libluna: Add StringBuilder

libluna/CMakeLists.txt

@@ -14,6 +14,7 @@ set(FREESTANDING_SOURCES
     src/Buffer.cpp
     src/Stack.cpp
     src/String.cpp
+    src/StringBuilder.cpp
     src/StringView.cpp
     src/Utf8.cpp
     src/TarStream.cpp

libluna/include/luna/StringBuilder.h

@@ -0,0 +1,22 @@
+#pragma once
+#include <luna/Buffer.h>
+#include <luna/String.h>
+
+class StringBuilder
+{
+  public:
+    Result<void> add(const String& value);
+    Result<void> add(StringView value);
+    Result<void> add(void* value);
+    Result<void> add(long value);
+    Result<void> add(unsigned long value);
+    Result<void> add(char value);
+
+    Result<void> format(StringView fmt, ...);
+    Result<void> vformat(StringView fmt, va_list ap);
+
+    Result<String> string();
+
+  private:
+    Buffer m_data;
+};

libluna/src/StringBuilder.cpp

@@ -0,0 +1,65 @@
+#include <luna/Format.h>
+#include <luna/StringBuilder.h>
+#include <luna/Vector.h>
+
+Result<void> StringBuilder::add(StringView value)
+{
+    return m_data.append_data((const u8*)value.chars(), value.length());
+}
+
+Result<void> StringBuilder::add(const String& value)
+{
+    return add(value.view());
+}
+
+Result<void> StringBuilder::add(void* value)
+{
+    return format("%p"_sv, value);
+}
+
+Result<void> StringBuilder::add(long value)
+{
+    return format("%li"_sv, value);
+}
+
+Result<void> StringBuilder::add(unsigned long value)
+{
+    return format("%lu"_sv, value);
+}
+
+Result<void> StringBuilder::add(char value)
+{
+    return format("%c"_sv, value);
+}
+
+Result<void> StringBuilder::format(StringView fmt, ...)
+{
+    va_list ap;
+    va_start(ap, fmt);
+
+    auto rc = vformat(fmt, ap);
+
+    va_end(ap);
+
+    return rc;
+}
+
+Result<void> StringBuilder::vformat(StringView fmt, va_list ap)
+{
+    Vector<char> temp;
+
+    TRY(cstyle_format(
+        fmt.chars(), [](char c, void* buf) -> Result<void> { return ((Vector<char>*)buf)->try_append(c); }, &temp, ap));
+
+    TRY(m_data.append_data((u8*)temp.data(), temp.size()));
+
+    return {};
+}
+
+Result<String> StringBuilder::string()
+{
+    char nul = '\0';
+    TRY(m_data.append_data((u8*)&nul, 1));
+
+    return String::from_cstring((const char*)m_data.data());
+}