From d884099e0db8b4510847ec106b59ef7dca3c245b Mon Sep 17 00:00:00 2001
From: Kenneth Heafield <github@kheafield.com>
Date: Fri, 18 Jan 2013 17:12:51 +0000
Subject: KenLM dffafbf with lmplz source (but not built)

---
 klm/lm/filter/arpa_io.hh | 122 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 klm/lm/filter/arpa_io.hh

(limited to 'klm/lm/filter/arpa_io.hh')

diff --git a/klm/lm/filter/arpa_io.hh b/klm/lm/filter/arpa_io.hh
new file mode 100644
index 00000000..90f48447
--- /dev/null
+++ b/klm/lm/filter/arpa_io.hh
@@ -0,0 +1,122 @@
+#ifndef LM_FILTER_ARPA_IO__
+#define LM_FILTER_ARPA_IO__
+/* Input and output for ARPA format language model files.
+ */
+#include "lm/read_arpa.hh"
+#include "util/exception.hh"
+#include "util/string_piece.hh"
+#include "util/tokenize_piece.hh"
+
+#include <boost/noncopyable.hpp>
+#include <boost/scoped_array.hpp>
+
+#include <fstream>
+#include <string>
+#include <vector>
+
+#include <err.h>
+#include <string.h>
+
+namespace util { class FilePiece; }
+
+namespace lm {
+
+class ARPAInputException : public util::Exception {
+  public:
+    explicit ARPAInputException(const StringPiece &message) throw();
+    explicit ARPAInputException(const StringPiece &message, const StringPiece &line) throw();
+    virtual ~ARPAInputException() throw() {}
+
+    const char *what() const throw() { return what_.c_str(); }
+
+  private:
+    std::string what_;
+};
+
+class ARPAOutputException : public std::exception {
+  public:
+    ARPAOutputException(const char *prefix, const std::string &file_name) throw();
+    virtual ~ARPAOutputException() throw() {}
+
+    const char *what() const throw() { return what_.c_str(); }
+
+    const std::string &File() const throw() { return file_name_; }
+
+  private:
+    std::string what_;
+    const std::string file_name_;
+};
+
+// Handling for the counts of n-grams at the beginning of ARPA files.
+size_t SizeNeededForCounts(const std::vector<size_t> &number);
+
+/* Writes an ARPA file.  This has to be seekable so the counts can be written
+ * at the end.  Hence, I just have it own a std::fstream instead of accepting
+ * a separately held std::ostream.  
+ */
+class ARPAOutput : boost::noncopyable {
+  public:
+    explicit ARPAOutput(const char *name, size_t buffer_size = 65536);
+
+    void ReserveForCounts(std::streampos reserve);
+
+    void BeginLength(unsigned int length);
+
+    void AddNGram(const StringPiece &line) {
+      try {
+        file_ << line << '\n';
+      } catch (const std::ios_base::failure &f) {
+        throw ARPAOutputException("Writing an n-gram", file_name_);
+      }
+      ++fast_counter_;
+    }
+
+    void AddNGram(const StringPiece &ngram, const StringPiece &line) {
+      AddNGram(line);
+    }
+
+    template <class Iterator> void AddNGram(const Iterator &begin, const Iterator &end, const StringPiece &line) {
+      AddNGram(line);
+    }
+
+    void EndLength(unsigned int length);
+
+    void Finish();
+
+  private:
+    const std::string file_name_;
+    boost::scoped_array<char> buffer_;
+    std::fstream file_;
+    size_t fast_counter_;
+    std::vector<size_t> counts_;
+};
+
+
+template <class Output> void ReadNGrams(util::FilePiece &in, unsigned int length, size_t number, Output &out) {
+  ReadNGramHeader(in, length);
+  out.BeginLength(length);
+  for (size_t i = 0; i < number; ++i) {
+    StringPiece line = in.ReadLine();
+    util::TokenIter<util::SingleCharacter> tabber(line, '\t');
+    if (!tabber) throw ARPAInputException("blank line", line);
+    if (!++tabber) throw ARPAInputException("no tab", line);
+
+    out.AddNGram(*tabber, line);
+  }
+  out.EndLength(length);
+}
+
+template <class Output> void ReadARPA(util::FilePiece &in_lm, Output &out) {
+  std::vector<size_t> number;
+  ReadARPACounts(in_lm, number);
+  out.ReserveForCounts(SizeNeededForCounts(number));
+  for (unsigned int i = 0; i < number.size(); ++i) {
+    ReadNGrams(in_lm, i + 1, number[i], out);
+  }
+  ReadEnd(in_lm);
+  out.Finish();
+}
+
+} // namespace lm
+
+#endif // LM_FILTER_ARPA_IO__
-- 
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