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::*;
14 use fmt_macros as parse;
17 use syntax::codemap::{Span, respan};
18 use syntax::ext::base::*;
19 use syntax::ext::base;
20 use syntax::ext::build::AstBuilder;
21 use syntax::fold::Folder;
22 use syntax::parse::token::special_idents;
23 use syntax::parse::token;
26 use std::collections::HashMap;
39 struct Context<'a, 'b:'a> {
40 ecx: &'a mut ExtCtxt<'b>,
41 /// The macro's call site. References to unstable formatting internals must
42 /// use this span to pass the stability checker.
44 /// The span of the format string literal.
47 /// Parsed argument expressions and the types that we've found so far for
49 args: Vec<P<ast::Expr>>,
50 arg_types: Vec<Option<ArgumentType>>,
51 /// Parsed named expressions and the types that we've found for them so far.
52 /// Note that we keep a side-array of the ordering of the named arguments
53 /// found to be sure that we can translate them in the same order that they
55 names: HashMap<String, P<ast::Expr>>,
56 name_types: HashMap<String, ArgumentType>,
57 name_ordering: Vec<String>,
59 /// The latest consecutive literal strings, or empty if there weren't any.
62 /// Collection of the compiled `rt::Argument` structures
63 pieces: Vec<P<ast::Expr>>,
64 /// Collection of string literals
65 str_pieces: Vec<P<ast::Expr>>,
66 /// Stays `true` if all formatting parameters are default (as in "{}{}").
67 all_pieces_simple: bool,
69 name_positions: HashMap<String, usize>,
71 /// Updated as arguments are consumed or methods are entered
76 /// Parses the arguments from the given list of tokens, returning None
77 /// if there's a parse error so we can continue parsing other format!
80 /// If parsing succeeds, the return value is:
82 /// Some((fmtstr, unnamed arguments, ordering of named arguments,
85 fn parse_args(ecx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
86 -> Option<(P<ast::Expr>, Vec<P<ast::Expr>>, Vec<String>,
87 HashMap<String, P<ast::Expr>>)> {
88 let mut args = Vec::new();
89 let mut names = HashMap::<String, P<ast::Expr>>::new();
90 let mut order = Vec::new();
92 let mut p = ecx.new_parser_from_tts(tts);
94 if p.token == token::Eof {
95 ecx.span_err(sp, "requires at least a format string argument");
98 let fmtstr = panictry!(p.parse_expr());
99 let mut named = false;
100 while p.token != token::Eof {
101 if !p.eat(&token::Comma) {
102 ecx.span_err(sp, "expected token: `,`");
105 if p.token == token::Eof { break } // accept trailing commas
106 if named || (p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq)) {
108 let ident = match p.token {
109 token::Ident(i, _) => {
115 "expected ident, positional arguments \
116 cannot follow named arguments");
121 &format!("expected ident for named argument, found `{}`",
122 p.this_token_to_string()));
126 let name: &str = &ident.name.as_str();
128 panictry!(p.expect(&token::Eq));
129 let e = panictry!(p.parse_expr());
130 match names.get(name) {
133 ecx.struct_span_err(e.span,
134 &format!("duplicate argument named `{}`",
136 .span_note(prev.span, "previously here")
141 order.push(name.to_string());
142 names.insert(name.to_string(), e);
144 args.push(panictry!(p.parse_expr()));
147 Some((fmtstr, args, order, names))
150 impl<'a, 'b> Context<'a, 'b> {
151 /// Verifies one piece of a parse string. All errors are not emitted as
152 /// fatal so we can continue giving errors about this and possibly other
154 fn verify_piece(&mut self, p: &parse::Piece) {
156 parse::String(..) => {}
157 parse::NextArgument(ref arg) => {
158 // width/precision first, if they have implicit positional
159 // parameters it makes more sense to consume them first.
160 self.verify_count(arg.format.width);
161 self.verify_count(arg.format.precision);
163 // argument second, if it's an implicit positional parameter
164 // it's written second, so it should come after width/precision.
165 let pos = match arg.position {
166 parse::ArgumentNext => {
167 let i = self.next_arg;
168 if self.check_positional_ok() {
173 parse::ArgumentIs(i) => Exact(i),
174 parse::ArgumentNamed(s) => Named(s.to_string()),
177 let ty = Known(arg.format.ty.to_string());
178 self.verify_arg_type(pos, ty);
183 fn verify_count(&mut self, c: parse::Count) {
185 parse::CountImplied | parse::CountIs(..) => {}
186 parse::CountIsParam(i) => {
187 self.verify_arg_type(Exact(i), Unsigned);
189 parse::CountIsName(s) => {
190 self.verify_arg_type(Named(s.to_string()), Unsigned);
192 parse::CountIsNextParam => {
193 if self.check_positional_ok() {
194 let next_arg = self.next_arg;
195 self.verify_arg_type(Exact(next_arg), Unsigned);
202 fn check_positional_ok(&mut self) -> bool {
203 if self.nest_level != 0 {
204 self.ecx.span_err(self.fmtsp, "cannot use implicit positional \
205 arguments nested inside methods");
212 fn describe_num_args(&self) -> String {
213 match self.args.len() {
214 0 => "no arguments given".to_string(),
215 1 => "there is 1 argument".to_string(),
216 x => format!("there are {} arguments", x),
220 fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
223 if self.args.len() <= arg {
224 let msg = format!("invalid reference to argument `{}` ({})",
225 arg, self.describe_num_args());
227 self.ecx.span_err(self.fmtsp, &msg[..]);
231 let arg_type = match self.arg_types[arg] {
233 Some(ref x) => Some(x)
235 self.verify_same(self.args[arg].span, &ty, arg_type);
237 if self.arg_types[arg].is_none() {
238 self.arg_types[arg] = Some(ty);
243 let span = match self.names.get(&name) {
246 let msg = format!("there is no argument named `{}`", name);
247 self.ecx.span_err(self.fmtsp, &msg[..]);
251 self.verify_same(span, &ty, self.name_types.get(&name));
252 if !self.name_types.contains_key(&name) {
253 self.name_types.insert(name.clone(), ty);
255 // Assign this named argument a slot in the arguments array if
256 // it hasn't already been assigned a slot.
257 if !self.name_positions.contains_key(&name) {
258 let slot = self.name_positions.len();
259 self.name_positions.insert(name, slot);
265 /// When we're keeping track of the types that are declared for certain
266 /// arguments, we assume that `None` means we haven't seen this argument
267 /// yet, `Some(None)` means that we've seen the argument, but no format was
268 /// specified, and `Some(Some(x))` means that the argument was declared to
271 /// Obviously `Some(Some(x)) != Some(Some(y))`, but we consider it true
272 /// that: `Some(None) == Some(Some(x))`
273 fn verify_same(&self,
276 before: Option<&ArgumentType>) {
277 let cur = match before {
285 (&Known(ref cur), &Known(ref ty)) => {
286 self.ecx.span_err(sp,
287 &format!("argument redeclared with type `{}` when \
288 it was previously `{}`",
292 (&Known(ref cur), _) => {
293 self.ecx.span_err(sp,
294 &format!("argument used to format with `{}` was \
295 attempted to not be used for formatting",
298 (_, &Known(ref ty)) => {
299 self.ecx.span_err(sp,
300 &format!("argument previously used as a format \
301 argument attempted to be used as `{}`",
305 self.ecx.span_err(sp, "argument declared with multiple formats");
310 fn rtpath(ecx: &ExtCtxt, s: &str) -> Vec<ast::Ident> {
311 ecx.std_path(&["fmt", "rt", "v1", s])
314 fn trans_count(&self, c: parse::Count) -> P<ast::Expr> {
316 let count = |c, arg| {
317 let mut path = Context::rtpath(self.ecx, "Count");
318 path.push(self.ecx.ident_of(c));
320 Some(arg) => self.ecx.expr_call_global(sp, path, vec![arg]),
321 None => self.ecx.expr_path(self.ecx.path_global(sp, path)),
325 parse::CountIs(i) => count("Is", Some(self.ecx.expr_usize(sp, i))),
326 parse::CountIsParam(i) => {
327 count("Param", Some(self.ecx.expr_usize(sp, i)))
329 parse::CountImplied => count("Implied", None),
330 parse::CountIsNextParam => count("NextParam", None),
331 parse::CountIsName(n) => {
332 let i = match self.name_positions.get(n) {
334 None => 0, // error already emitted elsewhere
336 let i = i + self.args.len();
337 count("Param", Some(self.ecx.expr_usize(sp, i)))
342 /// Translate the accumulated string literals to a literal expression
343 fn trans_literal_string(&mut self) -> P<ast::Expr> {
345 let s = token::intern_and_get_ident(&self.literal);
346 self.literal.clear();
347 self.ecx.expr_str(sp, s)
350 /// Translate a `parse::Piece` to a static `rt::Argument` or append
351 /// to the `literal` string.
352 fn trans_piece(&mut self, piece: &parse::Piece) -> Option<P<ast::Expr>> {
355 parse::String(s) => {
356 self.literal.push_str(s);
359 parse::NextArgument(ref arg) => {
360 // Translate the position
363 let mut path = Context::rtpath(self.ecx, "Position");
364 path.push(self.ecx.ident_of(c));
367 let arg = self.ecx.expr_usize(sp, i);
368 self.ecx.expr_call_global(sp, path, vec![arg])
371 self.ecx.expr_path(self.ecx.path_global(sp, path))
376 // These two have a direct mapping
377 parse::ArgumentNext => pos("Next", None),
378 parse::ArgumentIs(i) => pos("At", Some(i)),
380 // Named arguments are converted to positional arguments
381 // at the end of the list of arguments
382 parse::ArgumentNamed(n) => {
383 let i = match self.name_positions.get(n) {
385 None => 0, // error already emitted elsewhere
387 let i = i + self.args.len();
393 let simple_arg = parse::Argument {
394 position: parse::ArgumentNext,
395 format: parse::FormatSpec {
396 fill: arg.format.fill,
397 align: parse::AlignUnknown,
399 precision: parse::CountImplied,
400 width: parse::CountImplied,
405 let fill = match arg.format.fill { Some(c) => c, None => ' ' };
407 if *arg != simple_arg || fill != ' ' {
408 self.all_pieces_simple = false;
411 // Translate the format
412 let fill = self.ecx.expr_lit(sp, ast::LitChar(fill));
414 let mut p = Context::rtpath(self.ecx, "Alignment");
415 p.push(self.ecx.ident_of(name));
416 self.ecx.path_global(sp, p)
418 let align = match arg.format.align {
419 parse::AlignLeft => align("Left"),
420 parse::AlignRight => align("Right"),
421 parse::AlignCenter => align("Center"),
422 parse::AlignUnknown => align("Unknown"),
424 let align = self.ecx.expr_path(align);
425 let flags = self.ecx.expr_u32(sp, arg.format.flags);
426 let prec = self.trans_count(arg.format.precision);
427 let width = self.trans_count(arg.format.width);
428 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
429 let fmt = self.ecx.expr_struct(sp, path, vec!(
430 self.ecx.field_imm(sp, self.ecx.ident_of("fill"), fill),
431 self.ecx.field_imm(sp, self.ecx.ident_of("align"), align),
432 self.ecx.field_imm(sp, self.ecx.ident_of("flags"), flags),
433 self.ecx.field_imm(sp, self.ecx.ident_of("precision"), prec),
434 self.ecx.field_imm(sp, self.ecx.ident_of("width"), width)));
436 let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
437 Some(self.ecx.expr_struct(sp, path, vec!(
438 self.ecx.field_imm(sp, self.ecx.ident_of("position"), pos),
439 self.ecx.field_imm(sp, self.ecx.ident_of("format"), fmt))))
444 fn static_array(ecx: &mut ExtCtxt,
446 piece_ty: P<ast::Ty>,
447 pieces: Vec<P<ast::Expr>>)
449 let sp = piece_ty.span;
450 let ty = ecx.ty_rptr(sp,
451 ecx.ty(sp, ast::TyVec(piece_ty)),
452 Some(ecx.lifetime(sp, special_idents::static_lifetime.name)),
454 let slice = ecx.expr_vec_slice(sp, pieces);
455 // static instead of const to speed up codegen by not requiring this to be inlined
456 let st = ast::ItemStatic(ty, ast::MutImmutable, slice);
458 let name = ecx.ident_of(name);
459 let item = ecx.item(sp, name, vec![], st);
460 let decl = respan(sp, ast::DeclItem(item));
462 // Wrap the declaration in a block so that it forms a single expression.
463 ecx.expr_block(ecx.block(sp,
464 vec![P(respan(sp, ast::StmtDecl(P(decl), ast::DUMMY_NODE_ID)))],
465 Some(ecx.expr_ident(sp, name))))
468 /// Actually builds the expression which the iformat! block will be expanded
470 fn into_expr(mut self) -> P<ast::Expr> {
471 let mut locals = Vec::new();
472 let mut names = vec![None; self.name_positions.len()];
473 let mut pats = Vec::new();
474 let mut heads = Vec::new();
476 // First, build up the static array which will become our precompiled
478 let static_lifetime = self.ecx.lifetime(self.fmtsp, special_idents::static_lifetime.name);
479 let piece_ty = self.ecx.ty_rptr(
481 self.ecx.ty_ident(self.fmtsp, self.ecx.ident_of("str")),
482 Some(static_lifetime),
484 let pieces = Context::static_array(self.ecx,
490 // Right now there is a bug such that for the expression:
492 // the lifetime of `1` doesn't outlast the call to `bar`, so it's not
493 // valid for the call to `foo`. To work around this all arguments to the
494 // format! string are shoved into locals. Furthermore, we shove the address
495 // of each variable because we don't want to move out of the arguments
496 // passed to this function.
497 for (i, e) in self.args.into_iter().enumerate() {
498 let arg_ty = match self.arg_types[i].as_ref() {
500 None => continue // error already generated
503 let name = self.ecx.ident_of(&format!("__arg{}", i));
504 pats.push(self.ecx.pat_ident(e.span, name));
505 locals.push(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty,
506 self.ecx.expr_ident(e.span, name)));
507 heads.push(self.ecx.expr_addr_of(e.span, e));
509 for name in &self.name_ordering {
510 let e = match self.names.remove(name) {
514 let arg_ty = match self.name_types.get(name) {
519 let lname = self.ecx.ident_of(&format!("__arg{}",
521 pats.push(self.ecx.pat_ident(e.span, lname));
522 names[*self.name_positions.get(name).unwrap()] =
523 Some(Context::format_arg(self.ecx, self.macsp, e.span, arg_ty,
524 self.ecx.expr_ident(e.span, lname)));
525 heads.push(self.ecx.expr_addr_of(e.span, e));
528 // Now create a vector containing all the arguments
529 let args = locals.into_iter().chain(names.into_iter().map(|a| a.unwrap()));
531 let args_array = self.ecx.expr_vec(self.fmtsp, args.collect());
533 // Constructs an AST equivalent to:
535 // match (&arg0, &arg1) {
536 // (tmp0, tmp1) => args_array
545 // Because of #11585 the new temporary lifetime rule, the enclosing
546 // statements for these temporaries become the let's themselves.
547 // If one or more of them are RefCell's, RefCell borrow() will also
548 // end there; they don't last long enough for args_array to use them.
549 // The match expression solves the scope problem.
551 // Note, it may also very well be transformed to:
556 // ref tmp1 => args_array } } }
558 // But the nested match expression is proved to perform not as well
559 // as series of let's; the first approach does.
560 let pat = self.ecx.pat_tuple(self.fmtsp, pats);
561 let arm = self.ecx.arm(self.fmtsp, vec!(pat), args_array);
562 let head = self.ecx.expr(self.fmtsp, ast::ExprTup(heads));
563 let result = self.ecx.expr_match(self.fmtsp, head, vec!(arm));
565 let args_slice = self.ecx.expr_addr_of(self.fmtsp, result);
567 // Now create the fmt::Arguments struct with all our locals we created.
568 let (fn_name, fn_args) = if self.all_pieces_simple {
569 ("new_v1", vec![pieces, args_slice])
571 // Build up the static array which will store our precompiled
572 // nonstandard placeholders, if there are any.
573 let piece_ty = self.ecx.ty_path(self.ecx.path_global(
575 Context::rtpath(self.ecx, "Argument")));
576 let fmt = Context::static_array(self.ecx,
581 ("new_v1_formatted", vec![pieces, args_slice, fmt])
584 let path = self.ecx.std_path(&["fmt", "Arguments", fn_name]);
585 self.ecx.expr_call_global(self.macsp, path, fn_args)
588 fn format_arg(ecx: &ExtCtxt, macsp: Span, sp: Span,
589 ty: &ArgumentType, arg: P<ast::Expr>)
591 let trait_ = match *ty {
592 Known(ref tyname) => {
605 &format!("unknown format trait `{}`",
612 let path = ecx.std_path(&["fmt", "ArgumentV1", "from_usize"]);
613 return ecx.expr_call_global(macsp, path, vec![arg])
617 let path = ecx.std_path(&["fmt", trait_, "fmt"]);
618 let format_fn = ecx.path_global(sp, path);
619 let path = ecx.std_path(&["fmt", "ArgumentV1", "new"]);
620 ecx.expr_call_global(macsp, path, vec![arg, ecx.expr_path(format_fn)])
624 pub fn expand_format_args<'cx>(ecx: &'cx mut ExtCtxt, sp: Span,
625 tts: &[ast::TokenTree])
626 -> Box<base::MacResult+'cx> {
628 match parse_args(ecx, sp, tts) {
629 Some((efmt, args, order, names)) => {
630 MacEager::expr(expand_preparsed_format_args(ecx, sp, efmt,
633 None => DummyResult::expr(sp)
637 /// Take the various parts of `format_args!(efmt, args..., name=names...)`
638 /// and construct the appropriate formatting expression.
639 pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt, sp: Span,
641 args: Vec<P<ast::Expr>>,
642 name_ordering: Vec<String>,
643 names: HashMap<String, P<ast::Expr>>)
645 let arg_types: Vec<_> = (0..args.len()).map(|_| None).collect();
646 let macsp = ecx.call_site();
647 // Expand the format literal so that efmt.span will have a backtrace. This
648 // is essential for locating a bug when the format literal is generated in
649 // a macro. (e.g. println!("{}"), which uses concat!($fmt, "\n")).
650 let efmt = ecx.expander().fold_expr(efmt);
651 let mut cx = Context {
654 arg_types: arg_types,
656 name_positions: HashMap::new(),
657 name_types: HashMap::new(),
658 name_ordering: name_ordering,
661 literal: String::new(),
663 str_pieces: Vec::new(),
664 all_pieces_simple: true,
668 let fmt = match expr_to_string(cx.ecx,
670 "format argument must be a string literal.") {
671 Some((fmt, _)) => fmt,
672 None => return DummyResult::raw_expr(sp)
675 let mut parser = parse::Parser::new(&fmt);
678 match parser.next() {
680 if !parser.errors.is_empty() { break }
681 cx.verify_piece(&piece);
682 match cx.trans_piece(&piece) {
684 let s = cx.trans_literal_string();
685 cx.str_pieces.push(s);
686 cx.pieces.push(piece);
694 if !parser.errors.is_empty() {
695 cx.ecx.span_err(cx.fmtsp, &format!("invalid format string: {}",
696 parser.errors.remove(0)));
697 return DummyResult::raw_expr(sp);
699 if !cx.literal.is_empty() {
700 let s = cx.trans_literal_string();
701 cx.str_pieces.push(s);
704 // Make sure that all arguments were used and all arguments have types.
705 for (i, ty) in cx.arg_types.iter().enumerate() {
707 cx.ecx.span_err(cx.args[i].span, "argument never used");
710 for (name, e) in &cx.names {
711 if !cx.name_types.contains_key(name) {
712 cx.ecx.span_err(e.span, "named argument never used");