Add compatibility transformer for turning some Luau syntax into Lua

.gitignore

@@ -4,3 +4,5 @@
 # Roblox Studio lock files
 /*.rbxlx.lock
 /*.rbxl.lock
+
+/Sync/Server/tools

Luau/main.go

@@ -4,6 +4,7 @@ import (
 	luau "Luau/binding"
 	"context"
 	"fmt"
+	"math/rand"
 	"os"
 	"strings"
 
@@ -11,6 +12,15 @@ import (
 	sitter "github.com/smacker/go-tree-sitter"
 )
 
+func randomString(length int) string {
+	// generate random unicode string
+	var str string
+	for i := 0; i < length; i++ {
+		str += string(rune(rand.Intn(0x7E-0x21) + 0x21))
+	}
+	return str
+}
+
 func isInside(ntype string, node *sitter.Node) bool {
 	for node != nil {
 		if node.Type() == ntype {
@@ -23,7 +33,6 @@ func isInside(ntype string, node *sitter.Node) bool {
 
 func formatCode(sourceCode []byte, tree *sitter.Tree) string {
 	node := tree.RootNode()
-
 	if node.HasError() {
 		fmt.Println("Error parsing code")
 		return string(sourceCode)
@@ -68,7 +77,6 @@ func formatCode(sourceCode []byte, tree *sitter.Tree) string {
 			writeIndent()
 			formatted.WriteString("local ")
 		case "name":
-			
 			if parent.Parent().Type() == "call_stmt" && !isInside("local_var_stmt", &node) {
 				if len(insideLocal) > 1 && insideLocal[len(insideLocal)-2] {
 					formatted.WriteString("\n")
@@ -232,9 +240,127 @@ func formatCode(sourceCode []byte, tree *sitter.Tree) string {
 	return formatted.String()
 }
 
+func compatibility(sourceCode []byte, tree *sitter.Tree) string {
+	node := tree.RootNode()
+	if node.HasError() {
+		fmt.Println("Error parsing code")
+		return string(sourceCode)
+	}
+
+	// watch out for passing by reference
+	newSource := make([]byte, len(sourceCode))
+	copy(newSource, sourceCode)
+
+	type sub struct {
+		node      *sitter.Node
+		toReplace string
+	}
+	var toSub []sub
+
+	var findExprs func(node sitter.Node)
+	findExprs = func(node sitter.Node) {
+		start := node.StartByte()
+		end := node.EndByte()
+		rand := randomString(int(end - start))
+		ntype := node.Type()
+
+		if ntype == "ifexp" || (ntype == "binexp" && node.Child(1).Type() == "//") || (ntype == "var_stmt" && node.Child(1).Type() == "//=") {
+			// replace unsupported statements/expressions with a random string
+			newSource = append(newSource[:start], append([]byte(rand), newSource[end:]...)...)
+			toSub = append(toSub, sub{&node, rand})
+		} else {
+			for i := range int(node.ChildCount()) {
+				findExprs(*(node.Child(i)))
+			}
+		}
+	}
+
+	findExprs(*node)
+	sourceString := string(newSource)
+
+	for _, s := range toSub {
+		var replacement string
+
+		node := s.node
+		ntype := node.Type()
+
+		switch ntype {
+		case "ifexp":
+			fmt.Println(c.InBlue("replacing"))
+			secondCond := node.Child(3).Type()
+			hasElseIf := node.Child(4).Type() == "elseif"
+
+			if !hasElseIf && map[string]bool{
+				"number":        true,
+				"string":        true,
+				"string_interp": true,
+				"true":          true, // lelel
+			}[secondCond] {
+				// SPECIAL CASE: the second condition is guaranteed to be truthy
+				// this means it can be simplified to Lua's sorta-ternary operator, a and b or c
+
+				// doesn't simplify nested if expressions. GOOD ENOUGH
+				for i := range int(node.ChildCount()) {
+					child := node.Child(i)
+					fmt.Println(child.Type())
+					switch child.Type() {
+					case "then":
+						replacement += "and "
+					case "else":
+						replacement += "or "
+					case "elseif":
+						panic("elseif in special case")
+					case "if":
+						// nothing
+					default:
+						replacement += child.Content(sourceCode) + " "
+					}
+				}
+			} else {
+				replacement += "(function()"
+				for i := range int(node.ChildCount()) {
+					child := node.Child(i)
+					fmt.Println(child.Type())
+					switch child.Type() {
+					case "if", "elseif", "then":
+						replacement += child.Content(sourceCode) + " "
+					case "else":
+						replacement += "end "
+					default:
+						prev := node.Child(i - 1).Type()
+						if prev == "then" || prev == "else" {
+							replacement += "return "
+						}
+						replacement += child.Content(sourceCode) + " "
+					}
+				}
+				replacement += "end)()"
+			}
+		case "binexp":
+			// child 1 is the operator (//)
+			left := node.Child(0).Content(sourceCode)
+			right := node.Child(2).Content(sourceCode)
+			replacement = fmt.Sprintf("math.floor(%s/%s)", left, right)
+		case "var_stmt":
+			// child 1 is the operator (//=)
+			left := node.Child(0).Content(sourceCode)
+			right := node.Child(2).Content(sourceCode)
+
+			// todo: make it so if one of the exprs is a function it don't get evaluated twice
+			// nah jk im not doing that
+			replacement = fmt.Sprintf("%s=math.floor(%s/%s)", left, left, right)
+		default:
+			panic("unhandled node type " + ntype)
+		}
+
+		sourceString = strings.Replace(sourceString, s.toReplace, replacement, 1)
+	}
+
+	return sourceString
+}
+
 func main() {
-	parser := sitter.NewParser()
-	parser.SetLanguage(luau.GetLuau())
+	binding := luau.GetLuau()
 
 	filename := "test.luau"
 
@@ -244,17 +370,27 @@ func main() {
 		return
 	}
 
-	tree, _ := parser.ParseCtx(context.Background(), nil, sourceCode)
-	formatted := formatCode(sourceCode, tree)
+	code := string(sourceCode)
 
-	// replace all ending newlines with a single newline
-	formatted = strings.Trim(formatted, "\n") + "\n"
+	// keep parsing until no changes are made lmao
+	for {
+		parser := sitter.NewParser()
+		parser.SetLanguage(binding)
 
-	// write back to file
-	err = os.WriteFile(filename, []byte(formatted), 0o644)
+		newSource := []byte(code)
+		tree, err := parser.ParseCtx(context.Background(), nil, newSource)
 		if err != nil {
 			fmt.Println(err)
 			return
 		}
+		compatible := compatibility(newSource, tree)
+		// replace all ending newlines with a single newline
+		compatible = strings.Trim(compatible, "\n")
 
+		if compatible == string(code) {
+			break
+		}
+		code = compatible
+	}
+	fmt.Println(code)
 }