BAN: Rewrite String with small string optimizations
String now holds a 15 byte sso buffer. I'm not sure what the size should actually be but 15 will work for now. Maybe the sso buffer should be contained in an union with one bit flag in size instead of variant that uses extra 8 bytes for type index. This patch buffs sizeof(String) from 24 bytes to 32 bytes on 64 bit. I assume this is much better version than the old which had to make allocation even for empty strings :D.
This commit is contained in:
parent
09fcc613c7
commit
1af3ca19ab
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@ -1,102 +1,108 @@
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#include <BAN/Errors.h>
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#include <BAN/Math.h>
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#include <BAN/Move.h>
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#include <BAN/New.h>
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#include <BAN/String.h>
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#include <BAN/StringView.h>
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#include <string.h>
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#include <BAN/New.h>
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#include <BAN/Variant.h>
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namespace BAN
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{
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String::String()
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{
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MUST(copy_impl(""sv));
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}
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String::String(const String& other)
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{
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MUST(copy_impl(other.sv()));
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*this = other;
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}
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String::String(String&& other)
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{
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move_impl(move(other));
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*this = move(other);
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}
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String::String(StringView other)
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{
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MUST(copy_impl(other));
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*this = other;
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}
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String::~String()
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{
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BAN::deallocator(m_data);
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clear();
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}
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String& String::operator=(const String& other)
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{
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MUST(copy_impl(other.sv()));
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clear();
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if (!other.fits_in_sso())
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MUST(ensure_capacity(other.size()));
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memcpy(data(), other.data(), other.size() + 1);
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m_size = other.size();
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return *this;
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}
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String& String::operator=(String&& other)
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{
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BAN::deallocator(m_data);
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move_impl(move(other));
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clear();
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if (other.fits_in_sso())
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memcpy(data(), other.data(), other.size() + 1);
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else
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m_storage = other.m_storage.get<GeneralStorage>();
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m_size = other.m_size;
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other.m_size = 0;
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other.m_storage = SSOStorage();
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return *this;
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}
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String& String::operator=(StringView other)
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{
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MUST(copy_impl(other));
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clear();
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if (!fits_in_sso(other.size()))
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MUST(ensure_capacity(other.size()));
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memcpy(data(), other.data(), other.size());
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m_size = other.size();
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data()[m_size] = '\0';
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return *this;
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}
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ErrorOr<void> String::push_back(char ch)
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ErrorOr<void> String::push_back(char c)
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{
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TRY(ensure_capacity(m_size + 2));
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m_data[m_size] = ch;
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TRY(ensure_capacity(m_size + 1));
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data()[m_size] = c;
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m_size++;
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m_data[m_size] = '\0';
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data()[m_size] = '\0';
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return {};
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}
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ErrorOr<void> String::insert(char ch, size_type index)
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ErrorOr<void> String::insert(char c, size_type index)
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{
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ASSERT(index <= m_size);
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TRY(ensure_capacity(m_size + 1 + 1));
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memmove(m_data + index + 1, m_data + index, m_size - index);
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m_data[index] = ch;
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m_size += 1;
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m_data[m_size] = '\0';
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TRY(ensure_capacity(m_size + 1));
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memmove(data() + index + 1, data() + index, m_size - index);
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data()[index] = c;
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m_size++;
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data()[m_size] = '\0';
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return {};
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}
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ErrorOr<void> String::insert(StringView other, size_type index)
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ErrorOr<void> String::insert(StringView str, size_type index)
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{
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ASSERT(index <= m_size);
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TRY(ensure_capacity(m_size + other.size() + 1));
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memmove(m_data + index + other.size(), m_data + index, m_size - index);
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memcpy(m_data + index, other.data(), other.size());
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m_size += other.size();
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m_data[m_size] = '\0';
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TRY(ensure_capacity(m_size + str.size()));
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memmove(data() + index + str.size(), data() + index, m_size - index);
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memcpy(data() + index, str.data(), str.size());
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m_size += str.size();
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data()[m_size] = '\0';
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return {};
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}
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ErrorOr<void> String::append(StringView other)
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ErrorOr<void> String::append(StringView str)
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{
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TRY(ensure_capacity(m_size + other.size() + 1));
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memcpy(m_data + m_size, other.data(), other.size());
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m_size += other.size();
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m_data[m_size] = '\0';
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return {};
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}
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ErrorOr<void> String::append(const String& string)
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{
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TRY(append(string.sv()));
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TRY(ensure_capacity(m_size + str.size()));
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memcpy(data() + m_size, str.data(), str.size());
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m_size += str.size();
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data()[m_size] = '\0';
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return {};
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}
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@ -104,159 +110,161 @@ namespace BAN
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{
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ASSERT(m_size > 0);
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m_size--;
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m_data[m_size] = '\0';
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data()[m_size] = '\0';
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}
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void String::remove(size_type index)
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{
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erase(index, 1);
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}
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void String::erase(size_type index, size_type count)
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{
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ASSERT(index + count <= m_size);
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memmove(m_data + index, m_data + index + count, m_size - index - count);
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m_size -= count;
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m_data[m_size] = '\0';
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ASSERT(index < m_size);
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memcpy(data() + index, data() + index + 1, m_size - index);
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m_size--;
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data()[m_size] = '\0';
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}
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void String::clear()
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{
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if (!has_sso())
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{
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deallocator(m_storage.get<GeneralStorage>().data);
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m_storage = SSOStorage();
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}
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m_size = 0;
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m_data[0] = '\0';
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data()[m_size] = '\0';
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}
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char String::operator[](size_type index) const
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bool String::operator==(StringView str) const
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{
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ASSERT(index < m_size);
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return m_data[index];
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}
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char& String::operator[](size_type index)
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{
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ASSERT(index < m_size);
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return m_data[index];
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}
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bool String::operator==(const String& other) const
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{
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if (m_size != other.m_size)
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if (size() != str.size())
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return false;
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return memcmp(m_data, other.m_data, m_size) == 0;
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}
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bool String::operator==(StringView other) const
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{
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if (m_size != other.size())
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return false;
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return memcmp(m_data, other.data(), m_size) == 0;
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}
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bool String::operator==(const char* other) const
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{
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for (size_type i = 0; i <= m_size; i++)
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if (m_data[i] != other[i])
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for (size_type i = 0; i < m_size; i++)
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if (data()[i] != str.data()[i])
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return false;
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return true;
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}
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ErrorOr<void> String::resize(size_type size, char ch)
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bool String::operator==(const char* cstr) const
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{
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if (size < m_size)
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for (size_type i = 0; i < m_size; i++)
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if (data()[i] != cstr[i])
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return false;
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if (cstr[size()] != '\0')
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return false;
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return true;
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}
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ErrorOr<void> String::resize(size_type new_size, char init_c)
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{
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if (m_size == new_size)
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return {};
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// expanding
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if (m_size < new_size)
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{
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m_data[size] = '\0';
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m_size = size;
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TRY(ensure_capacity(new_size));
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memset(data() + m_size, init_c, new_size - m_size);
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m_size = new_size;
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data()[m_size] = '\0';
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return {};
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}
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else if (size > m_size)
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// shrink general -> sso
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if (!has_sso() && fits_in_sso(new_size))
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{
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TRY(ensure_capacity(size + 1));
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for (size_type i = m_size; i < size; i++)
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m_data[i] = ch;
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m_data[size] = '\0';
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m_size = size;
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char* data = m_storage.get<GeneralStorage>().data;
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m_storage = SSOStorage();
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memcpy(m_storage.get<SSOStorage>().storage, data, new_size);
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deallocator(data);
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}
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m_size = size;
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m_size = new_size;
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data()[m_size] = '\0';
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return {};
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}
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ErrorOr<void> String::reserve(size_type size)
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ErrorOr<void> String::reserve(size_type new_size)
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{
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TRY(ensure_capacity(size));
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TRY(ensure_capacity(new_size));
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return {};
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}
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ErrorOr<void> String::shrink_to_fit()
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{
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size_type temp = m_capacity;
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m_capacity = 0;
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auto error_or = ensure_capacity(m_size);
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if (error_or.is_error())
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if (has_sso())
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return {};
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if (fits_in_sso())
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{
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m_capacity = temp;
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return error_or;
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char* data = m_storage.get<GeneralStorage>().data;
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m_storage = SSOStorage();
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memcpy(m_storage.get<SSOStorage>().storage, data, m_size + 1);
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deallocator(data);
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return {};
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}
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GeneralStorage& storage = m_storage.get<GeneralStorage>();
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if (storage.capacity == m_size)
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return {};
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char* new_data = (char*)allocator(m_size + 1);
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if (new_data == nullptr)
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return BAN::Error::from_errno(ENOMEM);
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memcpy(new_data, storage.data, m_size);
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deallocator(storage.data);
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storage.capacity = m_size;
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storage.data = new_data;
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return {};
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}
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StringView String::sv() const
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{
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return StringView(*this);
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}
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bool String::empty() const
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{
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return m_size == 0;
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}
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String::size_type String::size() const
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{
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return m_size;
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}
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String::size_type String::capacity() const
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{
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return m_capacity;
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if (has_sso())
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return sso_capacity;
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return m_storage.get<GeneralStorage>().capacity;
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}
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char* String::data()
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{
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if (has_sso())
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return m_storage.get<SSOStorage>().storage;
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return m_storage.get<GeneralStorage>().data;
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}
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const char* String::data() const
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{
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return m_data;
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if (has_sso())
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return m_storage.get<SSOStorage>().storage;
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return m_storage.get<GeneralStorage>().data;
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}
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ErrorOr<void> String::ensure_capacity(size_type size)
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ErrorOr<void> String::ensure_capacity(size_type new_size)
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{
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if (m_capacity >= size)
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if (m_size >= new_size || fits_in_sso(new_size))
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return {};
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size_type new_cap = BAN::Math::max<size_type>(size, m_capacity * 2);
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void* new_data = BAN::allocator(new_cap);
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char* new_data = (char*)allocator(new_size + 1);
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if (new_data == nullptr)
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return Error::from_errno(ENOMEM);
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if (m_data)
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memcpy(new_data, m_data, m_size + 1);
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BAN::deallocator(m_data);
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m_data = (char*)new_data;
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m_capacity = new_cap;
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return BAN::Error::from_errno(ENOMEM);
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memcpy(new_data, data(), m_size + 1);
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if (has_sso())
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m_storage = GeneralStorage();
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else
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deallocator(m_storage.get<GeneralStorage>().data);
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auto& storage = m_storage.get<GeneralStorage>();
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storage.capacity = new_size;
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storage.data = new_data;
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return {};
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}
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ErrorOr<void> String::copy_impl(StringView other)
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bool String::has_sso() const
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{
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TRY(ensure_capacity(other.size() + 1));
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memcpy(m_data, other.data(), other.size());
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m_size = other.size();
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m_data[m_size] = '\0';
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return {};
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}
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void String::move_impl(String&& other)
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{
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m_data = other.m_data;
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m_size = other.m_size;
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m_capacity = other.m_capacity;
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other.m_data = nullptr;
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other.m_size = 0;
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other.m_capacity = 0;
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return m_storage.has<SSOStorage>();
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}
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}
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@ -1,8 +1,8 @@
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#pragma once
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#include <BAN/Errors.h>
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#include <BAN/ForwardList.h>
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#include <BAN/Formatter.h>
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#include <BAN/ForwardList.h>
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#include <BAN/Hash.h>
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#include <BAN/Iterators.h>
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@ -15,6 +15,7 @@ namespace BAN
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using size_type = size_t;
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using iterator = IteratorSimple<char, String>;
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using const_iterator = ConstIteratorSimple<char, String>;
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static constexpr size_type sso_capacity = 15;
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public:
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String();
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@ -34,29 +35,26 @@ namespace BAN
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ErrorOr<void> insert(char, size_type);
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ErrorOr<void> insert(StringView, size_type);
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ErrorOr<void> append(StringView);
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ErrorOr<void> append(const String&);
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void pop_back();
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void remove(size_type);
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void erase(size_type, size_type);
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void clear();
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const_iterator begin() const { return const_iterator(m_data); }
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iterator begin() { return iterator(m_data); }
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const_iterator end() const { return const_iterator(m_data + m_size); }
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iterator end() { return iterator(m_data + m_size); }
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const_iterator begin() const { return const_iterator(data()); }
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iterator begin() { return iterator(data()); }
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const_iterator end() const { return const_iterator(data() + size()); }
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iterator end() { return iterator(data() + size()); }
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char front() const { ASSERT(!empty()); return m_data[0]; }
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char& front() { ASSERT(!empty()); return m_data[0]; }
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char front() const { ASSERT(m_size > 0); return data()[0]; }
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char& front() { ASSERT(m_size > 0); return data()[0]; }
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char back() const { ASSERT(!empty()); return m_data[m_size - 1]; }
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char& back() { ASSERT(!empty()); return m_data[m_size - 1]; }
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char back() const { ASSERT(m_size > 0); return data()[m_size - 1]; }
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char& back() { ASSERT(m_size > 0); return data()[m_size - 1]; }
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char operator[](size_type) const;
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char& operator[](size_type);
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char operator[](size_type index) const { ASSERT(index < m_size); return data()[index]; }
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char& operator[](size_type index) { ASSERT(index < m_size); return data()[index]; }
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bool operator==(const String&) const;
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bool operator==(StringView) const;
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bool operator==(const char*) const;
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@ -64,24 +62,37 @@ namespace BAN
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ErrorOr<void> reserve(size_type);
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ErrorOr<void> shrink_to_fit();
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StringView sv() const;
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StringView sv() const { return StringView(data(), size()); }
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bool empty() const;
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size_type size() const;
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bool empty() const { return m_size == 0; }
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size_type size() const { return m_size; }
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size_type capacity() const;
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char* data();
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const char* data() const;
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private:
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ErrorOr<void> ensure_capacity(size_type);
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ErrorOr<void> copy_impl(StringView);
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void move_impl(String&&);
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bool has_sso() const;
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|
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bool fits_in_sso() const { return fits_in_sso(m_size); }
|
||||
static bool fits_in_sso(size_type size) { return size < sso_capacity; }
|
||||
|
||||
private:
|
||||
char* m_data = nullptr;
|
||||
size_type m_capacity = 0;
|
||||
size_type m_size = 0;
|
||||
struct SSOStorage
|
||||
{
|
||||
char storage[sso_capacity + 1] {};
|
||||
};
|
||||
struct GeneralStorage
|
||||
{
|
||||
size_type capacity { 0 };
|
||||
char* data;
|
||||
};
|
||||
|
||||
private:
|
||||
Variant<SSOStorage, GeneralStorage> m_storage { SSOStorage() };
|
||||
size_type m_size { 0 };
|
||||
};
|
||||
|
||||
template<typename... Args>
|
||||
|
|
|
|||
Loading…
Reference in New Issue