Prefer rb_check_arity when 0 or 1 arguments

Especially over checking argc then calling rb_scan_args just to
raise an ArgumentError.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66238 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

18 files changed, 72 insertions, 139 deletions

diff --git a/enum.c b/enum.c
index f446403b48..a739d335a9 100644
--- a/enum.c
+++ b/enum.c
@@ -2009,11 +2009,11 @@ enum_min_by(int argc, VALUE *argv, VALUE obj)
     struct MEMO *memo;
     VALUE num;
 
-    rb_scan_args(argc, argv, "01", &num);
+    rb_check_arity(argc, 0, 1);
 
     RETURN_SIZED_ENUMERATOR(obj, argc, argv, enum_size);
 
-    if (!NIL_P(num))
+    if (argc && !NIL_P(num = argv[0]))
         return rb_nmin_run(obj, num, 1, 0, 0);
 
     memo = MEMO_NEW(Qundef, Qnil, 0);
@@ -2116,11 +2116,11 @@ enum_max_by(int argc, VALUE *argv, VALUE obj)
     struct MEMO *memo;
     VALUE num;
 
-    rb_scan_args(argc, argv, "01", &num);
+    rb_check_arity(argc, 0, 1);
 
     RETURN_SIZED_ENUMERATOR(obj, argc, argv, enum_size);
 
-    if (!NIL_P(num))
+    if (argc && !NIL_P(num = argv[0]))
         return rb_nmin_run(obj, num, 1, 1, 0);
 
     memo = MEMO_NEW(Qundef, Qnil, 0);
@@ -2971,10 +2971,10 @@ enum_cycle(int argc, VALUE *argv, VALUE obj)
     VALUE nv = Qnil;
     long n, i, len;
 
-    rb_scan_args(argc, argv, "01", &nv);
+    rb_check_arity(argc, 0, 1);
 
     RETURN_SIZED_ENUMERATOR(obj, argc, argv, enum_cycle_size);
-    if (NIL_P(nv)) {
+    if (!argc || NIL_P(nv = argv[0])) {
         n = -1;
     }
     else {
@@ -3944,11 +3944,8 @@ enum_sum(int argc, VALUE* argv, VALUE obj)
     VALUE beg, end;
     int excl;
 
-    if (rb_scan_args(argc, argv, "01", &memo.v) == 0)
-        memo.v = LONG2FIX(0);
-
+    memo.v = (rb_check_arity(argc, 0, 1) == 0) ? LONG2FIX(0) : argv[0];
     memo.block_given = rb_block_given_p();
-
     memo.n = 0;
     memo.r = Qundef;
 
diff --git a/enumerator.c b/enumerator.c
index e84785a6b8..615f933778 100644
--- a/enumerator.c
+++ b/enumerator.c
@@ -604,12 +604,9 @@ enumerator_with_index(int argc, VALUE *argv, VALUE obj)
 {
     VALUE memo;
 
-    rb_scan_args(argc, argv, "01", &memo);
+    rb_check_arity(argc, 0, 1);
     RETURN_SIZED_ENUMERATOR(obj, argc, argv, enumerator_enum_size);
-    if (NIL_P(memo))
-	memo = INT2FIX(0);
-    else
-	memo = rb_to_int(memo);
+    memo = (!argc || NIL_P(memo = argv[0])) ? INT2FIX(0) : rb_to_int(memo);
     return enumerator_block_call(obj, enumerator_with_index_i, (VALUE)MEMO_NEW(memo, 0, 0));
 }
 
diff --git a/error.c b/error.c
index b4ba64b57a..2e2cc25ac2 100644
--- a/error.c
+++ b/error.c
@@ -946,7 +946,7 @@ exc_initialize(int argc, VALUE *argv, VALUE exc)
 {
     VALUE arg;
 
-    rb_scan_args(argc, argv, "01", &arg);
+    arg = (!rb_check_arity(argc, 0, 1) ? Qnil : argv[0]);
     return exc_init(exc, arg);
 }
 
diff --git a/gc.c b/gc.c
index 4de27892e8..a8e7192e25 100644
--- a/gc.c
+++ b/gc.c
@@ -2722,12 +2722,7 @@ os_each_obj(int argc, VALUE *argv, VALUE os)
 {
     VALUE of;
 
-    if (argc == 0) {
-	of = 0;
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &of);
-    }
+    of = (!rb_check_arity(argc, 0, 1) ? 0 : argv[0]);
     RETURN_ENUMERATOR(os, 1, &of);
     return os_obj_of(of);
 }
@@ -3487,9 +3482,10 @@ count_objects(int argc, VALUE *argv, VALUE os)
     size_t freed = 0;
     size_t total = 0;
     size_t i;
-    VALUE hash;
+    VALUE hash = Qnil;
 
-    if (rb_scan_args(argc, argv, "01", &hash) == 1) {
+    if (rb_check_arity(argc, 0, 1) == 1) {
+        hash = argv[0];
         if (!RB_TYPE_P(hash, T_HASH))
             rb_raise(rb_eTypeError, "non-hash given");
     }
@@ -7077,13 +7073,13 @@ gc_latest_gc_info(int argc, VALUE *argv, VALUE self)
     rb_objspace_t *objspace = &rb_objspace;
     VALUE arg = Qnil;
 
-    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
+    if (rb_check_arity(argc, 0, 1) == 1) {
+        arg = argv[0];
 	if (!SYMBOL_P(arg) && !RB_TYPE_P(arg, T_HASH)) {
 	    rb_raise(rb_eTypeError, "non-hash or symbol given");
 	}
     }
-
-    if (arg == Qnil) {
+    else {
 	arg = rb_hash_new();
     }
 
@@ -7452,7 +7448,8 @@ gc_stat(int argc, VALUE *argv, VALUE self)
 {
     VALUE arg = Qnil;
 
-    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
+    if (rb_check_arity(argc, 0, 1) == 1) {
+        arg = argv[0];
 	if (SYMBOL_P(arg)) {
 	    size_t value = gc_stat_internal(arg);
 	    return SIZET2NUM(value);
@@ -7461,8 +7458,7 @@ gc_stat(int argc, VALUE *argv, VALUE self)
 	    rb_raise(rb_eTypeError, "non-hash or symbol given");
 	}
     }
-
-    if (arg == Qnil) {
+    else {
         arg = rb_hash_new();
     }
     gc_stat_internal(arg);
@@ -9455,12 +9451,7 @@ gc_profile_report(int argc, VALUE *argv, VALUE self)
 {
     VALUE out;
 
-    if (argc == 0) {
-	out = rb_stdout;
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &out);
-    }
+    out = (!rb_check_arity(argc, 0, 1) ? rb_stdout : argv[0]);
     gc_profile_dump_on(out, rb_io_write);
 
     return Qnil;
diff --git a/io.c b/io.c
index ac35e1ee4f..1a22d34c50 100644
--- a/io.c
+++ b/io.c
@@ -7878,12 +7878,7 @@ rb_obj_display(int argc, VALUE *argv, VALUE self)
 {
     VALUE out;
 
-    if (argc == 0) {
-	out = rb_stdout;
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &out);
-    }
+    out = (!rb_check_arity(argc, 0, 1) ? rb_stdout : argv[0]);
     rb_io_write(out, self);
 
     return Qnil;
diff --git a/iseq.c b/iseq.c
index 0b5f7c14e4..8e890d4a67 100644
--- a/iseq.c
+++ b/iseq.c
@@ -3183,8 +3183,7 @@ rb_iseqw_local_variables(VALUE iseqval)
 static VALUE
 iseqw_to_binary(int argc, VALUE *argv, VALUE self)
 {
-    VALUE opt;
-    rb_scan_args(argc, argv, "01", &opt);
+    VALUE opt = !rb_check_arity(argc, 0, 1) ? Qnil : argv[0];
     return rb_iseq_ibf_dump(iseqw_check(self), opt);
 }
 
diff --git a/proc.c b/proc.c
index 50e09d76e7..fb286fa42b 100644
--- a/proc.c
+++ b/proc.c
@@ -2993,8 +2993,7 @@ proc_curry(int argc, const VALUE *argv, VALUE self)
     int sarity, max_arity, min_arity = rb_proc_min_max_arity(self, &max_arity);
     VALUE arity;
 
-    rb_scan_args(argc, argv, "01", &arity);
-    if (NIL_P(arity)) {
+    if (rb_check_arity(argc, 0, 1) == 0 || NIL_P(arity = argv[0])) {
 	arity = INT2FIX(min_arity);
     }
     else {
diff --git a/range.c b/range.c
index 9661feb718..c30852e500 100644
--- a/range.c
+++ b/range.c
@@ -397,12 +397,7 @@ range_step(int argc, VALUE *argv, VALUE range)
 
     b = RANGE_BEG(range);
     e = RANGE_END(range);
-    if (argc == 0) {
-        step = INT2FIX(1);
-    }
-    else {
-        rb_scan_args(argc, argv, "01", &step);
-    }
+    step = (!rb_check_arity(argc, 0, 1) ? INT2FIX(1) : argv[0]);
 
     if (!rb_block_given_p()) {
         if (rb_obj_is_kind_of(b, rb_cNumeric) && (NIL_P(e) || rb_obj_is_kind_of(e, rb_cNumeric))) {
diff --git a/rational.c b/rational.c
index b320ed5501..076d42707f 100644
--- a/rational.c
+++ b/rational.c
@@ -1385,10 +1385,10 @@ f_round_common(int argc, VALUE *argv, VALUE self, VALUE (*func)(VALUE))
 {
     VALUE n, b, s;
 
-    if (argc == 0)
+    if (rb_check_arity(argc, 0, 1) == 0)
 	return (*func)(self);
 
-    rb_scan_args(argc, argv, "01", &n);
+    n = argv[0];
 
     if (!k_integer_p(n))
 	rb_raise(rb_eTypeError, "not an integer");
@@ -1711,14 +1711,13 @@ nurat_rationalize(int argc, VALUE *argv, VALUE self)
 {
     VALUE e, a, b, p, q;
 
-    if (argc == 0)
+    if (rb_check_arity(argc, 0, 1) == 0)
 	return self;
 
     if (nurat_negative_p(self))
 	return rb_rational_uminus(nurat_rationalize(argc, argv, rb_rational_uminus(self)));
 
-    rb_scan_args(argc, argv, "01", &e);
-    e = f_abs(e);
+    e = f_abs(argv[0]);
     a = f_sub(self, e);
     b = f_add(self, e);
 
@@ -2283,16 +2282,13 @@ rb_flt_rationalize(VALUE flt)
 static VALUE
 float_rationalize(int argc, VALUE *argv, VALUE self)
 {
-    VALUE e;
     double d = RFLOAT_VALUE(self);
 
     if (d < 0.0)
         return rb_rational_uminus(float_rationalize(argc, argv, DBL2NUM(-d)));
 
-    rb_scan_args(argc, argv, "01", &e);
-
-    if (argc != 0) {
-        return rb_flt_rationalize_with_prec(self, e);
+    if (rb_check_arity(argc, 0, 1)) {
+        return rb_flt_rationalize_with_prec(self, argv[0]);
     }
     else {
         return rb_flt_rationalize(self);
diff --git a/signal.c b/signal.c
index 02c8393730..631fdae4e0 100644
--- a/signal.c
+++ b/signal.c
@@ -391,7 +391,7 @@ interrupt_init(int argc, VALUE *argv, VALUE self)
     VALUE args[2];
 
     args[0] = INT2FIX(SIGINT);
-    rb_scan_args(argc, argv, "01", &args[1]);
+    args[1] = rb_check_arity(argc, 0, 1) ? argv[0] : Qnil;
     return rb_call_super(2, args);
 }
 
diff --git a/string.c b/string.c
index ea72c0be48..6a89343bef 100644
--- a/string.c
+++ b/string.c
@@ -5724,16 +5724,9 @@ rb_str_include(VALUE str, VALUE arg)
 static VALUE
 rb_str_to_i(int argc, VALUE *argv, VALUE str)
 {
-    int base;
+    int base = 10;
 
-    if (argc == 0) base = 10;
-    else {
-	VALUE b;
-
-	rb_scan_args(argc, argv, "01", &b);
-	base = NUM2INT(b);
-    }
-    if (base < 0) {
+    if (rb_check_arity(argc, 0, 1) && (base = NUM2INT(argv[0])) < 0) {
 	rb_raise(rb_eArgError, "invalid radix %d", base);
     }
     return rb_str_to_inum(str, base, FALSE);
@@ -9369,20 +9362,14 @@ static VALUE
 rb_str_sum(int argc, VALUE *argv, VALUE str)
 {
     VALUE vbits;
-    int bits;
+    int bits = 16;
     char *ptr, *p, *pend;
     long len;
     VALUE sum = INT2FIX(0);
     unsigned long sum0 = 0;
 
-    if (argc == 0) {
-	bits = 16;
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &vbits);
-	bits = NUM2INT(vbits);
-        if (bits < 0)
-            bits = 0;
+    if (rb_check_arity(argc, 0, 1) && (bits = NUM2INT(argv[0])) < 0) {
+        bits = 0;
     }
     ptr = p = RSTRING_PTR(str);
     len = RSTRING_LEN(str);
@@ -10397,7 +10384,7 @@ unicode_normalize_common(int argc, VALUE *argv, VALUE str, ID id)
 	UnicodeNormalizeRequired = 1;
     }
     argv2[0] = str;
-    rb_scan_args(argc, argv, "01", &argv2[1]);
+    if (rb_check_arity(argc, 0, 1)) argv2[1] = argv[0];
     return rb_funcallv(mUnicodeNormalize, id, argc+1, argv2);
 }
 
diff --git a/thread.c b/thread.c
index d76f05aa41..faecec7a04 100644
--- a/thread.c
+++ b/thread.c
@@ -1111,19 +1111,18 @@ thread_join_m(int argc, VALUE *argv, VALUE self)
     VALUE limit;
     rb_hrtime_t rel, *to = 0;
 
-    rb_scan_args(argc, argv, "01", &limit);
-
     /*
      * This supports INFINITY and negative values, so we can't use
      * rb_time_interval right now...
      */
-    switch (TYPE(limit)) {
-      case T_NIL: break;
-      case T_FIXNUM:
+    if (!rb_check_arity(argc, 0, 1) || NIL_P(argv[0])) {
+        /* unlimited */
+    }
+    else if (FIXNUM_P(limit = argv[0])) {
         rel = rb_sec2hrtime(NUM2TIMET(limit));
         to = &rel;
-        break;
-      default:
+    }
+    else {
         to = double2hrtime(&rel, rb_num2dbl(limit));
     }
 
@@ -2041,20 +2040,19 @@ rb_thread_pending_interrupt_p(int argc, VALUE *argv, VALUE target_thread)
     if (rb_threadptr_pending_interrupt_empty_p(target_th)) {
 	return Qfalse;
     }
+    if (rb_check_arity(argc, 0, 1)) {
+        VALUE err = argv[0];
+        if (!rb_obj_is_kind_of(err, rb_cModule)) {
+            rb_raise(rb_eTypeError, "class or module required for rescue clause");
+        }
+        if (rb_threadptr_pending_interrupt_include_p(target_th, err)) {
+            return Qtrue;
+        }
+        else {
+            return Qfalse;
+        }
+    }
     else {
-	if (argc == 1) {
-	    VALUE err;
-	    rb_scan_args(argc, argv, "01", &err);
-	    if (!rb_obj_is_kind_of(err, rb_cModule)) {
-		rb_raise(rb_eTypeError, "class or module required for rescue clause");
-	    }
-	    if (rb_threadptr_pending_interrupt_include_p(target_th, err)) {
-		return Qtrue;
-	    }
-	    else {
-		return Qfalse;
-	    }
-	}
 	return Qtrue;
     }
 }
diff --git a/thread_sync.c b/thread_sync.c
index e478a96b88..4a3cb2ad6a 100644
--- a/thread_sync.c
+++ b/thread_sync.c
@@ -517,7 +517,7 @@ mutex_sleep(int argc, VALUE *argv, VALUE self)
 {
     VALUE timeout;
 
-    rb_scan_args(argc, argv, "01", &timeout);
+    timeout = rb_check_arity(argc, 0, 1) ? argv[0] : Qnil;
     return rb_mutex_sleep(self, timeout);
 }
 
diff --git a/time.c b/time.c
index f1cb7b6716..5c4a7f26b2 100644
--- a/time.c
+++ b/time.c
@@ -3764,9 +3764,8 @@ static VALUE
 time_localtime_m(int argc, VALUE *argv, VALUE time)
 {
     VALUE off;
-    rb_scan_args(argc, argv, "01", &off);
 
-    if (!NIL_P(off)) {
+    if (rb_check_arity(argc, 0, 1) && !NIL_P(off = argv[0])) {
         return time_zonelocal(time, off);
     }
 
@@ -3881,9 +3880,8 @@ static VALUE
 time_getlocaltime(int argc, VALUE *argv, VALUE time)
 {
     VALUE off;
-    rb_scan_args(argc, argv, "01", &off);
 
-    if (!NIL_P(off)) {
+    if (rb_check_arity(argc, 0, 1) && !NIL_P(off = argv[0])) {
         VALUE zone = off;
         if (maybe_tzobj_p(zone)) {
             VALUE t = time_dup(time);
@@ -4136,9 +4134,7 @@ time_round(int argc, VALUE *argv, VALUE time)
     long nd;
     struct time_object *tobj;
 
-    rb_scan_args(argc, argv, "01", &ndigits);
-
-    if (NIL_P(ndigits))
+    if (!rb_check_arity(argc, 0, 1) || NIL_P(ndigits = argv[0]))
         ndigits = INT2FIX(0);
     else
         ndigits = rb_to_int(ndigits);
diff --git a/transcode.c b/transcode.c
index 9462433130..5f9e4e9600 100644
--- a/transcode.c
+++ b/transcode.c
@@ -4115,10 +4115,9 @@ econv_putback(int argc, VALUE *argv, VALUE self)
     int putbackable;
     VALUE str, max;
 
-    rb_scan_args(argc, argv, "01", &max);
-
-    if (NIL_P(max))
+    if (!rb_check_arity(argc, 0, 1) || NIL_P(max = argv[0])) {
         n = rb_econv_putbackable(ec);
+    }
     else {
         n = NUM2INT(max);
         putbackable = rb_econv_putbackable(ec);
diff --git a/variable.c b/variable.c
index 968d404c05..89befc0c89 100644
--- a/variable.c
+++ b/variable.c
@@ -2728,16 +2728,11 @@ rb_const_list(void *data)
 VALUE
 rb_mod_constants(int argc, const VALUE *argv, VALUE mod)
 {
-    VALUE inherit;
+    bool inherit = TRUE;
 
-    if (argc == 0) {
-	inherit = Qtrue;
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &inherit);
-    }
+    if (rb_check_arity(argc, 0, 1)) inherit = RTEST(argv[0]);
 
-    if (RTEST(inherit)) {
+    if (inherit) {
 	return rb_const_list(rb_mod_const_of(mod, 0));
     }
     else {
@@ -3294,16 +3289,11 @@ cvar_list(void *data)
 VALUE
 rb_mod_class_variables(int argc, const VALUE *argv, VALUE mod)
 {
-    VALUE inherit;
+    bool inherit = TRUE;
     st_table *tbl;
 
-    if (argc == 0) {
-	inherit = Qtrue;
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &inherit);
-    }
-    if (RTEST(inherit)) {
+    if (rb_check_arity(argc, 0, 1)) inherit = RTEST(argv[0]);
+    if (inherit) {
 	tbl = mod_cvar_of(mod, 0);
     }
     else {
diff --git a/vm.c b/vm.c
index 5920f25fc4..2c69498c13 100644
--- a/vm.c
+++ b/vm.c
@@ -422,7 +422,8 @@ vm_stat(int argc, VALUE *argv, VALUE self)
     VALUE arg = Qnil;
     VALUE hash = Qnil, key = Qnil;
 
-    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
+    if (rb_check_arity(argc, 0, 1) == 1) {
+        arg = argv[0];
 	if (SYMBOL_P(arg))
 	    key = arg;
 	else if (RB_TYPE_P(arg, T_HASH))
diff --git a/vm_eval.c b/vm_eval.c
index 47191a0aab..9e1563dd8d 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1949,16 +1949,9 @@ catch_i(VALUE tag, VALUE data)
  */
 
 static VALUE
-rb_f_catch(int argc, VALUE *argv)
+rb_f_catch(int argc, VALUE *argv, VALUE self)
 {
-    VALUE tag;
-
-    if (argc == 0) {
-	tag = rb_obj_alloc(rb_cObject);
-    }
-    else {
-	rb_scan_args(argc, argv, "01", &tag);
-    }
+    VALUE tag = rb_check_arity(argc, 0, 1) ? argv[0] : rb_obj_alloc(rb_cObject);
     return rb_catch_obj(tag, catch_i, 0);
 }