Regex: Add support for `\K` that reset the start capture

1 files changed, 13 insertions, 0 deletions

diff --git a/src/regex_impl.cc b/src/regex_impl.cc
index 933af2ad..d3ca59d9 100644
--- a/src/regex_impl.cc
+++ b/src/regex_impl.cc
@@ -28,6 +28,7 @@ struct ParsedRegex
         NotWordBoundary,
         SubjectBegin,
         SubjectEnd,
+        ResetStart,
     };
 
     struct Quantifier
@@ -154,6 +155,7 @@ private:
                     case 'B': m_pos += 2; return new_node(ParsedRegex::NotWordBoundary);
                     case '`': m_pos += 2; return new_node(ParsedRegex::SubjectBegin);
                     case '\'': m_pos += 2; return new_node(ParsedRegex::SubjectEnd);
+                    case 'K': m_pos += 2; return new_node(ParsedRegex::ResetStart);
                 }
                 break;
             /* TODO: look ahead, look behind */
@@ -514,6 +516,10 @@ private:
             case ParsedRegex::SubjectEnd:
                 push_op(CompiledRegex::SubjectEnd);
                 break;
+            case ParsedRegex::ResetStart:
+                push_op(CompiledRegex::Save);
+                push_byte(0);
+                break;
         }
 
         for (auto& offset : goto_inner_end_offsets)
@@ -986,6 +992,13 @@ auto test_regex = UnitTest{[]{
         kak_assert(vm.exec("..."));
         kak_assert(not vm.exec("bla"));
     }
+
+    {
+        TestVM vm{R"(foo\Kbar)"};
+        kak_assert(vm.exec("foobar", true, true));
+        kak_assert(StringView{vm.m_captures[0], vm.m_captures[1]} == "bar");
+        kak_assert(not vm.exec("bar", true, true));
+    }
 }};
 
 }