ladybird/AK/StringBuilder.h

/*
 * Copyright (c) 2018-2021, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/ByteBuffer.h>
#include <AK/Format.h>
#include <AK/Forward.h>
#include <AK/StringView.h>
#include <stdarg.h>

namespace AK {

class StringBuilder {
public:
    enum class Mode {
        UTF8,
        UTF16,
    };

    static constexpr auto DEFAULT_MODE = Mode::UTF8;
    static constexpr size_t inline_capacity = 256;

    class Buffer {
    public:
        Buffer() = default;
        Buffer(Buffer const&);
        Buffer(Buffer&&);
        ~Buffer();

        Buffer& operator=(Buffer const&);
        Buffer& operator=(Buffer&&);

        [[nodiscard]] u8* data();
        [[nodiscard]] u8 const* data() const;

        [[nodiscard]] Bytes span() LIFETIME_BOUND;
        [[nodiscard]] ReadonlyBytes span() const LIFETIME_BOUND;

        [[nodiscard]] void* end_pointer();

        [[nodiscard]] size_t size() const { return m_size; }
        [[nodiscard]] size_t capacity() const { return m_inline ? inline_capacity : m_outline_capacity; }
        [[nodiscard]] bool is_inline() const { return m_inline; }

        void clear();
        void resize(size_t);
        void set_size(size_t);
        void ensure_capacity(size_t);

        ErrorOr<void> try_resize(size_t);
        ErrorOr<void> try_ensure_capacity(size_t);
        ErrorOr<void> try_append(char);
        ErrorOr<void> try_append(ReadonlyBytes);
        ErrorOr<void> try_append(void const*, size_t);

        void append(char);
        void append(void const*, size_t);

        struct OutlineBuffer {
            Bytes buffer;
            size_t capacity { 0 };
        };
        Optional<OutlineBuffer> leak_outline_buffer();

    private:
        void move_from(Buffer&&);
        void trim(size_t, bool may_discard_existing_data);
        void shrink_into_inline_buffer(size_t, bool may_discard_existing_data);
        ErrorOr<void> try_ensure_capacity_slowpath(size_t);

        union {
            u8 m_inline_buffer[inline_capacity];
            struct {
                u8* m_outline_buffer;
                size_t m_outline_capacity;
            };
        };
        size_t m_size { 0 };
        bool m_inline { true };
    };

    StringBuilder();
    explicit StringBuilder(size_t initial_capacity);

    explicit StringBuilder(Mode);
    StringBuilder(Mode, size_t initial_capacity_in_code_units);

    ~StringBuilder() = default;

    ErrorOr<void> try_append(StringView);
    ErrorOr<void> try_append(Utf16View const&);
    ErrorOr<void> try_append(char);
    ErrorOr<void> try_append_code_unit(char16_t);
    ErrorOr<void> try_append_code_point(u32);
    ErrorOr<void> try_append(char const*, size_t);
    ErrorOr<void> try_append_repeated(char, size_t);
    ErrorOr<void> try_append_repeated(StringView, size_t);
    ErrorOr<void> try_append_repeated(Utf16View const&, size_t);
    ErrorOr<void> try_append_escaped_for_json(StringView);
    ErrorOr<void> try_append_ascii_without_validation(ReadonlyBytes);

    template<typename... Parameters>
    ErrorOr<void> try_appendff(CheckedFormatString<Parameters...>&& fmtstr, Parameters const&... parameters)
    {
        VariadicFormatParams<AllowDebugOnlyFormatters::No, Parameters...> variadic_format_params { parameters... };
        return vformat(*this, fmtstr.view(), variadic_format_params);
    }

    void append(StringView);
    void append(Utf16View const&);
    void append(char);
    void append_code_unit(char16_t);
    void append_code_point(u32);
    void append(char const*, size_t);
    void appendvf(char const*, va_list);
    void append_repeated(char, size_t);
    void append_repeated(StringView, size_t);
    void append_repeated(Utf16View const&, size_t);
    void append_escaped_for_json(StringView);
    void append_as_lowercase(char);
    void append_ascii_without_validation(ReadonlyBytes);

    template<typename... Parameters>
    void appendff(CheckedFormatString<Parameters...>&& fmtstr, Parameters const&... parameters)
    {
        VariadicFormatParams<AllowDebugOnlyFormatters::No, Parameters...> variadic_format_params { parameters... };
        MUST(vformat(*this, fmtstr.view(), variadic_format_params));
    }

    [[nodiscard]] ByteString to_byte_string() const;

    [[nodiscard]] String to_string_without_validation();
    ErrorOr<String> to_string();

    [[nodiscard]] FlyString to_fly_string_without_validation() const;
    ErrorOr<FlyString> to_fly_string() const;

    Utf16String to_utf16_string();

    [[nodiscard]] ErrorOr<ByteBuffer> to_byte_buffer() const;

    [[nodiscard]] StringView string_view() const;
    [[nodiscard]] Utf16View utf16_string_view() const;
    void clear();

    [[nodiscard]] size_t length() const;
    [[nodiscard]] bool is_empty() const;
    void trim(size_t count);

    template<class SeparatorType, class CollectionType>
    void join(SeparatorType const& separator, CollectionType const& collection, StringView fmtstr = "{}"sv)
    {
        MUST(try_join(separator, collection, fmtstr));
    }

    template<class SeparatorType, class CollectionType>
    ErrorOr<void> try_join(SeparatorType const& separator, CollectionType const& collection, StringView fmtstr = "{}"sv)
    {
        bool first = true;
        for (auto& item : collection) {
            if (!first)
                TRY(try_append(separator));
            TRY(try_appendff(fmtstr, item));
            first = false;
        }
        return {};
    }

    Optional<Buffer::OutlineBuffer> leak_buffer_for_string_construction(Badge<Detail::StringData>) { return leak_buffer_for_string_construction(); }
    Optional<Buffer::OutlineBuffer> leak_buffer_for_string_construction(Badge<Detail::Utf16StringData>) { return leak_buffer_for_string_construction(); }

private:
    void initialize_buffer(Mode, size_t capacity);

    Optional<Buffer::OutlineBuffer> leak_buffer_for_string_construction();

    ErrorOr<void> will_append(size_t);
    ErrorOr<void> ensure_storage_is_utf16();

    u8* data();
    u8 const* data() const;

    Buffer m_buffer;
    Mode m_mode { DEFAULT_MODE };
    bool m_utf16_builder_is_ascii { true };
};

}

#if USING_AK_GLOBALLY
using AK::StringBuilder;
#endif