asset.h

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#pragma once

 
#include "fl/stl/int.h"
#include "fl/stl/noexcept.h"
#include "fl/stl/static_assert.h"
#include "fl/stl/string.h"
#include "fl/stl/string_view.h"
#include "fl/stl/url.h"
 
namespace fl {
 
namespace asset_detail {

constexpr fl::size clen(const char* s, fl::size n = 0) FL_NOEXCEPT {
    return s[n] == '\0' ? n : clen(s, n + 1);
}

constexpr bool is_parent_at(const char* p, fl::size i) FL_NOEXCEPT {
    // Segment start: either we're at the beginning, or preceded by a separator.
    return (i == 0 || p[i - 1] == '/' || p[i - 1] == '\\')
           && p[i] == '.' && p[i + 1] == '.'
           && (p[i + 2] == '\0' || p[i + 2] == '/' || p[i + 2] == '\\');
}

constexpr bool path_has_parent_segment_at(const char* p, fl::size i) FL_NOEXCEPT {
    return p[i] == '\0'
               ? false
               : (is_parent_at(p, i) ? true : path_has_parent_segment_at(p, i + 1));
}

constexpr bool path_has_parent_segment(const char* p) FL_NOEXCEPT {
    return (p == nullptr) ? false : path_has_parent_segment_at(p, 0);
}
 
} // namespace asset_detail

class asset_ref {
  public:
    constexpr asset_ref(const char* path, fl::size length) FL_NOEXCEPT
        : mPath(path), mLength(length) {}

    constexpr asset_ref() FL_NOEXCEPT : mPath(nullptr), mLength(0) {}

    asset_ref(const asset_ref&) FL_NOEXCEPT = default;
    asset_ref& operator=(const asset_ref&) FL_NOEXCEPT = default;

    constexpr explicit operator bool() const FL_NOEXCEPT {
        return mPath != nullptr && mLength > 0;
    }

    fl::string_view path() const FL_NOEXCEPT {
        return fl::string_view(mPath, mLength);
    }

    constexpr const char* c_str() const FL_NOEXCEPT { return mPath; }
    constexpr fl::size size() const FL_NOEXCEPT { return mLength; }
 
  private:
    const char* mPath;
    fl::size mLength;
};

constexpr asset_ref asset(const char* path) FL_NOEXCEPT {
    return asset_detail::path_has_parent_segment(path)
               ? asset_ref()
               : asset_ref(path, asset_detail::clen(path));
}

#define FL_ASSET(LITERAL_PATH)                                                 \
    ([]() -> ::fl::asset_ref {                                                 \
        FL_STATIC_ASSERT(                                                         \
            !::fl::asset_detail::path_has_parent_segment(LITERAL_PATH),        \
            "fl::asset path must not contain '..' segments");                  \
        return ::fl::asset_ref(                                                \
            (LITERAL_PATH), ::fl::asset_detail::clen(LITERAL_PATH));           \
    }())

fl::url resolve_asset(const asset_ref& a) FL_NOEXCEPT;

void register_asset(fl::string_view path, const fl::url& u) FL_NOEXCEPT;
 
} // namespace fl