Add C_QuestLog.GetNumQuestObjectives(questID)

The quest's objective count — the length GetQuestDetails(questID)
.requirements would have — read straight from the cache block with no
Lua tables or strings materialized. nil when the quest isn't cached
(same contract as GetQuestDetails).

Exists because materializing full detail tables in a login-path loop
is expensive at warm cache: GetQuestDetails copies description /
objectives / completion text into Lua strings (~5 KB per quest).
TurtleGuide's guide-load OIDX validation did exactly that for every
tagged step — fine on the first (cold-cache) session, but once the
quest cache was warm from questcache.wdb every subsequent login
exhausted vanilla's fixed Lua memory pool and crashed the client in
lmemPool.cpp:53. With this accessor the same validation costs a few
dozen byte reads regardless of cache temperature.

Author: brues-code

README.md

@@ -48,7 +48,7 @@ Full per-function reference: **[docs/API.md](docs/API.md)**.
 | [MerchantFrame](docs/API.md#merchantframe) | `C_MerchantFrame.GetBuybackItemID`, `C_MerchantFrame.GetItemInfo`, `C_MerchantFrame.GetNumJunkItems`, `C_MerchantFrame.IsMerchantItemRefundable`, `C_MerchantFrame.IsSellAllJunkEnabled`, `C_MerchantFrame.SellAllJunkItems` |
 | [NamePlate](docs/API.md#nameplate) | `C_NamePlate.GetNamePlateForGUID`, `C_NamePlate.GetNamePlateForUnit`, `C_NamePlate.GetNamePlateGUIDs`, `C_NamePlate.GetNamePlates` |
 | [NameCache](docs/API.md#namecache) | `C_PlayerCache.GetPlayerInfoByName`, `C_PlayerCache.IsEnabled`, `C_PlayerCache.IsScanEnabled`, `C_PlayerCache.RememberPlayer`, `C_PlayerCache.SetEnabled`, `C_PlayerCache.SetScanEnabled`, `C_PlayerInfo.GUIDIsCreature`, `C_PlayerInfo.GUIDIsGameObject`, `C_PlayerInfo.GUIDIsPet`, `C_PlayerInfo.GUIDIsPlayer`, `GetPlayerInfoByGUID`, `UnitNameFromGUID` |
-| [Quest](docs/API.md#quest) | `C_QuestLog.GetQuestDetails`, `C_QuestLog.GetQuestIDForLogIndex`, `C_QuestLog.GetTitleForQuestID`, `C_QuestLog.IsOnQuest`, `C_QuestLog.IsQuestDataCachedByID`, `C_QuestLog.IsUnitOnQuest`, `C_QuestLog.RequestLoadQuestByID`, `GetQuestLogLeaderBoardID` |
+| [Quest](docs/API.md#quest) | `C_QuestLog.GetNumQuestObjectives`, `C_QuestLog.GetQuestDetails`, `C_QuestLog.GetQuestIDForLogIndex`, `C_QuestLog.GetTitleForQuestID`, `C_QuestLog.IsOnQuest`, `C_QuestLog.IsQuestDataCachedByID`, `C_QuestLog.IsUnitOnQuest`, `C_QuestLog.RequestLoadQuestByID`, `GetQuestLogLeaderBoardID` |
 | [Screen](docs/API.md#screen) | `GetPhysicalScreenSize` |
 | [Spell](docs/API.md#spell) | `C_Spell.CancelSpellByID`, `C_Spell.CastAtCursor`, `C_Spell.CastAtUnit`, `C_Spell.CastingInfo`, `C_Spell.ChannelInfo`, `C_Spell.DoesSpellExist`, `C_Spell.GetSchoolString`, `C_Spell.GetSpellCooldown`, `C_Spell.GetSpellDescription`, `C_Spell.GetSpellInfo`, `C_Spell.GetSpellLink`, `C_Spell.GetSpellMechanicByID`, `C_Spell.GetSpellName`, `C_Spell.GetSpellPowerCost`, `C_Spell.GetSpellRadius`, `C_Spell.GetSpellReagents`, `C_Spell.GetSpellSubtext`, `C_Spell.GetSpellTexture`, `C_Spell.IsAutoAttackSpell`, `C_Spell.IsCurrentSpell`, `C_Spell.IsRangedAutoAttackSpell`, `C_Spell.IsSelfBuff`, `C_Spell.IsSpellHarmful`, `C_Spell.IsSpellHelpful`, `C_Spell.IsSpellPassive`, `C_Spell.IsSpellUsable`, `C_Spell.SpellHasRange`, `C_Spell.UnitCastingInfo`, `C_Spell.UnitChannelInfo`, `CancelSpellByName`, `CastSpellNoToggle`, `GetCraftSpellID`, `GetSpellInfo`, `GetSpellLink`, `GetSpellRadius`, `GetSpellSchool`, `IsHarmfulSpell`, `IsHelpfulSpell`, `IsPassiveSpell`, `IsPlayerSpell`, `IsSpellKnown`, `IsUsableSpell`, `SpellHasRange` |
 | [SpellBook](docs/API.md#spellbook) | `C_SpellBook.GetCurrentLevelSpells`, `C_SpellBook.GetSpellLevelLearned`, `C_SpellBook.GetSpellSkillLine`, `C_SpellBook.IsAutoAttackSpellBookItem`, `C_SpellBook.IsRangedAutoAttackSpellBookItem`, `FindSpellBookSlotByID` |

docs/API.md

@@ -291,6 +291,7 @@ build instructions.
   - [`C_QuestLog.IsUnitOnQuest(unit, questID)`](#c_questlogisunitonquestunit-questid)
   - [`C_QuestLog.GetTitleForQuestID(questID)`](#c_questloggettitleforquestidquestid)
   - [`C_QuestLog.GetQuestDetails(questID)`](#c_questloggetquestdetailsquestid)
+  - [`C_QuestLog.GetNumQuestObjectives(questID)`](#c_questloggetnumquestobjectivesquestid)
   - [`C_QuestLog.IsQuestDataCachedByID(questID)`](#c_questlogisquestdatacachedbyidquestid)
   - [`GetQuestLogLeaderBoardID(objectiveIndex [, questIndex])`](#getquestlogleaderboardidobjectiveindex--questindex)
 
@@ -7135,6 +7136,26 @@ Reagents for Reclaimers Inc.  level 40  (no tag)
 with `d.choiceItems = {{id=6793, count=1}, {id=6794, count=1}}`,
 `d.rewardMoney = 3500`, `d.rewardMoneyAtMaxLevel = 1920`, etc.
 
+### `C_QuestLog.GetNumQuestObjectives(questID)`
+
+The quest's objective count — exactly the length
+`GetQuestDetails(questID).requirements` would have — read straight from
+the quest cache with **no Lua tables or strings materialized**. Returns
+`nil` when the quest isn't cached (same contract as `GetQuestDetails`).
+
+```lua
+local n = C_QuestLog.GetNumQuestObjectives(1467)   -- 1
+```
+
+Use this instead of `GetQuestDetails` when only the count matters —
+e.g. bounds-checking authored objective indices across every step of a
+guide at load time. `GetQuestDetails` copies the quest's description /
+objectives / completion text into Lua strings and builds ~20 table
+fields per call; harmless one at a time, but a login-path loop over
+hundreds of cached quests can put real pressure on vanilla's
+fixed-size Lua memory pool. This accessor costs a few dozen byte reads
+regardless of cache temperature.
+
 ### `C_QuestLog.IsQuestDataCachedByID(questID)`
 
 Returns `true` if the quest's static data is currently in the

src/quest/Details.cpp

@@ -134,6 +134,43 @@ void PushRequirements(void *L, const uint8_t *data) {
     }
 }
 
+// `C_QuestLog.GetNumQuestObjectives(questID)` — the quest's objective
+// count (the length `GetQuestDetails(questID).requirements` would have),
+// read straight from the cache block with zero Lua table/string
+// materialization. Exists so per-step validation loops (guide addons
+// bounds-checking objective indices at load time) stay O(1)-cheap even
+// with a warm quest cache — materializing full detail tables for hundreds
+// of quests inside a login-path loop can exhaust vanilla's fixed Lua
+// memory pool. Returns nil when the quest isn't cached (same contract as
+// GetQuestDetails).
+int __fastcall Script_GetNumQuestObjectives(void *L) {
+    if (!Game::Lua::IsNumber(L, 1)) {
+        Game::Lua::Error(L,
+            "Usage: C_QuestLog.GetNumQuestObjectives(questID)");
+        return 0;
+    }
+    const int questID = static_cast<int>(Game::Lua::ToNumber(L, 1));
+    if (questID <= 0)
+        return 0;
+    const uint8_t *data = Quest::Cache::Peek(static_cast<uint32_t>(questID));
+    if (data == nullptr)
+        return 0;
+
+    int count = 0;
+    auto *npcOrGo = reinterpret_cast<const int32_t *>(
+        data + Quest::Cache::OFF_REQUIRED_NPC_OR_GO);
+    auto *items = reinterpret_cast<const uint32_t *>(
+        data + Quest::Cache::OFF_REQUIRED_ITEM);
+    for (int i = 0; i < Quest::Cache::OBJECTIVE_COUNT; ++i) {
+        if (npcOrGo[i] != 0)
+            ++count;
+        if (items[i] != 0)
+            ++count;
+    }
+    Game::Lua::PushNumber(L, static_cast<double>(count));
+    return 1;
+}
+
 int __fastcall Script_GetQuestDetails(void *L) {
     if (!Game::Lua::IsNumber(L, 1)) {
         Game::Lua::Error(L, "Usage: C_QuestLog.GetQuestDetails(questID)");
@@ -245,6 +282,8 @@ int __fastcall Script_GetQuestDetails(void *L) {
 void RegisterLuaFunctions() {
     Game::Lua::RegisterTableFunction("C_QuestLog", "GetQuestDetails",
                                      &Script_GetQuestDetails);
+    Game::Lua::RegisterTableFunction("C_QuestLog", "GetNumQuestObjectives",
+                                     &Script_GetNumQuestObjectives);
 }
 
 } // namespace