[wpiutil] Improve wpi::circular_buffer iterators (#3410)

The implementation of wpi::circular_buffer has been effectively replaced
with a dynamically sized copy of wpi::static_circular_buffer with a
resize() member function.

wpiutil/src/main/native/include/wpi/circular_buffer.inc

@@ -4,134 +4,10 @@
 
 #pragma once
 
-#include <algorithm>
-
 #include "wpi/circular_buffer.h"
 
 namespace wpi {
 
-template <class T>
-circular_buffer<T>::circular_buffer(size_t size) : m_data(size, T{}) {}
-
-/**
- * Returns number of elements in buffer
- */
-template <class T>
-typename circular_buffer<T>::size_type circular_buffer<T>::size() const {
-  return m_length;
-}
-
-/**
- * Returns value at front of buffer
- */
-template <class T>
-T& circular_buffer<T>::front() {
-  return (*this)[0];
-}
-
-/**
- * Returns value at front of buffer
- */
-template <class T>
-const T& circular_buffer<T>::front() const {
-  return (*this)[0];
-}
-
-/**
- * Returns value at back of buffer
- */
-template <class T>
-T& circular_buffer<T>::back() {
-  // If there are no elements in the buffer, do nothing
-  if (m_length == 0) {
-    return zero_val;
-  }
-
-  return m_data[(m_front + m_length - 1) % m_data.size()];
-}
-
-/**
- * Returns value at back of buffer
- */
-template <class T>
-const T& circular_buffer<T>::back() const {
-  // If there are no elements in the buffer, do nothing
-  if (m_length == 0) {
-    return zero_val;
-  }
-
-  return m_data[(m_front + m_length - 1) % m_data.size()];
-}
-
-/**
- * Push new value onto front of the buffer. The value at the back is overwritten
- * if the buffer is full.
- */
-template <class T>
-void circular_buffer<T>::push_front(T value) {
-  if (m_data.size() == 0) {
-    return;
-  }
-
-  m_front = ModuloDec(m_front);
-
-  m_data[m_front] = value;
-
-  if (m_length < m_data.size()) {
-    m_length++;
-  }
-}
-
-/**
- * Push new value onto back of the buffer. The value at the front is overwritten
- * if the buffer is full.
- */
-template <class T>
-void circular_buffer<T>::push_back(T value) {
-  if (m_data.size() == 0) {
-    return;
-  }
-
-  m_data[(m_front + m_length) % m_data.size()] = value;
-
-  if (m_length < m_data.size()) {
-    m_length++;
-  } else {
-    // Increment front if buffer is full to maintain size
-    m_front = ModuloInc(m_front);
-  }
-}
-
-/**
- * Pop value at front of buffer.
- */
-template <class T>
-T circular_buffer<T>::pop_front() {
-  // If there are no elements in the buffer, do nothing
-  if (m_length == 0) {
-    return T{0};
-  }
-
-  T& temp = m_data[m_front];
-  m_front = ModuloInc(m_front);
-  m_length--;
-  return temp;
-}
-
-/**
- * Pop value at back of buffer.
- */
-template <class T>
-T circular_buffer<T>::pop_back() {
-  // If there are no elements in the buffer, do nothing
-  if (m_length == 0) {
-    return T{0};
-  }
-
-  m_length--;
-  return m_data[(m_front + m_length) % m_data.size()];
-}
-
 /**
  * Resizes internal buffer to given size.
  */
@@ -185,54 +61,4 @@ void circular_buffer<T>::resize(size_t size) {
   }
 }
 
-/**
- * Sets internal buffer contents to zero.
- */
-template <class T>
-void circular_buffer<T>::reset() {
-  std::fill(m_data.begin(), m_data.end(), T{0});
-  m_front = 0;
-  m_length = 0;
-}
-
-/**
- * @return Element at index starting from front of buffer.
- */
-template <class T>
-T& circular_buffer<T>::operator[](size_t index) {
-  return m_data[(m_front + index) % m_data.size()];
-}
-
-/**
- * @return Element at index starting from front of buffer.
- */
-template <class T>
-const T& circular_buffer<T>::operator[](size_t index) const {
-  return m_data[(m_front + index) % m_data.size()];
-}
-
-/**
- * Increment an index modulo the length of the buffer.
- *
- * @return The result of the modulo operation.
- */
-template <class T>
-size_t circular_buffer<T>::ModuloInc(size_t index) {
-  return (index + 1) % m_data.size();
-}
-
-/**
- * Decrement an index modulo the length of the buffer.
- *
- * @return The result of the modulo operation.
- */
-template <class T>
-size_t circular_buffer<T>::ModuloDec(size_t index) {
-  if (index == 0) {
-    return m_data.size() - 1;
-  } else {
-    return index - 1;
-  }
-}
-
 }  // namespace wpi