Add reserved word checks for Lua variable names and table keys in conversion functions

Author: MariusStorhaug

src/functions/private/ConvertFrom-LuaTable.ps1

@@ -81,6 +81,14 @@
         }
 
         if ($assignmentDetected) {
+            # Lua 5.4 reserved words per §3.1
+            $reservedWords = @(
+                'and', 'break', 'do', 'else', 'elseif', 'end',
+                'false', 'for', 'function', 'goto', 'if', 'in',
+                'local', 'nil', 'not', 'or', 'repeat', 'return',
+                'then', 'true', 'until', 'while'
+            )
+
             # Parse one or more assignment statements into an ordered dictionary
             $assignments = [ordered]@{}
             while ($script:luaPos -lt $script:luaString.Length) {
@@ -100,6 +108,11 @@
                 }
                 $varName = $script:luaString.Substring($identStart, $script:luaPos - $identStart)
 
+                # Lua grammar: variable names cannot be reserved words (§3.1)
+                if ($varName -in $reservedWords) {
+                    throw "Reserved word '$varName' cannot be used as a variable name at position $identStart."
+                }
+
                 Skip-LuaWhitespace
 
                 # Expect '='

src/functions/private/ConvertTo-LuaTable.ps1

@@ -58,7 +58,7 @@
         # Enum handling
         if ($InputObject -is [enum]) {
             if ($EnumsAsStrings) {
-                $escaped = $InputObject.ToString() -replace '\\', '\\\\' -replace '"', '\"'
+                $escaped = $InputObject.ToString() -replace '\\', '\\' -replace '"', '\"'
                 return "`"$escaped`""
             }
             $underlyingType = [System.Enum]::GetUnderlyingType($InputObject.GetType())

src/functions/private/Read-LuaTable.ps1

@@ -13,6 +13,14 @@
     begin {}
 
     process {
+        # Lua 5.4 reserved words per §3.1
+        $reservedWords = @(
+            'and', 'break', 'do', 'else', 'elseif', 'end',
+            'false', 'for', 'function', 'goto', 'if', 'in',
+            'local', 'nil', 'not', 'or', 'repeat', 'return',
+            'then', 'true', 'until', 'while'
+        )
+
         $script:luaCurrentDepth++
         if ($script:luaCurrentDepth -gt $script:luaMaxDepth) {
             throw "Maximum nesting depth ($($script:luaMaxDepth)) exceeded."
@@ -78,6 +86,10 @@
 
                 if ($script:luaPos -lt $script:luaString.Length -and
                     $script:luaString[$script:luaPos] -eq '=') {
+                    # Lua grammar: Name cannot be a reserved word (§3.1)
+                    if ($ident -in $reservedWords) {
+                        throw "Reserved word '$ident' cannot be used as a bare identifier key in a Lua table. Use bracket notation: [\"$ident\"] = value."
+                    }
                     # Key = value pair
                     $script:luaPos++ # skip =
                     Skip-LuaWhitespace

tests/Lua.Tests.ps1

@@ -507,6 +507,28 @@ B = { val = 2 }
         It 'Throws on assignment with missing value' {
             { ConvertFrom-Lua -InputObject 'A = ' } | Should -Throw '*Unexpected end of input*'
         }
+
+        It 'Throws on reserved word as bare table key' {
+            { ConvertFrom-Lua -InputObject '{ end = 1 }' } | Should -Throw '*Reserved word*'
+        }
+
+        It 'Throws on reserved word as bare table key (while)' {
+            { ConvertFrom-Lua -InputObject '{ while = "loop" }' } | Should -Throw '*Reserved word*'
+        }
+
+        It 'Allows reserved words in bracket notation' {
+            $result = ConvertFrom-Lua -InputObject '{ ["end"] = 1, ["while"] = 2 }' -AsHashtable
+            $result['end'] | Should -Be 1
+            $result['while'] | Should -Be 2
+        }
+
+        It 'Throws on reserved word as assignment variable name' {
+            { ConvertFrom-Lua -InputObject 'end = 1' } | Should -Throw '*Reserved word*'
+        }
+
+        It 'Throws on reserved word as assignment variable name (return as assignment)' {
+            { ConvertFrom-Lua -InputObject 'return = 42' } | Should -Throw '*Reserved word*'
+        }
     }
 
     Context 'Pipeline input' {