fix logical expression short-circuit evaluation (#27)

src/operators.ts

@@ -37,8 +37,15 @@ const binaryBooleanArithmetic = (
 const bool = (value: LuaType): boolean => coerceToBoolean(value)
 
 // logical
-const and = (l: LuaType, r: LuaType): LuaType => coerceToBoolean(l) ? r : l
-const or = (l: LuaType, r: LuaType): LuaType => coerceToBoolean(l) ? l : r
+const and = (l: () => LuaType, r: () => LuaType): LuaType => {
+	const lv = l()
+	return coerceToBoolean(lv) ? r() : lv
+}
+
+const or = (l: () => LuaType, r: () => LuaType): LuaType => {
+	const lv = l()
+	return coerceToBoolean(lv) ? lv : r()
+}
 
 // unary
 const not = (value: LuaType): boolean => !bool(value)

src/parser.ts

@@ -303,10 +303,10 @@ const generate = (node: luaparse.Node): string | MemExpr => {
             const operator = node.operator
 
             if (operator === 'and') {
-                return `__lua.and(${left},${right})`
+                return `__lua.and(() => ${left}, () => ${right})`
             }
             if (operator === 'or') {
-                return `__lua.or(${left},${right})`
+                return `__lua.or(() => ${left}, () => ${right})`
             }
             throw new Error(`Unhandled logical operator: ${node.operator}`)
         }