src: make it easy to print strings

StringBuilder is utility struct. Connects Format..() functions with
your allocated string.
Abstracting creating string is eases printing messages to user.

include/StringBuilder.h

@@ -0,0 +1,72 @@
+#include "memory.h"
+#include "text.h"
+
+struct string_builder {
+  struct string *outBuffer;
+  struct string *stringBuffer;
+  u64 length;
+};
+
+static inline void
+StringBuilderAppendString(struct string_builder *stringBuilder, struct string *string)
+{
+  struct string *outBuffer = stringBuilder->outBuffer;
+  memcpy(outBuffer->value + stringBuilder->length, string->value, string->length);
+  stringBuilder->length += string->length;
+  debug_assert(stringBuilder->length <= outBuffer->length);
+}
+
+static inline void
+StringBuilderAppendU64(struct string_builder *stringBuilder, u64 value)
+{
+  struct string *outBuffer = stringBuilder->outBuffer;
+  struct string *stringBuffer = stringBuilder->stringBuffer;
+
+  struct string string = FormatU64(stringBuffer, value);
+  memcpy(outBuffer->value + stringBuilder->length, string.value, string.length);
+  stringBuilder->length += string.length;
+  debug_assert(stringBuilder->length <= outBuffer->length);
+}
+
+static inline void
+StringBuilderAppendHex(struct string_builder *stringBuilder, u64 value)
+{
+  struct string *outBuffer = stringBuilder->outBuffer;
+  struct string *stringBuffer = stringBuilder->stringBuffer;
+
+  struct string string = FormatHex(stringBuffer, value);
+  memcpy(outBuffer->value + stringBuilder->length, string.value, string.length);
+  stringBuilder->length += string.length;
+  debug_assert(stringBuilder->length <= outBuffer->length);
+}
+
+static inline void
+StringBuilderAppendF32(struct string_builder *stringBuilder, f32 value, u64 fractionCount)
+{
+  struct string *outBuffer = stringBuilder->outBuffer;
+  struct string *stringBuffer = stringBuilder->stringBuffer;
+
+  struct string string = FormatF32(stringBuffer, value, fractionCount);
+  memcpy(outBuffer->value + stringBuilder->length, string.value, string.length);
+  stringBuilder->length += string.length;
+  debug_assert(stringBuilder->length <= outBuffer->length);
+}
+
+/*
+ * Returns string that is ready for transmit.
+ * Also resets length of builder.
+ *
+ * @code
+ *   StringBuilderAppend..(stringBuilder, x);
+ *   struct string string = StringBuilderFlush(stringBuilder);
+ *   write(x, string.value, string.length);
+ * @endcode
+ */
+static inline struct string
+StringBuilderFlush(struct string_builder *stringBuilder)
+{
+  struct string *outBuffer = stringBuilder->outBuffer;
+  struct string result = (struct string){.value = outBuffer->value, .length = stringBuilder->length};
+  stringBuilder->length = 0;
+  return result;
+}

meson.build

@@ -14,6 +14,7 @@ add_project_arguments(
     '-funroll-loops',
     '-fomit-frame-pointer',
 
+    '-Wno-unused-result',
     '-Wno-unused-function',
 
     '-DCOMPILER_GCC=' + (cc.get_id() == 'gcc').to_int().to_string(),