genjs.ml

(*
 * Copyright (C)2005-2013 Haxe Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *)

open Ast
open Type
open Common

type pos = Ast.pos

type sourcemap = {
	sources : (string) DynArray.t;
	sources_hash : (string, int) Hashtbl.t;
	mappings : Buffer.t;

	mutable source_last_line : int;
	mutable source_last_col : int;
	mutable source_last_file : int;
	mutable print_comma : bool;
	mutable output_last_col : int;
	mutable output_current_col : int;
}

type ctx = {
	com : Common.context;
	buf : Buffer.t;
	packages : (string list,unit) Hashtbl.t;
	smap : sourcemap;
	js_modern : bool;
	js_flatten : bool;
	mutable current : tclass;
	mutable statics : (tclass * string * texpr) list;
	mutable inits : texpr list;
	mutable tabs : string;
	mutable in_value : tvar option;
	mutable in_loop : bool;
	mutable handle_break : bool;
	mutable id_counter : int;
	mutable type_accessor : module_type -> string;
	mutable separator : bool;
	mutable found_expose : bool;
}

let dot_path = Ast.s_type_path

let flat_path (p,s) =
	(* Replace _ with _$ in paths to prevent name collisions. *)
	let escape str = String.concat "_$" (ExtString.String.nsplit str "_") in

	match p with
	| [] -> escape s
	| _ -> String.concat "_" (List.map escape p) ^ "_" ^ (escape s)

let s_path ctx = if ctx.js_flatten then flat_path else dot_path

let kwds =
	let h = Hashtbl.create 0 in
	List.iter (fun s -> Hashtbl.add h s ()) [
		(* JS reserved words: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words *)
		"break"; "case"; "catch"; "class"; "const"; "continue"; "debugger"; "default"; "delete";
		"do"; "else"; "enum"; "export"; "extends"; "finally"; "for"; "function"; "if"; "implements";
		"import"; "in"; "instanceof"; "interface"; "let"; "new"; "package"; "private"; "protected";
		"public"; "return"; "static"; "super"; "switch"; "this"; "throw"; "try"; "typeof"; "var";
		"void"; "while"; "with"; "yield";
	];
	h

(* Identifiers Haxe reserves to make the JS output cleaner. These can still be used in untyped code (TLocal),
   but are escaped upon declaration. *)
let kwds2 =
	let h = Hashtbl.create 0 in
	List.iter (fun s -> Hashtbl.add h s ()) [
		"console"; "window";
	];
	h

let valid_js_ident s =
	try
		for i = 0 to String.length s - 1 do
			match String.unsafe_get s i with
			| 'a'..'z' | 'A'..'Z' | '$' | '_' -> ()
			| '0'..'9' when i > 0 -> ()
			| _ -> raise Exit
		done;
		true
	with Exit ->
		false

let field s = if Hashtbl.mem kwds s then "[\"" ^ s ^ "\"]" else "." ^ s
let ident s = if Hashtbl.mem kwds s then "$" ^ s else s
let check_var_declaration v = if Hashtbl.mem kwds2 v.v_name then v.v_name <- "$" ^ v.v_name

let anon_field s = if Hashtbl.mem kwds s || not (valid_js_ident s) then "'" ^ s ^ "'" else s
let static_field s =
	match s with
	| "length" | "name" -> ".$" ^ s
	| s -> field s

let has_feature ctx = Common.has_feature ctx.com
let add_feature ctx = Common.add_feature ctx.com

let handle_newlines ctx str =
	if ctx.com.debug then
		let rec loop from =
			try begin
				let next = String.index_from str from '\n' + 1 in
				Buffer.add_char ctx.smap.mappings ';';
				ctx.smap.output_last_col <- 0;
				ctx.smap.print_comma <- false;
				loop next
			end with Not_found ->
				ctx.smap.output_current_col <- String.length str - from
		in
		loop 0
	else ()

let spr ctx s =
	ctx.separator <- false;
	handle_newlines ctx s;
	Buffer.add_string ctx.buf s

let print ctx =
	ctx.separator <- false;
	Printf.kprintf (fun s -> begin
		handle_newlines ctx s;
		Buffer.add_string ctx.buf s
	end)

let unsupported p = error "This expression cannot be compiled to Javascript" p

let add_mapping ctx e =
	if not ctx.com.debug || e.epos.pmin < 0 then () else
	let pos = e.epos in
	let smap = ctx.smap in
	let file = try
		Hashtbl.find smap.sources_hash pos.pfile
	with Not_found ->
		let length = DynArray.length smap.sources in
		Hashtbl.replace smap.sources_hash pos.pfile length;
		DynArray.add smap.sources pos.pfile;
		length
	in
	let line, col = Lexer.find_pos pos in
	let line = line - 1 in
	let col = col - 1 in
	if smap.source_last_file != file || smap.source_last_line != line || smap.source_last_col != col then begin
		if smap.print_comma then
			Buffer.add_char smap.mappings ','
		else
			smap.print_comma <- true;

		let base64_vlq number =
			let encode_digit digit =
				let chars = [|
					'A';'B';'C';'D';'E';'F';'G';'H';'I';'J';'K';'L';'M';'N';'O';'P';
					'Q';'R';'S';'T';'U';'V';'W';'X';'Y';'Z';'a';'b';'c';'d';'e';'f';
					'g';'h';'i';'j';'k';'l';'m';'n';'o';'p';'q';'r';'s';'t';'u';'v';
					'w';'x';'y';'z';'0';'1';'2';'3';'4';'5';'6';'7';'8';'9';'+';'/'
				|] in
				Array.unsafe_get chars digit
			in
			let to_vlq number =
				if number < 0 then
					((-number) lsl 1) + 1
				else
					number lsl 1
			in
			let rec loop vlq =
				let shift = 5 in
				let base = 1 lsl shift in
				let mask = base - 1 in
				let continuation_bit = base in
				let digit = vlq land mask in
				let next = vlq asr shift in
				Buffer.add_char smap.mappings (encode_digit (
					if next > 0 then digit lor continuation_bit else digit));
				if next > 0 then loop next else ()
			in
			loop (to_vlq number)
		in

		base64_vlq (smap.output_current_col - smap.output_last_col);
		base64_vlq (file - smap.source_last_file);
		base64_vlq (line - smap.source_last_line);
		base64_vlq (col - smap.source_last_col);

		smap.source_last_file <- file;
		smap.source_last_line <- line;
		smap.source_last_col <- col;
		smap.output_last_col <- smap.output_current_col
	end

let basename path =
	try
		let idx = String.rindex path '/' in
		String.sub path (idx + 1) (String.length path - idx - 1)
	with Not_found -> path

let write_mappings ctx =
	let basefile = basename ctx.com.file in
	print ctx "\n//# sourceMappingURL=%s.map" basefile;
	let channel = open_out_bin (ctx.com.file ^ ".map") in
	let sources = DynArray.to_list ctx.smap.sources in
	let to_url file =
		ExtString.String.map (fun c -> if c == '\\' then '/' else c) (Common.get_full_path file)
	in
	output_string channel "{\n";
	output_string channel "\"version\":3,\n";
	output_string channel ("\"file\":\"" ^ basefile ^ "\",\n");
	output_string channel ("\"sourceRoot\":\"file://\",\n");
	output_string channel ("\"sources\":[" ^
		(String.concat "," (List.map (fun s -> "\"" ^ to_url s ^ "\"") sources)) ^
		"],\n");
	output_string channel "\"names\":[],\n";
	output_string channel "\"mappings\":\"";
	Buffer.output_buffer channel ctx.smap.mappings;
	output_string channel "\"\n";
	output_string channel "}";
	close_out channel

let newline ctx =
	match Buffer.nth ctx.buf (Buffer.length ctx.buf - 1) with
	| '}' | '{' | ':' when not ctx.separator -> print ctx "\n%s" ctx.tabs
	| _ -> print ctx ";\n%s" ctx.tabs

let newprop ctx =
	match Buffer.nth ctx.buf (Buffer.length ctx.buf - 1) with
	| '{' -> print ctx "\n%s" ctx.tabs
	| _ -> print ctx "\n%s," ctx.tabs

let semicolon ctx =
	match Buffer.nth ctx.buf (Buffer.length ctx.buf - 1) with
	| '}' when not ctx.separator -> ()
	| _ -> spr ctx ";"

let rec concat ctx s f = function
	| [] -> ()
	| [x] -> f x
	| x :: l ->
		f x;
		spr ctx s;
		concat ctx s f l

let fun_block ctx f p =
	let e = List.fold_left (fun e (a,c) ->
		match c with
		| None | Some TNull -> e
		| Some c -> Codegen.concat (Codegen.set_default ctx.com a c p) e
	) f.tf_expr f.tf_args in
	e

let open_block ctx =
	let oldt = ctx.tabs in
	ctx.tabs <- "\t" ^ ctx.tabs;
	(fun() -> ctx.tabs <- oldt)

let rec has_return e =
	match e.eexpr with
	| TBlock [] -> false
	| TBlock el -> has_return (List.hd (List.rev el))
	| TReturn _ -> true
	| _ -> false

let rec iter_switch_break in_switch e =
	match e.eexpr with
	| TFunction _ | TWhile _ | TFor _ -> ()
	| TSwitch _ | TPatMatch _ when not in_switch -> iter_switch_break true e
	| TBreak when in_switch -> raise Exit
	| _ -> iter (iter_switch_break in_switch) e

let handle_break ctx e =
	let old = ctx.in_loop, ctx.handle_break in
	ctx.in_loop <- true;
	try
		iter_switch_break false e;
		ctx.handle_break <- false;
		(fun() ->
			ctx.in_loop <- fst old;
			ctx.handle_break <- snd old;
		)
	with
		Exit ->
			spr ctx "try {";
			let b = open_block ctx in
			newline ctx;
			ctx.handle_break <- true;
			(fun() ->
				b();
				ctx.in_loop <- fst old;
				ctx.handle_break <- snd old;
				newline ctx;
				spr ctx "} catch( e ) { if( e != \"__break__\" ) throw e; }";
			)

let handle_expose ctx path meta =
	let rec loop = function
		| (Meta.Expose, args, pos) :: l when ctx.js_modern ->
			ctx.found_expose <- true;
			let exposed_path = (match args with
				| [EConst (String s), _] -> s
				| [] -> path
				| _ -> error "Invalid @:expose parameters" pos
			) in
			print ctx "$hxExpose(%s, \"%s\")" path exposed_path;
			newline ctx
		| _ :: l -> loop l
		| [] -> ()
	in
	loop meta

let this ctx = match ctx.in_value with None -> "this" | Some _ -> "$this"

let is_dynamic_iterator ctx e =
	let check x =
		has_feature ctx "HxOverrides.iter" && (match follow x.etype with TInst ({ cl_path = [],"Array" },_) | TAnon _ | TDynamic _ | TMono _ -> true | _ -> false)
	in
	match e.eexpr with
	| TField (x,f) when field_name f = "iterator" -> check x
	| _ ->
		false

let gen_constant ctx p = function
	| TInt i -> print ctx "%ld" i
	| TFloat s -> spr ctx s
	| TString s ->
		if String.contains s '\000' then error "A String cannot contain \\0 characters" p;
		print ctx "\"%s\"" (Ast.s_escape s)
	| TBool b -> spr ctx (if b then "true" else "false")
	| TNull -> spr ctx "null"
	| TThis -> spr ctx (this ctx)
	| TSuper -> assert false

let rec gen_call ctx e el in_value =
	match e.eexpr , el with
	| TConst TSuper , params ->
		(match ctx.current.cl_super with
		| None -> error "Missing api.setCurrentClass" e.epos
		| Some (c,_) ->
			print ctx "%s.call(%s" (ctx.type_accessor (TClassDecl c)) (this ctx);
			List.iter (fun p -> print ctx ","; gen_value ctx p) params;
			spr ctx ")";
		);
	| TField ({ eexpr = TConst TSuper },f) , params ->
		(match ctx.current.cl_super with
		| None -> error "Missing api.setCurrentClass" e.epos
		| Some (c,_) ->
			let name = field_name f in
			print ctx "%s.prototype%s.call(%s" (ctx.type_accessor (TClassDecl c)) (field name) (this ctx);
			List.iter (fun p -> print ctx ","; gen_value ctx p) params;
			spr ctx ")";
		);
	| TCall (x,_) , el when (match x.eexpr with TLocal { v_name = "__js__" } -> false | _ -> true) ->
		spr ctx "(";
		gen_value ctx e;
		spr ctx ")";
		spr ctx "(";
		concat ctx "," (gen_value ctx) el;
		spr ctx ")";
	| TLocal { v_name = "__new__" }, { eexpr = TConst (TString cl) } :: params ->
		print ctx "new %s(" cl;
		concat ctx "," (gen_value ctx) params;
		spr ctx ")";
	| TLocal { v_name = "__new__" }, e :: params ->
		spr ctx "new ";
		gen_value ctx e;
		spr ctx "(";
		concat ctx "," (gen_value ctx) params;
		spr ctx ")";
	| TLocal { v_name = "__js__" }, [{ eexpr = TConst (TString code) }] ->
		spr ctx (String.concat "\n" (ExtString.String.nsplit code "\r\n"))
	| TLocal { v_name = "__instanceof__" },  [o;t] ->
		spr ctx "(";
		gen_value ctx o;
		print ctx " instanceof ";
		gen_value ctx t;
		spr ctx ")";
	| TLocal ({v_name = "__define_feature__"}), [_;e] ->
		gen_expr ctx e
	| TLocal { v_name = "__feature__" }, { eexpr = TConst (TString f) } :: eif :: eelse ->
		(if has_feature ctx f then
			gen_value ctx eif
		else match eelse with
			| [] -> ()
			| e :: _ -> gen_value ctx e)
	| TLocal { v_name = "__resources__" }, [] ->
		spr ctx "[";
		concat ctx "," (fun (name,data) ->
			spr ctx "{ ";
			spr ctx "name : ";
			gen_constant ctx e.epos (TString name);
			spr ctx ", data : ";
			gen_constant ctx e.epos (TString (Codegen.bytes_serialize data));
			spr ctx "}"
		) (Hashtbl.fold (fun name data acc -> (name,data) :: acc) ctx.com.resources []);
		spr ctx "]";
	| TLocal { v_name = "`trace" }, [e;infos] ->
		if has_feature ctx "haxe.Log.trace" then begin
			let t = (try List.find (fun t -> t_path t = (["haxe"],"Log")) ctx.com.types with _ -> assert false) in
			spr ctx (ctx.type_accessor t);
			spr ctx ".trace(";
			gen_value ctx e;
			spr ctx ",";
			gen_value ctx infos;
			spr ctx ")";
		end else begin
			spr ctx "console.log(";
			gen_value ctx e;
			spr ctx ")";
		end
	| _ ->
		gen_value ctx e;
		spr ctx "(";
		concat ctx "," (gen_value ctx) el;
		spr ctx ")"

and gen_expr ctx e =
	add_mapping ctx e;
	match e.eexpr with
	| TConst c -> gen_constant ctx e.epos c
	| TLocal v -> spr ctx (ident v.v_name)
	| TArray (e1,{ eexpr = TConst (TString s) }) when valid_js_ident s && (match e1.eexpr with TConst (TInt _|TFloat _) -> false | _ -> true) ->
		gen_value ctx e1;
		spr ctx (field s)
	| TArray (e1,e2) ->
		gen_value ctx e1;
		spr ctx "[";
		gen_value ctx e2;
		spr ctx "]";
	| TBinop (op,{ eexpr = TField (x,f) },e2) when field_name f = "iterator" ->
		gen_value ctx x;
		spr ctx (field "iterator");
		print ctx " %s " (Ast.s_binop op);
		gen_value ctx e2;
	| TBinop (op,e1,e2) ->
		gen_value ctx e1;
		print ctx " %s " (Ast.s_binop op);
		gen_value ctx e2;
	| TField (x,f) when field_name f = "iterator" && is_dynamic_iterator ctx e ->
		add_feature ctx "use.$iterator";
		print ctx "$iterator(";
		gen_value ctx x;
		print ctx ")";
	| TField (x,FClosure (_,f)) ->
		add_feature ctx "use.$bind";
		(match x.eexpr with
		| TConst _ | TLocal _ ->
			print ctx "$bind(";
			gen_value ctx x;
			print ctx ",";
			gen_value ctx x;
			print ctx "%s)" (field f.cf_name)
		| _ ->
			print ctx "($_=";
			gen_value ctx x;
			print ctx ",$bind($_,$_%s))" (field f.cf_name))
	| TEnumParameter (x,_,i) ->
		gen_value ctx x;
		print ctx "[%i]" (i + 2)
	| TField ({ eexpr = TConst (TInt _ | TFloat _) } as x,f) ->
		gen_expr ctx { e with eexpr = TField(mk (TParenthesis x) x.etype x.epos,f) }
	| TField (x,f) ->
		gen_value ctx x;
		let name = field_name f in
		spr ctx (match f with FStatic _ | FEnum _ -> static_field name | FInstance _ | FAnon _ | FDynamic _ | FClosure _ -> field name)
	| TTypeExpr t ->
		spr ctx (ctx.type_accessor t)
	| TParenthesis e ->
		spr ctx "(";
		gen_value ctx e;
		spr ctx ")";
	| TMeta (_,e) ->
		gen_expr ctx e
	| TReturn eo ->
		if ctx.in_value <> None then unsupported e.epos;
		(match eo with
		| None ->
			spr ctx "return"
		| Some e ->
			spr ctx "return ";
			gen_value ctx e);
	| TBreak ->
		if not ctx.in_loop then unsupported e.epos;
		if ctx.handle_break then spr ctx "throw \"__break__\"" else spr ctx "break"
	| TContinue ->
		if not ctx.in_loop then unsupported e.epos;
		spr ctx "continue"
	| TBlock el ->
		print ctx "{";
		let bend = open_block ctx in
		List.iter (gen_block ctx) el;
		bend();
		newline ctx;
		print ctx "}";
	| TFunction f ->
		let old = ctx.in_value, ctx.in_loop in
		ctx.in_value <- None;
		ctx.in_loop <- false;
		print ctx "function(%s) " (String.concat "," (List.map ident (List.map arg_name f.tf_args)));
		gen_expr ctx (fun_block ctx f e.epos);
		ctx.in_value <- fst old;
		ctx.in_loop <- snd old;
		ctx.separator <- true
	| TCall (e,el) ->
		gen_call ctx e el false
	| TArrayDecl el ->
		spr ctx "[";
		concat ctx "," (gen_value ctx) el;
		spr ctx "]"
	| TThrow e ->
		spr ctx "throw ";
		gen_value ctx e;
	| TVars [] ->
		()
	| TVars vl ->
		spr ctx "var ";
		concat ctx ", " (fun (v,e) ->
			check_var_declaration v;
			spr ctx (ident v.v_name);
			match e with
			| None -> ()
			| Some e ->
				spr ctx " = ";
				gen_value ctx e
		) vl;
	| TNew (c,_,el) ->
		print ctx "new %s(" (ctx.type_accessor (TClassDecl c));
		concat ctx "," (gen_value ctx) el;
		spr ctx ")"
	| TIf (cond,e,eelse) ->
		spr ctx "if";
		gen_value ctx cond;
		spr ctx " ";
		gen_expr ctx e;
		(match eelse with
		| None -> ()
		| Some e2 ->
			(match e.eexpr with
			| TObjectDecl _ -> ctx.separator <- false
			| _ -> ());
			semicolon ctx;
			spr ctx " else ";
			gen_expr ctx e2);
	| TUnop (op,Ast.Prefix,e) ->
		spr ctx (Ast.s_unop op);
		gen_value ctx e
	| TUnop (op,Ast.Postfix,e) ->
		gen_value ctx e;
		spr ctx (Ast.s_unop op)
	| TWhile (cond,e,Ast.NormalWhile) ->
		let handle_break = handle_break ctx e in
		spr ctx "while";
		gen_value ctx cond;
		spr ctx " ";
		gen_expr ctx e;
		handle_break();
	| TWhile (cond,e,Ast.DoWhile) ->
		let handle_break = handle_break ctx e in
		spr ctx "do ";
		gen_expr ctx e;
		semicolon ctx;
		spr ctx " while";
		gen_value ctx cond;
		handle_break();
	| TObjectDecl fields ->
		spr ctx "{ ";
		concat ctx ", " (fun (f,e) -> print ctx "%s : " (anon_field f); gen_value ctx e) fields;
		spr ctx "}";
		ctx.separator <- true
	| TFor (v,it,e) ->
		check_var_declaration v;
		let handle_break = handle_break ctx e in
		let it = ident (match it.eexpr with
			| TLocal v -> v.v_name
			| _ ->
				let id = ctx.id_counter in
				ctx.id_counter <- ctx.id_counter + 1;
				let name = "$it" ^ string_of_int id in
				print ctx "var %s = " name;
				gen_value ctx it;
				newline ctx;
				name
		) in
		print ctx "while( %s.hasNext() ) {" it;
		let bend = open_block ctx in
		newline ctx;
		print ctx "var %s = %s.next()" (ident v.v_name) it;
		gen_block ctx e;
		bend();
		newline ctx;
		spr ctx "}";
		handle_break();
	| TTry (e,catchs) ->
		spr ctx "try ";
		gen_expr ctx e;
		let vname = (match catchs with [(v,_)] -> check_var_declaration v; v.v_name | _ ->
			let id = ctx.id_counter in
			ctx.id_counter <- ctx.id_counter + 1;
			"$e" ^ string_of_int id
		) in
		print ctx " catch( %s ) {" vname;
		let bend = open_block ctx in
		let last = ref false in
		let else_block = ref false in
		List.iter (fun (v,e) ->
			if !last then () else
			let t = (match follow v.v_type with
			| TEnum (e,_) -> Some (TEnumDecl e)
			| TInst (c,_) -> Some (TClassDecl c)
			| TAbstract (a,_) -> Some (TAbstractDecl a)
			| TFun _
			| TLazy _
			| TType _
			| TAnon _ ->
				assert false
			| TMono _
			| TDynamic _ ->
				None
			) in
			match t with
			| None ->
				last := true;
				if !else_block then print ctx "{";
				if vname <> v.v_name then begin
					newline ctx;
					print ctx "var %s = %s" v.v_name vname;
				end;
				gen_block ctx e;
				if !else_block then begin
					newline ctx;
					print ctx "}";
				end
			| Some t ->
				if not !else_block then newline ctx;
				print ctx "if( %s.__instanceof(%s," (ctx.type_accessor (TClassDecl { null_class with cl_path = ["js"],"Boot" })) vname;
				gen_value ctx (mk (TTypeExpr t) (mk_mono()) e.epos);
				spr ctx ") ) {";
				let bend = open_block ctx in
				if vname <> v.v_name then begin
					newline ctx;
					print ctx "var %s = %s" v.v_name vname;
				end;
				gen_block ctx e;
				bend();
				newline ctx;
				spr ctx "} else ";
				else_block := true
		) catchs;
		if not !last then print ctx "throw(%s)" vname;
		bend();
		newline ctx;
		spr ctx "}";
	| TPatMatch dt -> assert false
	| TSwitch (e,cases,def) ->
		spr ctx "switch";
		gen_value ctx e;
		spr ctx " {";
		newline ctx;
		List.iter (fun (el,e2) ->
			List.iter (fun e ->
				match e.eexpr with
				| TConst(c) when c = TNull ->
					spr ctx "case null: case undefined:";
				| _ ->
					spr ctx "case ";
					gen_value ctx e;
					spr ctx ":"
			) el;
			let bend = open_block ctx in
			gen_block ctx e2;
			if not (has_return e2) then begin
				newline ctx;
				print ctx "break";
			end;
			bend();
			newline ctx;
		) cases;
		(match def with
		| None -> ()
		| Some e ->
			spr ctx "default:";
			let bend = open_block ctx in
			gen_block ctx e;
			bend();
			newline ctx;
		);
		spr ctx "}"
	| TCast (e,None) ->
		gen_expr ctx e
	| TCast (e1,Some t) ->
		print ctx "%s.__cast(" (ctx.type_accessor (TClassDecl { null_class with cl_path = ["js"],"Boot" }));
		gen_expr ctx e1;
		spr ctx " , ";
		spr ctx (ctx.type_accessor t);
		spr ctx ")"


and gen_block ?(after=false) ctx e =
	match e.eexpr with
	| TBlock el ->
		List.iter (gen_block ~after ctx) el
	| TCall ({ eexpr = TLocal { v_name = "__feature__" } }, { eexpr = TConst (TString f) } :: eif :: eelse) ->
		if has_feature ctx f then
			gen_block ~after ctx eif
		else (match eelse with
			| [] -> ()
			| [e] -> gen_block ~after ctx e
			| _ -> assert false)
	| _ ->
		if not after then newline ctx;
		gen_expr ctx e;
		if after then newline ctx

and gen_value ctx e =
	add_mapping ctx e;
	let assign e =
		mk (TBinop (Ast.OpAssign,
			mk (TLocal (match ctx.in_value with None -> assert false | Some v -> v)) t_dynamic e.epos,
			e
		)) e.etype e.epos
	in
	let value() =
		let old = ctx.in_value, ctx.in_loop in
		let r = alloc_var "$r" t_dynamic in
		ctx.in_value <- Some r;
		ctx.in_loop <- false;
		spr ctx "(function($this) ";
		spr ctx "{";
		let b = open_block ctx in
		newline ctx;
		spr ctx "var $r";
		newline ctx;
		(fun() ->
			newline ctx;
			spr ctx "return $r";
			b();
			newline ctx;
			spr ctx "}";
			ctx.in_value <- fst old;
			ctx.in_loop <- snd old;
			print ctx "(%s))" (this ctx)
		)
	in
	match e.eexpr with
	| TConst _
	| TLocal _
	| TArray _
	| TBinop _
	| TField _
	| TEnumParameter _
	| TTypeExpr _
	| TParenthesis _
	| TObjectDecl _
	| TArrayDecl _
	| TNew _
	| TUnop _
	| TFunction _ ->
		gen_expr ctx e
	| TMeta (_,e1) ->
		gen_value ctx e1
	| TCall (e,el) ->
		gen_call ctx e el true
	| TReturn _
	| TBreak
	| TContinue ->
		unsupported e.epos
	| TCast (e1, None) ->
		gen_value ctx e1
	| TCast (e1, Some t) ->
		print ctx "%s.__cast(" (ctx.type_accessor (TClassDecl { null_class with cl_path = ["js"],"Boot" }));
		gen_value ctx e1;
		spr ctx " , ";
		spr ctx (ctx.type_accessor t);
		spr ctx ")"
	| TVars _
	| TFor _
	| TWhile _
	| TThrow _ ->
		(* value is discarded anyway *)
		let v = value() in
		gen_expr ctx e;
		v()
	| TBlock [e] ->
		gen_value ctx e
	| TBlock el ->
		let v = value() in
		let rec loop = function
			| [] ->
				spr ctx "return null";
			| [e] ->
				gen_expr ctx (assign e);
			| e :: l ->
				gen_expr ctx e;
				newline ctx;
				loop l
		in
		loop el;
		v();
	| TIf (cond,e,eo) ->
		(* remove parenthesis unless it's an operation with higher precedence than ?: *)
		let cond = (match cond.eexpr with
			| TParenthesis { eexpr = TBinop ((Ast.OpAssign | Ast.OpAssignOp _),_,_) } -> cond
			| TParenthesis e -> e
			| _ -> cond
		) in
		gen_value ctx cond;
		spr ctx "?";
		gen_value ctx e;
		spr ctx ":";
		(match eo with
		| None -> spr ctx "null"
		| Some e -> gen_value ctx e);
	| TSwitch (cond,cases,def) ->
		let v = value() in
		gen_expr ctx (mk (TSwitch (cond,
			List.map (fun (e1,e2) -> (e1,assign e2)) cases,
			match def with None -> None | Some e -> Some (assign e)
		)) e.etype e.epos);
		v()
	| TPatMatch dt -> assert false
	| TTry (b,catchs) ->
		let v = value() in
		let block e = mk (TBlock [e]) e.etype e.epos in
		gen_expr ctx (mk (TTry (block (assign b),
			List.map (fun (v,e) -> v, block (assign e)) catchs
		)) e.etype e.epos);
		v()

let generate_package_create ctx (p,_) =
	let rec loop acc = function
		| [] -> ()
		| p :: l when Hashtbl.mem ctx.packages (p :: acc) -> loop (p :: acc) l
		| p :: l ->
			Hashtbl.add ctx.packages (p :: acc) ();
			(match acc with
			| [] ->
				if ctx.js_modern then
					print ctx "var %s = {}" p
				else
					print ctx "var %s = %s || {}" p p
			| _ ->
				let p = String.concat "." (List.rev acc) ^ (field p) in
				if ctx.js_modern then
					print ctx "%s = {}" p
				else
					print ctx "if(!%s) %s = {}" p p
			);
			newline ctx;
			loop (p :: acc) l
	in
	match p with
	| [] -> print ctx "var "
	| _ -> loop [] p

let check_field_name c f =
	match f.cf_name with
	| "prototype" | "__proto__" | "constructor" ->
		error ("The field name '" ^ f.cf_name ^ "'  is not allowed in JS") (match f.cf_expr with None -> c.cl_pos | Some e -> e.epos);
	| _ -> ()

let gen_class_static_field ctx c f =
	match f.cf_expr with
	| None | Some { eexpr = TConst TNull } when not (has_feature ctx "Type.getClassFields") ->
		()
	| None when is_extern_field f ->
		()
	| None ->
		print ctx "%s%s = null" (s_path ctx c.cl_path) (static_field f.cf_name);
		newline ctx
	| Some e ->
		match e.eexpr with
		| TFunction _ ->
			let path = (s_path ctx c.cl_path) ^ (static_field f.cf_name) in
			ctx.id_counter <- 0;
			print ctx "%s = " path;
			gen_value ctx e;
			newline ctx;
			handle_expose ctx path f.cf_meta
		| _ ->
			ctx.statics <- (c,f.cf_name,e) :: ctx.statics

let can_gen_class_field ctx = function
	| { cf_expr = (None | Some { eexpr = TConst TNull }) } when not (has_feature ctx "Type.getInstanceFields") ->
		false
	| f ->
		not (is_extern_field f)

let gen_class_field ctx c f =
	check_field_name c f;
	match f.cf_expr with
	| None ->
		newprop ctx;
		print ctx "%s: " (anon_field f.cf_name);
		print ctx "null";
	| Some e ->
		newprop ctx;
		print ctx "%s: " (anon_field f.cf_name);
		ctx.id_counter <- 0;
		gen_value ctx e;
		ctx.separator <- false

let generate_class ctx c =
	ctx.current <- c;
	ctx.id_counter <- 0;
	(match c.cl_path with
	| [],"Function" -> error "This class redefine a native one" c.cl_pos
	| _ -> ());
	let p = s_path ctx c.cl_path in
	let hxClasses = has_feature ctx "Type.resolveClass" in
	if ctx.js_flatten then
		print ctx "var "
	else
		generate_package_create ctx c.cl_path;
	if ctx.js_modern || not hxClasses then
		print ctx "%s = " p
	else
		print ctx "%s = $hxClasses[\"%s\"] = " p (dot_path c.cl_path);
	(match c.cl_constructor with
	| Some { cf_expr = Some e } -> gen_expr ctx e
	| _ -> (print ctx "function() { }"); ctx.seperator <- true);
	newline ctx;
	if ctx.js_modern && hxClasses then begin
		print ctx "$hxClasses[\"%s\"] = %s" (dot_path c.cl_path) p;
		newline ctx;
	end;
	handle_expose ctx p c.cl_meta;
	if has_feature ctx "js.Boot.isClass" then begin
		print ctx "%s.__name__ = " p;
		if has_feature ctx "Type.getClassName" then
			print ctx "[%s]" (String.concat "," (List.map (fun s -> Printf.sprintf "\"%s\"" (Ast.s_escape s)) (fst c.cl_path @ [snd c.cl_path])))
		else
			print ctx "true";
		newline ctx;
	end;
	(match c.cl_implements with
	| [] -> ()
	| l ->
		print ctx "%s.__interfaces__ = [%s]" p (String.concat "," (List.map (fun (i,_) -> s_path ctx i.cl_path) l));
		newline ctx;
	);

	let gen_props props =
		String.concat "," (List.map (fun (p,v) -> p ^":\""^v^"\"") props) in
	let has_property_reflection =
		(has_feature ctx "Reflect.getProperty") || (has_feature ctx "Reflect.setProperty") in

	if has_property_reflection then begin
		(match Codegen.get_properties c.cl_ordered_statics with
		| [] -> ()
		| props ->
			print ctx "%s.__properties__ = {%s}" p (gen_props props);
			newline ctx);
	end;

	List.iter (gen_class_static_field ctx c) c.cl_ordered_statics;

	let has_class = has_feature ctx "js.Boot.getClass" && (c.cl_super <> None || c.cl_ordered_fields <> [] || c.cl_constructor <> None) in
	let has_prototype = c.cl_super <> None || has_class || List.exists (can_gen_class_field ctx) c.cl_ordered_fields in
	if has_prototype then begin
		(match c.cl_super with
		| None -> print ctx "%s.prototype = {" p;
		| Some (csup,_) ->
			let psup = s_path ctx csup.cl_path in
			print ctx "%s.__super__ = %s" p psup;
			newline ctx;
			print ctx "%s.prototype = $extend(%s.prototype,{" p psup;
		);

		let bend = open_block ctx in
		List.iter (fun f -> if can_gen_class_field ctx f then gen_class_field ctx c f) c.cl_ordered_fields;
		if has_class then begin
			newprop ctx;
			print ctx "__class__: %s" p;
		end;

		if has_property_reflection then begin
			let props = Codegen.get_properties c.cl_ordered_fields in
			(match c.cl_super with
			| _ when props = [] -> ()
			| Some (csup,_) when Codegen.has_properties csup ->
				newprop ctx;
				let psup = s_path ctx csup.cl_path in
				print ctx "__properties__: $extend(%s.prototype.__properties__,{%s})" psup (gen_props props)
			| _ ->
				newprop ctx;
				print ctx "__properties__: {%s}" (gen_props props));
		end;

		bend();
		print ctx "\n}";
		(match c.cl_super with None -> () | _ -> print ctx ")");
		newline ctx
	end

let generate_enum ctx e =
	let p = s_path ctx e.e_path in
	let ename = List.map (fun s -> Printf.sprintf "\"%s\"" (Ast.s_escape s)) (fst e.e_path @ [snd e.e_path]) in
	if ctx.js_flatten then
		print ctx "var "
	else
		generate_package_create ctx e.e_path;
	print ctx "%s = " p;
	if has_feature ctx "Type.resolveEnum" then print ctx "$hxClasses[\"%s\"] = " (dot_path e.e_path);
	print ctx "{";
	if has_feature ctx "js.Boot.isEnum" then print ctx " __ename__ : %s," (if has_feature ctx "Type.getEnumName" then "[" ^ String.concat "," ename ^ "]" else "true");
	print ctx " __constructs__ : [%s] }" (String.concat "," (List.map (fun s -> Printf.sprintf "\"%s\"" s) e.e_names));
	newline ctx;
	List.iter (fun n ->
		let f = PMap.find n e.e_constrs in
		print ctx "%s%s = " p (field f.ef_name);
		(match f.ef_type with
		| TFun (args,_) ->
			let sargs = String.concat "," (List.map (fun (n,_,_) -> ident n) args) in
			print ctx "function(%s) { var $x = [\"%s\",%d,%s]; $x.__enum__ = %s; $x.toString = $estr; return $x; }" sargs f.ef_name f.ef_index sargs p;
		| _ ->
			print ctx "[\"%s\",%d]" f.ef_name f.ef_index;
			newline ctx;
			print ctx "%s%s.toString = $estr" p (field f.ef_name);
			newline ctx;
			print ctx "%s%s.__enum__ = %s" p (field f.ef_name) p;
		);
		newline ctx
	) e.e_names;
	match Codegen.build_metadata ctx.com (TEnumDecl e) with
	| None -> ()
	| Some e ->
		print ctx "%s.__meta__ = " p;
		gen_expr ctx e;
		newline ctx

let generate_static ctx (c,f,e) =
	print ctx "%s%s = " (s_path ctx c.cl_path) (static_field f);
	gen_value ctx e;
	newline ctx

let generate_type ctx = function
	| TClassDecl c ->
		(match c.cl_init with
		| None -> ()
		| Some e ->
			ctx.inits <- e :: ctx.inits);
		if not c.cl_extern then
			generate_class ctx c
		else if not ctx.js_flatten && Meta.has Meta.InitPackage c.cl_meta then
			generate_package_create ctx c.cl_path
	| TEnumDecl e when e.e_extern ->
		()
	| TEnumDecl e -> generate_enum ctx e
	| TTypeDecl _ | TAbstractDecl _ -> ()

let set_current_class ctx c =
	ctx.current <- c

let alloc_ctx com =
	let ctx = {
		com = com;
		buf = Buffer.create 16000;
		packages = Hashtbl.create 0;
		smap = {
			source_last_line = 0;
			source_last_col = 0;
			source_last_file = 0;
			print_comma = false;
			output_last_col = 0;
			output_current_col = 0;
			sources = DynArray.create();
			sources_hash = Hashtbl.create 0;
			mappings = Buffer.create 16;
		};
		js_modern = not (Common.defined com Define.JsClassic);
		js_flatten = Common.defined com Define.JsFlatten;
		statics = [];
		inits = [];
		current = null_class;
		tabs = "";
		in_value = None;
		in_loop = false;
		handle_break = false;
		id_counter = 0;
		type_accessor = (fun _ -> assert false);
		separator = false;
		found_expose = false;
	} in
	ctx.type_accessor <- (fun t -> s_path ctx (t_path t));
	ctx

let gen_single_expr ctx e expr =
	if expr then gen_expr ctx e else gen_value ctx e;
	let str = Buffer.contents ctx.buf in
	Buffer.reset ctx.buf;
	ctx.id_counter <- 0;
	str

let generate com =
	let t = Common.timer "generate js" in
	(match com.js_gen with
	| Some g -> g()
	| None ->
	let ctx = alloc_ctx com in

	if has_feature ctx "Class" || has_feature ctx "Type.getClassName" then add_feature ctx "js.Boot.isClass";
	if has_feature ctx "Enum" || has_feature ctx "Type.getEnumName" then add_feature ctx "js.Boot.isEnum";

	if ctx.js_modern then begin
		(* Additional ES5 strict mode keywords. *)
		List.iter (fun s -> Hashtbl.replace kwds s ()) [ "arguments"; "eval" ];

		(* Wrap output in a closure. *)
		print ctx "(function () { \"use strict\"";
		newline ctx;
	end;

	(* TODO: fix $estr *)
	let vars = [] in
	let vars = (if has_feature ctx "Type.resolveClass" || has_feature ctx "Type.resolveEnum" then ("$hxClasses = " ^ (if ctx.js_modern then "{}" else "$hxClasses || {}")) :: vars else vars) in
	let vars = (if List.exists (function TEnumDecl { e_extern = false } -> true | _ -> false) com.types
		then ("$estr = function() { return " ^ (ctx.type_accessor (TClassDecl { null_class with cl_path = ["js"],"Boot" })) ^ ".__string_rec(this,''); }") :: vars
		else vars) in
	(match List.rev vars with
	| [] -> ()
	| vl ->
		print ctx "var %s" (String.concat "," vl);
		ctx.separator <- true;
		newline ctx
	);
	if List.exists (function TClassDecl { cl_extern = false; cl_super = Some _ } -> true | _ -> false) com.types then begin
		print ctx "function $extend(from, fields) {
	function inherit() {}; inherit.prototype = from; var proto = new inherit();
	for (var name in fields) proto[name] = fields[name];
	if( fields.toString !== Object.prototype.toString ) proto.toString = fields.toString;
	return proto;
}
";
	end;
	List.iter (generate_type ctx) com.types;
	let rec chk_features e =
		if is_dynamic_iterator ctx e then add_feature ctx "use.$iterator";
		match e.eexpr with
		| TField (_,FClosure _) ->
			add_feature ctx "use.$bind"
		| _ ->
			Type.iter chk_features e
	in
	List.iter chk_features ctx.inits;
	List.iter (fun (_,_,e) -> chk_features e) ctx.statics;
	if has_feature ctx "use.$iterator" then begin
		add_feature ctx "use.$bind";
		print ctx "function $iterator(o) { if( o instanceof Array ) return function() { return HxOverrides.iter(o); }; return typeof(o.iterator) == 'function' ? $bind(o,o.iterator) : o.iterator; }";
		ctx.separator <- true;
		newline ctx;
	end;
	if has_feature ctx "use.$bind" then begin
		print ctx "var $_, $fid = 0";
		newline ctx;
		print ctx "function $bind(o,m) { if( m == null ) return null; if( m.__id__ == null ) m.__id__ = $fid++; var f; if( o.hx__closures__ == null ) o.hx__closures__ = {}; else f = o.hx__closures__[m.__id__]; if( f == null ) { f = function(){ return f.method.apply(f.scope, arguments); }; f.scope = o; f.method = m; o.hx__closures__[m.__id__] = f; } return f; }";
		ctx.separator <- true;
		newline ctx;
	end;
	List.iter (gen_block ~after:true ctx) (List.rev ctx.inits);
	List.iter (generate_static ctx) (List.rev ctx.statics);
	(match com.main with
	| None -> ()
	| Some e -> gen_expr ctx e; newline ctx);
	if ctx.found_expose then begin
        (* TODO(bruno): Remove runtime branching when standard node haxelib is available *)
		print ctx
"function $hxExpose(src, path) {
	var o = typeof window != \"undefined\" ? window : exports;
	var parts = path.split(\".\");
	for(var ii = 0; ii < parts.length-1; ++ii) {
		var p = parts[ii];
		if(typeof o[p] == \"undefined\") o[p] = {};
		o = o[p];
	}
	o[parts[parts.length-1]] = src;
}";
		newline ctx;
	end;
	if ctx.js_modern then begin
		print ctx "})()";
		newline ctx;
	end;
	if com.debug then write_mappings ctx else (try Sys.remove (com.file ^ ".map") with _ -> ());
	let ch = open_out_bin com.file in
	output_string ch (Buffer.contents ctx.buf);
	close_out ch);
	t()