From 105908204be798c5c93c5346243a0d7f046fc62b Mon Sep 17 00:00:00 2001
From: Zef Hemel <zef@zef.me>
Date: Sat, 22 Feb 2025 21:28:00 +0100
Subject: [PATCH] Fixes #1253

More accurate type classification and eager evaluation of left "and" operand.
---
 common/space_lua/eval.ts                | 15 +++++++++++++++
 common/space_lua/language_core_test.lua |  8 ++++++++
 common/space_lua/runtime.ts             |  7 ++++++-
 common/space_lua/stdlib.ts              |  8 +++++---
 4 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/common/space_lua/eval.ts b/common/space_lua/eval.ts
index 7b3d7514..0c9cfbc7 100644
--- a/common/space_lua/eval.ts
+++ b/common/space_lua/eval.ts
@@ -154,6 +154,21 @@ export function evalExpression(
           } else {
             return evalExpression(e.right, env, sf);
           }
+        } else if (e.operator === "and") {
+          // Special case: eagerly evaluate left before even attempting right
+          const left = evalExpression(e.left, env, sf);
+          if (left instanceof Promise) {
+            return left.then((left) => {
+              if (!luaTruthy(left)) {
+                return left;
+              }
+              return evalExpression(e.right, env, sf);
+            });
+          } else if (!luaTruthy(left)) {
+            return left;
+          } else {
+            return evalExpression(e.right, env, sf);
+          }
         }
         const values = evalPromiseValues([
           evalExpression(e.left, env, sf),
diff --git a/common/space_lua/language_core_test.lua b/common/space_lua/language_core_test.lua
index b5da8684..eba1c8c3 100644
--- a/common/space_lua/language_core_test.lua
+++ b/common/space_lua/language_core_test.lua
@@ -433,3 +433,11 @@ end
 
 assertEqual(sum(1, 2, 3), 6)
 assertEqual(sum(1, 2, 3, 4, 5), 15)
+
+local data = { { name = "John", favorite = { color = "blue" } }, { name = "Jane" } }
+assertEqual(type(data[1].favorite), "table")
+assertEqual(data[1].favorite.color, "blue")
+
+local r = query [[from p = data where type(p.favorite) == "table" and p.favorite.color == "blue"]]
+assertEqual(#r, 1)
+assertEqual(r[1].name, "John")
diff --git a/common/space_lua/runtime.ts b/common/space_lua/runtime.ts
index e9342697..e12a1343 100644
--- a/common/space_lua/runtime.ts
+++ b/common/space_lua/runtime.ts
@@ -657,9 +657,12 @@ export function luaKeys(val: any): any[] {
   }
 }
 
-export function luaTypeOf(val: any): LuaType {
+export function luaTypeOf(val: any): LuaType | Promise<LuaType> {
   if (val === null || val === undefined) {
     return "nil";
+  }
+  if (val instanceof Promise) {
+    return val.then((v) => luaTypeOf(v));
   } else if (typeof val === "boolean") {
     return "boolean";
   } else if (typeof val === "number") {
@@ -672,6 +675,8 @@ export function luaTypeOf(val: any): LuaType {
     return "table";
   } else if (typeof val === "function" || val.call) {
     return "function";
+  } else if (typeof val === "object" && val.constructor === Object) {
+    return "table";
   } else {
     return "userdata";
   }
diff --git a/common/space_lua/stdlib.ts b/common/space_lua/stdlib.ts
index b9b6ad9a..30ef7a46 100644
--- a/common/space_lua/stdlib.ts
+++ b/common/space_lua/stdlib.ts
@@ -80,9 +80,11 @@ const unpackFunction = new LuaBuiltinFunction(async (sf, t: LuaTable) => {
   return new LuaMultiRes(values);
 });
 
-const typeFunction = new LuaBuiltinFunction((_sf, value: LuaValue): string => {
-  return luaTypeOf(value);
-});
+const typeFunction = new LuaBuiltinFunction(
+  (_sf, value: LuaValue): string | Promise<string> => {
+    return luaTypeOf(value);
+  },
+);
 
 const tostringFunction = new LuaBuiltinFunction((_sf, value: any) => {
   return luaToString(value);