rust/src/libsyntax/ext/format.rs
2015-01-10 11:31:53 +11:00

731 lines
29 KiB
Rust

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use self::ArgumentType::*;
use self::Position::*;
use ast;
use codemap::{Span, respan};
use ext::base::*;
use ext::base;
use ext::build::AstBuilder;
use fmt_macros as parse;
use parse::token::{InternedString, special_idents};
use parse::token;
use ptr::P;
use std::collections::HashMap;
use std::iter::repeat;
#[derive(PartialEq)]
enum ArgumentType {
Known(String),
Unsigned
}
enum Position {
Exact(uint),
Named(String),
}
struct Context<'a, 'b:'a> {
ecx: &'a mut ExtCtxt<'b>,
fmtsp: Span,
/// Parsed argument expressions and the types that we've found so far for
/// them.
args: Vec<P<ast::Expr>>,
arg_types: Vec<Option<ArgumentType>>,
/// Parsed named expressions and the types that we've found for them so far.
/// Note that we keep a side-array of the ordering of the named arguments
/// found to be sure that we can translate them in the same order that they
/// were declared in.
names: HashMap<String, P<ast::Expr>>,
name_types: HashMap<String, ArgumentType>,
name_ordering: Vec<String>,
/// The latest consecutive literal strings, or empty if there weren't any.
literal: String,
/// Collection of the compiled `rt::Argument` structures
pieces: Vec<P<ast::Expr>>,
/// Collection of string literals
str_pieces: Vec<P<ast::Expr>>,
/// Stays `true` if all formatting parameters are default (as in "{}{}").
all_pieces_simple: bool,
name_positions: HashMap<String, uint>,
/// Updated as arguments are consumed or methods are entered
nest_level: uint,
next_arg: uint,
}
/// Parses the arguments from the given list of tokens, returning None
/// if there's a parse error so we can continue parsing other format!
/// expressions.
///
/// If parsing succeeds, the return value is:
///
/// Some((fmtstr, unnamed arguments, ordering of named arguments,
/// named arguments))
fn parse_args(ecx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
-> Option<(P<ast::Expr>, Vec<P<ast::Expr>>, Vec<String>,
HashMap<String, P<ast::Expr>>)> {
let mut args = Vec::new();
let mut names = HashMap::<String, P<ast::Expr>>::new();
let mut order = Vec::new();
let mut p = ecx.new_parser_from_tts(tts);
if p.token == token::Eof {
ecx.span_err(sp, "requires at least a format string argument");
return None;
}
let fmtstr = p.parse_expr();
let mut named = false;
while p.token != token::Eof {
if !p.eat(&token::Comma) {
ecx.span_err(sp, "expected token: `,`");
return None;
}
if p.token == token::Eof { break } // accept trailing commas
if named || (p.token.is_ident() && p.look_ahead(1, |t| *t == token::Eq)) {
named = true;
let ident = match p.token {
token::Ident(i, _) => {
p.bump();
i
}
_ if named => {
ecx.span_err(p.span,
"expected ident, positional arguments \
cannot follow named arguments");
return None;
}
_ => {
ecx.span_err(p.span,
&format!("expected ident for named argument, found `{}`",
p.this_token_to_string())[]);
return None;
}
};
let interned_name = token::get_ident(ident);
let name = interned_name.get();
p.expect(&token::Eq);
let e = p.parse_expr();
match names.get(name) {
None => {}
Some(prev) => {
ecx.span_err(e.span,
&format!("duplicate argument named `{}`",
name)[]);
ecx.parse_sess.span_diagnostic.span_note(prev.span, "previously here");
continue
}
}
order.push(name.to_string());
names.insert(name.to_string(), e);
} else {
args.push(p.parse_expr());
}
}
Some((fmtstr, args, order, names))
}
impl<'a, 'b> Context<'a, 'b> {
/// Verifies one piece of a parse string. All errors are not emitted as
/// fatal so we can continue giving errors about this and possibly other
/// format strings.
fn verify_piece(&mut self, p: &parse::Piece) {
match *p {
parse::String(..) => {}
parse::NextArgument(ref arg) => {
// width/precision first, if they have implicit positional
// parameters it makes more sense to consume them first.
self.verify_count(arg.format.width);
self.verify_count(arg.format.precision);
// argument second, if it's an implicit positional parameter
// it's written second, so it should come after width/precision.
let pos = match arg.position {
parse::ArgumentNext => {
let i = self.next_arg;
if self.check_positional_ok() {
self.next_arg += 1;
}
Exact(i)
}
parse::ArgumentIs(i) => Exact(i),
parse::ArgumentNamed(s) => Named(s.to_string()),
};
let ty = Known(arg.format.ty.to_string());
self.verify_arg_type(pos, ty);
}
}
}
fn verify_count(&mut self, c: parse::Count) {
match c {
parse::CountImplied | parse::CountIs(..) => {}
parse::CountIsParam(i) => {
self.verify_arg_type(Exact(i), Unsigned);
}
parse::CountIsName(s) => {
self.verify_arg_type(Named(s.to_string()), Unsigned);
}
parse::CountIsNextParam => {
if self.check_positional_ok() {
let next_arg = self.next_arg;
self.verify_arg_type(Exact(next_arg), Unsigned);
self.next_arg += 1;
}
}
}
}
fn check_positional_ok(&mut self) -> bool {
if self.nest_level != 0 {
self.ecx.span_err(self.fmtsp, "cannot use implicit positional \
arguments nested inside methods");
false
} else {
true
}
}
fn describe_num_args(&self) -> String {
match self.args.len() {
0 => "no arguments given".to_string(),
1 => "there is 1 argument".to_string(),
x => format!("there are {} arguments", x),
}
}
fn verify_arg_type(&mut self, arg: Position, ty: ArgumentType) {
match arg {
Exact(arg) => {
if self.args.len() <= arg {
let msg = format!("invalid reference to argument `{}` ({})",
arg, self.describe_num_args());
self.ecx.span_err(self.fmtsp, &msg[]);
return;
}
{
let arg_type = match self.arg_types[arg] {
None => None,
Some(ref x) => Some(x)
};
self.verify_same(self.args[arg].span, &ty, arg_type);
}
if self.arg_types[arg].is_none() {
self.arg_types[arg] = Some(ty);
}
}
Named(name) => {
let span = match self.names.get(&name) {
Some(e) => e.span,
None => {
let msg = format!("there is no argument named `{}`", name);
self.ecx.span_err(self.fmtsp, &msg[]);
return;
}
};
self.verify_same(span, &ty, self.name_types.get(&name));
if !self.name_types.contains_key(&name) {
self.name_types.insert(name.clone(), ty);
}
// Assign this named argument a slot in the arguments array if
// it hasn't already been assigned a slot.
if !self.name_positions.contains_key(&name) {
let slot = self.name_positions.len();
self.name_positions.insert(name, slot);
}
}
}
}
/// When we're keeping track of the types that are declared for certain
/// arguments, we assume that `None` means we haven't seen this argument
/// yet, `Some(None)` means that we've seen the argument, but no format was
/// specified, and `Some(Some(x))` means that the argument was declared to
/// have type `x`.
///
/// Obviously `Some(Some(x)) != Some(Some(y))`, but we consider it true
/// that: `Some(None) == Some(Some(x))`
fn verify_same(&self,
sp: Span,
ty: &ArgumentType,
before: Option<&ArgumentType>) {
let cur = match before {
None => return,
Some(t) => t,
};
if *ty == *cur {
return
}
match (cur, ty) {
(&Known(ref cur), &Known(ref ty)) => {
self.ecx.span_err(sp,
&format!("argument redeclared with type `{}` when \
it was previously `{}`",
*ty,
*cur)[]);
}
(&Known(ref cur), _) => {
self.ecx.span_err(sp,
&format!("argument used to format with `{}` was \
attempted to not be used for formatting",
*cur)[]);
}
(_, &Known(ref ty)) => {
self.ecx.span_err(sp,
&format!("argument previously used as a format \
argument attempted to be used as `{}`",
*ty)[]);
}
(_, _) => {
self.ecx.span_err(sp, "argument declared with multiple formats");
}
}
}
/// These attributes are applied to all statics that this syntax extension
/// will generate.
fn static_attrs(ecx: &ExtCtxt, fmtsp: Span) -> Vec<ast::Attribute> {
// Flag statics as `inline` so LLVM can merge duplicate globals as much
// as possible (which we're generating a whole lot of).
let unnamed = ecx.meta_word(fmtsp, InternedString::new("inline"));
let unnamed = ecx.attribute(fmtsp, unnamed);
// Do not warn format string as dead code
let dead_code = ecx.meta_word(fmtsp, InternedString::new("dead_code"));
let allow_dead_code = ecx.meta_list(fmtsp,
InternedString::new("allow"),
vec![dead_code]);
let allow_dead_code = ecx.attribute(fmtsp, allow_dead_code);
vec![unnamed, allow_dead_code]
}
fn rtpath(ecx: &ExtCtxt, s: &str) -> Vec<ast::Ident> {
vec![ecx.ident_of("std"), ecx.ident_of("fmt"), ecx.ident_of("rt"), ecx.ident_of(s)]
}
fn trans_count(&self, c: parse::Count) -> P<ast::Expr> {
let sp = self.fmtsp;
match c {
parse::CountIs(i) => {
self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "CountIs"),
vec!(self.ecx.expr_uint(sp, i)))
}
parse::CountIsParam(i) => {
self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "CountIsParam"),
vec!(self.ecx.expr_uint(sp, i)))
}
parse::CountImplied => {
let path = self.ecx.path_global(sp, Context::rtpath(self.ecx,
"CountImplied"));
self.ecx.expr_path(path)
}
parse::CountIsNextParam => {
let path = self.ecx.path_global(sp, Context::rtpath(self.ecx,
"CountIsNextParam"));
self.ecx.expr_path(path)
}
parse::CountIsName(n) => {
let i = match self.name_positions.get(n) {
Some(&i) => i,
None => 0, // error already emitted elsewhere
};
let i = i + self.args.len();
self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "CountIsParam"),
vec!(self.ecx.expr_uint(sp, i)))
}
}
}
/// Translate the accumulated string literals to a literal expression
fn trans_literal_string(&mut self) -> P<ast::Expr> {
let sp = self.fmtsp;
let s = token::intern_and_get_ident(&self.literal[]);
self.literal.clear();
self.ecx.expr_str(sp, s)
}
/// Translate a `parse::Piece` to a static `rt::Argument` or append
/// to the `literal` string.
fn trans_piece(&mut self, piece: &parse::Piece) -> Option<P<ast::Expr>> {
let sp = self.fmtsp;
match *piece {
parse::String(s) => {
self.literal.push_str(s);
None
}
parse::NextArgument(ref arg) => {
// Translate the position
let pos = match arg.position {
// These two have a direct mapping
parse::ArgumentNext => {
let path = self.ecx.path_global(sp, Context::rtpath(self.ecx,
"ArgumentNext"));
self.ecx.expr_path(path)
}
parse::ArgumentIs(i) => {
self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "ArgumentIs"),
vec!(self.ecx.expr_uint(sp, i)))
}
// Named arguments are converted to positional arguments at
// the end of the list of arguments
parse::ArgumentNamed(n) => {
let i = match self.name_positions.get(n) {
Some(&i) => i,
None => 0, // error already emitted elsewhere
};
let i = i + self.args.len();
self.ecx.expr_call_global(sp, Context::rtpath(self.ecx, "ArgumentIs"),
vec!(self.ecx.expr_uint(sp, i)))
}
};
let simple_arg = parse::Argument {
position: parse::ArgumentNext,
format: parse::FormatSpec {
fill: arg.format.fill,
align: parse::AlignUnknown,
flags: 0,
precision: parse::CountImplied,
width: parse::CountImplied,
ty: arg.format.ty
}
};
let fill = match arg.format.fill { Some(c) => c, None => ' ' };
if *arg != simple_arg || fill != ' ' {
self.all_pieces_simple = false;
}
// Translate the format
let fill = self.ecx.expr_lit(sp, ast::LitChar(fill));
let align = match arg.format.align {
parse::AlignLeft => {
self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignLeft"))
}
parse::AlignRight => {
self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignRight"))
}
parse::AlignCenter => {
self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignCenter"))
}
parse::AlignUnknown => {
self.ecx.path_global(sp, Context::rtpath(self.ecx, "AlignUnknown"))
}
};
let align = self.ecx.expr_path(align);
let flags = self.ecx.expr_uint(sp, arg.format.flags);
let prec = self.trans_count(arg.format.precision);
let width = self.trans_count(arg.format.width);
let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "FormatSpec"));
let fmt = self.ecx.expr_struct(sp, path, vec!(
self.ecx.field_imm(sp, self.ecx.ident_of("fill"), fill),
self.ecx.field_imm(sp, self.ecx.ident_of("align"), align),
self.ecx.field_imm(sp, self.ecx.ident_of("flags"), flags),
self.ecx.field_imm(sp, self.ecx.ident_of("precision"), prec),
self.ecx.field_imm(sp, self.ecx.ident_of("width"), width)));
let path = self.ecx.path_global(sp, Context::rtpath(self.ecx, "Argument"));
Some(self.ecx.expr_struct(sp, path, vec!(
self.ecx.field_imm(sp, self.ecx.ident_of("position"), pos),
self.ecx.field_imm(sp, self.ecx.ident_of("format"), fmt))))
}
}
}
fn static_array(ecx: &mut ExtCtxt,
name: &str,
piece_ty: P<ast::Ty>,
pieces: Vec<P<ast::Expr>>)
-> P<ast::Expr> {
let fmtsp = piece_ty.span;
let ty = ecx.ty_rptr(fmtsp,
ecx.ty(fmtsp, ast::TyVec(piece_ty)),
Some(ecx.lifetime(fmtsp, special_idents::static_lifetime.name)),
ast::MutImmutable);
let slice = ecx.expr_vec_slice(fmtsp, pieces);
let st = ast::ItemStatic(ty, ast::MutImmutable, slice);
let name = ecx.ident_of(name);
let item = ecx.item(fmtsp, name, Context::static_attrs(ecx, fmtsp), st);
let decl = respan(fmtsp, ast::DeclItem(item));
// Wrap the declaration in a block so that it forms a single expression.
ecx.expr_block(ecx.block(fmtsp,
vec![P(respan(fmtsp, ast::StmtDecl(P(decl), ast::DUMMY_NODE_ID)))],
Some(ecx.expr_ident(fmtsp, name))))
}
/// Actually builds the expression which the iformat! block will be expanded
/// to
fn into_expr(mut self) -> P<ast::Expr> {
let mut locals = Vec::new();
let mut names: Vec<_> = repeat(None).take(self.name_positions.len()).collect();
let mut pats = Vec::new();
let mut heads = Vec::new();
// First, build up the static array which will become our precompiled
// format "string"
let static_lifetime = self.ecx.lifetime(self.fmtsp, special_idents::static_lifetime.name);
let piece_ty = self.ecx.ty_rptr(
self.fmtsp,
self.ecx.ty_ident(self.fmtsp, self.ecx.ident_of("str")),
Some(static_lifetime),
ast::MutImmutable);
let pieces = Context::static_array(self.ecx,
"__STATIC_FMTSTR",
piece_ty,
self.str_pieces);
// Right now there is a bug such that for the expression:
// foo(bar(&1))
// the lifetime of `1` doesn't outlast the call to `bar`, so it's not
// valid for the call to `foo`. To work around this all arguments to the
// format! string are shoved into locals. Furthermore, we shove the address
// of each variable because we don't want to move out of the arguments
// passed to this function.
for (i, e) in self.args.into_iter().enumerate() {
let arg_ty = match self.arg_types[i].as_ref() {
Some(ty) => ty,
None => continue // error already generated
};
let name = self.ecx.ident_of(&format!("__arg{}", i)[]);
pats.push(self.ecx.pat_ident(e.span, name));
locals.push(Context::format_arg(self.ecx, e.span, arg_ty,
self.ecx.expr_ident(e.span, name)));
heads.push(self.ecx.expr_addr_of(e.span, e));
}
for name in self.name_ordering.iter() {
let e = match self.names.remove(name) {
Some(e) => e,
None => continue
};
let arg_ty = match self.name_types.get(name) {
Some(ty) => ty,
None => continue
};
let lname = self.ecx.ident_of(&format!("__arg{}",
*name)[]);
pats.push(self.ecx.pat_ident(e.span, lname));
names[self.name_positions[*name]] =
Some(Context::format_arg(self.ecx, e.span, arg_ty,
self.ecx.expr_ident(e.span, lname)));
heads.push(self.ecx.expr_addr_of(e.span, e));
}
// Now create a vector containing all the arguments
let args = locals.into_iter().chain(names.into_iter().map(|a| a.unwrap()));
let args_array = self.ecx.expr_vec(self.fmtsp, args.collect());
// Constructs an AST equivalent to:
//
// match (&arg0, &arg1) {
// (tmp0, tmp1) => args_array
// }
//
// It was:
//
// let tmp0 = &arg0;
// let tmp1 = &arg1;
// args_array
//
// Because of #11585 the new temporary lifetime rule, the enclosing
// statements for these temporaries become the let's themselves.
// If one or more of them are RefCell's, RefCell borrow() will also
// end there; they don't last long enough for args_array to use them.
// The match expression solves the scope problem.
//
// Note, it may also very well be transformed to:
//
// match arg0 {
// ref tmp0 => {
// match arg1 => {
// ref tmp1 => args_array } } }
//
// But the nested match expression is proved to perform not as well
// as series of let's; the first approach does.
let pat = self.ecx.pat_tuple(self.fmtsp, pats);
let arm = self.ecx.arm(self.fmtsp, vec!(pat), args_array);
let head = self.ecx.expr(self.fmtsp, ast::ExprTup(heads));
let result = self.ecx.expr_match(self.fmtsp, head, vec!(arm));
let args_slice = self.ecx.expr_addr_of(self.fmtsp, result);
// Now create the fmt::Arguments struct with all our locals we created.
let (fn_name, fn_args) = if self.all_pieces_simple {
("new", vec![pieces, args_slice])
} else {
// Build up the static array which will store our precompiled
// nonstandard placeholders, if there are any.
let piece_ty = self.ecx.ty_path(self.ecx.path_global(
self.fmtsp,
Context::rtpath(self.ecx, "Argument")));
let fmt = Context::static_array(self.ecx,
"__STATIC_FMTARGS",
piece_ty,
self.pieces);
("with_placeholders", vec![pieces, fmt, args_slice])
};
self.ecx.expr_call_global(self.fmtsp, vec!(
self.ecx.ident_of("std"),
self.ecx.ident_of("fmt"),
self.ecx.ident_of("Arguments"),
self.ecx.ident_of(fn_name)), fn_args)
}
fn format_arg(ecx: &ExtCtxt, sp: Span,
ty: &ArgumentType, arg: P<ast::Expr>)
-> P<ast::Expr> {
let trait_ = match *ty {
Known(ref tyname) => {
match &tyname[] {
"" => "String",
"?" => "Show",
"e" => "LowerExp",
"E" => "UpperExp",
"o" => "Octal",
"p" => "Pointer",
"b" => "Binary",
"x" => "LowerHex",
"X" => "UpperHex",
_ => {
ecx.span_err(sp,
&format!("unknown format trait `{}`",
*tyname)[]);
"Dummy"
}
}
}
Unsigned => {
return ecx.expr_call_global(sp, vec![
ecx.ident_of("std"),
ecx.ident_of("fmt"),
ecx.ident_of("argumentuint")], vec![arg])
}
};
let format_fn = ecx.path_global(sp, vec![
ecx.ident_of("std"),
ecx.ident_of("fmt"),
ecx.ident_of(trait_),
ecx.ident_of("fmt")]);
ecx.expr_call_global(sp, vec![
ecx.ident_of("std"),
ecx.ident_of("fmt"),
ecx.ident_of("argument")], vec![ecx.expr_path(format_fn), arg])
}
}
pub fn expand_format_args<'cx>(ecx: &'cx mut ExtCtxt, sp: Span,
tts: &[ast::TokenTree])
-> Box<base::MacResult+'cx> {
match parse_args(ecx, sp, tts) {
Some((efmt, args, order, names)) => {
MacExpr::new(expand_preparsed_format_args(ecx, sp, efmt,
args, order, names))
}
None => DummyResult::expr(sp)
}
}
/// Take the various parts of `format_args!(efmt, args..., name=names...)`
/// and construct the appropriate formatting expression.
pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt, sp: Span,
efmt: P<ast::Expr>,
args: Vec<P<ast::Expr>>,
name_ordering: Vec<String>,
names: HashMap<String, P<ast::Expr>>)
-> P<ast::Expr> {
let arg_types: Vec<_> = range(0, args.len()).map(|_| None).collect();
let mut cx = Context {
ecx: ecx,
args: args,
arg_types: arg_types,
names: names,
name_positions: HashMap::new(),
name_types: HashMap::new(),
name_ordering: name_ordering,
nest_level: 0,
next_arg: 0,
literal: String::new(),
pieces: Vec::new(),
str_pieces: Vec::new(),
all_pieces_simple: true,
fmtsp: sp,
};
cx.fmtsp = efmt.span;
let fmt = match expr_to_string(cx.ecx,
efmt,
"format argument must be a string literal.") {
Some((fmt, _)) => fmt,
None => return DummyResult::raw_expr(sp)
};
let mut parser = parse::Parser::new(fmt.get());
loop {
match parser.next() {
Some(piece) => {
if parser.errors.len() > 0 { break }
cx.verify_piece(&piece);
match cx.trans_piece(&piece) {
Some(piece) => {
let s = cx.trans_literal_string();
cx.str_pieces.push(s);
cx.pieces.push(piece);
}
None => {}
}
}
None => break
}
}
if !parser.errors.is_empty() {
cx.ecx.span_err(cx.fmtsp, &format!("invalid format string: {}",
parser.errors.remove(0))[]);
return DummyResult::raw_expr(sp);
}
if !cx.literal.is_empty() {
let s = cx.trans_literal_string();
cx.str_pieces.push(s);
}
// Make sure that all arguments were used and all arguments have types.
for (i, ty) in cx.arg_types.iter().enumerate() {
if ty.is_none() {
cx.ecx.span_err(cx.args[i].span, "argument never used");
}
}
for (name, e) in cx.names.iter() {
if !cx.name_types.contains_key(name) {
cx.ecx.span_err(e.span, "named argument never used");
}
}
cx.into_expr()
}