Add parameter setting API and simplify presolve apply functions

[termoshtt]

Summary

New Feature: Parameter Setting API

• libpapilo_presolve_set_param_bool / set_param_int / set_param_double / parse_param
• libpapilo_param_result_t enum for proper error handling
  • LIBPAPILO_PARAM_OK, NOT_FOUND, WRONG_TYPE, INVALID_VALUE

API Cleanup

• Removed: libpapilo_presolve_apply (convenience function → can be implemented at higher layers)
• Removed: libpapilo_presolve_apply_simple (replaced by apply_full)
• Kept: libpapilo_presolve_apply_full (main presolve entry point)
• Kept: libpapilo_presolve_apply_reductions (low-level API)

Motivation

Enable fine-grained control over individual presolvers. This API allows enabling/disabling specific presolvers before running presolve.

Example Usage

libpapilo_presolve_t* presolve = libpapilo_presolve_create(message);
libpapilo_presolve_add_default_presolvers(presolve);

// Disable parallel column detection
libpapilo_param_result_t result = 
    libpapilo_presolve_set_param_bool(presolve, "parallelcols.enabled", 0);
if (result != LIBPAPILO_PARAM_OK) {
    // Handle error
}

// Run presolve with full output
libpapilo_postsolve_storage_t* postsolve = nullptr;
libpapilo_statistics_t* statistics = nullptr;
libpapilo_presolve_apply_full(presolve, problem, &postsolve, &statistics);

libpapilo_presolve_free(presolve);

Test Plan

• Parameter API tests (8 test cases)
  • set_param_bool, set_param_int, set_param_double, parse_param
  • Error cases (unknown key, parse error, before presolvers added)
• Behavioral test: verify parallelcols.enabled=0 actually prevents ParallelCol detection

Breaking Changes

• libpapilo_presolve_apply removed
• libpapilo_presolve_apply_simple removed

Migrate to libpapilo_presolve_apply_full if using these functions.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR extends the libpapilo C API to allow configuring presolve behavior via parameter keys on a user-managed presolve object, and adds a new “full output” presolve entry point suitable for downstream integrations that need to disable specific presolvers (e.g., parallelcols) before running presolve.

Changes:

• Add C API functions to set/parse presolve parameters (set_param_bool, set_param_int, set_param_double, parse_param).
• Add libpapilo_presolve_apply_full to run presolve using a caller-configured presolve object and return postsolve storage + statistics.
• Add a new Catch2 test suite covering the new APIs and a behavioral test for disabling parallelcols.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
src/libpapilo.h	Declares the new parameter-setting APIs and presolve_apply_full with added documentation.
src/libpapilo.cpp	Implements parameter-setting wrappers and the new presolve_apply_full entry point.
test/libpapilo/ParameterTest.cpp	Adds API-level tests and a behavioral test verifying parallelcols.enabled behavior.
test/libpapilo/CMakeLists.txt	Registers the new test file and its individual Catch2 test cases with CTest.

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[termoshtt]

@codex please review

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

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