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Merged
6 commits merged into from
Mar 15, 2011
Merged

Recursive elseif #273

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214c323
Teach rustc to parse 'else if'
brson Jan 30, 2011
c848ed1
Merge branch 'master' into forgraydon-elseif
brson Feb 1, 2011
3fedb18
Allow the else part of an expr_if to be either expr_if or expr_block
brson Feb 1, 2011
9fc4db6
Merge branch 'master' into recursive-elseif
brson Mar 8, 2011
2a66294
Remove extra blocks from the translation of expr_block
brson Mar 11, 2011
bbb6836
Merge branch 'master' into recursive-elseif
brson Mar 13, 2011
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2 changes: 1 addition & 1 deletion src/comp/front/ast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -223,7 +223,7 @@ tag expr_ {
expr_unary(unop, @expr, ann);
expr_lit(@lit, ann);
expr_cast(@expr, @ty, ann);
expr_if(@expr, block, vec[tup(@expr, block)], option.t[block], ann);
expr_if(@expr, block, option.t[@expr], ann);
expr_while(@expr, block, ann);
expr_for(@decl, @expr, block, ann);
expr_for_each(@decl, @expr, block, ann);
Expand Down
29 changes: 11 additions & 18 deletions src/comp/front/eval.rs
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Expand Up @@ -289,7 +289,7 @@ impure fn eval_crate_directive_expr(parser p,

alt (x.node) {

case (ast.expr_if(?cond, ?thn, ?elifs, ?elopt, _)) {
case (ast.expr_if(?cond, ?thn, ?elopt, _)) {
auto cv = eval_expr(sess, e, cond);
if (!val_is_bool(cv)) {
sess.span_err(x.span, "bad cond type in 'if'");
Expand All @@ -301,24 +301,11 @@ impure fn eval_crate_directive_expr(parser p,
index);
}

for (tup(@ast.expr, ast.block) elif in elifs) {
auto cv = eval_expr(sess, e, elif._0);
if (!val_is_bool(cv)) {
sess.span_err(x.span, "bad cond type in 'else if'");
}

if (val_as_bool(cv)) {
ret eval_crate_directive_block(p, e, elif._1, prefix,
view_items, items,
index);
}
}

alt (elopt) {
case (some[ast.block](?els)) {
ret eval_crate_directive_block(p, e, els, prefix,
view_items, items,
index);
case (some[@ast.expr](?els)) {
ret eval_crate_directive_expr(p, e, els, prefix,
view_items, items,
index);
}
case (_) {
// Absent-else is ok.
Expand Down Expand Up @@ -353,6 +340,12 @@ impure fn eval_crate_directive_expr(parser p,
sess.span_err(x.span, "no cases matched in 'alt'");
}

case (ast.expr_block(?block, _)) {
ret eval_crate_directive_block(p, e, block, prefix,
view_items, items,
index);
}

case (_) {
sess.span_err(x.span, "unsupported expr type");
}
Expand Down
54 changes: 23 additions & 31 deletions src/comp/front/parser.rs
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Expand Up @@ -1094,40 +1094,32 @@ impure fn parse_if_expr(parser p) -> @ast.expr {
auto cond = parse_expr(p);
expect(p, token.RPAREN);
auto thn = parse_block(p);
let option.t[@ast.expr] els = none[@ast.expr];
hi = thn.span;

let vec[tup(@ast.expr, ast.block)] elifs = vec();
let option.t[ast.block] els = none[ast.block];
let bool parsing_elses = true;
while (parsing_elses) {
alt (p.peek()) {
case (token.ELSE) {
expect(p, token.ELSE);
alt (p.peek()) {
case (token.IF) {
expect(p, token.IF);
expect(p, token.LPAREN);
auto elifcond = parse_expr(p);
expect(p, token.RPAREN);
auto elifthn = parse_block(p);
elifs += tup(elifcond, elifthn);
hi = elifthn.span;
}
case (_) {
auto eblk = parse_block(p);
els = some(eblk);
hi = eblk.span;
parsing_elses = false;
}
}
}
case (_) {
parsing_elses = false;
}
alt (p.peek()) {
case (token.ELSE) {
auto elexpr = parse_else_expr(p);
els = some(elexpr);
hi = elexpr.span;
}
case (_) { /* fall through */ }
}

ret @spanned(lo, hi, ast.expr_if(cond, thn, elifs, els, ast.ann_none));
ret @spanned(lo, hi, ast.expr_if(cond, thn, els, ast.ann_none));
}

impure fn parse_else_expr(parser p) -> @ast.expr {
expect(p, token.ELSE);
alt (p.peek()) {
case (token.IF) {
ret parse_if_expr(p);
}
case (_) {
auto blk = parse_block(p);
ret @spanned(blk.span, blk.span,
ast.expr_block(blk, ast.ann_none));
}
}
}

impure fn parse_head_local(parser p) -> @ast.decl {
Expand Down Expand Up @@ -1530,7 +1522,7 @@ fn stmt_ends_with_semi(@ast.stmt stmt) -> bool {
case (ast.expr_unary(_,_,_)) { ret true; }
case (ast.expr_lit(_,_)) { ret true; }
case (ast.expr_cast(_,_,_)) { ret true; }
case (ast.expr_if(_,_,_,_,_)) { ret false; }
case (ast.expr_if(_,_,_,_)) { ret false; }
case (ast.expr_for(_,_,_,_)) { ret false; }
case (ast.expr_for_each(_,_,_,_))
{ ret false; }
Expand Down
30 changes: 9 additions & 21 deletions src/comp/middle/fold.rs
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Expand Up @@ -105,8 +105,7 @@ type ast_fold[ENV] =

(fn(&ENV e, &span sp,
@expr cond, &block thn,
&vec[tup(@expr, block)] elifs,
&option.t[block] els,
&option.t[@expr] els,
ann a) -> @expr) fold_expr_if,

(fn(&ENV e, &span sp,
Expand Down Expand Up @@ -565,27 +564,17 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
ret fld.fold_expr_cast(env_, e.span, ee, tt, at);
}

case (ast.expr_if(?cnd, ?thn, ?elifs, ?els, ?t)) {
case (ast.expr_if(?cnd, ?thn, ?els, ?t)) {
auto ccnd = fold_expr(env_, fld, cnd);
auto tthn = fold_block(env_, fld, thn);

let vec[tup(@ast.expr, ast.block)] eelifs = vec();
for (tup(@expr, block) elif in elifs) {
auto elifcnd = elif._0;
auto elifthn = elif._1;
auto elifccnd = fold_expr(env_, fld, elifcnd);
auto eliftthn = fold_block(env_, fld, elifthn);
eelifs += tup(elifccnd, eliftthn);
}

auto eels = none[block];
auto eels = none[@expr];
alt (els) {
case (some[block](?b)) {
eels = some(fold_block(env_, fld, b));
case (some[@expr](?e)) {
eels = some(fold_expr(env_, fld, e));
}
case (_) { /* fall through */ }
}
ret fld.fold_expr_if(env_, e.span, ccnd, tthn, eelifs, eels, t);
ret fld.fold_expr_if(env_, e.span, ccnd, tthn, eels, t);
}

case (ast.expr_for(?decl, ?seq, ?body, ?t)) {
Expand Down Expand Up @@ -1137,9 +1126,8 @@ fn identity_fold_expr_cast[ENV](&ENV env, &span sp, @ast.expr e,

fn identity_fold_expr_if[ENV](&ENV env, &span sp,
@expr cond, &block thn,
&vec[tup(@expr, block)] elifs,
&option.t[block] els, ann a) -> @expr {
ret @respan(sp, ast.expr_if(cond, thn, elifs, els, a));
&option.t[@expr] els, ann a) -> @expr {
ret @respan(sp, ast.expr_if(cond, thn, els, a));
}

fn identity_fold_expr_for[ENV](&ENV env, &span sp,
Expand Down Expand Up @@ -1483,7 +1471,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
fold_expr_unary = bind identity_fold_expr_unary[ENV](_,_,_,_,_),
fold_expr_lit = bind identity_fold_expr_lit[ENV](_,_,_,_),
fold_expr_cast = bind identity_fold_expr_cast[ENV](_,_,_,_,_),
fold_expr_if = bind identity_fold_expr_if[ENV](_,_,_,_,_,_,_),
fold_expr_if = bind identity_fold_expr_if[ENV](_,_,_,_,_,_),
fold_expr_for = bind identity_fold_expr_for[ENV](_,_,_,_,_,_),
fold_expr_for_each
= bind identity_fold_expr_for_each[ENV](_,_,_,_,_,_),
Expand Down
40 changes: 9 additions & 31 deletions src/comp/middle/trans.rs
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Expand Up @@ -2833,9 +2833,8 @@ fn join_results(@block_ctxt parent_cx,
ret res(join_cx, phi);
}

fn trans_if(@block_ctxt cx, @ast.expr cond, &ast.block thn,
&vec[tup(@ast.expr, ast.block)] elifs,
&option.t[ast.block] els) -> result {
fn trans_if(@block_ctxt cx, @ast.expr cond,
&ast.block thn, &option.t[@ast.expr] els) -> result {

auto cond_res = trans_expr(cx, cond);

Expand All @@ -2845,25 +2844,11 @@ fn trans_if(@block_ctxt cx, @ast.expr cond, &ast.block thn,
auto else_cx = new_scope_block_ctxt(cx, "else");
auto else_res = res(else_cx, C_nil());

auto num_elifs = _vec.len[tup(@ast.expr, ast.block)](elifs);
if (num_elifs > 0u) {
auto next_elif = elifs.(0u);
auto next_elifthn = next_elif._0;
auto next_elifcnd = next_elif._1;
auto rest_elifs = _vec.shift[tup(@ast.expr, ast.block)](elifs);
else_res = trans_if(else_cx, next_elifthn, next_elifcnd,
rest_elifs, els);
}

/* else: FIXME: rustboot has a problem here
with preconditions inside an else block */
if (num_elifs == 0u) {
alt (els) {
case (some[ast.block](?eblk)) {
else_res = trans_block(else_cx, eblk);
}
case (_) { /* fall through */ }
alt (els) {
case (some[@ast.expr](?elexpr)) {
else_res = trans_expr(else_cx, elexpr);
}
case (_) { /* fall through */ }
}

cond_res.bcx.build.CondBr(cond_res.val,
Expand Down Expand Up @@ -4303,8 +4288,8 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
ret trans_binary(cx, op, x, y);
}

case (ast.expr_if(?cond, ?thn, ?elifs, ?els, _)) {
ret trans_if(cx, cond, thn, elifs, els);
case (ast.expr_if(?cond, ?thn, ?els, _)) {
ret trans_if(cx, cond, thn, els);
}

case (ast.expr_for(?decl, ?seq, ?body, _)) {
Expand All @@ -4328,14 +4313,7 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
}

case (ast.expr_block(?blk, _)) {
auto sub_cx = new_scope_block_ctxt(cx, "block-expr body");
auto next_cx = new_sub_block_ctxt(cx, "next");
auto sub = trans_block(sub_cx, blk);

cx.build.Br(sub_cx.llbb);
sub.bcx.build.Br(next_cx.llbb);

ret res(next_cx, sub.val);
ret trans_block(cx, blk);
}

case (ast.expr_assign(?dst, ?src, ?ann)) {
Expand Down
2 changes: 1 addition & 1 deletion src/comp/middle/ty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -702,7 +702,7 @@ fn expr_ty(@ast.expr expr) -> @t {
case (ast.expr_unary(_, _, ?ann)) { ret ann_to_type(ann); }
case (ast.expr_lit(_, ?ann)) { ret ann_to_type(ann); }
case (ast.expr_cast(_, _, ?ann)) { ret ann_to_type(ann); }
case (ast.expr_if(_, _, _, _, ?ann)) { ret ann_to_type(ann); }
case (ast.expr_if(_, _, _, ?ann)) { ret ann_to_type(ann); }
case (ast.expr_for(_, _, _, ?ann)) { ret ann_to_type(ann); }
case (ast.expr_for_each(_, _, _, ?ann))
{ ret ann_to_type(ann); }
Expand Down
53 changes: 15 additions & 38 deletions src/comp/middle/typeck.rs
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Expand Up @@ -1263,28 +1263,20 @@ fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
e_1 = ast.expr_cast(sube, ast_ty,
ast.ann_type(t, none[vec[@ty.t]]));
}
case (ast.expr_if(?cond, ?then_0, ?elifs_0, ?else_0, ?ann)) {
case (ast.expr_if(?cond, ?then_0, ?else_0, ?ann)) {
auto t = demand_full(fcx, e.span, expected,
ann_to_type(ann), adk);
auto then_1 = demand_block(fcx, expected, then_0);

let vec[tup(@ast.expr, ast.block)] elifs_1 = vec();
for (tup(@ast.expr, ast.block) elif in elifs_0) {
auto elifcond = elif._0;
auto elifthn_0 = elif._1;
auto elifthn_1 = demand_block(fcx, expected, elifthn_0);
elifs_1 += tup(elifcond, elifthn_1);
}

auto else_1;
alt (else_0) {
case (none[ast.block]) { else_1 = none[ast.block]; }
case (some[ast.block](?b_0)) {
auto b_1 = demand_block(fcx, expected, b_0);
else_1 = some[ast.block](b_1);
case (none[@ast.expr]) { else_1 = none[@ast.expr]; }
case (some[@ast.expr](?e_0)) {
auto e_1 = demand_expr(fcx, expected, e_0);
else_1 = some[@ast.expr](e_1);
}
}
e_1 = ast.expr_if(cond, then_1, elifs_1, else_1,
e_1 = ast.expr_if(cond, then_1, else_1,
ast.ann_type(t, none[vec[@ty.t]]));
}
case (ast.expr_for(?decl, ?seq, ?bloc, ?ann)) {
Expand Down Expand Up @@ -1795,39 +1787,24 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
ann));
}

case (ast.expr_if(?cond, ?thn, ?elifs, ?elsopt, _)) {
case (ast.expr_if(?cond, ?thn, ?elsopt, _)) {
auto cond_0 = check_expr(fcx, cond);
auto cond_1 = demand_expr(fcx, plain_ty(ty.ty_bool), cond_0);

auto thn_0 = check_block(fcx, thn);
auto thn_t = block_ty(thn_0);

auto num_elifs = _vec.len[tup(@ast.expr, ast.block)](elifs);
let vec[tup(@ast.expr, ast.block)] elifs_1 = vec();
for each (uint i in _uint.range(0u, num_elifs)) {
auto elif = elifs.(i);
auto elifcond = elif._0;
auto elifcond_0 = check_expr(fcx, cond);
auto elifcond_1 = demand_expr(fcx,
plain_ty(ty.ty_bool),
elifcond_0);
auto elifthn = elif._1;
auto elifthn_0 = check_block(fcx, elifthn);
auto elifthn_1 = demand_block(fcx, thn_t, elifthn_0);
elifs_1 += tup(elifcond_1, elifthn_1);
}

auto elsopt_1;
auto elsopt_t;
alt (elsopt) {
case (some[ast.block](?els)) {
auto els_0 = check_block(fcx, els);
auto els_1 = demand_block(fcx, thn_t, els_0);
elsopt_1 = some[ast.block](els_1);
elsopt_t = block_ty(els_1);
case (some[@ast.expr](?els)) {
auto els_0 = check_expr(fcx, els);
auto els_1 = demand_expr(fcx, thn_t, els_0);
elsopt_1 = some[@ast.expr](els_1);
elsopt_t = expr_ty(els_1);
}
case (none[ast.block]) {
elsopt_1 = none[ast.block];
case (none[@ast.expr]) {
elsopt_1 = none[@ast.expr];
elsopt_t = plain_ty(ty.ty_nil);
}
}
Expand All @@ -1837,7 +1814,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
auto ann = ast.ann_type(elsopt_t, none[vec[@ty.t]]);
ret @fold.respan[ast.expr_](expr.span,
ast.expr_if(cond_1, thn_1,
elifs_1, elsopt_1, ann));
elsopt_1, ann));
}

case (ast.expr_for(?decl, ?seq, ?body, _)) {
Expand Down
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