Update after review

expandSelector is now returning vector<string> directly
minor changes

src/Common/parseGlobs.cpp

@@ -122,17 +122,18 @@ std::string makeRegexpPatternFromGlobs(const std::string & initial_str_with_glob
     return buf_final_processing.str();
 }
 
-void expandSelector(const std::string & path, Strings & for_match_paths_expanded)
+namespace
 {
-    /// regexp for {expr1,expr2,expr3}, expr.. should be without "{", "}", "*" and ","
+void expandSelectorGlobImpl(const std::string & path, std::vector<std::string> & for_match_paths_expanded)
+{
+    /// regexp for {expr1,expr2,....};
+    /// expr1, expr2,... cannot contain any of these: '{', '}', ','
     static const re2::RE2 selector_regex(R"({([^{}*,]+,[^{}*]*[^{}*,])})");
 
     std::string_view path_view(path);
     std::string_view matched;
 
-    if (RE2::FindAndConsume(&path_view, selector_regex, &matched))
-        std::string buffer(matched);
-    else
+    if (!RE2::FindAndConsume(&path_view, selector_regex, &matched))
     {
         for_match_paths_expanded.push_back(path);
         return;
@@ -140,7 +141,7 @@ void expandSelector(const std::string & path, Strings & for_match_paths_expanded
 
     Strings expanded_paths;
 
-    std::vector<size_t> anchor_positions = {};
+    std::vector<size_t> anchor_positions;
     bool opened = false, closed = false;
 
     for (std::string::const_iterator it = path.begin(); it != path.end(); it++)
@@ -181,7 +182,15 @@ void expandSelector(const std::string & path, Strings & for_match_paths_expanded
         std::string expanded_matcher = common_prefix
                                        + path.substr(anchor_positions[i-1] + 1, (anchor_positions[i] - anchor_positions[i-1] - 1))
                                        + common_suffix;
-        expandSelector(expanded_matcher, for_match_paths_expanded);
+        expandSelectorGlobImpl(expanded_matcher, for_match_paths_expanded);
     }
 }
 }
+
+std::vector<std::string> expandSelectionGlob(const std::string & path)
+{
+    std::vector<std::string> result;
+    expandSelectorGlobImpl(path, result);
+    return result;
+}
+}

src/Common/parseGlobs.h

@@ -7,6 +7,8 @@ namespace DB
     /// Parse globs in string and make a regexp for it.
     std::string makeRegexpPatternFromGlobs(const std::string & initial_str_with_globs);
 
-    /// Process {a,b,c...} globs separately: don't match it against regex, but generate a,b,c strings instead.
-    void expandSelector(const std::string & path, std::vector<std::string> & for_match_paths_expanded);
+    /// Process {a,b,c...} globs:
+    /// Don't match it against regex, but generate a,b,c strings instead and process each of them separately.
+    /// E.g. for a string like `file{1,2,3}.csv` return vector of strings: {`file1.csv`,`file2.csv`,`file3.csv`}
+    std::vector<std::string> expandSelectionGlob(const std::string & path);
 }

src/Storages/HDFS/StorageHDFS.cpp

@@ -173,8 +173,7 @@ namespace
         HDFSBuilderWrapper builder = createHDFSBuilder(uri_without_path + "/", context->getGlobalContext()->getConfigRef());
         HDFSFSPtr fs = createHDFSFS(builder.get());
 
-        Strings paths;
-        expandSelector(path_from_uri, paths);
+        Strings paths = expandSelectionGlob(path_from_uri);
 
         std::vector<StorageHDFS::PathWithInfo> res;
 

src/Storages/StorageFile.cpp

@@ -196,8 +196,7 @@ std::vector<std::string> listFilesWithRegexpMatching(
 {
     std::vector<std::string> result;
 
-    Strings for_match_paths_expanded;
-    expandSelector(for_match, for_match_paths_expanded);
+    Strings for_match_paths_expanded = expandSelectionGlob(for_match);
 
     for (const auto & for_match_expanded : for_match_paths_expanded)
         listFilesWithRegexpMatchingImpl("/", for_match_expanded, total_bytes_to_read, result);