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Improve iterator handling in scan

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This commit is contained in:
Victor Zverovich 2023-12-29 06:34:49 -08:00
parent a3bf40838f
commit bfba2f9e92
1 changed files with 13 additions and 17 deletions
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30
test/scan.h
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@ -395,8 +395,10 @@ struct scan_handler : error_handler {
int next_arg_id_;
scan_arg arg_;
template <typename T = unsigned> auto read_uint() -> optional<T> {
auto it = scan_ctx_.begin(), end = scan_ctx_.end();
using iterator = scan_buffer::iterator;
template <typename T = unsigned> auto read_uint(iterator& it) -> optional<T> {
auto end = scan_ctx_.end();
if (it == end) return {};
char c = *it;
if (c < '0' || c > '9') on_error("invalid input");
@ -412,7 +414,6 @@ struct scan_handler : error_handler {
++num_digits;
if (c < '0' || c > '9') break;
} while (it != end);
scan_ctx_.advance_to(it);
// Check overflow.
if (num_digits <= std::numeric_limits<int>::digits10) return value;
@ -424,14 +425,11 @@ struct scan_handler : error_handler {
throw format_error("number is too big");
}
template <typename T = int> auto read_int() -> optional<T> {
auto it = scan_ctx_.begin(), end = scan_ctx_.end();
template <typename T = int> auto read_int(iterator& it) -> optional<T> {
auto end = scan_ctx_.end();
bool negative = it != end && *it == '-';
if (negative) {
++it;
scan_ctx_.advance_to(it);
}
if (auto abs_value = read_uint<typename std::make_unsigned<T>::type>()) {
if (negative) ++it;
if (auto abs_value = read_uint<typename std::make_unsigned<T>::type>(it)) {
auto value = static_cast<T>(*abs_value);
return negative ? -value : value;
}
@ -469,24 +467,22 @@ struct scan_handler : error_handler {
void on_replacement_field(int, const char*) {
auto it = scan_ctx_.begin(), end = scan_ctx_.end();
while (it != end && is_whitespace(*it)) ++it;
scan_ctx_.advance_to(it);
switch (arg_.type) {
case scan_type::int_type:
if (auto value = read_int()) *arg_.int_value = *value;
if (auto value = read_int(it)) *arg_.int_value = *value;
break;
case scan_type::uint_type:
if (auto value = read_uint()) *arg_.uint_value = *value;
if (auto value = read_uint(it)) *arg_.uint_value = *value;
break;
case scan_type::long_long_type:
if (auto value = read_int<long long>()) *arg_.long_long_value = *value;
if (auto value = read_int<long long>(it)) *arg_.long_long_value = *value;
break;
case scan_type::ulong_long_type:
if (auto value = read_uint<unsigned long long>())
if (auto value = read_uint<unsigned long long>(it))
*arg_.ulong_long_value = *value;
break;
case scan_type::string_type:
while (it != end && *it != ' ') arg_.string->push_back(*it++);
scan_ctx_.advance_to(it);
break;
case scan_type::string_view_type: {
auto range = to_contiguous(it);
@ -497,13 +493,13 @@ struct scan_handler : error_handler {
size_t size = to_unsigned(p - range.begin);
*arg_.string_view = {range.begin, size};
advance(it, size);
scan_ctx_.advance_to(it);
break;
}
case scan_type::none_type:
case scan_type::custom_type:
assert(false);
}
scan_ctx_.advance_to(it);
}
auto on_format_specs(int, const char* begin, const char*) -> const char* {