-
Notifications
You must be signed in to change notification settings - Fork 13k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Allow omission of the '.' after nullary tag patterns
This commit allows patterns like:
alt x { some(_) { ... } none { } }
without the '.' after none. The parser suspends judgment about
whether a bare ident is a tag or a new bound variable; instead,
the resolver disambiguates.
This means that any code after resolution that pattern-matches on
patterns needs to call pat_util::normalize_pat, which consults
an environment to do this disambiguation.
In addition, local variables are no longer allowed to shadow
tag names, so this required changing some code (e.g. renaming
variables named "mut", and renaming ast::sub to subtract).
The parser currently accepts patterns with and without the '.'.
Once the compiler and libraries are changed, it will no longer
accept the '.'.- Loading branch information
1 parent
a7bd817
commit c3bc8fa
Showing
25 changed files
with
405 additions
and
190 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,119 @@ | ||
| import syntax::ast::*; | ||
| import syntax::ast_util; | ||
| import syntax::ast_util::respan; | ||
| import syntax::fold; | ||
| import syntax::fold::*; | ||
|
|
||
| export normalize_arms; | ||
| export normalize_pat; | ||
| export normalize_pat_def_map; | ||
| export pat_binding_ids; | ||
| export pat_bindings; | ||
| export pat_id_map; | ||
| export path_to_ident; | ||
|
|
||
| fn normalize_pat_def_map(dm: resolve::def_map, p: @pat) -> @pat { | ||
| // have to do it the hard way b/c ast fold doesn't pass around | ||
| // node IDs. bother. | ||
| alt p.node { | ||
| pat_wild. { p } | ||
| pat_ident(_, none.) { normalize_one(dm, p) } | ||
| pat_ident(q, some(r)) { | ||
| @{node: pat_ident(q, some(normalize_pat_def_map(dm, r))) | ||
| with *p} | ||
| } | ||
| pat_tag(a_path, subs) { | ||
| @{node: pat_tag(a_path, | ||
| vec::map(subs, {|p| normalize_pat_def_map(dm, p)})) with *p} | ||
| } | ||
| pat_rec(field_pats, b) { | ||
| @{node: pat_rec(vec::map(field_pats, | ||
| {|fp| {pat: normalize_pat_def_map(dm, fp.pat) with fp}}), b) | ||
| with *p} | ||
| } | ||
| pat_tup(subs) { | ||
| @{node: pat_tup(vec::map(subs, {|p| normalize_pat_def_map(dm, p)})) | ||
| with *p} | ||
| } | ||
| pat_box(q) { | ||
| @{node: pat_box(normalize_pat_def_map(dm, q)) | ||
| with *p} | ||
| } | ||
| pat_uniq(q) { | ||
| @{node: pat_uniq(normalize_pat_def_map(dm, q)) | ||
| with *p} | ||
| } | ||
| pat_lit(_) { p } | ||
| pat_range(_,_) { p } | ||
| } | ||
| } | ||
|
|
||
| fn normalize_one(dm: resolve::def_map, p: @pat) -> @pat { | ||
| alt dm.find(p.id) { | ||
| some(d) { | ||
| alt p.node { | ||
| pat_ident(tag_path, _) { @{id: p.id, | ||
| node: pat_tag(tag_path, []), | ||
| span: p.span} } | ||
| _ { p } | ||
| } | ||
| } | ||
| none. { p } | ||
| } | ||
| } | ||
|
|
||
| fn normalize_pat(tcx: ty::ctxt, p: @pat) -> @pat { | ||
| normalize_pat_def_map(tcx.def_map, p) | ||
| } | ||
|
|
||
| fn normalize_arms(tcx: ty::ctxt, arms:[arm]) -> [arm] { | ||
| vec::map(arms, {|a| | ||
| {pats: | ||
| vec::map(a.pats, {|p| | ||
| pat_util::normalize_pat(tcx, p)}) | ||
| with a}}) | ||
| } | ||
|
|
||
| type pat_id_map = std::map::hashmap<str, node_id>; | ||
|
|
||
| // This is used because same-named variables in alternative patterns need to | ||
| // use the node_id of their namesake in the first pattern. | ||
| fn pat_id_map(tcx: ty::ctxt, pat: @pat) -> pat_id_map { | ||
| let map = std::map::new_str_hash::<node_id>(); | ||
| pat_bindings(normalize_pat(tcx, pat)) {|bound| | ||
| let name = path_to_ident(alt bound.node | ||
| { pat_ident(n, _) { n } }); | ||
| map.insert(name, bound.id); | ||
| }; | ||
| ret map; | ||
| } | ||
|
|
||
| // This does *not* normalize. The pattern should be already normalized | ||
| // if you want to get a normalized pattern out of it. | ||
| // Could return a constrained type in order to express that (future work) | ||
| fn pat_bindings(pat: @pat, it: block(@pat)) { | ||
| alt pat.node { | ||
| pat_ident(_, option::none.) { it(pat); } | ||
| pat_ident(_, option::some(sub)) { it(pat); pat_bindings(sub, it); } | ||
| pat_tag(_, sub) { for p in sub { pat_bindings(p, it); } } | ||
| pat_rec(fields, _) { for f in fields { pat_bindings(f.pat, it); } } | ||
| pat_tup(elts) { for elt in elts { pat_bindings(elt, it); } } | ||
| pat_box(sub) { pat_bindings(sub, it); } | ||
| pat_uniq(sub) { pat_bindings(sub, it); } | ||
| pat_wild. | pat_lit(_) | pat_range(_, _) { } | ||
| } | ||
| } | ||
|
|
||
| fn pat_binding_ids(pat: @pat) -> [node_id] { | ||
| let found = []; | ||
| pat_bindings(pat) {|b| found += [b.id]; }; | ||
| ret found; | ||
| } | ||
|
|
||
| fn path_to_ident(p: @path) -> ident { | ||
| alt vec::last(p.node.idents) { | ||
| none. { // sigh | ||
| fail "Malformed path"; } | ||
| some(i) { ret i; } | ||
| } | ||
| } |
Oops, something went wrong.