* enc/unicode.c, test/ruby/enc/test_case_mapping.rb: Implemented :fold

  option for String#downcase by using case folding data from
  regular expression engine, and added a few simple tests.
  (with Kimihito Matsui)


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53747 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 39 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 61df2a6c4b..313e452a1f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sat Feb  6 14:37:16 2016  Martin Duerst  <duerst@it.aoyama.ac.jp>
+
+	* enc/unicode.c, test/ruby/enc/test_case_mapping.rb: Implemented :fold
+	  option for String#downcase by using case folding data from
+	  regular expression engine, and added a few simple tests.
+	  (with Kimihito Matsui)
+
 Fri Feb  5 20:08:59 2016  Martin Duerst  <duerst@it.aoyama.ac.jp>
 
 	* test/ruby/enc/test_case_mapping.rb: added tests for :ascii option.
diff --git a/enc/unicode.c b/enc/unicode.c
index 3f41ea3844..cb9b0a94b4 100644
--- a/enc/unicode.c
+++ b/enc/unicode.c
@@ -628,40 +628,61 @@ onigenc_unicode_case_map(OnigCaseFoldType* flagP,
 	if (code<='z') { /* ASCII comes first */
 	    if (code>='a' && code<='z') {
 	        if (flags&ONIGENC_CASE_UPCASE) {
+		    MODIFIED;
 		    if (flags&ONIGENC_CASE_FOLD_TURKISH_AZERI && code==0x0069) /* i -> I WITH DOT ABOVE */
 			code = 0x0130;
 		    else
 			code += 'A'-'a';
-		    MODIFIED;
 		}
 	    }
 	    else if (code>='A' && code<='Z') {
 		if (flags&ONIGENC_CASE_DOWNCASE) {
+		    MODIFIED;
 		    if (flags&ONIGENC_CASE_FOLD_TURKISH_AZERI && code==0x0049) /* I -> DOTLESS i */
 			code = 0x0131;
 		    else
 			code += 'a'-'A';
-		    MODIFIED;
 		}
 	    }
 	}
 	else if (!(flags&ONIGENC_CASE_ASCII_ONLY) && code>=0x00C0) { /* deal with non-ASCII; nothing relevant below U+00C0 */
+	    const CodePointList3 *folded;
+
 	    if (code==0x0130) {
 		if (flags&ONIGENC_CASE_DOWNCASE) {
+		    MODIFIED;
 		    if (flags&ONIGENC_CASE_FOLD_TURKISH_AZERI)
 			code = 0x0069; /* I WITH DOT ABOVE -> i */
 		    else { /* make dot above explicit */
 			to += ONIGENC_CODE_TO_MBC(enc, 0x0069, to);
 			code = 0x0307; /* dot above */
 		    }
-		    MODIFIED;
 		}
 	    }
-	    /* the following case can be removed once we rely on data,
+	    /* the following special case for  DOTLESS i -> I
+	     * can be removed once we rely on data,
 	     * because the mapping is always the same */
-	    else if (code==0x0131 && (flags&ONIGENC_CASE_UPCASE)) { /* DOTLESS i -> I */
+	    else if (code==0x0131 && (flags&ONIGENC_CASE_UPCASE)) {
 		code = 0x0049; MODIFIED;
 	    }
+	    else if ((folded = onigenc_unicode_fold_lookup(code)) != 0) {
+		if (flags&ONIGENC_CASE_FOLD) {
+		    const OnigCodePoint *next = folded->code;
+		    int count = OnigCodePointCount(folded->n);
+		    MODIFIED;
+		    if (count==1)
+		        code = *next;
+		    else if (count==2) {
+			to += ONIGENC_CODE_TO_MBC(enc, *next++, to);
+			code = *next;
+		    }
+		    else { /* count == 3 */
+			to += ONIGENC_CODE_TO_MBC(enc, *next++, to);
+			to += ONIGENC_CODE_TO_MBC(enc, *next++, to);
+			code = *next;
+		    }
+		}
+	    }
 	}
 	to += ONIGENC_CODE_TO_MBC(enc, code, to);
 	/* switch from titlecase to lowercase for capitalize */
diff --git a/test/ruby/enc/test_case_mapping.rb b/test/ruby/enc/test_case_mapping.rb
index 3ac647717d..2c712e448d 100644
--- a/test/ruby/enc/test_case_mapping.rb
+++ b/test/ruby/enc/test_case_mapping.rb
@@ -59,6 +59,12 @@ class TestCaseMappingPreliminary < Test::Unit::TestCase
     check_swapcase_properties   'rÉsumÉ dÜrst ĬÑŦĖŘŊÃŢIJŇŐŃÆŁĨŻÀŤĬŌŅ', 'RÉSUMÉ DÜRST ĬÑŦĖŘŊÃŢIJŇŐŃÆŁĨŻÀŤĬŌŅ', :ascii
   end
 
+  def test_fold_option
+    check_downcase_properties   'ss', 'ß', :fold
+    check_downcase_properties   'fifl', 'fifl', :fold
+    check_downcase_properties   'σ', 'ς', :fold
+  end
+
   def test_turcic
     check_downcase_properties   'yukihiro matsumoto (matz)', 'Yukihiro MATSUMOTO (MATZ)', :turkic
     check_upcase_properties     'YUKİHİRO MATSUMOTO (MATZ)', 'Yukihiro Matsumoto (matz)', :turkic