From f3041b7ebc7321bbee87615659beba14c72024ba Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sun, 27 Oct 2013 18:13:36 +0900
Subject: [PATCH] support rest arguments

---
 include/picrin/irep.h |  1 +
 src/codegen.c         | 21 +++++++++++++++++----
 src/vm.c              | 14 ++++++++++++--
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/include/picrin/irep.h b/include/picrin/irep.h
index 1771d3ed..37d20fb4 100644
--- a/include/picrin/irep.h
+++ b/include/picrin/irep.h
@@ -49,6 +49,7 @@ struct pic_irep {
   struct pic_code *code;
   size_t clen, ccapa;
   int argc;
+  bool varg;
 };
 
 #endif
diff --git a/src/codegen.c b/src/codegen.c
index eebce9d4..ac4063f1 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -13,8 +13,10 @@ typedef struct codegen_scope {
 
   /* local variables are 1-indexed */
   struct xhash *local_tbl;
+  /* does not count rest argument variable */
   size_t argc;
   int *cv_tbl;
+  bool varg;
 } codegen_scope;
 
 static codegen_scope *
@@ -27,6 +29,7 @@ new_global_scope(pic_state *pic)
   scope->local_tbl = pic->global_tbl;
   scope->argc = -1;
   scope->cv_tbl = NULL;
+  scope->varg = false;
   return scope;
 }
 
@@ -41,14 +44,25 @@ new_local_scope(pic_state *pic, pic_value args, codegen_scope *scope)
   new_scope = (codegen_scope *)pic_alloc(pic, sizeof(codegen_scope));
   new_scope->up = scope;
   new_scope->local_tbl = x = xh_new();
+  new_scope->varg = false;
 
   i = 1;
-  for (v = args; ! pic_nil_p(v); v = pic_cdr(pic, v)) {
+  for (v = args; pic_pair_p(v); v = pic_cdr(pic, v)) {
     pic_value sym;
 
     sym = pic_car(pic, v);
     xh_put(x, pic_symbol_ptr(sym)->name, i++);
   }
+  if (pic_nil_p(v)) {
+    /* pass */
+  }
+  else if (pic_symbol_p(v)) {
+    new_scope->varg = true;
+    xh_put(x, pic_symbol_ptr(v)->name, i);
+  }
+  else {
+    pic_error(pic, "logic flaw");
+  }
   new_scope->argc = i;
   new_scope->cv_tbl = (int *)pic_calloc(pic, i, sizeof(int));
 
@@ -75,6 +89,7 @@ new_irep(pic_state *pic)
   irep->clen = 0;
   irep->ccapa = 1024;
   irep->argc = -1;
+  irep->varg = false;
   return irep;
 }
 
@@ -546,9 +561,6 @@ codegen_lambda(codegen_state *state, pic_value obj)
   if (! valid_formal(pic, args)) {
     pic_error(pic, "syntax error");
   }
-  if (! pic_list_p(pic, args)) {
-    pic_error(pic, "variable-length argument not supported (for now)");
-  }
 
   /* inner environment */
   prev_irep = state->irep;
@@ -557,6 +569,7 @@ codegen_lambda(codegen_state *state, pic_value obj)
   state->scope = new_local_scope(pic, args, state->scope);
   state->irep = irep = new_irep(pic);
   irep->argc = state->scope->argc;
+  irep->varg = state->scope->varg;
   {
     /* body */
     body = pic_cdr(pic, pic_cdr(pic, obj));
diff --git a/src/vm.c b/src/vm.c
index 5e569beb..4848e79f 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -245,10 +245,20 @@ pic_run(pic_state *pic, struct pic_proc *proc, pic_value args)
       }
       else {
 	int i;
+	pic_value rest;
 
 	if (ci->argc != proc->u.irep->argc) {
-	  pic->errmsg = "wrong number of arguments";
-	  goto L_RAISE;
+	  if (! (proc->u.irep->varg && ci->argc >= proc->u.irep->argc)) {
+	    pic->errmsg = "wrong number of arguments";
+	    goto L_RAISE;
+	  }
+	  /* prepare rest args */
+	  rest = pic_nil_value();
+	  for (i = 0; i < ci->argc - proc->u.irep->argc; ++i) {
+	    pic_gc_protect(pic, v = POP());
+	    rest = pic_cons(pic, v, rest);
+	  }
+	  PUSH(rest);
 	}
 	for (i = 0; i < proc->u.irep->argc; ++i) {
 	  proc->env->values[i] = ci->fp[i];