From 45091789eb9e49856ea6c2f3606639d43f4584e7 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Mon, 13 Apr 2026 14:56:39 +0200
Subject: kstd: move formatting implementation to kstd

---
 libs/kstd/src/vformat.cpp | 224 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 224 insertions(+)
 create mode 100644 libs/kstd/src/vformat.cpp

(limited to 'libs/kstd/src')

diff --git a/libs/kstd/src/vformat.cpp b/libs/kstd/src/vformat.cpp
new file mode 100644
index 0000000..51aca84
--- /dev/null
+++ b/libs/kstd/src/vformat.cpp
@@ -0,0 +1,224 @@
+#include <kstd/format>
+#include <kstd/string>
+
+#include <algorithm>
+#include <cstddef>
+#include <iterator>
+#include <string_view>
+#include <utility>
+
+namespace kstd::bits::format
+{
+
+  auto vformat_to(output_buffer & buffer, std::string_view format, format_args args) -> void
+  {
+    auto context = kstd::format_context{buffer, args};
+    auto parse_context = kstd::format_parse_context{format, args.size()};
+
+    auto it = parse_context.begin();
+    auto end = parse_context.end();
+
+    while (it != end)
+    {
+      if (*it != '{' && *it != '}')
+      {
+        auto start = it;
+        while (it != end && *it != '{' && *it != '}')
+        {
+          std::advance(it, 1);
+        }
+        parse_context.advance_to(it);
+        context.push(std::string_view(start, it - start));
+        continue;
+      }
+
+      if (*it == '{')
+      {
+        std::advance(it, 1);
+        if (it != end && *it == '{')
+        {
+          context.push('{');
+          std::advance(it, 1);
+          parse_context.advance_to(it);
+          continue;
+        }
+
+        parse_context.advance_to(it);
+        auto index = 0uz;
+
+        if (it != end && *it >= '0' && *it <= '9')
+        {
+          while (it != end && *it >= '0' && *it <= '9')
+          {
+            index = index * 10 + static_cast<std::size_t>(*it - '0');
+            std::advance(it, 1);
+          }
+          parse_context.check_arg_id(index);
+        }
+        else
+        {
+          index = parse_context.next_arg_id();
+        }
+
+        if (it != end && *it == ':')
+        {
+          std::advance(it, 1);
+        }
+
+        parse_context.advance_to(it);
+
+        if (index < args.size())
+        {
+          auto const & arg = args[index];
+          switch (arg.type)
+          {
+            case kstd::bits::format::arg_type::boolean:
+            {
+              auto fmt = kstd::formatter<bool>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.boolean, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::character:
+            {
+              auto fmt = kstd::formatter<char>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.character, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::integer:
+            {
+              auto fmt = kstd::formatter<long long>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.integer, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::unsigned_integer:
+            {
+              auto fmt = kstd::formatter<unsigned long long>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.unsigned_integer, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::string_view:
+            {
+              auto fmt = kstd::formatter<std::string_view>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.string_view, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::c_string:
+            {
+              auto fmt = kstd::formatter<char const *>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.c_string, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::pointer:
+            {
+              auto fmt = kstd::formatter<void const *>{};
+              auto const parsed = fmt.parse(parse_context);
+              parse_context.advance_to(parsed);
+              fmt.format(arg.value.pointer, context);
+              break;
+            }
+            case kstd::bits::format::arg_type::user_defined:
+            {
+              if (arg.value.user_defined.format)
+              {
+                arg.value.user_defined.format(arg.value.user_defined.pointer, parse_context, context);
+              }
+              else
+              {
+                context.push("{?}");
+              }
+              break;
+            }
+            default:
+            {
+              context.push("{fmt-err: unknown-type}");
+              break;
+            }
+          }
+        }
+        else
+        {
+          context.push("{fmt-err: bound}");
+        }
+
+        it = parse_context.begin();
+
+        if (it != end && *it == '}')
+        {
+          std::advance(it, 1);
+          parse_context.advance_to(it);
+        }
+        else
+        {
+          context.push("{fmt-err: unconsumed}");
+          while (it != end && *it != '}')
+          {
+            std::advance(it, 1);
+          }
+
+          if (it != end)
+          {
+            std::advance(it, 1);
+            parse_context.advance_to(it);
+          }
+        }
+      }
+      else if (*it == '}')
+      {
+        std::advance(it, 1);
+        if (it != end && *it == '}')
+        {
+          context.push('}');
+          std::advance(it, 1);
+          parse_context.advance_to(it);
+        }
+        else
+        {
+          context.push("{fmt-err: unescaped}");
+          parse_context.advance_to(it);
+        }
+      }
+    }
+  }
+
+  auto string_writer::push(std::string_view text) -> void
+  {
+    m_result.append(text);
+  }
+
+  auto string_writer::push(char character) -> void
+  {
+    m_result.push_back(character);
+  }
+
+  auto string_writer::release() -> string &&
+  {
+    return std::move(m_result);
+  }
+
+  string_iterator_writer::string_iterator_writer(string::iterator it)
+      : m_iter{it}
+  {}
+
+  auto string_iterator_writer::push(std::string_view text) -> void
+  {
+    std::ranges::for_each(text, [this](auto c) { push(c); });
+  }
+
+  auto string_iterator_writer::push(char character) -> void
+  {
+    *m_iter++ = character;
+  }
+
+}  // namespace kstd::bits::format
\ No newline at end of file
-- 
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