From 5f1827beb3199a9f4cec44de5001d599be55cfc8 Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Fri, 19 Aug 2022 12:52:29 +0200
Subject: EUSwitch and #tag

---
 src/cffc.hff  | 13 +++++++++++-
 src/parse.cff | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 75 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/cffc.hff b/src/cffc.hff
index c8c90ac..131b3d9 100644
--- a/src/cffc.hff
+++ b/src/cffc.hff
@@ -184,6 +184,16 @@ struct ISwitchCase {
    t [#]Stmt
 }
 
+struct EUSwitchCase {
+   capt *const u8,
+   captptr bool,
+   captid int,
+   variant int,
+   captty *const Type,
+   fld *AggField,
+   t [#]Stmt
+}
+
 struct Stmt {
    loc Loc,
    u enum union {
@@ -202,7 +212,8 @@ struct Stmt {
       Return Option<Expr>,
       Expr Expr,
       Decl *Decl,
-      ISwitch struct { ex Expr, cs [#]ISwitchCase, f [#]Stmt }
+      ISwitch struct { ex Expr, cs [#]ISwitchCase, f [#]Stmt },
+      EUSwitch struct { ex Expr, cs [#]EUSwitchCase, f [#]Stmt },
    }
 }
 
diff --git a/src/parse.cff b/src/parse.cff
index e237a90..4f78b21 100644
--- a/src/parse.cff
+++ b/src/parse.cff
@@ -1548,7 +1548,15 @@ fn pexpostfix(P *Parser) Expr {
             case else;
                fatal(P, ex.loc, "invalid operand to `#len' (%t)", ex.ty);
             }
-         // case lexmatch(P, &tok, '#tag');
+         case lexmatch(P, &tok, '#tag');
+            let ty = ex.ty;
+            if ty->is(:Ptr) {
+               ty = ty.u.Ptr;
+            }
+            if !ty->is(:Agg) or ty.u.Agg.kind != :EUnion {
+               fatal(P, ex.loc, "invalid operand to #tag (%t)", ex.ty);
+            }
+            ex = { tok.loc, ty.u.Agg.enumty, :EUTag(exprdup(P.alloc, ex)) };
 
          case else;
             lexexpects(P, :ident, "field name");
@@ -2027,8 +2035,60 @@ fn pstiswitch(P *Parser, loc Loc, ex Expr) Stmt {
    return { loc, :ISwitch { ex, cs->move(P.alloc), f }};
 }
 
-fn psteuswitch(P *Parser, loc Loc, ex Expr) Stmt {
-   let ty = ex.ty;
+fn psteuswitch(P *Parser, loc Loc, test Expr) Stmt {
+   let cs Vec<EUSwitchCase> = {};
+   let tok Tok #?;
+   let f [#]Stmt = {};
+   let elsep = #f;
+
+   while !lexmatch(P, &tok, '}') {
+      let c EUSwitchCase = {};
+      lexexpect(P, :kw_case);
+      if lexmatch(P, &tok, :kw_else) {
+         if elsep {
+            err(P, tok.loc, "duplicate 'case else' block");
+         }
+         elsep = #t;
+         f = parseblock0(P);
+         continue;
+      }
+      let vname = (tok = lexexpect(P, :ident)).u.ident;
+      c.fld = findaggfield(test.ty, vname);
+      if c.fld == #null {
+         fatal(P, tok.loc, "%t has no such variant %qT", test.ty, tok);
+      }
+      c.variant = c.fld - test.ty.u.Agg.flds.#ptr;
+      if c.fld.ty != #null and lexmatch(P, &tok, '*') {
+         if !islvalue(test) {
+            fatal(P, tok.loc, "cannot capture by pointer, test expression is not lvalue");
+         }
+         c.captptr = #t;
+         if lexpeek(P).t != :ident {
+            lexexpect(P, :ident);
+         }
+      }
+      let env = mkenv(P.curenv, P.alloc);
+      if c.fld.ty != #null and lexmatch(P, &tok, :ident) {
+         let ty = c.fld.ty;
+         c.capt = tok.u.ident;
+         if c.captptr {
+            ty = mkptrtype(test.ty.konst ? constify(ty) : ty);
+         }
+         pushenv(P, env);
+         putdecl(P, tok.loc, {
+            c.capt, tok.loc, .u: :Let { c.captty = ty, :None, #f, P.curfn.id }
+         });
+      }
+      lexexpect(P, ';');
+      c.t = parseblock0(P);
+      if c.capt {
+         popenv(P);
+      }
+      envfree(env);
+   }
+
+
+   return { loc, :EUSwitch { test, cs->move(P.alloc), f }};
 }
 
 fn pstswitch(P *Parser, loc Loc) Stmt {
-- 
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