intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 109 insertions, 0 deletions

diff --git a/util/folder/iterator.h b/util/folder/iterator.h
new file mode 100644
index 0000000000..69e025b9c4
--- /dev/null
+++ b/util/folder/iterator.h
@@ -0,0 +1,109 @@
+#pragma once
+
+#include "fts.h"
+
+#include <util/system/error.h>
+#include <util/generic/ptr.h>
+#include <util/generic/iterator.h>
+#include <util/generic/yexception.h>
+
+/// Note this magic API traverses directory hierarchy
+
+class TDirIterator: public TInputRangeAdaptor<TDirIterator> {
+    struct TFtsDestroy {
+        static inline void Destroy(FTS* f) noexcept {
+            yfts_close(f);
+        }
+    };
+
+public:
+    class TError: public TSystemError {
+    public:
+        inline TError(int err)
+            : TSystemError(err)
+        {
+        }
+    };
+
+    using TCompare = int (*)(const FTSENT**, const FTSENT**);
+
+    struct TOptions {
+        inline TOptions() {
+            Init(FTS_PHYSICAL);
+        }
+
+        inline TOptions(int opts) {
+            Init(opts);
+        }
+
+        inline TOptions& SetMaxLevel(size_t level) noexcept {
+            MaxLevel = level;
+
+            return *this;
+        }
+
+        inline TOptions& SetSortFunctor(TCompare cmp) noexcept {
+            Cmp = cmp;
+
+            return *this;
+        }
+
+        TOptions& SetSortByName() noexcept;
+
+        int FtsOptions;
+        size_t MaxLevel;
+        TCompare Cmp;
+
+    private:
+        inline void Init(int opts) noexcept {
+            FtsOptions = opts | FTS_NOCHDIR;
+            MaxLevel = Max<size_t>();
+            Cmp = nullptr;
+        }
+    };
+
+    inline TDirIterator(const TString& path, const TOptions& options = TOptions())
+        : Options_(options)
+        , Path_(path)
+    {
+        Trees_[0] = Path_.begin();
+        Trees_[1] = nullptr;
+
+        ClearLastSystemError();
+        FileTree_.Reset(yfts_open(Trees_, Options_.FtsOptions, Options_.Cmp));
+
+        const int err = LastSystemError();
+
+        if (err) {
+            ythrow TError(err) << "can not open '" << Path_ << "'";
+        }
+    }
+
+    inline FTSENT* Next() {
+        FTSENT* ret = yfts_read(FileTree_.Get());
+
+        if (ret) {
+            if ((size_t)(ret->fts_level + 1) > Options_.MaxLevel) {
+                yfts_set(FileTree_.Get(), ret, FTS_SKIP);
+            }
+        } else {
+            const int err = LastSystemError();
+
+            if (err) {
+                ythrow TError(err) << "error while iterating " << Path_;
+            }
+        }
+
+        return ret;
+    }
+
+    inline void Skip(FTSENT* ent) {
+        yfts_set(FileTree_.Get(), ent, FTS_SKIP);
+    }
+
+private:
+    TOptions Options_;
+    TString Path_;
+    char* Trees_[2];
+    THolder<FTS, TFtsDestroy> FileTree_;
+};