tagged unions

2 files changed, 18 insertions, 1 deletions

diff --git a/src/cffc.hff b/src/cffc.hff
index eff95e4..686de57 100644
--- a/src/cffc.hff
+++ b/src/cffc.hff
@@ -168,6 +168,7 @@ struct Expr {
       Call struct { lhs *Expr, args [#]Expr },
       ZeroIni,
       EnumIni struct { name *const u8, val i64 },
+      EUnionIni struct { var *const AggField, ex *Expr },
       AggIni struct { flds [#]*const AggField, exs [#]Expr },
       ArrIni struct { idxs [#]u32, exs [#]Expr, maxn i64 },
       Stmt [#]Stmt,
diff --git a/src/parse.cff b/src/parse.cff
index 84df71a..0aa9fb9 100644
--- a/src/parse.cff
+++ b/src/parse.cff
@@ -1226,6 +1226,7 @@ fn pexprimary(P *Parser) Expr {
          fatal(P, tok.loc, "cannot infer type for variant");
       }
       let ty = P.targty;
+      P.targty = #null;
       if ty->is(:Enum) {
          let name = (tok = lexexpects(P, :ident, "variant name")).u.ident;
          let i i64 #?;
@@ -1240,7 +1241,22 @@ fn pexprimary(P *Parser) Expr {
          } while #f;
          ex = { tok.loc, ty, :EnumIni { name, i }};
       } else if ty->is(:Agg) and ty.u.Agg.kind == :EUnion {
-         assert(#f, "NYI");
+         let name = (tok = lexexpects(P, :ident, "variant name")).u.ident;
+         let fld = findaggfield(ty, name);
+         if fld == #null {
+            fatal(P, tok.loc, "%t has no such variant %qT", ty, tok);
+         }
+         let iex *Expr = #null;
+         if lexpeek(P).t == '(' or lexpeek(P).t == '{' {
+            P.targty = fld.ty;
+            iex = exprdup(P.alloc, parseexpr(P));
+            if fld.ty == #null {
+               fatal(P, iex.loc, "%t variant %qT is empty", ty, tok);
+            }
+         } else if fld.ty {
+            fatal(P, P.tokloc, "%t variant %qT must be initialized", ty, tok);
+         }
+         ex = { tok.loc, ty, :EUnionIni { fld, iex }};
       } else {
          fatal(P, tok.loc, "cannot infer type for variant");
       }