refactor: make the backend implementation more generic

[rkaminsk]

Pull request overview

Refactors backend handling to support additional backends by targeting a more generic/abstract program interface and refining step vs. grounding boundaries.

Changes

• Introduces begin_step(), end_ground(), and end_step() to separate “grounding step” from “solver step”.
• Updates output and parsing layers to use the new end_ground() lifecycle hook.
• Refactors solver backend implementation to forward to Potassco::AbstractProgram and updates theory backend wiring.

Changed Files

File	Description
lib/output/src/text.cc	Renames output lifecycle hook from do_end_step to do_end_ground.
lib/output/src/backend.cc	Renames lifecycle hook and performs end-of-ground translations for backend output.
lib/output/include/clingo/output/backend.hh	Changes TheoryData to reference a TheoryBackend instead of owning it.
lib/input/src/parse/aspif.cc	Updates aspif parsing to explicitly manage begin_step / end_ground / end_step.
lib/ground/tests/matcher.cc	Updates test stub output implementation for renamed hook.
lib/core/include/clingo/core/output.hh	Renames OutputStm::end_step() to end_ground() and updates virtual API.
lib/core/include/clingo/core/backend.hh	Splits backend finalization into begin_step, end_ground, and end_step; removes TheoryBackend::end().
lib/control/src/solver.cc	Refactors backend implementation to forward to Potassco::AbstractProgram and adapts solver/aspif integration to new lifecycle.
lib/control/src/grounder.cc	Switches grounder to call end_ground() after grounding.
lib/input/tests/aspif.cc	Adds tests for aspif parsing.

[Copilot]

Pull request overview

Refactors backend handling to support additional backends by targeting a more generic/abstract program interface and refining step vs. grounding boundaries.

Changes:

• Introduces begin_step(), end_ground(), and end_step() to separate “grounding step” from “solver step”.
• Updates output and parsing layers to use the new end_ground() lifecycle hook.
• Refactors solver backend implementation to forward to Potassco::AbstractProgram and updates theory backend wiring.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
lib/output/src/text.cc	Renames output lifecycle hook from do_end_step to do_end_ground.
lib/output/src/backend.cc	Renames lifecycle hook and performs end-of-ground translations for backend output.
lib/output/include/clingo/output/backend.hh	Changes TheoryData to reference a TheoryBackend instead of owning it.
lib/input/src/parse/aspif.cc	Updates aspif parsing to explicitly manage begin_step / end_ground / end_step.
lib/ground/tests/matcher.cc	Updates test stub output implementation for renamed hook.
lib/core/include/clingo/core/output.hh	Renames OutputStm::end_step() to end_ground() and updates virtual API.
lib/core/include/clingo/core/backend.hh	Splits backend finalization into begin_step, end_ground, and end_step; removes TheoryBackend::end().
lib/control/src/solver.cc	Refactors backend implementation to forward to Potassco::AbstractProgram and adapts solver/aspif integration to new lifecycle.
lib/control/src/grounder.cc	Switches grounder to call end_ground() after grounding.

Comments suppressed due to low confidence (1)

lib/output/src/backend.cc:1623

• OutputBackend::do_end_ground() finishes internal translations but never calls ProgramBackend::end_ground(). With the new backend interface, this means backends will not be notified when a grounding step completes. Call the underlying backend's end_ground() as part of this method (likely after the translations are flushed).

    void do_end_ground() override {
        bld_.compute_sccs();
        minimize_.tr(bld_);
        cond_lit_.tr(bld_);
        disjunction_.tr(bld_);
        min_.tr(bld_);
        max_.tr(bld_);
        sum_.tr(bld_);
        bld_.tr();
    }

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

@rkaminsk I've opened a new pull request, #597, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

Pull request overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

lib/output/include/clingo/output/backend.hh:142

• With the switch from std::unique_ptr<TheoryBackend> to TheoryBackend*, TheoryData becomes implicitly copyable again. Copying a TheoryData duplicates its internal id-generation state and caches, which can lead to duplicated ids being emitted to the same backend. Consider explicitly deleting the copy constructor/assignment (and possibly defining move semantics) to prevent accidental copies.

    SymbolStore *store_;
    TheoryBackend *backend_;
    Util::OutputBuffer buf_;
    StringMap strings_;
    NumMap nums_;
    FunMap funs_;
    TupMap tups_;
    ElemMap elems_;
    AtomMap atoms_;
    prg_id_t ids_ = 0;

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

@rkaminsk I've opened a new pull request, #598, to work on those changes. Once the pull request is ready, I'll request review from you.