gistfile1.diff

diff --git a/re.cpp b/re.cpp
index dc7fbe7..3d800fe 100644
--- a/re.cpp
+++ b/re.cpp
@@ -9,6 +9,7 @@
 
 #include "unicode/regex.h"
 #include "unicode/unistr.h"
+#include "unicode/schriter.h"
 #include "ruby/ruby.h"
 #include "encoding.h"
 #include "objc.h"
@@ -108,7 +109,7 @@ str_to_unistr(VALUE str)
 }
 
 static void
-sanitize_regexp_string(UnicodeString *unistr)
+sanitize_regexp_string(UnicodeString *unistr, int option)
 {
     // ICU does not support [[:word::], so we need to replace all
     // occurences by \w.
@@ -120,6 +121,58 @@ sanitize_regexp_string(UnicodeString *unistr)
     while ((pos = unistr->indexOf(word_str)) >= 0) {
 	unistr->replace(pos, 10, repl_str);
     }
+
+    // ICU treats '#' as the start of a comment, even inside of '[]',
+    // so we need to escape the '#'
+    if (option & REGEXP_OPT_EXTENDED) {
+        StringCharacterIterator iter(*unistr);
+        UChar curr_char = iter.first();
+        int32_t brackets = 0, braces = 0, parens = 0;
+        do {
+            switch (curr_char) {
+                case '[':
+                    if (unistr->charAt(iter.getIndex() - 1) != '\\') {
+                        brackets++;
+                    }
+                    break;
+                case ']':
+                    if ((brackets > 0) && (unistr->charAt(iter.getIndex() - 1) != '\\')) {
+                        brackets--;
+                    }
+                    break;
+                case '{':
+                    if (unistr->charAt(iter.getIndex() - 1) != '\\') {
+                        braces++;
+                    }
+                    break;
+                case '}':
+                    if ((braces > 0) && (unistr->charAt(iter.getIndex() - 1) != '\\')) {
+                        braces--;
+                    }
+                    break;
+                case '(':
+                    if (unistr->charAt(iter.getIndex() - 1) != '\\') {
+                        parens++;
+                    }
+                    break;
+                case ')':
+                    if ((parens > 0) && (unistr->charAt(iter.getIndex() - 1) != '\\')) {
+                        parens--;
+                    }
+                    break;
+                case '#':
+                    if (((brackets > 0) || (braces > 0) || (parens > 0))
+                        && (unistr->charAt(iter.getIndex() - 1) != '?')
+                        && (unistr->charAt(iter.getIndex() - 1) != '\\')) {
+                        pos = iter.getIndex();
+                        unistr->insert(pos, '\\');
+                        iter.setText(*unistr);
+                        iter.setIndex(pos + 1);
+                    }
+            };
+            curr_char = iter.next();
+        } while (iter.hasNext());
+    }
 }
 
 static bool
@@ -130,7 +183,7 @@ init_from_string(rb_regexp_t *regexp, VALUE str, int option, VALUE *excp)
     UnicodeString *unistr = str_to_unistr(str);
     assert(unistr != NULL);
 
-    sanitize_regexp_string(unistr);
+    sanitize_regexp_string(unistr, option);
 
     UParseError pe;
     UErrorCode status = U_ZERO_ERROR;