From 1bc5bc0b106f658a64519607dc11b03cf04e93eb Mon Sep 17 00:00:00 2001
From: Kyle Isom <kyle@imap.cc>
Date: Mon, 9 Oct 2023 10:24:40 -0700
Subject: [PATCH] Move Buffer from kge.

---
 Buffer.cc      | 180 +++++++++++++++++++++++++++++++++++++++++++++++++
 Buffer.h       |  48 +++++++++++++
 CMakeLists.txt |   4 ++
 bufferTest.cc  |  16 +++++
 4 files changed, 248 insertions(+)
 create mode 100644 Buffer.cc
 create mode 100644 Buffer.h
 create mode 100644 bufferTest.cc

diff --git a/Buffer.cc b/Buffer.cc
new file mode 100644
index 0000000..37d43cd
--- /dev/null
+++ b/Buffer.cc
@@ -0,0 +1,180 @@
+//
+// Created by kyle on 2023-10-09.
+//
+
+#include <cassert>
+#include <cstring>
+#include "Buffer.h"
+
+namespace klib {
+
+
+constexpr size_t	defaultCapacity = 32;
+constexpr size_t	maxReasonableLine = 8192;
+
+
+static size_t
+nearestPower(size_t x)
+{
+	if (x == 0) {
+		return 0;
+	}
+
+	x--;
+
+	x |= x >> 1;
+	x |= x >> 2;
+	x |= x >> 4;
+	x |= x >> 8;
+	x |= x >> 16;
+	x |= x >> 32;
+
+	return x;
+}
+
+
+Buffer::Buffer()
+    : contents(nullptr), length(0), capacity(0)
+{
+	this->Resize(defaultCapacity);			
+}
+
+
+Buffer::Buffer(size_t initialCapacity)
+    : contents(nullptr), length(0), capacity(0)
+{
+	this->Resize(initialCapacity);			
+}
+
+
+Buffer::Buffer(const char *data)
+    : contents(nullptr), length(0), capacity(0)
+{
+	size_t	datalen = strnlen(data, maxReasonableLine);
+
+	this->Append((uint8_t *)data, datalen);
+}
+
+
+bool
+Buffer::Append(uint8_t *data, size_t datalen)
+{
+	auto	resized = false;
+	auto	newCap = this->mustGrow(datalen);
+
+	if (newCap > 0) {
+		this->Resize(newCap);
+		resized = true;
+	}
+
+	memcpy(this->contents + this->length, data, datalen);
+	this->length += datalen;
+	return resized;
+}
+
+bool
+Buffer::Append(uint8_t c)
+{
+	return this->Append(&c, 1);
+}
+
+bool
+Buffer::Insert(size_t index, uint8_t *data, size_t datalen)
+{
+	auto	resized = this->shift(index, datalen);
+
+	memcpy(this->contents + index, data, datalen);
+	return resized;
+}
+
+bool
+Buffer::Insert(size_t index, uint8_t c)
+{
+	return this->Insert(index, &c, 1);
+}
+
+
+void
+Buffer::Resize(size_t newCapacity)
+{
+	if (newCapacity < this->length) {
+		return;
+	}
+
+	uint8_t *newContents = new uint8_t[newCapacity];
+
+	if (this->length > 0) {
+		memcpy(newContents, this->contents, this->length);
+	}
+
+	if (this->contents != nullptr) {
+		delete this->contents;
+	}
+
+	this->contents = newContents;
+	this->capacity = newCapacity;
+}
+
+size_t
+Buffer::Trim()
+{
+	size_t	projectedCapacity = nearestPower(this->length);
+
+	assert(projectedCapacity >= length);
+
+	if (projectedCapacity < this->capacity) {
+		this->Resize(projectedCapacity);
+		return this->Capacity();
+	}
+
+	return 0;
+}
+
+void
+Buffer::Clear()
+{
+	memset(this->contents, 0, this->length);
+	this->length = 0;
+}
+
+void
+Buffer::Reclaim()
+{
+	delete this->contents;
+	this->length = 0;
+	this->capacity = 0;
+}
+
+size_t
+Buffer::mustGrow(size_t delta)
+{
+	if ((delta + this->length) < this->capacity) {
+		return 0;
+	}
+
+	auto newCapacity = delta + this->length;
+	return nearestPower(newCapacity);
+}
+
+
+bool
+Buffer::shift(size_t offset, size_t delta)
+{
+	auto	resized = false;
+	auto	newCap = this->mustGrow(delta);
+
+	if (newCap > 0) {
+		this->Resize(newCap);
+		resized = true;
+	}
+
+	
+	for (size_t i = this->length; i >= offset; i++) {
+		this->contents[i+delta] = this->contents[i];
+	}
+
+	return resized;
+}
+
+
+} // namespace klib
diff --git a/Buffer.h b/Buffer.h
new file mode 100644
index 0000000..df379f9
--- /dev/null
+++ b/Buffer.h
@@ -0,0 +1,48 @@
+//
+// Created by kyle on 2023-10-09.
+//
+
+#ifndef KGE_BUFFER_H
+#define KGE_BUFFER_H
+
+#include <cstdint>
+
+
+namespace klib {
+
+
+class Buffer {
+public:
+	Buffer();
+	Buffer(size_t);
+	Buffer(const char *);
+
+	uint8_t	*Contents() { return this->contents; }
+	size_t	 Size() { return this->length; };
+	size_t	 Capacity() { return this->capacity; }
+
+	bool	 Append(uint8_t *data, size_t datalen);
+	bool	 Append(uint8_t c);
+	bool	 Insert(size_t index, uint8_t *data, size_t datalen);
+	bool	 Insert(size_t index, uint8_t c);
+
+	// bool	 Remove(size_t index, size_t length);
+
+	/* memory management */
+	void	 Resize(size_t newCapacity);
+	size_t	 Trim();
+	void	 Clear();
+	void	 Reclaim();
+
+private:
+	size_t	 mustGrow(size_t delta);
+	bool	 shift(size_t offset, size_t delta);
+
+	uint8_t	*contents;
+	size_t	 length;
+	size_t	 capacity;
+};
+
+} // namespace klib
+
+#endif //KGE_BUFFER_H
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 412b972..aea49dc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,6 +16,7 @@ add_compile_options("-DDESKTOP_BUILD")
 
 add_library(klib STATIC
 	Arena.cc
+	Buffer.cc
 	TLV.cc
 	Dictionary.cc)
 
@@ -25,3 +26,6 @@ target_link_libraries(tlv_test klib)
 add_executable(dictionary_test dictionaryTest.cc)
 target_link_libraries(dictionary_test klib)
 
+add_executable(buffer_test bufferTest.cc)
+target_link_libraries(buffer_test klib)
+
diff --git a/bufferTest.cc b/bufferTest.cc
new file mode 100644
index 0000000..e075b94
--- /dev/null
+++ b/bufferTest.cc
@@ -0,0 +1,16 @@
+#include <iostream>
+
+#include "Buffer.h"
+
+
+int
+main()
+{
+	klib::Buffer	buffer("hlo, world");
+
+	std::cout << buffer.Contents() << std::endl;
+
+	buffer.Insert(1, (uint8_t *)"el", 2);
+
+	std::cout << buffer.Contents() << std::endl;
+}