string_buffer.h

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/*  string_buffer.h                                                       */
/**************************************************************************/
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#pragma once

#include "core/string/ustring.h"

template <int SHORT_BUFFER_SIZE = 64>
class StringBuffer {
	char32_t short_buffer[SHORT_BUFFER_SIZE];
	String buffer;
	int string_length = 0;

	_FORCE_INLINE_ char32_t *current_buffer_ptr() {
		return static_cast<String &>(buffer).is_empty() ? short_buffer : buffer.ptrw();
	}

public:
	StringBuffer &append(char32_t p_char);
	StringBuffer &append(const String &p_string);
	StringBuffer &append(const char *p_str);
	StringBuffer &append(const char32_t *p_str, int p_clip_to_len = -1);

	_FORCE_INLINE_ void operator+=(char32_t p_char) {
		append(p_char);
	}

	_FORCE_INLINE_ void operator+=(const String &p_string) {
		append(p_string);
	}

	_FORCE_INLINE_ void operator+=(const char *p_str) {
		append(p_str);
	}

	_FORCE_INLINE_ void operator+=(const char32_t *p_str) {
		append(p_str);
	}

	StringBuffer &reserve(int p_size);

	int length() const;

	String as_string();

	double as_double();
	int64_t as_int();

	_FORCE_INLINE_ operator String() {
		return as_string();
	}
};

template <int SHORT_BUFFER_SIZE>
StringBuffer<SHORT_BUFFER_SIZE> &StringBuffer<SHORT_BUFFER_SIZE>::append(char32_t p_char) {
	reserve(string_length + 2);
	current_buffer_ptr()[string_length++] = p_char;
	return *this;
}

template <int SHORT_BUFFER_SIZE>
StringBuffer<SHORT_BUFFER_SIZE> &StringBuffer<SHORT_BUFFER_SIZE>::append(const String &p_string) {
	return append(p_string.get_data());
}

template <int SHORT_BUFFER_SIZE>
StringBuffer<SHORT_BUFFER_SIZE> &StringBuffer<SHORT_BUFFER_SIZE>::append(const char *p_str) {
	int len = strlen(p_str);
	reserve(string_length + len + 1);

	char32_t *buf = current_buffer_ptr();
	for (const char *c_ptr = p_str; *c_ptr; ++c_ptr) {
		buf[string_length++] = *c_ptr;
	}
	return *this;
}

template <int SHORT_BUFFER_SIZE>
StringBuffer<SHORT_BUFFER_SIZE> &StringBuffer<SHORT_BUFFER_SIZE>::append(const char32_t *p_str, int p_clip_to_len) {
	int len = 0;
	while ((p_clip_to_len < 0 || len < p_clip_to_len) && p_str[len]) {
		++len;
	}
	reserve(string_length + len + 1);
	memcpy(&(current_buffer_ptr()[string_length]), p_str, len * sizeof(char32_t));
	string_length += len;

	return *this;
}

template <int SHORT_BUFFER_SIZE>
StringBuffer<SHORT_BUFFER_SIZE> &StringBuffer<SHORT_BUFFER_SIZE>::reserve(int p_size) {
	ERR_FAIL_COND_V_MSG(p_size < length(), *this, "reserve() called with a capacity smaller than the current size. This is likely a mistake.");
	if (p_size <= SHORT_BUFFER_SIZE || p_size <= buffer.size()) {
		return *this;
	}

	bool need_copy = string_length > 0 && buffer.is_empty();
	buffer.resize_uninitialized(next_power_of_2((uint32_t)p_size));
	if (need_copy) {
		memcpy(buffer.ptrw(), short_buffer, string_length * sizeof(char32_t));
	}

	return *this;
}

template <int SHORT_BUFFER_SIZE>
int StringBuffer<SHORT_BUFFER_SIZE>::length() const {
	return string_length;
}

template <int SHORT_BUFFER_SIZE>
String StringBuffer<SHORT_BUFFER_SIZE>::as_string() {
	current_buffer_ptr()[string_length] = '\0';
	if (buffer.is_empty()) {
		return String(short_buffer);
	} else {
		buffer.resize_uninitialized(string_length + 1);
		return buffer;
	}
}

template <int SHORT_BUFFER_SIZE>
double StringBuffer<SHORT_BUFFER_SIZE>::as_double() {
	current_buffer_ptr()[string_length] = '\0';
	return String::to_float(current_buffer_ptr());
}

template <int SHORT_BUFFER_SIZE>
int64_t StringBuffer<SHORT_BUFFER_SIZE>::as_int() {
	current_buffer_ptr()[string_length] = '\0';
	return String::to_int(current_buffer_ptr());
}