/*------------------------------------------------------------------------- richlex.c - Lexical analysis routines for parsing richtext messages. Copyright (c) 1992 Rhys Weatherley Permission to use, copy, modify, and distribute this material for any purpose and without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies, and that the name of Rhys Weatherley not be used in advertising or publicity pertaining to this material without specific, prior written permission. RHYS WEATHERLEY MAKES NO REPRESENTATIONS ABOUT THE ACCURACY OR SUITABILITY OF THIS MATERIAL FOR ANY PURPOSE. IT IS PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. Revision History: ================ Version DD/MM/YY By Description ------- -------- -- -------------------------------------- 1.0 31/01/92 RW Original Version of richlex.c You may contact the author by: ============================= e-mail: rhys@cs.uq.oz.au mail: Rhys Weatherley 5 Horizon Drive Jamboree Heights Queensland 4074 Australia -------------------------------------------------------------------------*/ #include #include "richlex.h" #include int CorrectionEnabled = 1; /* Zero if correction has been disabled */ #ifndef AMIGA extern int fgetc (); extern int fputc (); #endif int (*RichtextGetc) () = fgetc; /* Function to call to get characters */ int (*RichtextPutc) () = fputc; /* Function to call to put characters */ #define RGET(f) ((*RichtextGetc)(f)) #define RPUT(c,f) ((*RichtextPutc)(c,f)) #define MAX_STACK_SIZE 500 #define MAX_FLUSH_SIZE 3 static int StackSize=0; static char Stack[MAX_STACK_SIZE][MAX_TOKEN_SIZE]; static char NextToken[MAX_TOKEN_SIZE]; static int FlushStack=0; static int FlushSize=0; static int EndInpFile=0; /* * Reset the richtext parsing mechanism. */ richtextreset() { StackSize = 0; FlushStack = 0; FlushSize = 0; EndInpFile = 0; } /* * Find a match between NextToken and an element on the stack. * Returns the number of elements down from the top it is. * i.e. 0 if not on the stack, 1 if at the top, etc. */ static int richtextmatchup() { int i = StackSize; while (i > 0 && i > (StackSize - MAX_FLUSH_SIZE)) { --i; if (!strcmp(NextToken,Stack[i])) return(StackSize - i); } return(0); } /* * Determine if the current token is one of the singleton * richtext commands: , , . */ static richtextsingle() { return (!strcmp(NextToken,"nl") || !strcmp(NextToken,"lt") || !strcmp(NextToken,"np")); } /* * Get the next token from the input stream. RICHTEXT_COMMAND * or RICHTEXT_NEG_COMMAND are returned if it is a richtext command. * e.g. "" or "". The "token" buffer will receive the * name of the command (without <,> or /) if it is a command. This * function will also truncate commands longer than MAX_TOKEN_SIZE - 1 * characters and abort command parsing if white space is encountered, * so, for example, errors like "" don't cause * problems: it will be corrected to "hi kids". */ richtextlex(file,token) void *file; char *token; { int c,i,cmd; /* Perform any flushing of balancing commands that is necessary */ if (FlushStack) { /* Flush out some extra closing commands */ strcpy(token,Stack[StackSize - FlushSize + (--FlushStack)]); return(RICHTEXT_NEG_COMMAND); } else if (FlushSize) { /* Finished flushing: output the pending close command */ StackSize -= FlushSize; if (StackSize > 0) --StackSize; /* Remove the command that was being matched up */ FlushSize = 0; strcpy(token,NextToken); if (EndInpFile) return(EOF); /* The last flush was the end-of-file cleanup */ else return(RICHTEXT_NEG_COMMAND); } /* Fetch a new character or richtext command */ for (;;) { /* Loop so we can come back on ignored commands */ c = RGET(file); if (c == '<') { /* Read a command token from the input file */ cmd = RICHTEXT_COMMAND; if ((c = RGET(file)) == '/') { cmd = RICHTEXT_NEG_COMMAND; c = RGET(file); } for (i = 0; i < (MAX_TOKEN_SIZE - 1) && c != '>' && c != EOF && !isspace(c); ++i) { NextToken[i] = isupper(c) ? tolower(c) : c; c = RGET(file); } if (c != '>' && c != EOF && !isspace(c)) { /* We have a long command: skip the rest of it */ while (c != '>' && c != EOF && !isspace(c)) c = RGET(file); } if (c == EOF) { if (!StackSize) return(EOF); /* Flush the remaining commands at the end of the input file */ FlushSize = StackSize; FlushStack = FlushSize; EndInpFile = 1; return(richtextlex(file,token)); /* Flush something out */ } NextToken[i] = '\0'; /* Check to see if we need to correct anything */ if (!CorrectionEnabled) { /* No correction to do: just skip the correction phase */ strcpy(token,NextToken); return(cmd); } if (cmd == RICHTEXT_COMMAND) { /* Save the command on the stack if not a singleton command */ if (!richtextsingle()) strcpy (Stack[StackSize++],NextToken); } else if (!(i = richtextmatchup())) continue; /* No matchup - just drop it */ else if (i == 1) --StackSize; /* Correct match at the stack top */ else { /* Flush some correction elements from the stack */ FlushSize = i - 1; FlushStack = FlushSize; return(richtextlex(file,token)); } strcpy(token,NextToken); return(cmd); } else if (c == EOF && StackSize) { /* Flush the remaining commands at the end of the input file */ FlushSize = StackSize; FlushStack = FlushSize; EndInpFile = 1; return(richtextlex(file,token)); /* Flush something out */ } else return(c); } } /* * Output a string via "RichtextPutc". */ static richtextoutstr(str,outparam) char *str; void *outparam; { while (*str) { RPUT(*str,outparam); ++str; } } /* * Read the input stream, correct the richtext, and write the * results to the output stream. */ richtextcorrect(inparam,outparam) void *inparam,*outparam; { int c; char token[MAX_TOKEN_SIZE]; while ((c = richtextlex(inparam,token)) != EOF) { if (c == RICHTEXT_COMMAND) { RPUT('<',outparam); richtextoutstr(token,outparam); RPUT('>',outparam); } else if (c == RICHTEXT_NEG_COMMAND) { RPUT('<',outparam); RPUT('/',outparam); richtextoutstr(token,outparam); RPUT('>',outparam); } else RPUT(c,outparam); } }