StreamableSolverInitArguments:
     scs: Optional[StreamableScsInitArguments] = None
     highs: Optional[StreamableHighsInitArguments] = None
     santorini: Optional[StreamableSantoriniInitArguments] = None
+    cplex: Optional[StreamableCplexInitArguments] = None
 
     def to_proto(self) -> parameters_pb2.SolverInitializerProto:
         """Returns a protocol buffer equivalent of this."""

ortools/math_opt/python/mathopt.py

@@ -71,14 +71,15 @@
     parse_objective_parameters, parse_solution_hint)
 from ortools.math_opt.python.objectives import AuxiliaryObjective, Objective
 from ortools.math_opt.python.parameters import (Emphasis, GlpkParameters,
-                                                GurobiParameters, LPAlgorithm,
+                                                GurobiParameters, CplexParameters, LPAlgorithm,
                                                 SolveParameters, SolverType,
                                                 emphasis_from_proto,
                                                 emphasis_to_proto,
                                                 lp_algorithm_from_proto,
                                                 lp_algorithm_to_proto,
                                                 parse_glpk_parameters,
                                                 parse_gurobi_parameters,
+                                                parse_cplex_parameters,
                                                 parse_solve_parameters,
                                                 solver_type_from_proto,
                                                 solver_type_to_proto)