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import util::interner::interner;
import diagnostic::span_handler;
import ast::{token_tree,tt_delim,tt_flat,tt_dotdotdot,tt_interpolate,ident};
import earley_parser::{arb_depth,seq,leaf};
import codemap::span;
import parse::token::{EOF,ACTUALLY,IDENT,token,w_ident};
import std::map::{hashmap,box_str_hash};
export tt_reader, new_tt_reader, dup_tt_reader, tt_next_token;
enum tt_frame_up { /* to break a circularity */
tt_frame_up(option<tt_frame>)
}
/* TODO: figure out how to have a uniquely linked stack, and change to `~` */
///an unzipping of `token_tree`s
type tt_frame = @{
readme: ~[ast::token_tree],
mut idx: uint,
dotdotdoted: bool,
sep: option<token>,
up: tt_frame_up,
};
type tt_reader = @{
sp_diag: span_handler,
interner: @interner<@str>,
mut cur: tt_frame,
/* for MBE-style macro transcription */
interpolations: std::map::hashmap<ident, @arb_depth>,
mut repeat_idx: ~[mut uint],
mut repeat_len: ~[uint],
/* cached: */
mut cur_tok: token,
mut cur_span: span
};
/** This can do Macro-By-Example transcription. On the other hand, if
* `src` contains no `tt_dotdotdot`s and `tt_interpolate`s, `interp` can (and
* should) be none. */
fn new_tt_reader(sp_diag: span_handler, itr: @interner<@str>,
interp: option<std::map::hashmap<ident,@arb_depth>>,
src: ~[ast::token_tree])
-> tt_reader {
let r = @{sp_diag: sp_diag, interner: itr,
mut cur: @{readme: src, mut idx: 0u, dotdotdoted: false,
sep: none, up: tt_frame_up(option::none)},
interpolations: alt interp { /* just a convienience */
none { std::map::box_str_hash::<@arb_depth>() }
some(x) { x }
},
mut repeat_idx: ~[mut], mut repeat_len: ~[],
/* dummy values, never read: */
mut cur_tok: EOF,
mut cur_span: ast_util::mk_sp(0u,0u)
};
tt_next_token(r); /* get cur_tok and cur_span set up */
ret r;
}
pure fn dup_tt_frame(&&f: tt_frame) -> tt_frame {
@{readme: f.readme, mut idx: f.idx, dotdotdoted: f.dotdotdoted,
sep: f.sep, up: alt f.up {
tt_frame_up(some(up_frame)) {
tt_frame_up(some(dup_tt_frame(up_frame)))
}
tt_frame_up(none) { tt_frame_up(none) }
}
}
}
pure fn dup_tt_reader(&&r: tt_reader) -> tt_reader {
@{sp_diag: r.sp_diag, interner: r.interner,
mut cur: dup_tt_frame(r.cur),
interpolations: r.interpolations,
mut repeat_idx: copy r.repeat_idx, mut repeat_len: copy r.repeat_len,
mut cur_tok: r.cur_tok, mut cur_span: r.cur_span}
}
pure fn lookup_cur_ad_by_ad(r: tt_reader, start: @arb_depth) -> @arb_depth {
pure fn red(&&ad: @arb_depth, &&idx: uint) -> @arb_depth {
alt *ad {
leaf(_) { ad /* end of the line; duplicate henceforth */ }
seq(ads, _) { ads[idx] }
}
}
vec::foldl(start, r.repeat_idx, red)
}
fn lookup_cur_ad(r: tt_reader, name: ident) -> @arb_depth {
lookup_cur_ad_by_ad(r, r.interpolations.get(name))
}
enum lis {
lis_unconstrained, lis_constraint(uint, ident), lis_contradiction(str)
}
fn lockstep_iter_size(&&t: token_tree, &&r: tt_reader) -> lis {
fn lis_merge(lhs: lis, rhs: lis) -> lis {
alt lhs {
lis_unconstrained { rhs }
lis_contradiction(_) { lhs }
lis_constraint(l_len, l_id) {
alt rhs {
lis_unconstrained { lhs }
lis_contradiction(_) { rhs }
lis_constraint(r_len, _) if l_len == r_len { lhs }
lis_constraint(r_len, r_id) {
lis_contradiction(#fmt["Inconsistent lockstep iteration: \
'%s' has %u items, but '%s' has %u",
*l_id, l_len, *r_id, r_len])
}
}
}
}
}
alt t {
tt_delim(tts) | tt_dotdotdot(_, tts, _, _) {
vec::foldl(lis_unconstrained, tts, {|lis, tt|
lis_merge(lis, lockstep_iter_size(tt, r)) })
}
tt_flat(*) { lis_unconstrained }
tt_interpolate(_, name) {
alt *lookup_cur_ad(r, name) {
leaf(_) { lis_unconstrained }
seq(ads, _) { lis_constraint(ads.len(), name) }
}
}
}
}
fn tt_next_token(&&r: tt_reader) -> {tok: token, sp: span} {
let ret_val = { tok: r.cur_tok, sp: r.cur_span };
while r.cur.idx >= vec::len(r.cur.readme) {
/* done with this set; pop or repeat? */
if ! r.cur.dotdotdoted
|| r.repeat_idx.last() == r.repeat_len.last() - 1 {
alt r.cur.up {
tt_frame_up(none) {
r.cur_tok = EOF;
ret ret_val;
}
tt_frame_up(some(tt_f)) {
if r.cur.dotdotdoted {
vec::pop(r.repeat_idx); vec::pop(r.repeat_len);
}
r.cur = tt_f;
r.cur.idx += 1u;
}
}
} else { /* repeat */
r.cur.idx = 0u;
r.repeat_idx[r.repeat_idx.len() - 1u] += 1u;
alt r.cur.sep {
some(tk) {
r.cur_tok = tk; /* repeat same span, I guess */
ret ret_val;
}
none {}
}
}
}
loop { /* because it's easiest, this handles `tt_delim` not starting
with a `tt_flat`, even though it won't happen */
alt r.cur.readme[r.cur.idx] {
tt_delim(tts) {
r.cur = @{readme: tts, mut idx: 0u, dotdotdoted: false,
sep: none, up: tt_frame_up(option::some(r.cur)) };
// if this could be 0-length, we'd need to potentially recur here
}
tt_flat(sp, tok) {
r.cur_span = sp; r.cur_tok = tok;
r.cur.idx += 1u;
ret ret_val;
}
tt_dotdotdot(sp, tts, sep, zerok) {
alt lockstep_iter_size(tt_dotdotdot(sp, tts, sep, zerok), r) {
lis_unconstrained {
r.sp_diag.span_fatal(
sp, /* blame macro writer */
"attempted to repeat an expression containing no syntax \
variables matched as repeating at this depth");
}
lis_contradiction(msg) { /* TODO blame macro invoker instead*/
r.sp_diag.span_fatal(sp, msg);
}
lis_constraint(len, _) {
vec::push(r.repeat_len, len);
vec::push(r.repeat_idx, 0u);
r.cur = @{readme: tts, mut idx: 0u, dotdotdoted: true,
sep: sep, up: tt_frame_up(option::some(r.cur)) };
if len == 0 {
if !zerok {
r.sp_diag.span_fatal(sp, /* TODO blame invoker */
"this must repeat at least \
once");
}
/* we need to pop before we proceed, so recur */
ret tt_next_token(r);
}
}
}
}
// TODO: think about span stuff here
tt_interpolate(sp, ident) {
alt *lookup_cur_ad(r, ident) {
/* sidestep the interpolation tricks for ident because
(a) idents can be in lots of places, so it'd be a pain
(b) we actually can, since it's a token. */
leaf(w_ident(sn,b)) {
r.cur_span = sp; r.cur_tok = IDENT(sn,b);
r.cur.idx += 1u;
ret ret_val;
}
leaf(w_nt) {
r.cur_span = sp; r.cur_tok = ACTUALLY(w_nt);
r.cur.idx += 1u;
ret ret_val;
}
seq(*) {
r.sp_diag.span_fatal(
copy r.cur_span, /* blame the macro writer */
#fmt["variable '%s' is still repeating at this depth",
*ident]);
}
}
}
}
}
}
|
