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Add restricted-parse mode, and parse bind expressions.

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This commit is contained in:
Graydon Hoare 2010-12-31 17:28:43 -08:00
parent 2f6f0dcfbf
commit 0a2e7f2149
1 changed files with 68 additions and 10 deletions
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78
src/comp/front/parser.rs
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@ -15,6 +15,8 @@ state type parser =
fn peek() -> token.token;
impure fn bump();
impure fn err(str s);
impure fn restrict(bool r);
fn is_restricted() -> bool;
fn get_session() -> session.session;
fn get_span() -> common.span;
fn next_def_id() -> ast.def_id;
@ -27,6 +29,7 @@ impure fn new_parser(session.session sess,
mutable common.pos lo,
mutable common.pos hi,
mutable ast.def_num def,
mutable bool restricted,
ast.crate_num crate,
lexer.reader rdr)
{
@ -47,6 +50,14 @@ impure fn new_parser(session.session sess,
sess.span_err(span, m);
}
impure fn restrict(bool r) {
restricted = r;
}
fn is_restricted() -> bool {
ret restricted;
}
fn get_session() -> session.session {
ret sess;
}
@ -65,7 +76,7 @@ impure fn new_parser(session.session sess,
auto rdr = lexer.new_reader(srdr, path);
auto npos = rdr.get_curr_pos();
ret stdio_parser(sess, lexer.next_token(rdr),
npos, npos, 0, crate, rdr);
npos, npos, 0, false, crate, rdr);
}
impure fn unexpected(parser p, token.token t) {
@ -481,6 +492,32 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
ex = ast.expr_rec(fs.node, ast.ann_none);
}
case (token.BIND) {
p.bump();
auto e = parse_restricted_expr(p);
impure fn parse_expr_opt(parser p) -> option.t[@ast.expr] {
log "parse expr opt: " + token.to_str(p.peek());
alt (p.peek()) {
case (token.UNDERSCORE) {
p.bump();
ret none[@ast.expr];
}
case (_) {
ret some[@ast.expr](parse_expr(p));
}
}
}
auto pf = parse_expr_opt;
auto es = parse_seq[option.t[@ast.expr]](token.LPAREN,
token.RPAREN,
some(token.COMMA),
pf, p);
hi = es.span;
auto e_ = ast.expr_bind(e, es.node, ast.ann_none);
e = @spanned(lo, hi, e_);
}
case (_) {
alt (parse_lit(p)) {
case (some[ast.lit](?lit)) {
@ -505,15 +542,19 @@ impure fn parse_path_expr(parser p) -> @ast.expr {
alt (p.peek()) {
case (token.LPAREN) {
// Call expr.
auto pf = parse_expr;
auto es = parse_seq[@ast.expr](token.LPAREN,
token.RPAREN,
some(token.COMMA),
pf, p);
hi = es.span;
auto e_ = ast.expr_call(e, es.node, ast.ann_none);
e = @spanned(lo, hi, e_);
if (p.is_restricted()) {
ret e;
} else {
// Call expr.
auto pf = parse_expr;
auto es = parse_seq[@ast.expr](token.LPAREN,
token.RPAREN,
some(token.COMMA),
pf, p);
hi = es.span;
auto e_ = ast.expr_call(e, es.node, ast.ann_none);
e = @spanned(lo, hi, e_);
}
}
case (token.DOT) {
@ -865,7 +906,24 @@ impure fn parse_alt_expr(parser p) -> @ast.expr {
ret @spanned(lo, hi, expr);
}
impure fn parse_restricted_expr(parser p) -> @ast.expr {
ret parse_expr_res(p, true);
}
impure fn parse_expr(parser p) -> @ast.expr {
ret parse_expr_res(p, false);
}
impure fn parse_expr_res(parser p, bool restrict) -> @ast.expr {
auto old = p.is_restricted();
p.restrict(restrict);
auto e = parse_expr_inner(p);
p.restrict(old);
ret e;
}
impure fn parse_expr_inner(parser p) -> @ast.expr {
alt (p.peek()) {
case (token.LBRACE) {
auto blk = parse_block(p);