doc: start to refactor doc

doc/src/premise_and_principle.dox

@@ -0,0 +1,38 @@
+/**
+
+\page premise_and_principle Premise and Principle
+
+When programming with this library, there is some premise and principle you should noticed.
+
+\section premise_and_principle__exception_is_error Exception is Error
+
+The most crucial spot of this library is <B>"Exception is Error"</B>.
+When some functions throw exception, it should cause program paniked, rather than recover from it.
+This is inspired from Rust, and also the compromise with STL.
+
+Most functions this library provided has Rust-Result-like return value.
+It means that programmer can handle error correctly.
+However, this library is based on STL, another library that may throw C++ exception to indicate error.
+We can not control this behavior of STL, so I forcely apply this rule.
+
+\section premise_and_principle__os_encoding OS Encoding
+
+This library has special treat with Windows to make it works on Windows.
+However, for other operating system, it do not have too much care.
+We brutally make a premise that other operating systems are UNIX-liked and use UTF8 as its encoding.
+
+\section premise_and_principle__string_encoding String Encoding
+
+Before using this library, you should know the encoding strategy of this library first.
+In short words, this library use UTF8 encoding everywhere except some special cases list following (not all).
+
+\li Traditional format function in yycc::string::op.
+Traditional format function provide some overloads for ordinary string formatting.
+That's because this feature is so common to use in some cases.
+\li The message of Rust panic in yycc::rust::panic.
+Due to the limitation of \c std::format, we only can use ordinary string as its message content.
+\li The message of standard library exception.
+For the compatibility with C++ standard library exception,
+we only can use ordinary string as the message of exception.
+
+*/