12.1 The Pascal preprocessor

gpcpp is based on the C preprocessor, so it does everything cpp does (see the cpp manual) and some more. In particular:

• Comments like cpp does, but within { ... } and (* ... *), also after // if delphi-comments is active, never within /* ... */. Also mixed comments ({ ... *), (* ... }) if enabled (mixed-comments) and nested comments (e.g. { ... { ... } ... }) if enabled (nested-comments)
• Macros and conditionals like cpp does, but both case sensitive and insensitive ones; no-macros to turn macro expansion off (e.g., for BP compatibility)
• ifopt for short and long options
• Include files like cpp does, but also with {$I ...} (BP style), which allows the file name extension to be omitted
• Recognize Pascal strings (to avoid looking for comments and directives within strings) enclosed in single (like Standard Pascal) or double quotes (like C).
• Option handling, sharing tables in gpc-options.h with the compiler:
  • Default option settings
  • Options can imply other options (e.g., borland-pascal -> no-macros etc.)
  • Short compiler directives
  • Short directive W (warnings) is disabled in borland-pascal and delphi because it has another meaning there
• Compiler directives ({$...} or (*$...*)):
  • pass them through, so the compiler can handle them
  • keep track of them for ifopt
  • handle those that affect the preprocessor (e.g., about comments)
  • allow comments within compiler directives if nested comments are enabled
  • local directives
  • case insensitive
• Slightly Pascal-like syntax for conditional compilation (not -> !, and -> &&, or -> ||, xor -> !=, shl -> <<, shr -> >>, False -> 0, True -> 1, <> -> !=, = -> ==)
• Line directives like cpp does, but recognize BP style (#42 or #$f0) character constants and don't confuse them with line directives (the latter seem to always have a space after the #)