Changed the behavior of mrb_range_beg_len(); close #3411

The new API is:

int mrb_range_beg_len(mrb, range, &beg, &len, len, trunc)

The new argument `trunc` is a boolean value that specifies
whether the function truncates the range. The new return value
is an integer instead of a boolean, that is:

 0: not a range
 1: range with proper edges
 2: out of range

To get the old behavior, you have to rewrite:

  mrb_range_beg_len(mrb, range, &beg, &len, len)

to:

  mrn_range_beg_len(mrb, range, &beg, &len, len, TRUE) == 1

[Breaking Change]

3 files changed, 30 insertions, 36 deletions

diff --git a/src/array.c b/src/array.c
index f9155d173..e41183d68 100644
--- a/src/array.c
+++ b/src/array.c
@@ -742,7 +742,7 @@ mrb_ary_aget(mrb_state *mrb, mrb_value self)
     switch (mrb_type(index)) {
       /* a[n..m] */
     case MRB_TT_RANGE:
-      if (mrb_range_beg_len(mrb, index, &i, &len, a->len)) {
+      if (mrb_range_beg_len(mrb, index, &i, &len, a->len, TRUE) == 1) {
         return ary_subseq(mrb, a, i, len);
       }
       else {
@@ -808,19 +808,16 @@ mrb_ary_aset(mrb_state *mrb, mrb_value self)
 
   mrb_ary_modify(mrb, mrb_ary_ptr(self));
   if (mrb_get_args(mrb, "oo|o", &v1, &v2, &v3) == 2) {
-    switch (mrb_type(v1)) {
     /* a[n..m] = v */
-    case MRB_TT_RANGE:
-      if (mrb_range_beg_len(mrb, v1, &i, &len, RARRAY_LEN(self))) {
-        mrb_ary_splice(mrb, self, i, len, v2);
-      }
+    switch (mrb_range_beg_len(mrb, v1, &i, &len, RARRAY_LEN(self), FALSE)) {
+    case 0:                   /* not range */
+      mrb_ary_set(mrb, self, aget_index(mrb, v1), v2);
       break;
-    /* a[n] = v */
-    case MRB_TT_FIXNUM:
-      mrb_ary_set(mrb, self, mrb_fixnum(v1), v2);
+    case 1:                   /* range */
+      mrb_ary_splice(mrb, self, i, len, v2);
       break;
-    default:
-      mrb_ary_set(mrb, self, aget_index(mrb, v1), v2);
+    case 2:                   /* out of range */
+      mrb_raisef(mrb, E_RANGE_ERROR, "%S out of range", v1);
       break;
     }
     return v2;
diff --git a/src/range.c b/src/range.c
index 73fe7589b..800e64611 100644
--- a/src/range.c
+++ b/src/range.c
@@ -248,13 +248,13 @@ mrb_range_include(mrb_state *mrb, mrb_value range)
   return mrb_bool_value(include_p);
 }
 
-static mrb_bool
-range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb_int len, mrb_bool trunc)
+int
+mrb_range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb_int len, mrb_bool trunc)
 {
   mrb_int beg, end;
   struct RRange *r;
 
-  if (mrb_type(range) != MRB_TT_RANGE) return FALSE;
+  if (mrb_type(range) != MRB_TT_RANGE) return 0;
   r = mrb_range_ptr(mrb, range);
 
   beg = mrb_int(mrb, r->edges->beg);
@@ -262,11 +262,11 @@ range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb
 
   if (beg < 0) {
     beg += len;
-    if (beg < 0) return FALSE;
+    if (beg < 0) return 2;
   }
 
   if (trunc) {
-    if (beg > len) return FALSE;
+    if (beg > len) return 2;
     if (end > len) end = len;
   }
 
@@ -278,13 +278,7 @@ range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb
 
   *begp = beg;
   *lenp = len;
-  return TRUE;
-}
-
-MRB_API mrb_bool
-mrb_range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb_int len)
-{
-  return range_beg_len(mrb, range, begp, lenp, len, TRUE);
+  return 1;
 }
 
 /* 15.2.14.4.12(x) */
@@ -405,7 +399,7 @@ mrb_get_values_at(mrb_state *mrb, mrb_value obj, mrb_int olen, mrb_int argc, con
     if (mrb_fixnum_p(argv[i])) {
       mrb_ary_push(mrb, result, func(mrb, obj, mrb_fixnum(argv[i])));
     }
-    else if (range_beg_len(mrb, argv[i], &beg, &len, olen, FALSE)) {
+    else if (mrb_range_beg_len(mrb, argv[i], &beg, &len, olen, FALSE) == 1) {
       mrb_int const end = olen < beg + len ? olen : beg + len;
       for (j = beg; j < end; ++j) {
         mrb_ary_push(mrb, result, func(mrb, obj, j));
diff --git a/src/string.c b/src/string.c
index 02c7ce426..7a75bb63e 100644
--- a/src/string.c
+++ b/src/string.c
@@ -1091,22 +1091,25 @@ num_index:
       return mrb_nil_value();
 
     case MRB_TT_RANGE:
-      /* check if indx is Range */
-      {
-        mrb_int beg, len;
+      goto range_arg;
 
-        len = RSTRING_CHAR_LEN(str);
-        if (mrb_range_beg_len(mrb, indx, &beg, &len, len)) {
-          return str_subseq(mrb, str, beg, len);
-        }
-        else {
-          return mrb_nil_value();
-        }
-      }
-    case MRB_TT_FLOAT:
     default:
       indx = mrb_Integer(mrb, indx);
       if (mrb_nil_p(indx)) {
+      range_arg:
+        {
+          mrb_int beg, len;
+
+          len = RSTRING_CHAR_LEN(str);
+          switch (mrb_range_beg_len(mrb, indx, &beg, &len, len, TRUE)) {
+          case 1:
+            return str_subseq(mrb, str, beg, len);
+          case 2:
+            return mrb_nil_value();
+          default:
+            break;
+          }
+        }
         mrb_raise(mrb, E_TYPE_ERROR, "can't convert to Fixnum");
       }
       idx = mrb_fixnum(indx);