zstring_span: fix for Expects, simplify functions

- `s[s.size() - 1]` is wrong for empty `s`, so `Expects(s.size() > 0)`
- no hard coded `'\0'`but `value_type{}`
- hard code `empty()` to return `false`
- simplify `as_string_span`: can never be `empty`
- clarify comment on `ensure_z`
This commit is contained in:
Werner Henze 2020-08-06 11:25:29 +02:00
parent f8d9f2e2e3
commit 2231d733c6

View File

@ -120,9 +120,8 @@ span<T, dynamic_extent> ensure_sentinel(T* seq,
}
//
// ensure_z - creates a span for a zero terminated strings.
// Will fail fast if a null-terminator cannot be found before
// the limit of size_type.
// ensure_z - creates a span for a zero terminated strings. The span will not contain the zero termination.
// Will fail fast if a null-terminator cannot be found before the limit of size_type.
//
template <typename CharT>
span<CharT, dynamic_extent> ensure_z(CharT* const& sz,
@ -395,7 +394,8 @@ public:
constexpr basic_zstring_span(impl_type s) : span_(s)
{
// expects a zero-terminated span
Expects(s[s.size() - 1] == '\0');
Expects(s.size() > 0);
Expects(s[s.size() - 1] == value_type{});
}
// copy
@ -410,12 +410,11 @@ public:
// move assign
constexpr basic_zstring_span& operator=(basic_zstring_span&& other) = default;
constexpr bool empty() const noexcept { return span_.size() == 0; }
constexpr bool empty() const noexcept { return false; }
constexpr string_span_type as_string_span() const noexcept
{
const auto sz = span_.size();
return {span_.data(), sz > 1 ? sz - 1 : 0};
return {span_.data(), span_.size() - 1};
}
constexpr string_span_type ensure_z() const { return gsl::ensure_z(span_); }