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#pragma once
#include <cctype>
#include <cstddef>
#include <cstdint>
#include <optional>
#include <string>
#include <string_view>
#include <utility>
#include <vector>
#include "layout.h"
namespace pixpat
{
// Pattern-specific parameters parsed from pixpat_pattern_opts::params.
// The wire format is a comma-separated list of "key=value" items;
// whitespace around tokens is trimmed, keys and values are
// case-insensitive ASCII, and neither may contain ',' or '='.
// Malformed input leaves ok() returning false — the pattern dispatcher
// fails the call when that happens.
//
// Patterns query keys by name via get() / get_int() / get_hex_color().
// Unknown keys are ignored: each pattern handles forward compatibility,
// not the parser.
class Params
{
public:
explicit Params(const char* csv);
bool ok() const noexcept {
return ok_;
}
std::optional<std::string_view> get(std::string_view key) const noexcept;
std::optional<int> get_int(std::string_view key) const noexcept;
std::optional<RGB16> get_hex_color(std::string_view key) const noexcept;
private:
std::vector<std::pair<std::string, std::string> > kv_;
bool ok_{ true };
};
namespace detail
{
inline char ascii_tolower(char c) noexcept
{
return (c >= 'A' && c <= 'Z') ? char(c + ('a' - 'A')) : c;
}
inline std::string_view trim(std::string_view s) noexcept
{
while (!s.empty() && std::isspace(static_cast<unsigned char>(s.front())))
s.remove_prefix(1);
while (!s.empty() && std::isspace(static_cast<unsigned char>(s.back())))
s.remove_suffix(1);
return s;
}
inline bool ieq(std::string_view a, std::string_view b) noexcept
{
if (a.size() != b.size())
return false;
for (size_t i = 0; i < a.size(); ++i)
if (ascii_tolower(a[i]) != ascii_tolower(b[i]))
return false;
return true;
}
} // namespace detail
inline Params::Params(const char* csv)
{
if (!csv || *csv == '\0')
return;
std::string_view s(csv);
while (!s.empty()) {
const size_t comma = s.find(',');
std::string_view item = (comma == std::string_view::npos)
? s : s.substr(0, comma);
s = (comma == std::string_view::npos)
? std::string_view{} : s.substr(comma + 1);
item = detail::trim(item);
if (item.empty()) {
ok_ = false;
return;
}
const size_t eq = item.find('=');
if (eq == std::string_view::npos) {
ok_ = false;
return;
}
const std::string_view k = detail::trim(item.substr(0, eq));
const std::string_view v = detail::trim(item.substr(eq + 1));
if (k.empty()) {
ok_ = false;
return;
}
kv_.emplace_back(std::string(k), std::string(v));
}
}
inline std::optional<std::string_view>
Params::get(std::string_view key) const noexcept
{
for (const auto& [k, v] : kv_)
if (detail::ieq(k, key))
return std::string_view(v);
return std::nullopt;
}
inline std::optional<int>
Params::get_int(std::string_view key) const noexcept
{
auto v = get(key);
if (!v || v->empty())
return std::nullopt;
int sign = 1;
size_t i = 0;
if ((*v)[0] == '-') { sign = -1; ++i; }
else if ((*v)[0] == '+') { ++i; }
if (i == v->size())
return std::nullopt;
int out = 0;
for (; i < v->size(); ++i) {
const char c = (*v)[i];
if (c < '0' || c > '9')
return std::nullopt;
out = out * 10 + (c - '0');
}
return sign * out;
}
// Parses a hex color string. The optional `0x`/`0X` prefix is allowed.
// The number of hex digits after the prefix selects the layout:
// 6 digits — 8-bit RRGGBB (alpha defaults to opaque)
// 8 digits — 8-bit AARRGGBB (alpha-first)
// 12 digits — 16-bit RRRRGGGGBBBB (alpha defaults to opaque)
// 16 digits — 16-bit AAAARRRRGGGGBBBB (alpha-first)
// 8-bit components are byte-replicated to the normalized 16-bit form
// (0xFF → 0xFFFF); 16-bit components are stored directly. Any other
// length, malformed digits, or stray separators yield std::nullopt.
inline std::optional<RGB16>
Params::get_hex_color(std::string_view key) const noexcept
{
auto v = get(key);
if (!v)
return std::nullopt;
std::string_view s = *v;
if (s.size() >= 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))
s.remove_prefix(2);
const auto digit = [](char c) -> int {
if (c >= '0' && c <= '9') return c - '0';
if (c >= 'a' && c <= 'f') return c - 'a' + 10;
if (c >= 'A' && c <= 'F') return c - 'A' + 10;
return -1;
};
const auto parse_n = [&](size_t off, size_t n) -> std::optional<unsigned> {
unsigned out = 0;
for (size_t i = 0; i < n; ++i) {
const int d = digit(s[off + i]);
if (d < 0)
return std::nullopt;
out = (out << 4) | unsigned(d);
}
return out;
};
bool has_alpha;
bool is_16bpc;
switch (s.size()) {
case 6: has_alpha = false; is_16bpc = false; break;
case 8: has_alpha = true; is_16bpc = false; break;
case 12: has_alpha = false; is_16bpc = true; break;
case 16: has_alpha = true; is_16bpc = true; break;
default: return std::nullopt;
}
const size_t per = is_16bpc ? 4 : 2;
const unsigned full = is_16bpc ? 0xFFFFu : 0xFFu;
unsigned a = full, r, g, b;
size_t off = 0;
if (has_alpha) {
auto av = parse_n(off, per);
if (!av) return std::nullopt;
a = *av;
off += per;
}
auto rv = parse_n(off, per);
if (!rv) return std::nullopt;
r = *rv;
off += per;
auto gv = parse_n(off, per);
if (!gv) return std::nullopt;
g = *gv;
off += per;
auto bv = parse_n(off, per);
if (!bv) return std::nullopt;
b = *bv;
if (is_16bpc) {
return RGB16{ uint16_t(r), uint16_t(g), uint16_t(b), uint16_t(a) };
} else {
const auto rep = [](unsigned x) noexcept {
return uint16_t((x << 8) | x);
};
return RGB16{ rep(r), rep(g), rep(b), rep(a) };
}
}
} // namespace pixpat
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