From 65642c1dad1138f4c72536b86123ffeefd33ba60 Mon Sep 17 00:00:00 2001
From: 魏曹先生 <1992414357@qq.com>
Date: Thu, 20 Aug 2026 03:49:21 +0800
Subject: feat(dispatch): add auto dispatch strategy selection
Introduce automatic dispatch strategy selection with three
mutually-exclusive features: `dispatch_linear`, `dispatch_tree`,
and `dispatch_phf`. When none are enabled, the generator picks
the optimal strategy at compile time based on command table shape.
Add CHD minimal perfect hash generator, refactor trie fallback
into a shared method to keep generated code linear, and add a
benchmark harness to validate strategy selection.
---
docs/dev/_sidebar.md | 10 +--
docs/dev/pages/issues/_modify-dispatcher-syntax.md | 2 +-
docs/dev/pages/issues/_remove-pack-macros.md | 2 +-
docs/dev/pages/issues/_remove-parser-feature.md | 2 +-
docs/dev/pages/issues/_remove-with-dispatcher.md | 2 +-
.../_t2_automated-dispatch-tree-optimization.md | 76 ++++++++++++++++++++++
.../t2_automated-dispatch-tree-optimization.md | 57 ----------------
7 files changed, 85 insertions(+), 66 deletions(-)
create mode 100644 docs/dev/pages/issues/_t2_automated-dispatch-tree-optimization.md
delete mode 100644 docs/dev/pages/issues/t2_automated-dispatch-tree-optimization.md
(limited to 'docs/dev')
diff --git a/docs/dev/_sidebar.md b/docs/dev/_sidebar.md
index e0a77d3..9ed13d1 100644
--- a/docs/dev/_sidebar.md
+++ b/docs/dev/_sidebar.md
@@ -1,18 +1,18 @@
- [Welcome!](README)
* ❓ Issues
* [[Solved] The Picker2 Arguments Parser](pages/issues/_add-picker2)
- * [[T1] Modify the dispatcher! Syntax](pages/issues/_modify-dispatcher-syntax)
- * [[T0] Remove the pack! Family of Macros](pages/issues/_remove-pack-macros)
- * [[T0] Remove the parser Feature](pages/issues/_remove-parser-feature)
+ * [[Solved] [T1] Modify the dispatcher! Syntax](pages/issues/_modify-dispatcher-syntax)
+ * [[Solved] [T0] Remove the pack! Family of Macros](pages/issues/_remove-pack-macros)
+ * [[Solved] [T0] Remove the parser Feature](pages/issues/_remove-parser-feature)
* [[Solved] Remove r_print! and r_println! Macros](pages/issues/_remove-r-print-macro)
- * [[T0] Remove with_dispatcher and with_dispatchers](pages/issues/_remove-with-dispatcher)
+ * [[Solved] [T0] Remove with_dispatcher and with_dispatchers](pages/issues/_remove-with-dispatcher)
+ * [[Solved] [T2] Automated dispatcher_tree Optimization Decisions](pages/issues/_t2_automated-dispatch-tree-optimization)
* [[Solved] The Command Macro](pages/issues/_the-command-macro)
* [[Solved] The Mod Pathfinder](pages/issues/_the-mod-pathfinder)
* [[T0] Generalize the REPL System](pages/issues/t0_generalize-repl-system)
* [[T1] Higher-Level Abstractions for the Completion System](pages/issues/t1_completion-higher-level-abstractions)
* [[T1] Move structural_renderer from mingling_core to mingling](pages/issues/t1_move-structural-renderer)
* [[T1] The pathf_export Attribute Macro](pages/issues/t1_pathf-export-macro)
- * [[T2] Automated dispatcher_tree Optimization Decisions](pages/issues/t2_automated-dispatch-tree-optimization)
* [The Next-Gen Mingling Pipeline](pages/issues/the-next-pipeline)
* [Some Situations Where You'd Be Like "Shit!"](pages/issues/the-shit-time)
* 💡 Abouts
diff --git a/docs/dev/pages/issues/_modify-dispatcher-syntax.md b/docs/dev/pages/issues/_modify-dispatcher-syntax.md
index ed409ef..cfee64b 100644
--- a/docs/dev/pages/issues/_modify-dispatcher-syntax.md
+++ b/docs/dev/pages/issues/_modify-dispatcher-syntax.md
@@ -1,4 +1,4 @@
-[T1] Modify the dispatcher! Syntax
+[Solved] [T1] Modify the dispatcher! Syntax
Breaking: drop the CMD* struct from the explicit form of dispatcher!
diff --git a/docs/dev/pages/issues/_remove-pack-macros.md b/docs/dev/pages/issues/_remove-pack-macros.md
index 74c21aa..153004e 100644
--- a/docs/dev/pages/issues/_remove-pack-macros.md
+++ b/docs/dev/pages/issues/_remove-pack-macros.md
@@ -1,4 +1,4 @@
-`[T0] Remove the pack! Family of Macros
+`[Solved] [T0] Remove the pack! Family of Macros
Breaking: retire the entire pack! family in favor of the Grouped derive
diff --git a/docs/dev/pages/issues/_remove-parser-feature.md b/docs/dev/pages/issues/_remove-parser-feature.md
index c2a11c0..7653c47 100644
--- a/docs/dev/pages/issues/_remove-parser-feature.md
+++ b/docs/dev/pages/issues/_remove-parser-feature.md
@@ -1,4 +1,4 @@
-[T0] Remove the parser Feature
+[Solved] [T0] Remove the parser Feature
Breaking: retire the legacy argument parsing in favor of picker
diff --git a/docs/dev/pages/issues/_remove-with-dispatcher.md b/docs/dev/pages/issues/_remove-with-dispatcher.md
index b0d972f..42b12e5 100644
--- a/docs/dev/pages/issues/_remove-with-dispatcher.md
+++ b/docs/dev/pages/issues/_remove-with-dispatcher.md
@@ -1,4 +1,4 @@
-[T0] Remove with_dispatcher and with_dispatchers
+[Solved] [T0] Remove with_dispatcher and with_dispatchers
Breaking: make Dispatcher registration compile-time collected in all modes
diff --git a/docs/dev/pages/issues/_t2_automated-dispatch-tree-optimization.md b/docs/dev/pages/issues/_t2_automated-dispatch-tree-optimization.md
new file mode 100644
index 0000000..d2e2473
--- /dev/null
+++ b/docs/dev/pages/issues/_t2_automated-dispatch-tree-optimization.md
@@ -0,0 +1,76 @@
+[Solved] [T2] Automated dispatcher_tree Optimization Decisions
+
+ Feature: let Mingling decide when dispatch_tree pays off (implemented)
+
+
+> [!NOTE]
+>
+> This item is **implemented**. It depends on [Remove with_dispatcher and with_dispatchers](t0_remove-with-dispatcher).
+
+## Background
+
+`dispatch_tree` provides a faster dispatch path, but it is not always a win. Currently users must manually enable the `dispatch_tree` feature and make the trade-off themselves.
+
+After dispatcher registration becomes compile-time collected (see [Remove with_dispatcher and with_dispatchers](t0_remove-with-dispatcher)), Mingling can know the full set and depth of registered commands at compile time — making automated decisions implementable.
+
+## Plan
+
+Mingling can automatically decide whether to use `dispatcher_tree` to optimize dispatch efficiency based on the current number and depth of registered commands, so users no longer need to manually enable the `dispatch_tree` feature.
+
+### Conditions
+
+`dispatch_tree` has an advantage in cases where command depth is too high and the number of commands is too large. However, if the number of commands is too small, the increased CPU prediction failure rate will inevitably make it less efficient than linear lookup; specifics need to be tuned during implementation.
+
+### Resolve the `pathf` + `dispatch_tree` build-dependency issue
+
+Additionally, the issue where `pathf` + `dispatch_tree` must be explicitly specified in `[build-dependencies]` will be resolved:
+
+```toml
+# Before
+[build-dependencies.mingling]
+version = "0.4.0"
+features = [ "build", "pathf", "dispatch_tree" ] # `dispatch_tree` must be explicitly specified for `pathf` to recognize it
+
+# After
+[build-dependencies.mingling]
+version = "0.4.0"
+features = [ "build", "pathf" ] # No `dispatch_tree` feature; `pathf` no longer needs to consider its branches
+```
+
+## Final Implementation
+
+The automated dispatch-strategy selection is now in place. A new `dispatch_auto` module (the default when no dispatch feature is enabled) picks at macro-expansion time from three strategies — **linear list**, **char trie**, and **perfect hash** — based on a cost model calibrated against the `dev/bench/dispatch` benchmark matrix.
+
+### Two new dispatch features
+
+In addition to the existing `dispatch_tree`, two new mutually-exclusive features now exist:
+
+- **`dispatch_linear`** — force linear longest-prefix list (the former default).
+- **`dispatch_phf`** — force a CHD minimal perfect hash (constant-time lookup, O(1) code size).
+- **`dispatch_tree`** — force the char-level trie.
+- **(none)** — **auto mode**: pick the best strategy from the command table.
+
+Enabling more than one triggers a `compile_error!`.
+
+### Auto-selection heuristic
+
+`dispatch_auto::select_strategy` inspects the normalized command table (names, depth, nesting) and picks:
+
+- **deep nested chains at modest sizes** (`max_words ≥ 8`, `n ≤ 128`) → linear list (short memcmps beat the trie's per-level char walk plus fallback calls);
+- **single-word tables with long names** (avg_len ≥ 16–24) → perfect hash (one hash beats the char walk);
+- **small tables** (`n ≤ 64`) → linear vs trie by an internal cost model;
+- **everything else** → char trie (O(depth) hits, linear code size after the fallback-chain refactor).
+
+The heuristic is empirical and may drift as the benchmark matrix grows.
+
+### Benchmark harness
+
+A workspace-internal harness `dev/bench/dispatch` (`cargo dispatch-bench`) measures all four strategies across a `len×count×type` matrix (4/8/16/32 × 128/256 × single/multi/nested4/nested10), reporting per-cell ns/op for hits and misses, geometric means, and how often auto matches the per-cell best / stays within 5%.
+
+### Trie code-size fix
+
+The trie generator was rewritten so the longest-prefix fallback is a single shared `__trie_fallback` method (called, not inlined, per arm) rather than inlined into every arm. This keeps generated code linear in the table size — a 1024×16 nested table previously emitted ~13 MB of tokens.
+
+
+ Written by @Weicao-CatilGrass
+
diff --git a/docs/dev/pages/issues/t2_automated-dispatch-tree-optimization.md b/docs/dev/pages/issues/t2_automated-dispatch-tree-optimization.md
deleted file mode 100644
index 691fd1a..0000000
--- a/docs/dev/pages/issues/t2_automated-dispatch-tree-optimization.md
+++ /dev/null
@@ -1,57 +0,0 @@
-[T2] Automated dispatcher_tree Optimization Decisions
-
- Feature: let Mingling decide when dispatch_tree pays off (under consideration)
-
-
-> [!NOTE]
->
-> This item is **under consideration**. It depends on [Remove with_dispatcher and with_dispatchers](t0_remove-with-dispatcher).
-
-## Background
-
-`dispatch_tree` provides a faster dispatch path, but it is not always a win. Currently users must manually enable the `dispatch_tree` feature and make the trade-off themselves.
-
-After dispatcher registration becomes compile-time collected (see [Remove with_dispatcher and with_dispatchers](t0_remove-with-dispatcher)), Mingling can know the full set and depth of registered commands at compile time — making automated decisions implementable.
-
-## Plan
-
-Mingling can automatically decide whether to use `dispatcher_tree` to optimize dispatch efficiency based on the current number and depth of registered commands, so users no longer need to manually enable the `dispatch_tree` feature.
-
-### Conditions
-
-`dispatch_tree` has an advantage in cases where command depth is too high and the number of commands is too large. However, if the number of commands is too small, the increased CPU prediction failure rate will inevitably make it less efficient than linear lookup; specifics need to be tuned during implementation.
-
-### Resolve the `pathf` + `dispatch_tree` build-dependency issue
-
-Additionally, the issue where `pathf` + `dispatch_tree` must be explicitly specified in `[build-dependencies]` will be resolved:
-
-```toml
-# Before
-[build-dependencies.mingling]
-version = "0.4.0"
-features = [ "build", "pathf", "dispatch_tree" ] # `dispatch_tree` must be explicitly specified for `pathf` to recognize it
-
-# After
-[build-dependencies.mingling]
-version = "0.4.0"
-features = [ "build", "pathf" ] # No `dispatch_tree` feature; `pathf` no longer needs to consider its branches
-```
-
-## Tasks
-
-- [ ] Collect statistics about registered commands (count, depth) at compile time
-- [ ] Benchmark / tune the threshold between linear lookup and `dispatch_tree`
-- [ ] Implement the automatic decision and wire it into dispatch code generation
-- [ ] Remove the manual `dispatch_tree` feature toggle (or keep it as an override?)
-- [ ] Refactor `pathf` so it no longer branches on `dispatch_tree`
-- [ ] Update examples, tests, and docs
-
-## 🕘 Progress
-
-- [ ] Under Consideration
-- [ ] In Progress
-- [ ] Complete
-
-
- Written by @Weicao-CatilGrass
-
--
cgit