From 77dd89282880373645769101c6f795a9a5ce6ff3 Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Mon, 10 Oct 2022 16:18:02 +0200
Subject: varargs

---
 pez.c    | 61 +++++++++++++++++++++++++++++++++++++++++++++++++------------
 test.pez |  9 +++++++++
 2 files changed, 58 insertions(+), 12 deletions(-)

diff --git a/pez.c b/pez.c
index 19d53ce..622ebc6 100644
--- a/pez.c
+++ b/pez.c
@@ -1021,6 +1021,8 @@ fixtrunc(fixnum f) { return f & ~(uint32_t)0xFFF; }
     _(upval,  1)              \
     _(setupv,-1)              \
     _(close,  0)              \
+    _(argc,   1)              \
+    _(vararg, 0)              \
     _(global, 0)              \
     _(setglo,-2)              \
     _(putglo,-2)              \
@@ -1619,6 +1621,19 @@ exefn(PezContext *cx, Fn *fn, uint nargs)
             uint8_t idx = code[ip++];
             closeups(cx, &locals[idx]);
         }
+        CASE(Oargc) {
+            TRY(push(cx, box_num(inttofix(nargs - pr->nparams))));
+        }
+        CASE(Ovararg) {
+            Val a = pop(cx);
+            fixnum num = unbox_num(a);
+            int idx = fixtoint(num) + pr->nparams;
+            if (!isnum(a) || num < 0 || fixtrunc(num) != num) {
+                runerr(cx, fn, ip, "SEL expected positive integer index");
+                return 0;
+            }
+            TRY(push(cx, idx >= nargs ? VOID : args[idx]));
+        }
         CASE(Oglobal) {
             Val k = pop(cx), *v;
             if ((v = getglobal(cx, k))) {
@@ -2487,6 +2502,15 @@ compclosure(Comp *cm, Proto *pr)
     return 1;
 }
 
+static bool
+reserved(const char *s)
+{
+    return !strcmp(s, "FOR")
+        || !strcmp(s, "RET")
+        || !strcmp(s, "SEL")
+        || !strcmp(s, "SEL$");
+}
+
 static bool
 lambdaexpr(Comp *cm, const char *name)
 {
@@ -2510,13 +2534,23 @@ lambdaexpr(Comp *cm, const char *name)
             char name[NAMEMAX];
             int c;
             eatspaces(cm);
-            if ((c = peekchr(cm)) != '_' && !aisalpha(c)) {
-                comperr(cm, c, "expected identifier");
-                return 0;
+            if ((c = peekchr(cm)) == '_' || aisalpha(c)) {
+                ETRY(readident(cm, name, sizeof name));
+                if (reserved(name)) {
+                    comperr(cm, *name, "'%s' is a reserved keyword", name);
+                    goto Err;
+                }
+                ETRY(addparam(cm, name));
+            } else if (c == '*') {
+                nextchr(cm);
+                proto->variadic = 1;
+                matchspchr(cm, ',');
+                ETRY(expectspchr(cm, ']'));
+                break;
+            } else {
+                comperr(cm, c, "expected param name");
+                goto Err;
             }
-            ETRY(readident(cm, name, sizeof name));
-
-            ETRY(addparam(cm, name));
 
             if (!matchspchr(cm, ',')) {
                 ETRY(expectspchr(cm, ']'));
@@ -2554,12 +2588,6 @@ flushconst(Comp *cm)
     return 1;
 }
 
-static bool
-reserved(const char *s)
-{
-    return !strcmp(s, "FOR") || !strcmp(s, "RET");
-}
-
 static bool
 primaryexpr(Comp *cm)
 {
@@ -2615,6 +2643,15 @@ primaryexpr(Comp *cm)
         // identifier
         *buf = c;
         TRY(readident(cm, buf + 1, sizeof buf - 1));
+        if (!strcmp(buf, "SEL$")) {
+            return compop(cm, Oargc);
+        } else if (!strcmp(buf, "SEL")) {
+            TRY(expectspchr(cm, '['));
+            TRY(expr(cm));
+            TRY(expectspchr(cm, ']'));
+            TRY(compop(cm, Ovararg));
+            return 1;
+        }
         if (reserved(buf)) {
             comperr(cm, *buf, "'%s' is a reserved keyword", buf);
             return 0;
diff --git a/test.pez b/test.pez
index eb98d75..b6dcd8c 100644
--- a/test.pez
+++ b/test.pez
@@ -26,3 +26,12 @@ FOR [@x: 0][< 10][+ 1]
         m[x, y] = x ^ y
 
 printf["%a == %a\n", m[3,7], 3^7]
+
+@add: {[*]
+    @acc = 0
+    FOR [@i: 0][< SEL$][+ 1]
+        acc += SEL[i]
+    acc
+}
+
+printf["4+1+3: %a\n", add[4,1,3]]
-- 
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