1 files changed, 105 insertions, 0 deletions
diff --git a/klm/util/file_piece.hh b/klm/util/file_piece.hh
new file mode 100644
index 00000000..704f0ac6
--- /dev/null
+++ b/klm/util/file_piece.hh
@@ -0,0 +1,105 @@
+#ifndef UTIL_FILE_PIECE__
+#define UTIL_FILE_PIECE__
+
+#include "util/ersatz_progress.hh"
+#include "util/exception.hh"
+#include "util/mmap.hh"
+#include "util/scoped.hh"
+#include "util/string_piece.hh"
+
+#include <string>
+
+#include <cstddef>
+
+namespace util {
+
+class EndOfFileException : public Exception {
+  public:
+    EndOfFileException() throw();
+    ~EndOfFileException() throw();
+};
+
+class ParseNumberException : public Exception {
+  public:
+    explicit ParseNumberException(StringPiece value) throw();
+    ~ParseNumberException() throw() {}
+};
+
+int OpenReadOrThrow(const char *name);
+
+// Return value for SizeFile when it can't size properly.  
+const off_t kBadSize = -1;
+off_t SizeFile(int fd);
+
+class FilePiece {
+  public:
+    // 32 MB default.
+    explicit FilePiece(const char *file, std::ostream *show_progress = NULL, off_t min_buffer = 33554432);
+    // Takes ownership of fd.  name is used for messages.  
+    explicit FilePiece(const char *name, int fd, std::ostream *show_progress = NULL, off_t min_buffer = 33554432);
+     
+    char get() throw(EndOfFileException) { 
+      if (position_ == position_end_) Shift();
+      return *(position_++);
+    }
+
+    // Memory backing the returned StringPiece may vanish on the next call.  
+    // Leaves the delimiter, if any, to be returned by get().
+    StringPiece ReadDelimited() throw(EndOfFileException) {
+      SkipSpaces();
+      return Consume(FindDelimiterOrEOF());
+    }
+    // Unlike ReadDelimited, this includes leading spaces and consumes the delimiter.
+    // It is similar to getline in that way.  
+    StringPiece ReadLine(char delim = '\n') throw(EndOfFileException);
+
+    float ReadFloat() throw(EndOfFileException, ParseNumberException);
+
+    void SkipSpaces() throw (EndOfFileException);
+
+    off_t Offset() const {
+      return position_ - data_.begin() + mapped_offset_;
+    }
+
+    // Only for testing.  
+    void ForceFallbackToRead() {
+      fallback_to_read_ = true;
+    }
+    
+  private:
+    void Initialize(const char *name, std::ostream *show_progress, off_t min_buffer);
+
+    StringPiece Consume(const char *to) {
+      StringPiece ret(position_, to - position_);
+      position_ = to;
+      return ret;
+    }
+
+    const char *FindDelimiterOrEOF() throw(EndOfFileException);
+
+    void Shift() throw (EndOfFileException);
+    // Backends to Shift().
+    void MMapShift(off_t desired_begin) throw ();
+    void ReadShift(off_t desired_begin) throw ();
+
+    const char *position_, *last_space_, *position_end_;
+
+    scoped_fd file_;
+    const off_t total_size_;
+    const off_t page_;
+
+    size_t default_map_size_;
+    off_t mapped_offset_;
+
+    // Order matters: file_ should always be destroyed after this.
+    scoped_memory data_;
+
+    bool at_end_;
+    bool fallback_to_read_;
+
+    ErsatzProgress progress_;
+};
+
+} // namespace util
+
+#endif // UTIL_FILE_PIECE__