Use a raw string literal in the alt-string json_view test

clang-tidy (modernize-raw-string-literal) rejects the escaped literal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

docs/mkdocs/docs/features/types/template_parameters.md

@@ -406,6 +406,7 @@ using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
 | `#!cpp operator<<(std::ostream&, const json_pointer&)`                                                                            | streamability to `#!cpp std::ostream`                                                                                                                                                        |
 | [`to_string`](../../api/basic_json/to_string.md)                                                                                  | conversion of `StringType` to `#!cpp std::string` (the function returns a `#!cpp std::string`)                                                                                               |
 | exception messages                                                                                                                | `data()` and `size()`, or `begin()` and `end()`                                                                                                                                              |
+| [`basic_json_view::dump`](../../api/basic_json_view/dump.md)                                                                      | `reserve(n)` and `resize(n)` (one argument); `capacity()` is **not** required                                                                                                                |
 
 ### Compatible types
 

include/nlohmann/detail/view/serializer.hpp

@@ -47,6 +47,7 @@ class output_buffer
         : m_out(sized(out, estimate))
         , m_pos(&m_out[0])
         , m_end(m_pos + m_out.size())
+        , m_reserved((std::max)(estimate, m_out.size()))
     {}
 
     void finish()
@@ -116,11 +117,12 @@ class output_buffer
         const auto used = static_cast<std::size_t>(m_pos - m_out.data());
         // (a step does not go beyond the reserved estimate, so that a good
         // estimate is never copied to a larger allocation; not a clamp: the
-        // lower bound used + n + 256 can exceed capacity(), and then it must win)
+        // lower bound used + n + 256 can exceed m_reserved, and then it must win)
-        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_out.capacity()), used + n + 256);
+        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_reserved), used + n + 256);
-        if (size > m_out.capacity())
+        if (size > m_reserved)
         {
-            m_out.reserve((std::max)(m_out.capacity() * 2, size));
+            m_reserved = (std::max)(m_reserved * 2, size);
+            m_out.reserve(m_reserved);
         }
         m_out.resize(size);
         m_pos = &m_out[0] + used;
@@ -130,6 +132,9 @@ class output_buffer
     StringType& m_out;
     char* m_pos;
     char* m_end;
+    /// what was last passed to reserve(), a lower bound of the capacity
+    /// (StringType need not have a capacity() member)
+    std::size_t m_reserved;
 };
 
 /// The length of the run at s that dump() writes unchanged without

single_include/nlohmann/json_view.hpp

@@ -8511,6 +8511,7 @@ class output_buffer
         : m_out(sized(out, estimate))
         , m_pos(&m_out[0])
         , m_end(m_pos + m_out.size())
+        , m_reserved((std::max)(estimate, m_out.size()))
     {}
 
     void finish()
@@ -8580,11 +8581,12 @@ class output_buffer
         const auto used = static_cast<std::size_t>(m_pos - m_out.data());
         // (a step does not go beyond the reserved estimate, so that a good
         // estimate is never copied to a larger allocation; not a clamp: the
-        // lower bound used + n + 256 can exceed capacity(), and then it must win)
+        // lower bound used + n + 256 can exceed m_reserved, and then it must win)
-        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_out.capacity()), used + n + 256);
+        const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_reserved), used + n + 256);
-        if (size > m_out.capacity())
+        if (size > m_reserved)
         {
-            m_out.reserve((std::max)(m_out.capacity() * 2, size));
+            m_reserved = (std::max)(m_reserved * 2, size);
+            m_out.reserve(m_reserved);
         }
         m_out.resize(size);
         m_pos = &m_out[0] + used;
@@ -8594,6 +8596,9 @@ class output_buffer
     StringType& m_out;
     char* m_pos;
     char* m_end;
+    /// what was last passed to reserve(), a lower bound of the capacity
+    /// (StringType need not have a capacity() member)
+    std::size_t m_reserved;
 };
 
 /// The length of the run at s that dump() writes unchanged without

tests/src/unit-alt-string.cpp

@@ -10,6 +10,7 @@
 #include "doctest_compatibility.h"
 
 #include <nlohmann/json.hpp>
+#include <nlohmann/json_view.hpp>
 
 #include <cstdint>
 #include <string>
@@ -483,4 +484,56 @@ TEST_CASE("alternative string type")
     }
 }
 
+TEST_CASE("alternative string type with json_view")
+{
+    // regression test for #5994: basic_json_view::dump() called
+    // StringType::capacity(), which alt_string (and the documented StringType
+    // requirements) do not provide
+    using alt_document = nlohmann::basic_json_document<alt_json, nlohmann::view_mode::read_only>;
+    using alt_editable_document = nlohmann::basic_json_document<alt_json, nlohmann::view_mode::editable>;
+
+    const char* text = R"({"a":[1,"x\u00e4"],"b":{"c":true,"d":null},"e":2.5})";
+    const alt_json j = alt_json::parse(text);
+
+    SECTION("read-only document")
+    {
+        const alt_document d = alt_document::parse(text);
+        CHECK(d.root().dump() == j.dump());
+        CHECK(d.root().dump(2) == j.dump(2));
+        CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
+        CHECK(d.root().materialize() == j);
+        CHECK(d.root().contains(alt_string("b")));
+        CHECK(d.root()[alt_string("b")][alt_string("c")].dump() == "true");
+    }
+
+    SECTION("long output")
+    {
+        // more than one growth step of the output buffer
+        alt_json big = alt_json::array();
+        for (int i = 0; i < 20000; ++i)
+        {
+            big.push_back(alt_json::parse(text));
+        }
+        const alt_string big_text = big.dump();
+        const alt_document d = alt_document::parse(big_text);
+        CHECK(d.root().dump() == big_text);
+        CHECK(d.root().dump(4) == big.dump(4));
+    }
+
+    SECTION("editable document")
+    {
+        alt_editable_document d = alt_editable_document::parse(text);
+        d.set(d.root(), "f", "new");
+        d.push_back(d.root()[alt_string("a")], 3);
+        alt_json expected = j;
+        expected["f"] = "new";
+        expected["a"].push_back(3);
+        CHECK(d.root().materialize() == expected);
+        CHECK(alt_json::parse(d.root().dump()) == expected);
+
+        const alt_editable_document loaded = alt_editable_document::load(d.save());
+        CHECK(loaded.root().materialize() == expected);
+    }
+}
+
 DOCTEST_CLANG_SUPPRESS_WARNING_POP