decomp3: more engine stuff, fix ja macro detection for jak 2/3, unmerged let matcher, part-tracker-spawn macro (#3436)

- `aligner`
- `effect-control`
- `pov-camera`
- `powerups`
- `los-control-h`
- `airlock`
- `water-anim`
- `blocking-plane`
- `proc-focusable-spawner`
- `idle-control`
- `enemy-h`
- `nav-enemy-h`
- `enemy`
- `enemy-states`
- `particle-curves`
- `base-plat`
- `plat`
- `bouncer`
- `elevator`
- `rigid-body`
- `rigid-body-queue`
- `process-taskable`
- `scene-actor`
- `warp-gate`
- `guard-projectile`
- `metalhead-projectile`
- `los-control`
- `joint-exploder`
- `ragdoll-test`
- `debris`
- `shield-sphere`
- `text`
- `target-launch`

decompiler/IR2/GenericElementMatcher.cpp

@@ -243,6 +243,15 @@ Matcher Matcher::let(bool is_star,
   return m;
 }
 
+Matcher Matcher::unmerged_let(const std::vector<LetEntryMatcher>& entries,
+                              const std::vector<Matcher>& elts) {
+  Matcher m;
+  m.m_kind = Kind::UNMERGED_LET;
+  m.m_entry_matchers = entries;
+  m.m_sub_matchers = elts;
+  return m;
+}
+
 bool Matcher::do_match(Form* input, MatchResult::Maps* maps_out, const Env* const env) const {
   switch (m_kind) {
     case Kind::ANY:
@@ -722,6 +731,64 @@ bool Matcher::do_match(Form* input, MatchResult::Maps* maps_out, const Env* cons
       return false;
     }
 
+    case Kind::UNMERGED_LET: {
+      auto as_let = dynamic_cast<LetElement*>(input->try_as_single_active_element());
+      if (as_let) {
+        size_t entries_matched = 0;
+        Form* innermost_let_body = nullptr;
+        // first try to find the innermost let, matching all let entries with the entry matchers
+        // throughout
+        as_let->apply_form([&](Form* form) {
+          for (int idx = 0; idx < form->size(); idx++) {
+            auto* f = form->at(idx);
+            // if this is the entry of the outermost let, try to do the first match
+            if (f->parent_form->parent_element == as_let) {
+              if (m_entry_matchers.at(entries_matched)
+                      .do_match(as_let->entries().at(0), maps_out, env)) {
+                entries_matched++;
+              } else {
+                return;
+              }
+            }
+            auto let = dynamic_cast<LetElement*>(f);
+            if (!let) {
+              continue;
+            }
+
+            auto let_body = dynamic_cast<LetElement*>(let->body()->at(0));
+            if (!let_body) {
+              break;
+            }
+
+            if (m_entry_matchers.at(entries_matched)
+                    .do_match(let_body->entries().at(0), maps_out, env)) {
+              entries_matched++;
+            } else {
+              return;
+            }
+
+            if (entries_matched == m_entry_matchers.size()) {
+              innermost_let_body = let_body->body();
+              return;
+            }
+          }
+        });
+
+        if (entries_matched == m_entry_matchers.size() && innermost_let_body) {
+          // now match body of innermost let
+          for (int i = 0; i < (int)m_sub_matchers.size(); ++i) {
+            Form fake;
+            fake.elts().push_back(innermost_let_body->elts().at(i));
+            if (!m_sub_matchers.at(i).do_match(&fake, maps_out, env)) {
+              return false;
+            }
+          }
+          return true;
+        }
+      }
+      return false;
+    }
+
     default:
       ASSERT(false);
       return false;