Preprocessor

Preprocessing Files

MTSC includes a heavily modified C/C++ preprocessor based on Boost Wave. For compatibility, it is gated behind the -p/--preprocessor CLI flag. Since #abc is already valid JavaScript for ES6 private class fields, MTSC instead looks for preprocessor directives within single-line triple-slash comments (e.g. ///#define ...).

Directives

Unless otherwise stated, the following directives behave like their C/C++ counterparts. Unknown directives raise a warning.

Macro Directives

• ///#define
  • Variadics and placemarkers are supported
• ///#undef

Control Directives

• ///#if
  • Supports defined() and __has_include()
• ///#ifdef
• ///#ifndef
• ///#else
• ///#elif
• ///#endif

Misc Directives

• ///#include
• ///#include_next
• ///#error
• ///#warning
• ///#line
• ///#pragma
• ///#embed
  • Only supports the ///#embed "path/to/file..." form
  • The byte contents of the relative file are inserted as comma separated hex literals

Pragmas

The forms ///#pragma arg, _Pragma(arg), and __pragma(arg) all work as normal. Unless otherwise stated, the following pragma options behave like their C/C++ counterparts. Unknown pragma options raise a warning.

Common Pragmas

• ///#pragma once
• ///#pragma region
  • Accepted, but does nothing
• ///#pragma endregion
  • Accepted, but does nothing

MTSC Specific Pragmas

• ///#pragma mtsc line(arg)
  • Acts as an extended form of ///#line
  • If arg starts with a + or -, the current line number is shifted down or up respectively by the number of lines following the sign
  • If arg has no sign, this sets the current line number to the value of arg
  • Because of this, line(123), line(+123), and line(-123) all act different
• ///#pragma mtsc eval(arg)
  • Experimental and not yet documented

Macros

Unless otherwise stated, the following macros behave like their C/C++ counterparts.

Common Macros

• __LINE__
• __FILE__
• __BASE_FILE__
• __DATE__
• __TIME__
• __INCLUDE_LEVEL__

MTSC Specific Macros

• __MTSC_VERSION__
  • A string constant with the current version number (e.g., "5.4.2")
• __NEWLINE__
  • Holds a newline token to allow embedding newlines in macro values
• __MAIN__
  • 1 if in __BASE_FILE__ and 0 otherwise
  • Can be used with ///#if to make a script executable or act as a library depending on compilation