From 7e9c02441ca43dc8f11ac579e7ca924111ae0da3 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Tue, 13 Jan 2026 17:52:27 -0500
Subject: [PATCH] xo-object2: + DString iterator methods

---
 xo-object2/include/xo/object2/DString.hpp | 19 +++++++
 xo-object2/utest/DString.test.cpp         | 66 +++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/xo-object2/include/xo/object2/DString.hpp b/xo-object2/include/xo/object2/DString.hpp
index 0292c818..7f8e1eeb 100644
--- a/xo-object2/include/xo/object2/DString.hpp
+++ b/xo-object2/include/xo/object2/DString.hpp
@@ -25,9 +25,21 @@ namespace xo {
          **/
         struct DString {
         public:
+            /** @defgroup dstring-types type traits **/
+            ///@{
+            /** character traits for this DString **/
+            using traits_type = std::char_traits<char>;
+            /** type of each character in this DString **/
+            using value_type = char;
             using size_type = std::uint32_t;
+            /** representation for a read/write iterator **/
+            using iterator = char *;
+            /** representation for a readonly iterator **/
+            using const_iterator = const char *;
+            /** xo allocator **/
             using AAllocator = xo::mm::AAllocator;
 
+            ///@}
             /** @defgroup dstring-ctors constructors **/
             ///@{
 
@@ -66,6 +78,13 @@ namespace xo {
             ///@}
             /** @defgroup dstring-iterators iterators **/
             ///@{
+            iterator begin() noexcept { return &chars_[0]; }
+            iterator end() noexcept { return &chars_[size_]; }
+
+            const_iterator cbegin() const noexcept { return &chars_[0]; }
+            const_iterator cend() const noexcept { return &chars_[size_]; }
+            const_iterator begin() const noexcept { return cbegin(); }
+            const_iterator end() const noexcept { return cend(); }
 
             ///@}
             /** @defgroup dstring-assign assignment **/
diff --git a/xo-object2/utest/DString.test.cpp b/xo-object2/utest/DString.test.cpp
index b757c1b6..c6d217f1 100644
--- a/xo-object2/utest/DString.test.cpp
+++ b/xo-object2/utest/DString.test.cpp
@@ -6,7 +6,9 @@
 #include <xo/object2/DString.hpp>
 #include <xo/alloc2/arena/IAllocator_DArena.hpp>
 #include <catch2/catch.hpp>
+#include <cctype>
 #include <cstring>
+#include <string>
 
 namespace xo {
     using xo::scm::DString;
@@ -177,6 +179,70 @@ namespace xo {
 
             REQUIRE(std::strcmp(cstr, "hello") == 0);
         }
+
+        TEST_CASE("DString-begin-end", "[object2][DString]")
+        {
+            ArenaConfig cfg { .name_ = "testarena",
+                              .size_ = 4*1024 };
+            DArena arena = DArena::map(cfg);
+            auto alloc = with_facet<AAllocator>::mkobj(&arena);
+
+            DString * s = DString::from_cstr(alloc, "hello");
+
+            REQUIRE(s->begin() == s->chars());
+            REQUIRE(s->end() == s->chars() + 5);
+            REQUIRE(s->end() - s->begin() == 5);
+
+            *s->begin() = 'H';
+            REQUIRE(std::strcmp(s->chars(), "Hello") == 0);
+        }
+
+        TEST_CASE("DString-cbegin-cend", "[object2][DString]")
+        {
+            ArenaConfig cfg { .name_ = "testarena",
+                              .size_ = 4*1024 };
+            DArena arena = DArena::map(cfg);
+            auto alloc = with_facet<AAllocator>::mkobj(&arena);
+
+            DString * s = DString::from_cstr(alloc, "hello");
+
+            REQUIRE(s->cbegin() == s->chars());
+            REQUIRE(s->cend() == s->chars() + 5);
+            REQUIRE(s->cend() - s->cbegin() == 5);
+        }
+
+        TEST_CASE("DString-range-for", "[object2][DString]")
+        {
+            ArenaConfig cfg { .name_ = "testarena",
+                              .size_ = 4*1024 };
+            DArena arena = DArena::map(cfg);
+            auto alloc = with_facet<AAllocator>::mkobj(&arena);
+
+            DString * s = DString::from_cstr(alloc, "hello");
+
+            std::string result;
+            for (char c : *s) {
+                result += c;
+            }
+
+            REQUIRE(result == "hello");
+        }
+
+        TEST_CASE("DString-iterator-modify", "[object2][DString]")
+        {
+            ArenaConfig cfg { .name_ = "testarena",
+                              .size_ = 4*1024 };
+            DArena arena = DArena::map(cfg);
+            auto alloc = with_facet<AAllocator>::mkobj(&arena);
+
+            DString * s = DString::from_cstr(alloc, "hello");
+
+            for (auto it = s->begin(); it != s->end(); ++it) {
+                *it = std::toupper(*it);
+            }
+
+            REQUIRE(std::strcmp(s->chars(), "HELLO") == 0);
+        }
     } /*namespace ut*/
 } /*namespace xo*/