1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use self::ArgumentType::*;
12 use self::Position::*;
15 use codemap::{Span, respan};
18 use ext::build::AstBuilder;
19 use fmt_macros as parse;
20 use parse::token::special_idents;
24 use std::collections::HashMap;
25 use std::iter::repeat;
38 struct Context<'a, 'b:'a> {
39 ecx: &'a mut ExtCtxt<'b>,
42 /// Parsed argument expressions and the types that we've found so far for
44 args: Vec<P<ast::Expr>>,
45 arg_types: Vec<Option<ArgumentType>>,
46 /// Parsed named expressions and the types that we've found for them so far.
47 /// Note that we keep a side-array of the ordering of the named arguments
48 /// found to be sure that we can translate them in the same order that they
50 names: HashMap<String, P<ast::Expr>>,
51 name_types: HashMap<String, ArgumentType>,
52 name_ordering: Vec<String>,
54 /// The latest consecutive literal strings, or empty if there weren't any.
57 /// Collection of the compiled `rt::Argument` structures
58 pieces: Vec<P<ast::Expr>>,
59 /// Collection of string literals
60 str_pieces: Vec<P<ast::Expr>>,
61 /// Stays `true` if all formatting parameters are default (as in "{}{}").
62 all_pieces_simple: bool,
64 name_positions: HashMap<String, usize>,
66 /// Updated as arguments are consumed or methods are entered
71 /// Parses the arguments from the given list of tokens, returning None
72 /// if there's a parse error so we can continue parsing other format!
75 /// If parsing succeeds, the return value is:
77 /// Some((fmtstr, unnamed arguments, ordering of named arguments,
79 fn parse_args(ecx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
80 -> Option<(P<ast::Expr>, Vec<P<ast::Expr>>, Vec<String>,
81 HashMap<String, P<ast::Expr>>)> {
82 let mut args = Vec::new();
83 let mut names = HashMap::<String, P<ast::Expr>>::new();
84 let mut order = Vec::new();
86 let mut p = ecx.new_parser_from_tts(tts);
88 if p.token == token::Eof {
89 ecx.span_err(sp, "requires at least a format string argument");
92 let fmtstr = p.parse_expr();
93 let mut named = false;
94 while p.token != token::Eof {
95 if !p.eat(&token::Comma) {
96 ecx.span_err(sp, "expected token: `,`");
99 if p.token == token::Eof { break } // accept trailing commas
100 if named || (p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq)) {
102 let ident = match p.token {
103 token::Ident(i, _) => {
109 "expected ident, positional arguments \
110 cannot follow named arguments");
115 &format!("expected ident for named argument, found `{}`",
116 p.this_token_to_string())[]);
120 let interned_name = token::get_ident(ident);
121 let name = &interned_name[];
123 p.expect(&token::Eq);
124 let e = p.parse_expr();
125 match names.get(name) {
129 &format!("duplicate argument named `{}`",
131 ecx.parse_sess.span_diagnostic.span_note(prev.span, "previously here");
135 order.push(name.to_string());
136 names.insert(name.to_string(), e);
138 args.push(p.parse_expr());
141 Some((fmtstr, args, order, names))
144 impl<'a, 'b> Context<'a, 'b> {
145 /// Verifies one piece of a parse string. All errors are not emitted as
146 /// fatal so we can continue giving errors about this and possibly other
148 fn verify_piece(&mut self, p: &parse::Piece) {
150 parse::String(..) => {}
151 parse::NextArgument(ref arg) => {
152 // width/precision first, if they have implicit positional
153 // parameters it makes more sense to consume them first.
154 self.verify_count(arg.format.width);
155 self.verify_count(arg.format.precision);
157 // argument second, if it's an implicit positional parameter
158 // it's written second, so it should come after width/precision.
159 let pos = match arg.position {
160 parse::ArgumentNext => {
161 let i = self.next_arg;
162 if self.check_positional_ok() {
167 parse::ArgumentIs(i) => Exact(i),
168 parse::ArgumentNamed(s) => Named(s.to_string()),
171 let ty = Known(arg.format.ty.to_string());
172 self.verify_arg_type(pos, ty);
177 fn verify_count(&mut self, c: parse::Count) {
179 parse::CountImplied | parse::CountIs(..) => {}
180 parse::CountIsParam(i) => {
181 self.verify_arg_type(Exact(i), Unsigned);
183 parse::CountIsName(s) => {
184 self.verify_arg_type(Named(s.to_string()), Unsigned);
186 parse::CountIsNextParam => {
187 if self.check_positional_ok() {
188 let next_arg = self.next_arg;
189 self.verify_arg_type(Exact(next_arg), Unsigned);
196 fn check_positional_ok(&mut self) -> bool {
197 if self.nest_level != 0 {
198 self.ecx.span_err(self.fmtsp, "cannot use implicit positional \
199 arguments nested inside methods");
206 fn describe_num_args(&self) -> String {
207 match self.args.len() {
208 0 => "no arguments given".to_string(),
209 1 => "there is 1 argument".to_string(),
210 x => format!("there are {} arguments", x),
214 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
217 if self.args.len() <= arg {
218 let msg = format!("invalid reference to argument `{}` ({})",
219 arg, self.describe_num_args());
221 self.ecx.span_err(self.fmtsp, &msg[]);
225 let arg_type = match self.arg_types[arg] {
227 Some(ref x) => Some(x)
229 self.verify_same(self.args[arg].span, &ty, arg_type);
231 if self.arg_types[arg].is_none() {
232 self.arg_types[arg] = Some(ty);
237 let span = match self.names.get(&name) {
240 let msg = format!("there is no argument named `{}`", name);
241 self.ecx.span_err(self.fmtsp, &msg[]);
245 self.verify_same(span, &ty, self.name_types.get(&name));
246 if !self.name_types.contains_key(&name) {
247 self.name_types.insert(name.clone(), ty);
249 // Assign this named argument a slot in the arguments array if
250 // it hasn't already been assigned a slot.
251 if !self.name_positions.contains_key(&name) {
252 let slot = self.name_positions.len();
253 self.name_positions.insert(name, slot);
259 /// When we're keeping track of the types that are declared for certain
260 /// arguments, we assume that `None` means we haven't seen this argument
261 /// yet, `Some(None)` means that we've seen the argument, but no format was
262 /// specified, and `Some(Some(x))` means that the argument was declared to
265 /// Obviously `Some(Some(x)) != Some(Some(y))`, but we consider it true
266 /// that: `Some(None) == Some(Some(x))`
267 fn verify_same(&self,
270 before: Option<&ArgumentType>) {
271 let cur = match before {
279 (&Known(ref cur), &Known(ref ty)) => {
280 self.ecx.span_err(sp,
281 &format!("argument redeclared with type `{}` when \
282 it was previously `{}`",
286 (&Known(ref cur), _) => {
287 self.ecx.span_err(sp,
288 &format!("argument used to format with `{}` was \
289 attempted to not be used for formatting",
292 (_, &Known(ref ty)) => {
293 self.ecx.span_err(sp,
294 &format!("argument previously used as a format \
295 argument attempted to be used as `{}`",
299 self.ecx.span_err(sp, "argument declared with multiple formats");
304 fn rtpath(ecx: &ExtCtxt, s: &str) -> Vec<ast::Ident> {
305 vec![ecx.ident_of_std("core"), ecx.ident_of("fmt"), ecx.ident_of("rt"),
306 ecx.ident_of("v1"), ecx.ident_of(s)]
309 fn trans_count(&self, c: parse::Count) -> P<ast::Expr> {
311 let count = |c, arg| {
312 let mut path = Context::rtpath(self.ecx, "Count");
313 path.push(self.ecx.ident_of(c));
315 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
316 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
320 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
321 parse::CountIsParam(i) => {
322 count("Param", Some(self.ecx.expr_usize(sp, i)))
324 parse::CountImplied => count("Implied", None),
325 parse::CountIsNextParam => count("NextParam", None),
326 parse::CountIsName(n) => {
327 let i = match self.name_positions.get(n) {
329 None => 0, // error already emitted elsewhere
331 let i = i + self.args.len();
332 count("Param", Some(self.ecx.expr_usize(sp, i)))
337 /// Translate the accumulated string literals to a literal expression
338 fn trans_literal_string(&mut self) -> P<ast::Expr> {
340 let s = token::intern_and_get_ident(&self.literal[]);
341 self.literal.clear();
342 self.ecx.expr_str(sp, s)
345 /// Translate a `parse::Piece` to a static `rt::Argument` or append
346 /// to the `literal` string.
347 fn trans_piece(&mut self, piece: &parse::Piece) -> Option<P<ast::Expr>> {
350 parse::String(s) => {
351 self.literal.push_str(s);
354 parse::NextArgument(ref arg) => {
355 // Translate the position
358 let mut path = Context::rtpath(self.ecx, "Position");
359 path.push(self.ecx.ident_of(c));
362 let arg = self.ecx.expr_usize(sp, i);
363 self.ecx.expr_call_global(sp, path, vec![arg])
366 self.ecx.expr_path(self.ecx.path_global(sp, path))
371 // These two have a direct mapping
372 parse::ArgumentNext => pos("Next", None),
373 parse::ArgumentIs(i) => pos("At", Some(i)),
375 // Named arguments are converted to positional arguments
376 // at the end of the list of arguments
377 parse::ArgumentNamed(n) => {
378 let i = match self.name_positions.get(n) {
380 None => 0, // error already emitted elsewhere
382 let i = i + self.args.len();
388 let simple_arg = parse::Argument {
389 position: parse::ArgumentNext,
390 format: parse::FormatSpec {
391 fill: arg.format.fill,
392 align: parse::AlignUnknown,
394 precision: parse::CountImplied,
395 width: parse::CountImplied,
400 let fill = match arg.format.fill { Some(c) => c, None => ' ' };
402 if *arg != simple_arg || fill != ' ' {
403 self.all_pieces_simple = false;
406 // Translate the format
407 let fill = self.ecx.expr_lit(sp, ast::LitChar(fill));
409 let mut p = Context::rtpath(self.ecx, "Alignment");
410 p.push(self.ecx.ident_of(name));
411 self.ecx.path_global(sp, p)
413 let align = match arg.format.align {
414 parse::AlignLeft => align("Left"),
415 parse::AlignRight => align("Right"),
416 parse::AlignCenter => align("Center"),
417 parse::AlignUnknown => align("Unknown"),
419 let align = self.ecx.expr_path(align);
420 let flags = self.ecx.expr_usize(sp, arg.format.flags);
421 let prec = self.trans_count(arg.format.precision);
422 let width = self.trans_count(arg.format.width);
423 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
424 let fmt = self.ecx.expr_struct(sp, path, vec!(
425 self.ecx.field_imm(sp, self.ecx.ident_of("fill"), fill),
426 self.ecx.field_imm(sp, self.ecx.ident_of("align"), align),
427 self.ecx.field_imm(sp, self.ecx.ident_of("flags"), flags),
428 self.ecx.field_imm(sp, self.ecx.ident_of("precision"), prec),
429 self.ecx.field_imm(sp, self.ecx.ident_of("width"), width)));
431 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
432 Some(self.ecx.expr_struct(sp, path, vec!(
433 self.ecx.field_imm(sp, self.ecx.ident_of("position"), pos),
434 self.ecx.field_imm(sp, self.ecx.ident_of("format"), fmt))))
439 fn static_array(ecx: &mut ExtCtxt,
441 piece_ty: P<ast::Ty>,
442 pieces: Vec<P<ast::Expr>>)
444 let fmtsp = piece_ty.span;
445 let ty = ecx.ty_rptr(fmtsp,
446 ecx.ty(fmtsp, ast::TyVec(piece_ty)),
447 Some(ecx.lifetime(fmtsp, special_idents::static_lifetime.name)),
449 let slice = ecx.expr_vec_slice(fmtsp, pieces);
450 let st = ast::ItemStatic(ty, ast::MutImmutable, slice);
452 let name = ecx.ident_of(name);
453 let item = ecx.item(fmtsp, name, vec![], st);
454 let decl = respan(fmtsp, ast::DeclItem(item));
456 // Wrap the declaration in a block so that it forms a single expression.
457 ecx.expr_block(ecx.block(fmtsp,
458 vec![P(respan(fmtsp, ast::StmtDecl(P(decl), ast::DUMMY_NODE_ID)))],
459 Some(ecx.expr_ident(fmtsp, name))))
462 /// Actually builds the expression which the iformat! block will be expanded
464 fn into_expr(mut self) -> P<ast::Expr> {
465 let mut locals = Vec::new();
466 let mut names: Vec<_> = repeat(None).take(self.name_positions.len()).collect();
467 let mut pats = Vec::new();
468 let mut heads = Vec::new();
470 // First, build up the static array which will become our precompiled
472 let static_lifetime = self.ecx.lifetime(self.fmtsp, special_idents::static_lifetime.name);
473 let piece_ty = self.ecx.ty_rptr(
475 self.ecx.ty_ident(self.fmtsp, self.ecx.ident_of("str")),
476 Some(static_lifetime),
478 let pieces = Context::static_array(self.ecx,
484 // Right now there is a bug such that for the expression:
486 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
487 // valid for the call to `foo`. To work around this all arguments to the
488 // format! string are shoved into locals. Furthermore, we shove the address
489 // of each variable because we don't want to move out of the arguments
490 // passed to this function.
491 for (i, e) in self.args.into_iter().enumerate() {
492 let arg_ty = match self.arg_types[i].as_ref() {
494 None => continue // error already generated
497 let name = self.ecx.ident_of(&format!("__arg{}", i)[]);
498 pats.push(self.ecx.pat_ident(e.span, name));
499 locals.push(Context::format_arg(self.ecx, e.span, arg_ty,
500 self.ecx.expr_ident(e.span, name)));
501 heads.push(self.ecx.expr_addr_of(e.span, e));
503 for name in &self.name_ordering {
504 let e = match self.names.remove(name) {
508 let arg_ty = match self.name_types.get(name) {
513 let lname = self.ecx.ident_of(&format!("__arg{}",
515 pats.push(self.ecx.pat_ident(e.span, lname));
516 names[self.name_positions[*name]] =
517 Some(Context::format_arg(self.ecx, e.span, arg_ty,
518 self.ecx.expr_ident(e.span, lname)));
519 heads.push(self.ecx.expr_addr_of(e.span, e));
522 // Now create a vector containing all the arguments
523 let args = locals.into_iter().chain(names.into_iter().map(|a| a.unwrap()));
525 let args_array = self.ecx.expr_vec(self.fmtsp, args.collect());
527 // Constructs an AST equivalent to:
529 // match (&arg0, &arg1) {
530 // (tmp0, tmp1) => args_array
539 // Because of #11585 the new temporary lifetime rule, the enclosing
540 // statements for these temporaries become the let's themselves.
541 // If one or more of them are RefCell's, RefCell borrow() will also
542 // end there; they don't last long enough for args_array to use them.
543 // The match expression solves the scope problem.
545 // Note, it may also very well be transformed to:
550 // ref tmp1 => args_array } } }
552 // But the nested match expression is proved to perform not as well
553 // as series of let's; the first approach does.
554 let pat = self.ecx.pat_tuple(self.fmtsp, pats);
555 let arm = self.ecx.arm(self.fmtsp, vec!(pat), args_array);
556 let head = self.ecx.expr(self.fmtsp, ast::ExprTup(heads));
557 let result = self.ecx.expr_match(self.fmtsp, head, vec!(arm));
559 let args_slice = self.ecx.expr_addr_of(self.fmtsp, result);
561 // Now create the fmt::Arguments struct with all our locals we created.
562 let (fn_name, fn_args) = if self.all_pieces_simple {
563 ("new_v1", vec![pieces, args_slice])
565 // Build up the static array which will store our precompiled
566 // nonstandard placeholders, if there are any.
567 let piece_ty = self.ecx.ty_path(self.ecx.path_global(
569 Context::rtpath(self.ecx, "Argument")));
570 let fmt = Context::static_array(self.ecx,
575 ("new_v1_formatted", vec![pieces, args_slice, fmt])
578 self.ecx.expr_call_global(self.fmtsp, vec!(
579 self.ecx.ident_of_std("core"),
580 self.ecx.ident_of("fmt"),
581 self.ecx.ident_of("Arguments"),
582 self.ecx.ident_of(fn_name)), fn_args)
585 fn format_arg(ecx: &ExtCtxt, sp: Span,
586 ty: &ArgumentType, arg: P<ast::Expr>)
588 let trait_ = match *ty {
589 Known(ref tyname) => {
602 &format!("unknown format trait `{}`",
609 return ecx.expr_call_global(sp, vec![
610 ecx.ident_of_std("core"),
612 ecx.ident_of("ArgumentV1"),
613 ecx.ident_of("from_uint")], vec![arg])
617 let format_fn = ecx.path_global(sp, vec![
618 ecx.ident_of_std("core"),
620 ecx.ident_of(trait_),
621 ecx.ident_of("fmt")]);
622 ecx.expr_call_global(sp, vec![
623 ecx.ident_of_std("core"),
625 ecx.ident_of("ArgumentV1"),
626 ecx.ident_of("new")], vec![arg, ecx.expr_path(format_fn)])
630 pub fn expand_format_args<'cx>(ecx: &'cx mut ExtCtxt, sp: Span,
631 tts: &[ast::TokenTree])
632 -> Box<base::MacResult+'cx> {
634 match parse_args(ecx, sp, tts) {
635 Some((efmt, args, order, names)) => {
636 MacExpr::new(expand_preparsed_format_args(ecx, sp, efmt,
639 None => DummyResult::expr(sp)
643 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
644 /// and construct the appropriate formatting expression.
645 pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt, sp: Span,
647 args: Vec<P<ast::Expr>>,
648 name_ordering: Vec<String>,
649 names: HashMap<String, P<ast::Expr>>)
651 let arg_types: Vec<_> = (0..args.len()).map(|_| None).collect();
652 let mut cx = Context {
655 arg_types: arg_types,
657 name_positions: HashMap::new(),
658 name_types: HashMap::new(),
659 name_ordering: name_ordering,
662 literal: String::new(),
664 str_pieces: Vec::new(),
665 all_pieces_simple: true,
668 cx.fmtsp = efmt.span;
669 let fmt = match expr_to_string(cx.ecx,
671 "format argument must be a string literal.") {
672 Some((fmt, _)) => fmt,
673 None => return DummyResult::raw_expr(sp)
676 let mut parser = parse::Parser::new(&fmt);
679 match parser.next() {
681 if parser.errors.len() > 0 { break }
682 cx.verify_piece(&piece);
683 match cx.trans_piece(&piece) {
685 let s = cx.trans_literal_string();
686 cx.str_pieces.push(s);
687 cx.pieces.push(piece);
695 if !parser.errors.is_empty() {
696 cx.ecx.span_err(cx.fmtsp, &format!("invalid format string: {}",
697 parser.errors.remove(0))[]);
698 return DummyResult::raw_expr(sp);
700 if !cx.literal.is_empty() {
701 let s = cx.trans_literal_string();
702 cx.str_pieces.push(s);
705 // Make sure that all arguments were used and all arguments have types.
706 for (i, ty) in cx.arg_types.iter().enumerate() {
708 cx.ecx.span_err(cx.args[i].span, "argument never used");
711 for (name, e) in &cx.names {
712 if !cx.name_types.contains_key(name) {
713 cx.ecx.span_err(e.span, "named argument never used");