feat(wam-c): T9 fact-table inline (backtrackable, default in-range, capped) - #3300
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feat(wam-c): T9 fact-table inline (backtrackable, default in-range, capped)#3300s243a wants to merge 1 commit into
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…apped) Brings the Rust/F# T9 fact-table work to the C WAM target. The C target already emitted a static row table + first-arg bucket index, but its scan was deterministic (returned only the first matching row). T9 makes the in-window fact lowering backtrackable so every matching row is enumerated, and adds the t9 window / opt-out / oversized semantics around it. Policy (mirrors Rust/F#): an all-ground-facts predicate (arity >= 1) whose row count is in [t9_min_rows, t9_max_rows] (defaults 64..256) lowers to the backtrackable fact-table handler by default. Opt out with fact_table_inline(false); below t9_min_rows keeps the cheap deterministic scanner; above t9_max_rows declines + warns (steer to an external fact source). Mechanism (mirrors the runtime's disjunction side-stack CP): - Runtime (wam_runtime.h): WAM_FACT_TABLE_RETRY sentinel; WamFactTableFrame side-stack (flattened row table ptr + candidate indices + pos + arity + return_pc) saved/restored/pruned alongside disj_top in the ChoicePoint; a shared static-inline wam_fact_table_scan that, on a match, leaves a choice point for the remaining candidates before binding, so backtracking yields the next row. wam_run dispatches WAM_FACT_TABLE_RETRY to wam_resume_fact_table. - Emitter (wam_c_target.pl): wam_c_fact_table_classify + thresholds + wam_c_maybe_warn_oversized_facts; a fact_table(Rows) plan gated ahead of the deterministic fact_only branch in plan_wam_c_lowered_helper (Options now threaded through); wam_c_fact_table_helper_for_predicate emits the row table + bucket index (reused) and a handler that derefs the first arg, picks the bucket (or full scan) and drives wam_fact_table_scan. Registered as a foreign predicate, so it is reachable as a query and from another predicate unchanged. Tests: test_wam_c_fact_table_exec.pl (gcc-gated; query-mode matrix (+,-)/(-,+)/(-,-)/(+,+)/absent-key enumerated by forcing backtracking -> ALL 6 PASS) and test_wam_c_fact_table_emit.pl (planner gating, opt-out, below-min, above-cap+warning, value literals, emitted scan). Existing C target suite stays green. Matrix: add a `c` row, T9 ✓ capped. https://claude.ai/code/session_013gLfigNMgCkxybbp7m6fXw
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What
Brings T9 fact-table inline to the C WAM target (after Rust and F#).
Key difference from the other targets: C already had a static row table + first-arg bucket index + a per-row unify scan — but the scan was deterministic (returned only the first matching row, so
edge(a,X)over multipleafacts yielded just one solution). T9 makes the in-window fact lowering backtrackable so every matching row is enumerated, and adds the t9 window / opt-out / oversized policy around it.Policy (mirrors Rust/F#)
An all-ground-facts predicate (arity ≥ 1) whose row count is in
[t9_min_rows, t9_max_rows](defaults 64..256) lowers to the backtrackable fact-table handler by default. Opt out withfact_table_inline(false); belowt9_min_rowskeeps the cheap deterministic scanner; abovet9_max_rowsdeclines + warns (steer to an external fact source).Mechanism (mirrors the runtime's disjunction side-stack choice point)
wam_runtime.h): aWAM_FACT_TABLE_RETRYsentinel; aWamFactTableFrameside-stack (flattened row-table pointer + candidate index array + position + arity + return PC) saved/restored/pruned alongsidedisj_topin theChoicePoint; a sharedstatic inline wam_fact_table_scanthat, on a match, leaves a choice point for the remaining candidates before binding so backtracking yields the next row.wam_rundispatchesWAM_FACT_TABLE_RETRY→wam_resume_fact_table. (Made the scan a headerstatic inlineso both the generated handlers and the resume function can call it across translation units.)wam_c_target.pl):wam_c_fact_table_classify+ thresholds +wam_c_maybe_warn_oversized_facts; afact_table(Rows)plan gated ahead of the deterministicfact_onlybranch inplan_wam_c_lowered_helper(Options now threaded through the planner);wam_c_fact_table_helper_for_predicatereuses the existing row table + bucket index and emits a handler that derefs the first arg, picks the bucket (or full scan) and driveswam_fact_table_scan. Registered through the same foreign-predicate path as today's facts, so it's reachable as a query and from another predicate with zero dispatch changes.Tests
tests/test_wam_c_fact_table_exec.pl(gcc-gated): builds a project and a C driver that enumerates all solutions per arg mode by forcing backtracking (acollect/2foreign that records bindings and fails). Verifies(+,-)index lookup →[1,2,4]in source order,(-,+)value-bound scan →[b],(-,-)→ all 6,(+,+)membership, and absent-key → 0. ALL 6 PASS (exit-code assertions).tests/test_wam_c_fact_table_emit.pl(fast): planner gating (default→fact_table, opt-out/below-min/above-cap→fact_only), oversized warning, classifier, emitted scan + row table + bucket switch, value literals.Matrix: adds a
crow (the matrix previously had none), T9 = ✓ capped.🤖 Generated with Claude Code
https://claude.ai/code/session_013gLfigNMgCkxybbp7m6fXw
Generated by Claude Code