rust/src/libsyntax/ext/expand.rs

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// 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 core::prelude::*;
use ast::{crate, expr_, expr_mac, mac_invoc_tt};
use ast::{tt_delim, tt_tok, item_mac, stmt_, stmt_mac, stmt_expr, stmt_semi};
use ast;
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use attr;
use codemap::{span, CallInfo, ExpandedFrom, NameAndSpan};
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use ext::base::*;
use fold::*;
use parse::{parser, parse_expr_from_source_str, new_parser_from_tts};
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use core::option;
use core::vec;
use std::oldmap::HashMap;
pub fn expand_expr(exts: SyntaxExtensions, cx: ext_ctxt,
e: &expr_, s: span, fld: ast_fold,
orig: fn@(&expr_, span, ast_fold) -> (expr_, span))
-> (expr_, span) {
match *e {
// expr_mac should really be expr_ext or something; it's the
// entry-point for all syntax extensions.
expr_mac(ref mac) => {
match (*mac).node {
// Token-tree macros, these will be the only case when we're
// finished transitioning.
mac_invoc_tt(pth, ref tts) => {
assert (vec::len(pth.idents) == 1u);
/* using idents and token::special_idents would make the
the macro names be hygienic */
let extname = cx.parse_sess().interner.get(pth.idents[0]);
match exts.find(&extname) {
None => {
cx.span_fatal(
pth.span,
fmt!("macro undefined: '%s'", *extname))
}
Some(NormalTT(SyntaxExpanderTT{
expander: exp,
span: exp_sp
})) => {
cx.bt_push(ExpandedFrom(CallInfo {
call_site: s,
callee: NameAndSpan {
name: *extname,
span: exp_sp,
},
}));
let expanded = match exp(cx, mac.span, *tts) {
MRExpr(e) => e,
MRAny(expr_maker,_,_) => expr_maker(),
_ => {
cx.span_fatal(
pth.span,
fmt!(
"non-expr macro in expr pos: %s",
*extname
)
)
}
};
//keep going, outside-in
let fully_expanded = fld.fold_expr(expanded).node;
cx.bt_pop();
(fully_expanded, s)
}
_ => {
cx.span_fatal(
pth.span,
fmt!("'%s' is not a tt-style macro", *extname)
)
}
}
}
}
}
_ => orig(e, s, fld)
}
}
// This is a secondary mechanism for invoking syntax extensions on items:
// "decorator" attributes, such as #[auto_encode]. These are invoked by an
// attribute prefixing an item, and are interpreted by feeding the item
// through the named attribute _as a syntax extension_ and splicing in the
// resulting item vec into place in favour of the decorator. Note that
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// these do _not_ work for macro extensions, just ItemDecorator ones.
//
// NB: there is some redundancy between this and expand_item, below, and
// they might benefit from some amount of semantic and language-UI merger.
pub fn expand_mod_items(exts: SyntaxExtensions, cx: ext_ctxt,
module_: &ast::_mod, fld: ast_fold,
orig: fn@(&ast::_mod, ast_fold) -> ast::_mod)
-> ast::_mod {
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// Fold the contents first:
let module_ = orig(module_, fld);
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// For each item, look through the attributes. If any of them are
// decorated with "item decorators", then use that function to transform
// the item into a new set of items.
let new_items = do vec::flat_map(module_.items) |item| {
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do vec::foldr(item.attrs, ~[*item]) |attr, items| {
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let mname = attr::get_attr_name(attr);
match exts.find(&mname) {
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None | Some(NormalTT(_)) | Some(ItemTT(*)) => items,
Some(ItemDecorator(dec_fn)) => {
cx.bt_push(ExpandedFrom(CallInfo {
call_site: attr.span,
callee: NameAndSpan {
name: /*bad*/ copy *mname,
span: None
}
}));
let r = dec_fn(cx, attr.span, attr.node.value, items);
cx.bt_pop();
r
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}
}
}
};
ast::_mod { items: new_items, ..module_ }
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}
// When we enter a module, record it, for the sake of `module!`
pub fn expand_item(exts: SyntaxExtensions,
cx: ext_ctxt, it: @ast::item, fld: ast_fold,
orig: fn@(@ast::item, ast_fold) -> Option<@ast::item>)
-> Option<@ast::item> {
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let is_mod = match it.node {
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ast::item_mod(_) | ast::item_foreign_mod(_) => true,
_ => false
};
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let maybe_it = match it.node {
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ast::item_mac(*) => expand_item_mac(exts, cx, it, fld),
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_ => Some(it)
};
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match maybe_it {
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Some(it) => {
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if is_mod { cx.mod_push(it.ident); }
let ret_val = orig(it, fld);
if is_mod { cx.mod_pop(); }
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return ret_val;
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}
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None => return None
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}
}
// Support for item-position macro invocations, exactly the same
// logic as for expression-position macro invocations.
pub fn expand_item_mac(exts: SyntaxExtensions,
cx: ext_ctxt, &&it: @ast::item,
fld: ast_fold) -> Option<@ast::item> {
let (pth, tts) = match it.node {
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item_mac(codemap::spanned { node: mac_invoc_tt(pth, ref tts), _}) => {
(pth, (*tts))
}
_ => cx.span_bug(it.span, ~"invalid item macro invocation")
};
let extname = cx.parse_sess().interner.get(pth.idents[0]);
let expanded = match exts.find(&extname) {
None => cx.span_fatal(pth.span,
fmt!("macro undefined: '%s!'", *extname)),
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Some(NormalTT(ref expand)) => {
if it.ident != parse::token::special_idents::invalid {
cx.span_fatal(pth.span,
fmt!("macro %s! expects no ident argument, \
given '%s'", *extname,
*cx.parse_sess().interner.get(it.ident)));
}
cx.bt_push(ExpandedFrom(CallInfo {
call_site: it.span,
callee: NameAndSpan {
name: *extname,
span: (*expand).span
}
}));
((*expand).expander)(cx, it.span, tts)
}
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Some(ItemTT(ref expand)) => {
if it.ident == parse::token::special_idents::invalid {
cx.span_fatal(pth.span,
fmt!("macro %s! expects an ident argument",
*extname));
}
cx.bt_push(ExpandedFrom(CallInfo {
call_site: it.span,
callee: NameAndSpan {
name: *extname,
span: (*expand).span
}
}));
((*expand).expander)(cx, it.span, it.ident, tts)
}
_ => cx.span_fatal(
it.span, fmt!("%s! is not legal in item position", *extname))
};
let maybe_it = match expanded {
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MRItem(it) => fld.fold_item(it),
MRExpr(_) => cx.span_fatal(pth.span,
~"expr macro in item position: "
+ *extname),
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MRAny(_, item_maker, _) =>
option::chain(item_maker(), |i| {fld.fold_item(i)}),
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MRDef(ref mdef) => {
exts.insert(@/*bad*/ copy mdef.name, (*mdef).ext);
None
}
};
cx.bt_pop();
return maybe_it;
}
pub fn expand_stmt(exts: SyntaxExtensions, cx: ext_ctxt,
s: &stmt_, sp: span, fld: ast_fold,
orig: fn@(s: &stmt_, span, ast_fold) -> (stmt_, span))
-> (stmt_, span) {
let (mac, pth, tts, semi) = match *s {
stmt_mac(ref mac, semi) => {
match mac.node {
mac_invoc_tt(pth, ref tts) => ((*mac), pth, (*tts), semi)
}
}
_ => return orig(s, sp, fld)
};
assert(vec::len(pth.idents) == 1u);
let extname = cx.parse_sess().interner.get(pth.idents[0]);
let (fully_expanded, sp) = match exts.find(&extname) {
None =>
cx.span_fatal(pth.span, fmt!("macro undefined: '%s'", *extname)),
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Some(NormalTT(
SyntaxExpanderTT{expander: exp, span: exp_sp})) => {
cx.bt_push(ExpandedFrom(CallInfo {
call_site: sp,
callee: NameAndSpan { name: *extname, span: exp_sp }
}));
let expanded = match exp(cx, mac.span, tts) {
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MRExpr(e) =>
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@codemap::spanned { node: stmt_expr(e, cx.next_id()),
span: e.span},
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MRAny(_,_,stmt_mkr) => stmt_mkr(),
_ => cx.span_fatal(
pth.span,
fmt!("non-stmt macro in stmt pos: %s", *extname))
};
//keep going, outside-in
let fully_expanded = fld.fold_stmt(expanded).node;
cx.bt_pop();
(fully_expanded, sp)
}
_ => {
cx.span_fatal(pth.span,
fmt!("'%s' is not a tt-style macro", *extname))
}
};
return (match fully_expanded {
stmt_expr(e, stmt_id) if semi => stmt_semi(e, stmt_id),
_ => { fully_expanded } /* might already have a semi */
}, sp)
}
pub fn new_span(cx: ext_ctxt, sp: span) -> span {
/* this discards information in the case of macro-defining macros */
return span {lo: sp.lo, hi: sp.hi, expn_info: cx.backtrace()};
}
// FIXME (#2247): this is a terrible kludge to inject some macros into
// the default compilation environment. When the macro-definition system
// is substantially more mature, these should move from here, into a
// compiled part of libcore at very least.
pub fn core_macros() -> ~str {
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return
~"{
macro_rules! ignore (($($x:tt)*) => (()))
macro_rules! error ( ($( $arg:expr ),+) => (
log(::core::error, fmt!( $($arg),+ )) ))
macro_rules! warn ( ($( $arg:expr ),+) => (
log(::core::warn, fmt!( $($arg),+ )) ))
macro_rules! info ( ($( $arg:expr ),+) => (
log(::core::info, fmt!( $($arg),+ )) ))
macro_rules! debug ( ($( $arg:expr ),+) => (
log(::core::debug, fmt!( $($arg),+ )) ))
macro_rules! fail(
($msg: expr) => (
::core::sys::begin_unwind($msg, file!().to_owned(), line!())
);
() => (
fail!(~\"explicit failure\")
)
)
macro_rules! fail_unless(
($cond:expr) => {
if !$cond {
fail!(~\"assertion failed: \" + stringify!($cond))
}
}
)
macro_rules! condition (
{ $c:ident: $in:ty -> $out:ty; } => {
mod $c {
fn key(_x: @::core::condition::Handler<$in,$out>) { }
pub const cond : ::core::condition::Condition<$in,$out> =
::core::condition::Condition {
name: stringify!($c),
key: key
};
}
}
)
}";
}
pub fn expand_crate(parse_sess: @mut parse::ParseSess,
cfg: ast::crate_cfg, c: @crate) -> @crate {
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let exts = syntax_expander_table();
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let afp = default_ast_fold();
let cx: ext_ctxt = mk_ctxt(parse_sess, cfg);
let f_pre = @AstFoldFns {
fold_expr: |a,b,c| expand_expr(exts, cx, a, b, c, afp.fold_expr),
fold_mod: |a,b| expand_mod_items(exts, cx, a, b, afp.fold_mod),
fold_item: |a,b| expand_item(exts, cx, a, b, afp.fold_item),
fold_stmt: |a,b,c| expand_stmt(exts, cx, a, b, c, afp.fold_stmt),
new_span: |a| new_span(cx, a),
.. *afp};
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let f = make_fold(f_pre);
let cm = parse_expr_from_source_str(~"<core-macros>",
@core_macros(),
cfg,
parse_sess);
// This is run for its side-effects on the expander env,
// as it registers all the core macros as expanders.
f.fold_expr(cm);
@f.fold_crate(&*c)
}
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End: