[ruby/strscan] Fix a bug that scan_until behaves differently with

Regexp and String patterns
(ruby/strscan#138)

Fix ruby/strscan#131

ruby/strscan@e1cec2e726

Author: naitoh

ext/strscan/strscan.c

@@ -571,19 +571,20 @@ match_target(struct strscanner *p)
 }
 
 static inline void
-set_registers(struct strscanner *p, size_t length)
+set_registers(struct strscanner *p, size_t pos, size_t length)
 {
     const int at = 0;
     OnigRegion *regs = &(p->regs);
     onig_region_clear(regs);
     if (onig_region_set(regs, at, 0, 0)) return;
     if (p->fixed_anchor_p) {
-        regs->beg[at] = p->curr;
-        regs->end[at] = p->curr + length;
+        regs->beg[at] = pos + p->curr;
+        regs->end[at] = pos + p->curr + length;
     }
     else
     {
-        regs->end[at] = length;
+        regs->beg[at] = pos;
+        regs->end[at] = pos + length;
     }
 }
 
@@ -731,7 +732,7 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly
             if (memcmp(CURPTR(p), RSTRING_PTR(pattern), RSTRING_LEN(pattern)) != 0) {
                 return Qnil;
             }
-            set_registers(p, RSTRING_LEN(pattern));
+            set_registers(p, 0, RSTRING_LEN(pattern));
         }
         else {
             rb_encoding *enc = rb_enc_check(p->str, pattern);
@@ -740,7 +741,7 @@ strscan_do_scan(VALUE self, VALUE pattern, int succptr, int getstr, int headonly
             if (pos == -1) {
                 return Qnil;
             }
-            set_registers(p, RSTRING_LEN(pattern) + pos);
+            set_registers(p, pos, RSTRING_LEN(pattern));
         }
     }
 

test/strscan/test_stringscanner.rb

@@ -409,12 +409,8 @@ def test_matched
     s = create_string_scanner('stra strb strc')
     s.scan(/\w+/)
     assert_equal('stra', s.matched)
-    s.scan(/\s+/)
-    assert_equal(' ', s.matched)
-    s.scan('st')
-    assert_equal('st', s.matched)
-    s.scan(/\w+/)
-    assert_equal('rb', s.matched)
+    s.scan_until(/\w+/)
+    assert_equal('strb', s.matched)
     s.scan(/\s+/)
     assert_equal(' ', s.matched)
     s.scan(/\w+/)
@@ -432,6 +428,23 @@ def test_matched
     assert_equal('t', s.matched)
   end
 
+  def test_matched_string
+    omit("not implemented on TruffleRuby") if RUBY_ENGINE == "truffleruby"
+    s = create_string_scanner('stra strb strc')
+    s.scan('stra')
+    assert_equal('stra', s.matched)
+    s.scan_until('strb')
+    assert_equal('strb', s.matched)
+    s.scan(' ')
+    assert_equal(' ', s.matched)
+    s.scan('strc')
+    assert_equal('strc', s.matched)
+    s.scan('c')
+    assert_nil(s.matched)
+    s.getch
+    assert_nil(s.matched)
+  end
+
   def test_AREF
     s = create_string_scanner('stra strb strc')
 
@@ -522,6 +535,27 @@ def test_pre_match
     assert_nil(s.pre_match)
   end
 
+  def test_pre_match_string
+    omit("not implemented on TruffleRuby") if RUBY_ENGINE == "truffleruby"
+    s = create_string_scanner('a b c d e')
+    s.scan('a')
+    assert_equal('', s.pre_match)
+    s.skip(' ')
+    assert_equal('a', s.pre_match)
+    s.scan('b')
+    assert_equal('a ', s.pre_match)
+    s.scan_until('c')
+    assert_equal('a b ', s.pre_match)
+    s.getch
+    assert_equal('a b c', s.pre_match)
+    s.get_byte
+    assert_equal('a b c ', s.pre_match)
+    s.get_byte
+    assert_equal('a b c d', s.pre_match)
+    s.scan('never match')
+    assert_nil(s.pre_match)
+  end
+
   def test_post_match
     s = create_string_scanner('a b c d e')
     s.scan(/\w/)
@@ -546,6 +580,27 @@ def test_post_match
     assert_nil(s.post_match)
   end
 
+  def test_post_match_string
+    omit("not implemented on TruffleRuby") if RUBY_ENGINE == "truffleruby"
+    s = create_string_scanner('a b c d e')
+    s.scan('a')
+    assert_equal(' b c d e', s.post_match)
+    s.skip(' ')
+    assert_equal('b c d e', s.post_match)
+    s.scan('b')
+    assert_equal(' c d e', s.post_match)
+    s.scan_until('c')
+    assert_equal(' d e', s.post_match)
+    s.getch
+    assert_equal('d e', s.post_match)
+    s.get_byte
+    assert_equal(' e', s.post_match)
+    s.get_byte
+    assert_equal('e', s.post_match)
+    s.scan('never match')
+    assert_nil(s.post_match)
+  end
+
   def test_terminate
     s = create_string_scanner('ssss')
     s.getch