The STYX system comes up with a macro preprocessing facility -
based on the following macro definition syntax and evaluation process
during the lexical analysis:
| #include Path | supports modular grammar design
The macro will be replaced by the content of source file 'Path' and then rescanned. |
| #macro Name ( FormalParameter , ... ) = Text #end | supports text replacement
Parameter and replacement text are optional. The macro will be collected by the preprocessing module and skipped by the scanner. A macro expression ( Name ActualParameter Delimiter ... ) will be replaced by the previous definition and then rescanned. |
| ' Delimiter | introduces another - the second - character as delimiter for the
actual macro parameter.
Spaces will be used as default delimiter. To reactive the default behaviour specify ' -. The scanner skips these token. |
| #undefine Name | revokes a previous definition |
| #if[n]def Name IfPart #else ElsePart #end | supports conditional parsing
Dependant on the existence of macro 'Name' the scanner skips the 'ElsePart' or 'IfPart'. Its possible to introduce environment variables as macros. |
You can use this preprocessing facility if your regular grammar defines
the above kind of macros in the same way -
apart from token names and keywords.
( see below and styx reference )
Note:
The reentrant version of the preprocessing module expects that the
preprocessor ( constructed by the function 'SPP_init_reentrant' )
will be added to the scan stream as value of the context variable 'SPP_premac'.
| SPP_T | Abstract preprocessing type |
Identifier for the ( macro ) token names
#define SPP_TOK_IDE 0 // Identifier #define SPP_TOK_MACDFN 1 // Macro #define SPP_TOK_MACSEP 2 // Delimiter #define SPP_TOK_MACINC 3 // Include #define SPP_TOK_MACCOND 4 // Condition #define SPP_TOK_MACDEL 5 // Undefine
Identifier for macro token keywords
#define SPP_PAT_START 6 // #macro #define SPP_PAT_END 7 // #end #define SPP_PAT_IFDEF 8 // #ifdef #define SPP_PAT_IFNDEF 9 // #ifndef #define SPP_PAT_ELSE 10 // #else #define SPP_PAT_INC 11 // #include #define SPP_PAT_UNDEFINE 12 // #undefine
Identifier for include path and character set
#define SPP_INC_PATH 13 #define SPP_INC_CHARSET 14
void SPP_init(MAP(long,symbol) pPreParMap) | initializes STYX-konform macro preprocessing 'pPreParMap': re-definitions for macro token names, initial macro token keywords, include path and characterset |
SPP_T SPP_init_reentrant(MAP(long,symbol) pPreParMap) | reentrant version of SPP_init |
void SPP_addCtxMacro(symbol pMacNam) | adds ( lower case symbol ) 'pMacNam' as pre-defined macro |
void SPP_addCtxMacro_reentrant(SPP_T pPP, symbol pMacNam) | reentrant version of SPP_addCtxMacro |
void SPP_quit(void) | terminates STYX-konform macro preprocessing |
void SPP_quit_reentrant(SPP_T pPP) | reentrant version of SPP_quit |
int SPP_premac
(
Scn_Stream pStream, c_string cTokNam, c_string cTokVal, symbol* cMacVal
)
| preprocesses current token of non-binary scan stream 'pStream' 'cTokNam': name of separated token 'cTokVal': value of separated token 'cMacVal': preprocessing result ( see [scn_base] ) ( cTokNam, cTokVal: single byte or utf-8 characterset ) |