3 files changed, 151 insertions, 6 deletions

diff --git a/mrbgems/mruby-string-ext/mrblib/string.rb b/mrbgems/mruby-string-ext/mrblib/string.rb
index c3a7eb380..cb36d9a48 100644
--- a/mrbgems/mruby-string-ext/mrblib/string.rb
+++ b/mrbgems/mruby-string-ext/mrblib/string.rb
@@ -144,7 +144,20 @@ class String
   def casecmp(str)
     self.downcase <=> str.to_str.downcase
   rescue NoMethodError
-    raise TypeError, "no implicit conversion of #{str.class} into String"
+    nil
+  end
+
+  ##
+  # call-seq:
+  #   str.casecmp?(other)  -> true, false, or nil
+  #
+  # Returns true if str and other_str are equal after case folding,
+  # false if they are not equal, and nil if other_str is not a string.
+
+  def casecmp?(str)
+    c = self.casecmp(str)
+    return nil if c.nil?
+    return c == 0
   end
 
   def partition(sep)
diff --git a/mrbgems/mruby-string-ext/src/string.c b/mrbgems/mruby-string-ext/src/string.c
index ac3e82a45..ddceb03ff 100644
--- a/mrbgems/mruby-string-ext/src/string.c
+++ b/mrbgems/mruby-string-ext/src/string.c
@@ -44,12 +44,13 @@ mrb_str_byteslice(mrb_state *mrb, mrb_value str)
 {
   mrb_value a1;
   mrb_int len;
-  mrb_int argc;
 
-  argc = mrb_get_args(mrb, "o|i", &a1, &len);
-  if (argc == 2) {
+  if (mrb_get_argc(mrb) == 2) {
+    mrb_int pos;
+    mrb_get_args(mrb, "ii", &pos, &len);
     return mrb_str_substr(mrb, str, mrb_fixnum(a1), len);
   }
+  mrb_get_args(mrb, "o|i", &a1, &len);
   switch (mrb_type(a1)) {
   case MRB_TT_RANGE:
     {
@@ -652,6 +653,118 @@ mrb_str_upto(mrb_state *mrb, mrb_value beg)
   return beg;
 }
 
+/*
+ *  call-seq:
+ *     str.delete_prefix!(prefix) -> self or nil
+ *
+ *  Deletes leading <code>prefix</code> from <i>str</i>, returning
+ *  <code>nil</code> if no change was made.
+ *
+ *     "hello".delete_prefix!("hel") #=> "lo"
+ *     "hello".delete_prefix!("llo") #=> nil
+ */
+static mrb_value
+mrb_str_del_prefix_bang(mrb_state *mrb, mrb_value self)
+{
+  mrb_int plen, slen;
+  char *ptr, *s;
+  struct RString *str = RSTRING(self);
+
+  mrb_get_args(mrb, "s", &ptr, &plen);
+  slen = RSTR_LEN(str);
+  if (plen > slen) return mrb_nil_value();
+  s = RSTR_PTR(str);
+  if (memcmp(s, ptr, plen) != 0) return mrb_nil_value();
+  if (!MRB_FROZEN_P(str) && (RSTR_SHARED_P(str) || RSTR_FSHARED_P(str))) {
+    str->as.heap.ptr += plen;
+  }
+  else {
+    mrb_str_modify(mrb, str);
+    s = RSTR_PTR(str);
+    memmove(s, s+plen, slen-plen);
+  }
+  RSTR_SET_LEN(str, slen-plen);
+  return self;
+}
+
+/*
+ *  call-seq:
+ *     str.delete_prefix(prefix) -> new_str
+ *
+ *  Returns a copy of <i>str</i> with leading <code>prefix</code> deleted.
+ *
+ *     "hello".delete_prefix("hel") #=> "lo"
+ *     "hello".delete_prefix("llo") #=> "hello"
+ */
+static mrb_value
+mrb_str_del_prefix(mrb_state *mrb, mrb_value self)
+{
+  mrb_int plen, slen;
+  char *ptr;
+
+  mrb_get_args(mrb, "s", &ptr, &plen);
+  slen = RSTRING_LEN(self);
+  if (plen > slen) return mrb_str_dup(mrb, self);
+  if (memcmp(RSTRING_PTR(self), ptr, plen) != 0)
+    return mrb_str_dup(mrb, self);
+  return mrb_str_substr(mrb, self, plen, slen-plen);
+}
+
+/*
+ *  call-seq:
+ *     str.delete_suffix!(suffix) -> self or nil
+ *
+ *  Deletes trailing <code>suffix</code> from <i>str</i>, returning
+ *  <code>nil</code> if no change was made.
+ *
+ *     "hello".delete_suffix!("llo") #=> "he"
+ *     "hello".delete_suffix!("hel") #=> nil
+ */
+static mrb_value
+mrb_str_del_suffix_bang(mrb_state *mrb, mrb_value self)
+{
+  mrb_int plen, slen;
+  char *ptr, *s;
+  struct RString *str = RSTRING(self);
+
+  mrb_get_args(mrb, "s", &ptr, &plen);
+  slen = RSTR_LEN(str);
+  if (plen > slen) return mrb_nil_value();
+  s = RSTR_PTR(str);
+  if (memcmp(s+slen-plen, ptr, plen) != 0) return mrb_nil_value();
+  if (!MRB_FROZEN_P(str) && (RSTR_SHARED_P(str) || RSTR_FSHARED_P(str))) {
+    /* no need to modify string */
+  }
+  else {
+    mrb_str_modify(mrb, str);
+  }
+  RSTR_SET_LEN(str, slen-plen);
+  return self;
+}
+
+/*
+ *  call-seq:
+ *     str.delete_suffix(suffix) -> new_str
+ *
+ *  Returns a copy of <i>str</i> with leading <code>suffix</code> deleted.
+ *
+ *     "hello".delete_suffix("hel") #=> "lo"
+ *     "hello".delete_suffix("llo") #=> "hello"
+ */
+static mrb_value
+mrb_str_del_suffix(mrb_state *mrb, mrb_value self)
+{
+  mrb_int plen, slen;
+  char *ptr;
+
+  mrb_get_args(mrb, "s", &ptr, &plen);
+  slen = RSTRING_LEN(self);
+  if (plen > slen) return mrb_str_dup(mrb, self);
+  if (memcmp(RSTRING_PTR(self)+slen-plen, ptr, plen) != 0)
+    return mrb_str_dup(mrb, self);
+  return mrb_str_substr(mrb, self, 0, slen-plen);
+}
+
 void
 mrb_mruby_string_ext_gem_init(mrb_state* mrb)
 {
@@ -675,8 +788,12 @@ mrb_mruby_string_ext_gem_init(mrb_state* mrb)
   mrb_define_method(mrb, s, "succ!",           mrb_str_succ_bang,       MRB_ARGS_NONE());
   mrb_alias_method(mrb, s, mrb_intern_lit(mrb, "next"), mrb_intern_lit(mrb, "succ"));
   mrb_alias_method(mrb, s, mrb_intern_lit(mrb, "next!"), mrb_intern_lit(mrb, "succ!"));
-  mrb_define_method(mrb, s, "ord", mrb_str_ord, MRB_ARGS_NONE());
-  mrb_define_method(mrb, s, "upto", mrb_str_upto, MRB_ARGS_ANY());
+  mrb_define_method(mrb, s, "ord",             mrb_str_ord,             MRB_ARGS_NONE());
+  mrb_define_method(mrb, s, "upto",            mrb_str_upto,            MRB_ARGS_ANY());
+  mrb_define_method(mrb, s, "delete_prefix!",  mrb_str_del_prefix_bang, MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, s, "delete_prefix",   mrb_str_del_prefix,      MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, s, "delete_suffix!",  mrb_str_del_suffix_bang, MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, s, "delete_suffix",   mrb_str_del_suffix,      MRB_ARGS_REQ(1));
 
   mrb_define_method(mrb, mrb->fixnum_class, "chr", mrb_fixnum_chr, MRB_ARGS_NONE());
 }
diff --git a/mrbgems/mruby-string-ext/test/string.rb b/mrbgems/mruby-string-ext/test/string.rb
index 2a568c7d6..b6146fb90 100644
--- a/mrbgems/mruby-string-ext/test/string.rb
+++ b/mrbgems/mruby-string-ext/test/string.rb
@@ -1,3 +1,4 @@
+# coding: utf-8
 ##
 # String(Ext) Test
 
@@ -665,3 +666,17 @@ assert('String#each_codepoint(UTF-8)') do
   end
   assert_equal expect, cp
 end if UTF8STRING
+
+assert('String#delete_prefix') do
+  assert_equal "llo", "hello".delete_prefix("he")
+  assert_equal "hello", "hello".delete_prefix("llo")
+  assert_equal "llo", "hello".delete_prefix!("he")
+  assert_nil "hello".delete_prefix!("llo")
+end
+
+assert('String#delete_suffix') do
+  assert_equal "he", "hello".delete_suffix("llo")
+  assert_equal "hello", "hello".delete_suffix("he")
+  assert_equal "he", "hello".delete_suffix!("llo")
+  assert_nil "hello".delete_suffix!("he")
+end