1 files changed, 193 insertions, 0 deletions
diff --git a/klm/util/string_piece.cc b/klm/util/string_piece.cc
new file mode 100644
index 00000000..ec394b96
--- /dev/null
+++ b/klm/util/string_piece.cc
@@ -0,0 +1,193 @@
+// Copyright 2004 The RE2 Authors.  All Rights Reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in string_piece.hh.
+
+#include "util/string_piece.hh"
+
+#include <algorithm>
+
+#include <limits.h>
+
+#ifndef HAVE_ICU
+
+typedef StringPiece::size_type size_type;
+
+void StringPiece::CopyToString(std::string* target) const {
+  target->assign(ptr_, length_);
+}
+
+size_type StringPiece::find(const StringPiece& s, size_type pos) const {
+  // Not sure why length_ < 0 was here since it's std::size_t.
+  if (/*length_ < 0 || */pos > static_cast<size_type>(length_))
+    return npos;
+
+  const char* result = std::search(ptr_ + pos, ptr_ + length_,
+                                   s.ptr_, s.ptr_ + s.length_);
+  const size_type xpos = result - ptr_;
+  return xpos + s.length_ <= length_ ? xpos : npos;
+}
+
+size_type StringPiece::find(char c, size_type pos) const {
+  if (length_ <= 0 || pos >= static_cast<size_type>(length_)) {
+    return npos;
+  }
+  const char* result = std::find(ptr_ + pos, ptr_ + length_, c);
+  return result != ptr_ + length_ ? result - ptr_ : npos;
+}
+
+size_type StringPiece::rfind(const StringPiece& s, size_type pos) const {
+  if (length_ < s.length_) return npos;
+  const size_t ulen = length_;
+  if (s.length_ == 0) return std::min(ulen, pos);
+
+  const char* last = ptr_ + std::min(ulen - s.length_, pos) + s.length_;
+  const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
+  return result != last ? result - ptr_ : npos;
+}
+
+size_type StringPiece::rfind(char c, size_type pos) const {
+  if (length_ <= 0) return npos;
+  for (int i = std::min(pos, static_cast<size_type>(length_ - 1));
+       i >= 0; --i) {
+    if (ptr_[i] == c) {
+      return i;
+    }
+  }
+  return npos;
+}
+
+// For each character in characters_wanted, sets the index corresponding
+// to the ASCII code of that character to 1 in table.  This is used by
+// the find_.*_of methods below to tell whether or not a character is in
+// the lookup table in constant time.
+// The argument `table' must be an array that is large enough to hold all
+// the possible values of an unsigned char.  Thus it should be be declared
+// as follows:
+//   bool table[UCHAR_MAX + 1]
+static inline void BuildLookupTable(const StringPiece& characters_wanted,
+                                    bool* table) {
+  const size_type length = characters_wanted.length();
+  const char* const data = characters_wanted.data();
+  for (size_type i = 0; i < length; ++i) {
+    table[static_cast<unsigned char>(data[i])] = true;
+  }
+}
+
+size_type StringPiece::find_first_of(const StringPiece& s,
+                                     size_type pos) const {
+  if (length_ == 0 || s.length_ == 0)
+    return npos;
+
+  // Avoid the cost of BuildLookupTable() for a single-character search.
+  if (s.length_ == 1)
+    return find_first_of(s.ptr_[0], pos);
+
+  bool lookup[UCHAR_MAX + 1] = { false };
+  BuildLookupTable(s, lookup);
+  for (size_type i = pos; i < length_; ++i) {
+    if (lookup[static_cast<unsigned char>(ptr_[i])]) {
+      return i;
+    }
+  }
+  return npos;
+}
+
+size_type StringPiece::find_first_not_of(const StringPiece& s,
+                                         size_type pos) const {
+  if (length_ == 0)
+    return npos;
+
+  if (s.length_ == 0)
+    return 0;
+
+  // Avoid the cost of BuildLookupTable() for a single-character search.
+  if (s.length_ == 1)
+    return find_first_not_of(s.ptr_[0], pos);
+
+  bool lookup[UCHAR_MAX + 1] = { false };
+  BuildLookupTable(s, lookup);
+  for (size_type i = pos; i < length_; ++i) {
+    if (!lookup[static_cast<unsigned char>(ptr_[i])]) {
+      return i;
+    }
+  }
+  return npos;
+}
+
+size_type StringPiece::find_first_not_of(char c, size_type pos) const {
+  if (length_ == 0)
+    return npos;
+
+  for (; pos < length_; ++pos) {
+    if (ptr_[pos] != c) {
+      return pos;
+    }
+  }
+  return npos;
+}
+
+size_type StringPiece::find_last_of(const StringPiece& s, size_type pos) const {
+  if (length_ == 0 || s.length_ == 0)
+    return npos;
+
+  // Avoid the cost of BuildLookupTable() for a single-character search.
+  if (s.length_ == 1)
+    return find_last_of(s.ptr_[0], pos);
+
+  bool lookup[UCHAR_MAX + 1] = { false };
+  BuildLookupTable(s, lookup);
+  for (size_type i = std::min(pos, length_ - 1); ; --i) {
+    if (lookup[static_cast<unsigned char>(ptr_[i])])
+      return i;
+    if (i == 0)
+      break;
+  }
+  return npos;
+}
+
+size_type StringPiece::find_last_not_of(const StringPiece& s,
+                                        size_type pos) const {
+  if (length_ == 0)
+    return npos;
+
+  size_type i = std::min(pos, length_ - 1);
+  if (s.length_ == 0)
+    return i;
+
+  // Avoid the cost of BuildLookupTable() for a single-character search.
+  if (s.length_ == 1)
+    return find_last_not_of(s.ptr_[0], pos);
+
+  bool lookup[UCHAR_MAX + 1] = { false };
+  BuildLookupTable(s, lookup);
+  for (; ; --i) {
+    if (!lookup[static_cast<unsigned char>(ptr_[i])])
+      return i;
+    if (i == 0)
+      break;
+  }
+  return npos;
+}
+
+size_type StringPiece::find_last_not_of(char c, size_type pos) const {
+  if (length_ == 0)
+    return npos;
+
+  for (size_type i = std::min(pos, length_ - 1); ; --i) {
+    if (ptr_[i] != c)
+      return i;
+    if (i == 0)
+      break;
+  }
+  return npos;
+}
+
+StringPiece StringPiece::substr(size_type pos, size_type n) const {
+  if (pos > length_) pos = length_;
+  if (n > length_ - pos) n = length_ - pos;
+  return StringPiece(ptr_ + pos, n);
+}
+
+const size_type StringPiece::npos = size_type(-1);
+
+#endif // !HAVE_ICU