142 lines
4.4 KiB
C++
142 lines
4.4 KiB
C++
/** @file DString.hpp
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*
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* @author Roland Conybeare, Jan 2026
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**/
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#pragma once
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#include <xo/alloc2/Allocator.hpp>
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#include <xo/facet/obj.hpp>
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#include <string_view>
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#include <cstdint>
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namespace xo {
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namespace scm {
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/** @class DString
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* @brief String implementation with gc hooks
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*
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* String implementation for Schematika.
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* Size-prefixed and null-terminated.
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* Note however that string length != size for utf-8.
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*
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* Uses flexible array for chars,
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* with string contents in memory immediately
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* following the DString itself
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**/
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struct DString {
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public:
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using size_type = std::uint32_t;
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using AAllocator = xo::mm::AAllocator;
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/** @defgroup dstring-ctors constructors **/
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///@{
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/** create empty string with space for @cap chars
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* (including null terminator).
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* Use memory from allocator @p mm
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**/
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static DString * empty(obj<AAllocator> mm,
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size_type cap);
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/** create string containing a copy of null-terminated @p cstr.
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* Use memory from allocator @p mm
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**/
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static DString * from_cstr(obj<AAllocator> mm,
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const char * cstr);
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///@}
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/** @defgroup dstring-access access methods **/
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///@{
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/** get writeable access to string representation.
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* Caller responsible for calling fixup() if string length modified
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**/
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char * data() noexcept { return chars_; }
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/** return char at position @p pos in this string, counting from zero.
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* Does not check bounds. Undefined behavior if @p pos = @ref capacity_
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**/
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char & operator[](size_type pos) noexcept { return chars_[pos]; }
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const char & operator[](size_type pos) const noexcept { return chars_[pos]; }
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size_type capacity() const noexcept { return capacity_; }
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size_type size() const noexcept { return size_; }
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const char * chars() const noexcept { return chars_; }
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///@}
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/** @defgroup dstring-iterators iterators **/
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///@{
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///@}
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/** @defgroup dstring-assign assignment **/
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///@{
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/** put string into empty state **/
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void clear() noexcept { size_ = 0; chars_[0] = '\0'; }
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/** replace contents with @p other, or prefix of up to @p capacity - 1 chars **/
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DString & assign(const DString & other);
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// TODO - behave like std::string, to the extent feasible
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// insert
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// insert_range
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// erase
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// push_back
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// append
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// append_range
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// operator+=
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// replace
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// replace_with_range
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// copy
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// find
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// rfind
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// find_first_of
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// find_first_not_of
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// find_last_of
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// find_last_not_of
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// compare
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// starts_with
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// end_with
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// contains
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// substr
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/** recalculate string size if string contents modified without
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* through side effects
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**/
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size_type fixup_size() noexcept;
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///@}
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/** @defgroup dstring-conversion-operators conversion operators **/
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///@{
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operator std::string_view() const noexcept { return std::string_view(chars_); }
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/** @brief conversion oeprator to C-style string.
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*
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* Example
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* @code
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* DString s = ...;
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* ::strcmp(s, "obey...");
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* @endcode
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**/
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operator const char * () const noexcept { return &(chars_[0]); }
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///@}
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private:
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/** @defgroup dstring-instance-variables instance variables **/
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///@{
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/** extent of @ref chars_ array **/
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size_type capacity_ = 0;
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/** null terminator at @c chars_[size_] **/
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size_type size_ = 0;
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/** string contents **/
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char chars_[];
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///@}
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end DString.hpp */
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