From 552186ad51ef68589b96bb32695775a7b6cc90c2 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Wed, 30 Nov 2022 12:36:21 +0100
Subject: [PATCH] Add string_format and vstring_format

---
 luna/Format.cpp | 39 +++++++++++++++++++++++++++++++++++++++
 luna/Format.h   |  4 +++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/luna/Format.cpp b/luna/Format.cpp
index 7d086876..f3b1c62a 100644
--- a/luna/Format.cpp
+++ b/luna/Format.cpp
@@ -467,4 +467,43 @@ Result<usize> cstyle_format(const char* format, callback_t callback, void* arg,
     }
 
     return state.count;
+}
+
+struct StringFormatInfo
+{
+    char* buffer;
+    size_t remaining;
+};
+
+Result<usize> vstring_format(char* buf, size_t max, const char* format, va_list ap)
+{
+    StringFormatInfo info = {.buffer = buf, .remaining = max - 1};
+
+    usize result = TRY(cstyle_format(
+        format,
+        [](char c, void* arg) -> Result<void> {
+            StringFormatInfo* info_arg = (StringFormatInfo*)arg;
+            if (!info_arg->remaining) return {};
+            *(info_arg->buffer) = c;
+            info_arg->buffer++;
+            info_arg->remaining--;
+            return {};
+        },
+        &info, ap));
+
+    *(info.buffer) = 0;
+
+    return result;
+}
+
+Result<usize> string_format(char* buf, size_t max, const char* format, ...)
+{
+    va_list ap;
+    va_start(ap, format);
+
+    usize result = TRY(vstring_format(buf, max, format, ap));
+
+    va_end(ap);
+
+    return result;
 }
\ No newline at end of file
diff --git a/luna/Format.h b/luna/Format.h
index 1d06050e..3ad779f2 100644
--- a/luna/Format.h
+++ b/luna/Format.h
@@ -5,4 +5,6 @@
 
 typedef Result<void> (*callback_t)(char, void*);
 
-Result<usize> cstyle_format(const char* format, callback_t callback, void* arg, va_list ap);
\ No newline at end of file
+Result<usize> cstyle_format(const char* format, callback_t callback, void* arg, va_list ap);
+Result<usize> vstring_format(char* buf, size_t max, const char* format, va_list ap);
+Result<usize> string_format(char* buf, size_t max, const char* format, ...);
\ No newline at end of file