Merge #1055

1055: Allow keeping list of last matches to check against r=CohenArthur a=CohenArthur

When trying to figure out if a match can follow another, we must figure
out whether or not that match is in the follow-set of the other. If that
match is zeroable (i.e a repetition using the * or ? kleene operators),
then we must be able to check the match after them: should our current
match not be present, the match after must be part of the follow-set.
This commits allows us to performs such checks properly and to "look
past" zeroable matches. This is not done with any lookahead, simply by
keeping a list of pointers to possible previous matches and checking all
of them for ambiguities.

Addresses #947 
Closes #947 

Co-authored-by: Arthur Cohen <arthur.cohen@embecosm.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/gcc/rust/ast/rust-macro.h b/gcc/rust/ast/rust-macro.h
index 2b50ac1..1d92283 100644
--- a/gcc/rust/ast/rust-macro.h
+++ b/gcc/rust/ast/rust-macro.h
@@ -291,6 +291,10 @@ public:
   MacroRepOp get_op () const { return op; }
   const std::unique_ptr<MacroRepSep> &get_sep () const { return sep; }
   std::vector<std::unique_ptr<MacroMatch> > &get_matches () { return matches; }
+  const std::vector<std::unique_ptr<MacroMatch> > &get_matches () const
+  {
+    return matches;
+  }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -366,6 +370,10 @@ public:
 
   DelimType get_delim_type () const { return delim_type; }
   std::vector<std::unique_ptr<MacroMatch> > &get_matches () { return matches; }
+  const std::vector<std::unique_ptr<MacroMatch> > &get_matches () const
+  {
+    return matches;
+  }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather