ladybird/AK/StringView.h
Daniel Bertalan 4296425bd8 Everywhere: Remove redundant inequality comparison operators
C++20 can automatically synthesize `operator!=` from `operator==`, so
there is no point in writing such functions by hand if all they do is
call through to `operator==`.

This fixes a compile error with compilers that implement P2468 (Clang
16 currently). This paper restores the C++17 behavior that if both
`T::operator==(U)` and `T::operator!=(U)` exist, `U == T` won't be
rewritten in reverse to call `T::operator==(U)`. Removing `!=` operators
makes the rewriting possible again.
See https://reviews.llvm.org/D134529#3853062
2022-11-06 10:25:08 -07:00

362 lines
13 KiB
C++

/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/Checked.h>
#include <AK/EnumBits.h>
#include <AK/Forward.h>
#include <AK/Optional.h>
#include <AK/Span.h>
#include <AK/StdLibExtras.h>
#include <AK/StringHash.h>
#include <AK/StringUtils.h>
namespace AK {
class StringView {
public:
ALWAYS_INLINE constexpr StringView() = default;
ALWAYS_INLINE constexpr StringView(char const* characters, size_t length)
: m_characters(characters)
, m_length(length)
{
if (!is_constant_evaluated())
VERIFY(!Checked<uintptr_t>::addition_would_overflow((uintptr_t)characters, length));
}
ALWAYS_INLINE StringView(unsigned char const* characters, size_t length)
: m_characters((char const*)characters)
, m_length(length)
{
VERIFY(!Checked<uintptr_t>::addition_would_overflow((uintptr_t)characters, length));
}
ALWAYS_INLINE StringView(ReadonlyBytes bytes)
: m_characters(reinterpret_cast<char const*>(bytes.data()))
, m_length(bytes.size())
{
}
StringView(ByteBuffer const&);
#ifndef KERNEL
StringView(String const&);
StringView(FlyString const&);
#endif
explicit StringView(ByteBuffer&&) = delete;
#ifndef KERNEL
explicit StringView(String&&) = delete;
explicit StringView(FlyString&&) = delete;
#endif
[[nodiscard]] constexpr bool is_null() const
{
return m_characters == nullptr;
}
[[nodiscard]] constexpr bool is_empty() const { return m_length == 0; }
[[nodiscard]] constexpr char const* characters_without_null_termination() const { return m_characters; }
[[nodiscard]] constexpr size_t length() const { return m_length; }
[[nodiscard]] ReadonlyBytes bytes() const { return { m_characters, m_length }; }
constexpr char const& operator[](size_t index) const
{
if (!is_constant_evaluated())
VERIFY(index < m_length);
return m_characters[index];
}
using ConstIterator = SimpleIterator<const StringView, char const>;
[[nodiscard]] constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
[[nodiscard]] constexpr ConstIterator end() const { return ConstIterator::end(*this); }
[[nodiscard]] constexpr unsigned hash() const
{
if (is_empty())
return 0;
return string_hash(characters_without_null_termination(), length());
}
[[nodiscard]] bool starts_with(StringView, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
[[nodiscard]] bool ends_with(StringView, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
[[nodiscard]] bool starts_with(char) const;
[[nodiscard]] bool ends_with(char) const;
[[nodiscard]] bool matches(StringView mask, CaseSensitivity = CaseSensitivity::CaseInsensitive) const;
[[nodiscard]] bool matches(StringView mask, Vector<MaskSpan>&, CaseSensitivity = CaseSensitivity::CaseInsensitive) const;
[[nodiscard]] bool contains(char) const;
[[nodiscard]] bool contains(u32) const;
[[nodiscard]] bool contains(StringView, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
[[nodiscard]] bool equals_ignoring_case(StringView other) const;
[[nodiscard]] StringView trim(StringView characters, TrimMode mode = TrimMode::Both) const { return StringUtils::trim(*this, characters, mode); }
[[nodiscard]] StringView trim_whitespace(TrimMode mode = TrimMode::Both) const { return StringUtils::trim_whitespace(*this, mode); }
#ifndef KERNEL
[[nodiscard]] String to_lowercase_string() const;
[[nodiscard]] String to_uppercase_string() const;
[[nodiscard]] String to_titlecase_string() const;
#endif
[[nodiscard]] Optional<size_t> find(char needle, size_t start = 0) const
{
return StringUtils::find(*this, needle, start);
}
[[nodiscard]] Optional<size_t> find(StringView needle, size_t start = 0) const { return StringUtils::find(*this, needle, start); }
[[nodiscard]] Optional<size_t> find_last(char needle) const { return StringUtils::find_last(*this, needle); }
[[nodiscard]] Optional<size_t> find_last_not(char needle) const { return StringUtils::find_last_not(*this, needle); }
// FIXME: Implement find_last(StringView) for API symmetry.
[[nodiscard]] Vector<size_t> find_all(StringView needle) const;
using SearchDirection = StringUtils::SearchDirection;
[[nodiscard]] Optional<size_t> find_any_of(StringView needles, SearchDirection direction = SearchDirection::Forward) const { return StringUtils::find_any_of(*this, needles, direction); }
[[nodiscard]] constexpr StringView substring_view(size_t start, size_t length) const
{
if (!is_constant_evaluated())
VERIFY(start + length <= m_length);
return { m_characters + start, length };
}
[[nodiscard]] constexpr StringView substring_view(size_t start) const
{
if (!is_constant_evaluated())
VERIFY(start <= length());
return substring_view(start, length() - start);
}
[[nodiscard]] Vector<StringView> split_view(char, SplitBehavior = SplitBehavior::Nothing) const;
[[nodiscard]] Vector<StringView> split_view(StringView, SplitBehavior = SplitBehavior::Nothing) const;
[[nodiscard]] Vector<StringView> split_view_if(Function<bool(char)> const& predicate, SplitBehavior = SplitBehavior::Nothing) const;
[[nodiscard]] StringView find_last_split_view(char separator) const
{
auto begin = find_last(separator);
if (!begin.has_value())
return *this;
return substring_view(begin.release_value() + 1);
}
[[nodiscard]] StringView find_first_split_view(char separator) const
{
auto needle_begin = find(separator);
if (!needle_begin.has_value())
return *this;
return substring_view(0, needle_begin.release_value());
}
template<VoidFunction<StringView> Callback>
void for_each_split_view(char separator, SplitBehavior split_behavior, Callback callback) const
{
StringView seperator_view { &separator, 1 };
for_each_split_view(seperator_view, split_behavior, callback);
}
template<VoidFunction<StringView> Callback>
void for_each_split_view(StringView separator, SplitBehavior split_behavior, Callback callback) const
{
VERIFY(!separator.is_empty());
if (is_empty())
return;
StringView view { *this };
auto maybe_separator_index = find(separator);
bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
while (maybe_separator_index.has_value()) {
auto separator_index = maybe_separator_index.value();
auto part_with_separator = view.substring_view(0, separator_index + separator.length());
if (keep_empty || separator_index > 0) {
if (keep_separator)
callback(part_with_separator);
else
callback(part_with_separator.substring_view(0, separator_index));
}
view = view.substring_view_starting_after_substring(part_with_separator);
maybe_separator_index = view.find(separator);
}
if (keep_empty || !view.is_empty())
callback(view);
}
// Create a Vector of StringViews split by line endings. As of CommonMark
// 0.29, the spec defines a line ending as "a newline (U+000A), a carriage
// return (U+000D) not followed by a newline, or a carriage return and a
// following newline.".
[[nodiscard]] Vector<StringView> lines(bool consider_cr = true) const;
template<typename T = int>
Optional<T> to_int() const;
template<typename T = unsigned>
Optional<T> to_uint() const;
#ifndef KERNEL
Optional<double> to_double(TrimWhitespace trim_whitespace = TrimWhitespace::Yes) const;
Optional<float> to_float(TrimWhitespace trim_whitespace = TrimWhitespace::Yes) const;
#endif
// Create a new substring view of this string view, starting either at the beginning of
// the given substring view, or after its end, and continuing until the end of this string
// view (that is, for the remaining part of its length). For example,
//
// StringView str { "foobar" };
// StringView substr = str.substring_view(1, 2); // "oo"
// StringView substr_from = str.substring_view_starting_from_substring(subst); // "oobar"
// StringView substr_after = str.substring_view_starting_after_substring(subst); // "bar"
//
// Note that this only works if the string view passed as an argument is indeed a substring
// view of this string view, such as one created by substring_view() and split_view(). It
// does not work for arbitrary strings; for example declaring substr in the example above as
//
// StringView substr { "oo" };
//
// would not work.
[[nodiscard]] StringView substring_view_starting_from_substring(StringView substring) const;
[[nodiscard]] StringView substring_view_starting_after_substring(StringView substring) const;
[[nodiscard]] bool copy_characters_to_buffer(char* buffer, size_t buffer_size) const;
constexpr bool operator==(char const* cstring) const
{
if (is_null())
return cstring == nullptr;
if (!cstring)
return false;
// NOTE: `m_characters` is not guaranteed to be null-terminated, but `cstring` is.
char const* cp = cstring;
for (size_t i = 0; i < m_length; ++i) {
if (*cp == '\0')
return false;
if (m_characters[i] != *(cp++))
return false;
}
return *cp == '\0';
}
constexpr bool operator==(char const c) const
{
return m_length == 1 && *m_characters == c;
}
#ifndef KERNEL
bool operator==(String const&) const;
#endif
[[nodiscard]] constexpr int compare(StringView other) const
{
if (m_characters == nullptr)
return other.m_characters ? -1 : 0;
if (other.m_characters == nullptr)
return 1;
size_t rlen = min(m_length, other.m_length);
int c = __builtin_memcmp(m_characters, other.m_characters, rlen);
if (c == 0) {
if (length() < other.length())
return -1;
if (length() == other.length())
return 0;
return 1;
}
return c;
}
constexpr bool operator==(StringView other) const
{
return length() == other.length() && compare(other) == 0;
}
constexpr bool operator!=(StringView other) const
{
return length() != other.length() || compare(other) != 0;
}
constexpr bool operator<(StringView other) const { return compare(other) < 0; }
constexpr bool operator<=(StringView other) const { return compare(other) <= 0; }
constexpr bool operator>(StringView other) const { return compare(other) > 0; }
constexpr bool operator>=(StringView other) const { return compare(other) >= 0; }
#ifndef KERNEL
[[nodiscard]] String to_string() const;
#endif
[[nodiscard]] bool is_whitespace() const
{
return StringUtils::is_whitespace(*this);
}
#ifndef KERNEL
[[nodiscard]] String replace(StringView needle, StringView replacement, ReplaceMode) const;
#endif
[[nodiscard]] size_t count(StringView needle) const
{
return StringUtils::count(*this, needle);
}
template<typename... Ts>
[[nodiscard]] ALWAYS_INLINE constexpr bool is_one_of(Ts&&... strings) const
{
return (... || this->operator==(forward<Ts>(strings)));
}
template<typename... Ts>
[[nodiscard]] ALWAYS_INLINE constexpr bool is_one_of_ignoring_case(Ts&&... strings) const
{
return (... ||
[this, &strings]() -> bool {
if constexpr (requires(Ts a) { a.view()->StringView; })
return this->equals_ignoring_case(forward<Ts>(strings.view()));
else
return this->equals_ignoring_case(forward<Ts>(strings));
}());
}
private:
friend class String;
char const* m_characters { nullptr };
size_t m_length { 0 };
};
template<>
struct Traits<StringView> : public GenericTraits<StringView> {
static unsigned hash(StringView s) { return s.hash(); }
};
struct CaseInsensitiveStringViewTraits : public Traits<StringView> {
static unsigned hash(StringView s)
{
if (s.is_empty())
return 0;
return case_insensitive_string_hash(s.characters_without_null_termination(), s.length());
}
};
}
// FIXME: Remove this when clang fully supports consteval (specifically in the context of default parameter initialization).
// See: https://stackoverflow.com/questions/68789984/immediate-function-as-default-function-argument-initializer-in-clang
#if defined(AK_COMPILER_CLANG)
# define AK_STRING_VIEW_LITERAL_CONSTEVAL constexpr
#else
# define AK_STRING_VIEW_LITERAL_CONSTEVAL consteval
#endif
[[nodiscard]] ALWAYS_INLINE AK_STRING_VIEW_LITERAL_CONSTEVAL AK::StringView operator"" sv(char const* cstring, size_t length)
{
return AK::StringView(cstring, length);
}
using AK::CaseInsensitiveStringViewTraits;
using AK::StringView;