Remove all blimp network code.

blimp/net/delta_encoding.h

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BLIMP_NET_DELTA_ENCODING_H_
-#define BLIMP_NET_DELTA_ENCODING_H_
-
-#include <algorithm>
-#include <functional>
-#include <utility>
-
-// This file contains utility functions to concisely compute and apply
-// delta encodings of arbitrarily-typed sequences of values. Delta-encoded
-// numeric values tend to be smaller in magnitude than their source values
-// which, when combined with variable integer encoding (a la protobuf), results
-// in a smaller wire size.
-//
-// e.g. DeltaEncode([4, 1, 5]) => [4, -3, 4]
-//      DeltaDecode([4, -3, 4]) => [4, 1, 5]
-//
-// If ordering doesn't matter, then the function SortAndDeltaEncode()
-// can be used to compute a delta encoding with the smallest possible values.
-//
-// e.g. SortAndDeltaEncode([4, 1, 5]) => [1, 3, 1]
-//      DeltaDecode([1, 3, 1]) => [1, 4, 5]
-//
-// Delta encodings can also be computed for structured or non-numeric data
-// types as well, so long as functions are provided for differencing and
-// reconstituting the data. This can also be applied to delta encode or elide
-// across fields of a struct, for example.
-
-namespace blimp {
-
-// Homogeneously-typed signature for functions that compute and apply deltas.
-template <typename T>
-using BinaryFunction = T (*)(const T&, const T&);
-
-// Uses the subtraction operator to compute the delta across two values.
-template <typename T>
-inline T default_compute_delta(const T& lhs, const T& rhs) {
-  return lhs - rhs;
-}
-
-// Uses the addition operator to add a delta value to a base value.
-template <typename T>
-inline T default_apply_delta(const T& lhs, const T& rhs) {
-  return lhs + rhs;
-}
-
-// Uses the less-than (<) operator to determine if |lhs| is less-than |rhs|.
-template <typename T>
-inline bool lessthan(const T& lhs, const T& rhs) {
-  return lhs < rhs;
-}
-
-// Delta-encodes a iterated sequence of values in-place.
-// |begin|: An iterator pointing to the beginning of the sequence.
-// |end|: An iterator pointing to the end of the sequence.
-// |default_compute_delta_fn|: Optional function which computes the delta
-// between
-// every element and its next successor.
-template <typename I>
-void DeltaEncode(I begin,
-                 I end,
-                 BinaryFunction<typename std::iterator_traits<I>::value_type>
-                     default_compute_delta_fn = &default_compute_delta) {
-  if (begin == end) {
-    return;
-  }
-
-  I current = begin;
-  typename std::iterator_traits<I>::value_type value = *current;
-  ++current;
-  for (; current != end; ++current) {
-    value = (*default_compute_delta_fn)(*current, value);
-
-    // Put the delta in place and store the actual value into |value|, ready for
-    // the next iteration.
-    std::swap(*current, value);
-  }
-}
-
-// Delta-decodes a iterated sequence of values in-place.
-// |begin|: An iterator pointing to the beginning of the sequence.
-// |end|: An iterator pointing to the end of the sequence.
-// |apply_fn|: Optional binary function which combines the value of
-// every element with that of its immediate predecessor.
-template <typename I>
-void DeltaDecode(I begin,
-                 I end,
-                 BinaryFunction<typename std::iterator_traits<I>::value_type>
-                     apply_fn = &default_apply_delta) {
-  if (begin == end) {
-    return;
-  }
-
-  I current = begin;
-  typename std::iterator_traits<I>::value_type previous_value = *current;
-  ++current;
-  for (; current != end; ++current) {
-    *current = apply_fn(previous_value, *current);
-    previous_value = *current;
-  }
-}
-
-// Convenience function for sorting and delta-encoding a sequence of values.
-// The value type must support std::sort(), either by natively supporting
-// inequality comparison or with custom comparison function |comparison_fn|.
-template <typename I>
-inline void SortAndDeltaEncode(
-    I begin,
-    I end,
-    BinaryFunction<typename std::iterator_traits<I>::value_type>
-        default_compute_delta_fn = &default_compute_delta,
-    bool (*comparison_fn)(const typename std::iterator_traits<I>::value_type&,
-                          const typename std::iterator_traits<I>::value_type&) =
-        lessthan<typename std::iterator_traits<I>::value_type>) {
-  std::sort(begin, end, comparison_fn);
-  DeltaEncode(begin, end, default_compute_delta_fn);
-}
-
-}  // namespace blimp
-
-#endif  // BLIMP_NET_DELTA_ENCODING_H_