6 files changed, 218 insertions, 178 deletions
diff --git a/library/cpp/yt/string/format-inl.h b/library/cpp/yt/string/format-inl.h
index 188a699a3d..7f1f725966 100644
--- a/library/cpp/yt/string/format-inl.h
+++ b/library/cpp/yt/string/format-inl.h
@@ -38,110 +38,6 @@ namespace NYT {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-inline char* TStringBuilderBase::Preallocate(size_t size)
-{
-    Reserve(size + GetLength());
-    return Current_;
-}
-
-inline void TStringBuilderBase::Reserve(size_t size)
-{
-    if (Y_UNLIKELY(End_ - Begin_ < static_cast<ssize_t>(size))) {
-        size_t length = GetLength();
-        auto newLength = std::max(size, MinBufferLength);
-        DoReserve(newLength);
-        Current_ = Begin_ + length;
-    }
-}
-
-inline size_t TStringBuilderBase::GetLength() const
-{
-    return Current_ ? Current_ - Begin_ : 0;
-}
-
-inline TStringBuf TStringBuilderBase::GetBuffer() const
-{
-    return TStringBuf(Begin_, Current_);
-}
-
-inline void TStringBuilderBase::Advance(size_t size)
-{
-    Current_ += size;
-    YT_ASSERT(Current_ <= End_);
-}
-
-inline void TStringBuilderBase::AppendChar(char ch)
-{
-    *Preallocate(1) = ch;
-    Advance(1);
-}
-
-inline void TStringBuilderBase::AppendChar(char ch, int n)
-{
-    YT_ASSERT(n >= 0);
-    if (Y_LIKELY(0 != n)) {
-        char* dst = Preallocate(n);
-        ::memset(dst, ch, n);
-        Advance(n);
-    }
-}
-
-inline void TStringBuilderBase::AppendString(TStringBuf str)
-{
-    if (Y_LIKELY(str)) {
-        char* dst = Preallocate(str.length());
-        ::memcpy(dst, str.begin(), str.length());
-        Advance(str.length());
-    }
-}
-
-inline void TStringBuilderBase::AppendString(const char* str)
-{
-    AppendString(TStringBuf(str));
-}
-
-inline void TStringBuilderBase::Reset()
-{
-    Begin_ = Current_ = End_ = nullptr;
-    DoReset();
-}
-
-template <class... TArgs>
-void TStringBuilderBase::AppendFormat(TStringBuf format, TArgs&& ... args)
-{
-    Format(this, TRuntimeFormat{format}, std::forward<TArgs>(args)...);
-}
-
-template <size_t Length, class... TArgs>
-void TStringBuilderBase::AppendFormat(const char (&format)[Length], TArgs&& ... args)
-{
-    Format(this, TRuntimeFormat{format}, std::forward<TArgs>(args)...);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-
-inline TString TStringBuilder::Flush()
-{
-    Buffer_.resize(GetLength());
-    auto result = std::move(Buffer_);
-    Reset();
-    return result;
-}
-
-inline void TStringBuilder::DoReset()
-{
-    Buffer_ = {};
-}
-
-inline void TStringBuilder::DoReserve(size_t newLength)
-{
-    Buffer_.ReserveAndResize(newLength);
-    auto capacity = Buffer_.capacity();
-    Buffer_.ReserveAndResize(capacity);
-    Begin_ = &*Buffer_.begin();
-    End_ = Begin_ + capacity;
-}
-
 inline void FormatValue(TStringBuilderBase* builder, const TStringBuilder& value, TStringBuf /*spec*/)
 {
     builder->AppendString(value.GetBuffer());
diff --git a/library/cpp/yt/string/format.h b/library/cpp/yt/string/format.h
index a6ab1f76f4..5e5a76db9d 100644
--- a/library/cpp/yt/string/format.h
+++ b/library/cpp/yt/string/format.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "format_string.h"
+#include "string_builder.h"
 
 #include <util/generic/string.h>
 
@@ -61,65 +62,6 @@ TString Format(TFormatString<TArgs...> format, TArgs&&... args);
 
 ////////////////////////////////////////////////////////////////////////////////
 
-// StringBuilder(Base) definition.
-
-//! A simple helper for constructing strings by a sequence of appends.
-class TStringBuilderBase
-{
-public:
-    virtual ~TStringBuilderBase() = default;
-
-    char* Preallocate(size_t size);
-
-    void Reserve(size_t size);
-
-    size_t GetLength() const;
-
-    TStringBuf GetBuffer() const;
-
-    void Advance(size_t size);
-
-    void AppendChar(char ch);
-    void AppendChar(char ch, int n);
-
-    void AppendString(TStringBuf str);
-    void AppendString(const char* str);
-
-    template <size_t Length, class... TArgs>
-    void AppendFormat(const char (&format)[Length], TArgs&&... args);
-    template <class... TArgs>
-    void AppendFormat(TStringBuf format, TArgs&&... args);
-
-    void Reset();
-
-protected:
-    char* Begin_ = nullptr;
-    char* Current_ = nullptr;
-    char* End_ = nullptr;
-
-    virtual void DoReset() = 0;
-    virtual void DoReserve(size_t newLength) = 0;
-
-    static constexpr size_t MinBufferLength = 128;
-};
-
-////////////////////////////////////////////////////////////////////////////////
-
-class TStringBuilder
-    : public TStringBuilderBase
-{
-public:
-    TString Flush();
-
-protected:
-    TString Buffer_;
-
-    void DoReset() override;
-    void DoReserve(size_t size) override;
-};
-
-////////////////////////////////////////////////////////////////////////////////
-
 template <class... TArgs>
 void Format(TStringBuilderBase* builder, TFormatString<TArgs...> format, TArgs&&... args);
 
diff --git a/library/cpp/yt/string/string_builder-inl.h b/library/cpp/yt/string/string_builder-inl.h
new file mode 100644
index 0000000000..7027f9acc1
--- /dev/null
+++ b/library/cpp/yt/string/string_builder-inl.h
@@ -0,0 +1,121 @@
+#ifndef STRING_BUILDER_INL_H_
+#error "Direct inclusion of this file is not allowed, include string_builder.h"
+// For the sake of sane code completion.
+#include "string_builder.h"
+#endif
+
+#include "format_string.h"
+
+#include <library/cpp/yt/assert/assert.h>
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+inline char* TStringBuilderBase::Preallocate(size_t size)
+{
+    Reserve(size + GetLength());
+    return Current_;
+}
+
+inline void TStringBuilderBase::Reserve(size_t size)
+{
+    if (Y_UNLIKELY(End_ - Begin_ < static_cast<ssize_t>(size))) {
+        size_t length = GetLength();
+        auto newLength = std::max(size, MinBufferLength);
+        DoReserve(newLength);
+        Current_ = Begin_ + length;
+    }
+}
+
+inline size_t TStringBuilderBase::GetLength() const
+{
+    return Current_ ? Current_ - Begin_ : 0;
+}
+
+inline TStringBuf TStringBuilderBase::GetBuffer() const
+{
+    return TStringBuf(Begin_, Current_);
+}
+
+inline void TStringBuilderBase::Advance(size_t size)
+{
+    Current_ += size;
+    YT_ASSERT(Current_ <= End_);
+}
+
+inline void TStringBuilderBase::AppendChar(char ch)
+{
+    *Preallocate(1) = ch;
+    Advance(1);
+}
+
+inline void TStringBuilderBase::AppendChar(char ch, int n)
+{
+    YT_ASSERT(n >= 0);
+    if (Y_LIKELY(0 != n)) {
+        char* dst = Preallocate(n);
+        ::memset(dst, ch, n);
+        Advance(n);
+    }
+}
+
+inline void TStringBuilderBase::AppendString(TStringBuf str)
+{
+    if (Y_LIKELY(str)) {
+        char* dst = Preallocate(str.length());
+        ::memcpy(dst, str.begin(), str.length());
+        Advance(str.length());
+    }
+}
+
+inline void TStringBuilderBase::AppendString(const char* str)
+{
+    AppendString(TStringBuf(str));
+}
+
+inline void TStringBuilderBase::Reset()
+{
+    Begin_ = Current_ = End_ = nullptr;
+    DoReset();
+}
+
+template <class... TArgs>
+void TStringBuilderBase::AppendFormat(TStringBuf format, TArgs&& ... args)
+{
+    Format(this, TRuntimeFormat{format}, std::forward<TArgs>(args)...);
+}
+
+template <size_t Length, class... TArgs>
+void TStringBuilderBase::AppendFormat(const char (&format)[Length], TArgs&& ... args)
+{
+    Format(this, TRuntimeFormat{format}, std::forward<TArgs>(args)...);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+inline TString TStringBuilder::Flush()
+{
+    Buffer_.resize(GetLength());
+    auto result = std::move(Buffer_);
+    Reset();
+    return result;
+}
+
+inline void TStringBuilder::DoReset()
+{
+    Buffer_ = {};
+}
+
+inline void TStringBuilder::DoReserve(size_t newLength)
+{
+    Buffer_.ReserveAndResize(newLength);
+    auto capacity = Buffer_.capacity();
+    Buffer_.ReserveAndResize(capacity);
+    Begin_ = &*Buffer_.begin();
+    End_ = Begin_ + capacity;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
diff --git a/library/cpp/yt/string/string_builder.cpp b/library/cpp/yt/string/string_builder.cpp
new file mode 100644
index 0000000000..bca493fa32
--- /dev/null
+++ b/library/cpp/yt/string/string_builder.cpp
@@ -0,0 +1,30 @@
+#include "string_builder.h"
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+TDelimitedStringBuilderWrapper::TDelimitedStringBuilderWrapper(
+    TStringBuilderBase* builder,
+    TStringBuf delimiter)
+    : Builder_(builder)
+    , Delimiter_(delimiter)
+{ }
+
+TStringBuilderBase* TDelimitedStringBuilderWrapper::operator->()
+{
+    return operator&();
+}
+
+TStringBuilderBase* TDelimitedStringBuilderWrapper::operator&()
+{
+    if (!FirstCall_) {
+        Builder_->AppendString(Delimiter_);
+    }
+    FirstCall_ = false;
+    return Builder_;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
diff --git a/library/cpp/yt/string/string_builder.h b/library/cpp/yt/string/string_builder.h
index de1c1abb1e..ac3aa26a7c 100644
--- a/library/cpp/yt/string/string_builder.h
+++ b/library/cpp/yt/string/string_builder.h
@@ -1,13 +1,68 @@
 #pragma once
 
-#include "format.h"
-
 #include <util/generic/string.h>
 
 namespace NYT {
 
 ////////////////////////////////////////////////////////////////////////////////
 
+//! A simple helper for constructing strings by a sequence of appends.
+class TStringBuilderBase
+{
+public:
+    virtual ~TStringBuilderBase() = default;
+
+    char* Preallocate(size_t size);
+
+    void Reserve(size_t size);
+
+    size_t GetLength() const;
+
+    TStringBuf GetBuffer() const;
+
+    void Advance(size_t size);
+
+    void AppendChar(char ch);
+    void AppendChar(char ch, int n);
+
+    void AppendString(TStringBuf str);
+    void AppendString(const char* str);
+
+    template <size_t Length, class... TArgs>
+    void AppendFormat(const char (&format)[Length], TArgs&&... args);
+    template <class... TArgs>
+    void AppendFormat(TStringBuf format, TArgs&&... args);
+
+    void Reset();
+
+protected:
+    char* Begin_ = nullptr;
+    char* Current_ = nullptr;
+    char* End_ = nullptr;
+
+    virtual void DoReset() = 0;
+    virtual void DoReserve(size_t newLength) = 0;
+
+    static constexpr size_t MinBufferLength = 128;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+class TStringBuilder
+    : public TStringBuilderBase
+{
+public:
+    TString Flush();
+
+protected:
+    TString Buffer_;
+
+    void DoReset() override;
+    void DoReserve(size_t size) override;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
 //! Appends a certain delimiter starting from the second call.
 class TDelimitedStringBuilderWrapper
     : private TNonCopyable
@@ -15,19 +70,10 @@ class TDelimitedStringBuilderWrapper
 public:
     TDelimitedStringBuilderWrapper(
         TStringBuilderBase* builder,
-        TStringBuf delimiter = TStringBuf(", "))
-        : Builder_(builder)
-        , Delimiter_(delimiter)
-    { }
-
-    TStringBuilderBase* operator->()
-    {
-        if (!FirstCall_) {
-            Builder_->AppendString(Delimiter_);
-        }
-        FirstCall_ = false;
-        return Builder_;
-    }
+        TStringBuf delimiter = TStringBuf(", "));
+
+    TStringBuilderBase* operator->();
+    TStringBuilderBase* operator&();
 
 private:
     TStringBuilderBase* const Builder_;
@@ -39,3 +85,7 @@ private:
 ////////////////////////////////////////////////////////////////////////////////
 
 } // namespace NYT
+
+#define STRING_BUILDER_INL_H_
+#include "string_builder-inl.h"
+#undef STRING_BUILDER_INL_H_
diff --git a/library/cpp/yt/string/ya.make b/library/cpp/yt/string/ya.make
index db3a477b35..2071e0a115 100644
--- a/library/cpp/yt/string/ya.make
+++ b/library/cpp/yt/string/ya.make
@@ -8,6 +8,7 @@ SRCS(
     string.cpp
     format_string.cpp
     format.cpp
+    string_builder.cpp
 )
 
 PEERDIR(