wmerge.w

模拟器提供了一个简单易用的平台

If the environment variable \.{CWEBINPUTS} is set, or if the compiler flag 
of the same name was defined at compile time,
\.{CWEB} will look for include files in the directory thus named, if
it cannot find them in the current directory.
(Colon-separated paths are not supported.)
The remainder of the \.{@@i} line after the file name is ignored.

@d too_long() {include_depth--; 
        err_print("! Include file name too long"); goto restart;}

@ @<Try to open...@>= {
  char temp_file_name[max_file_name_length]; 
  char *cur_file_name_end=cur_file_name+max_file_name_length-1; 
  char *k=cur_file_name, *kk;
  int l; /* length of file name */

  while (*loc!=' '&&*loc!='\t'&&*loc!='"'&&k<=cur_file_name_end) *k++=*loc++;
  if (k>cur_file_name_end) too_long();
@.Include file name ...@>
  *k='\0';
  if ((cur_file=fopen(cur_file_name,"r"))!=NULL) {
    cur_line=0; 
    goto restart; /* success */
  }
  kk=getenv("CWEBINPUTS");
  if (kk!=NULL) {
    if ((l=strlen(kk))>max_file_name_length-2) too_long();
    strcpy(temp_file_name,kk);
  }
  else {
#ifdef CWEBINPUTS
    if ((l=strlen(CWEBINPUTS))>max_file_name_length-2) too_long();
    strcpy(temp_file_name,CWEBINPUTS);
#else
    l=0; 
#endif /* |CWEBINPUTS| */
  }
  if (l>0) {
    if (k+l+2>=cur_file_name_end)  too_long();
@.Include file name ...@>
    for (; k>= cur_file_name; k--) *(k+l+1)=*k;
    strcpy(cur_file_name,temp_file_name);
    cur_file_name[l]='/'; /* \UNIX/ pathname separator */
    if ((cur_file=fopen(cur_file_name,"r"))!=NULL) {
      cur_line=0; 
      goto restart; /* success */
    }
  }
  include_depth--; err_print("! Cannot open include file"); goto restart;
}

@ @<Read from |cur_file|...@>= {
  cur_line++;
  while (!input_ln(cur_file)) { /* pop the stack or quit */
    if (include_depth==0) {input_has_ended=1; break;}
    else {
      fclose(cur_file); include_depth--;
      if (changing && include_depth==change_depth) break;
      cur_line++;
    }
  }
  if (!changing && !input_has_ended)
   if (limit-buffer==change_limit-change_buffer)
    if (buffer[0]==change_buffer[0])
      if (change_limit>change_buffer) check_change();
}

@ @<Read from |change_file|...@>= {
  change_line++;
  if (!input_ln(change_file)) {
    err_print("! Change file ended without @@z");
@.Change file ended...@>
    buffer[0]='@@'; buffer[1]='z'; limit=buffer+2;
  }
  if (limit>buffer) { /* check if the change has ended */
    *limit=' ';
    if (buffer[0]=='@@') {
      if (isupper(buffer[1])) buffer[1]=tolower(buffer[1]);
      if (buffer[1]=='x' || buffer[1]=='y') {
        loc=buffer+2;
        err_print("! Where is the matching @@z?");
@.Where is the match...@>
      }
      else if (buffer[1]=='z') {
        prime_the_change_buffer(); changing=!changing; 
      }
    }
  }
}

@ At the end of the program, we will tell the user if the change file
had a line that didn't match any relevant line in |web_file|.

@<Funct...@>=
void
check_complete(){
  if (change_limit!=change_buffer) { /* |changing| is 0 */
    strncpy(buffer,change_buffer,change_limit-change_buffer+1);
    limit=buffer+(int)(change_limit-change_buffer);
    changing=1; change_depth=include_depth; loc=buffer;
    err_print("! Change file entry did not match");
  @.Change file entry did not match@>
  }
}

@* Reporting errors to the user.
A global variable called |history| will contain one of four values
at the end of every run: |spotless| means that no unusual messages were
printed; |harmless_message| means that a message of possible interest
was printed but no serious errors were detected; |error_message| means that
at least one error was found; |fatal_message| means that the program
terminated abnormally. The value of |history| does not influence the
behavior of the program; it is simply computed for the convenience
of systems that might want to use such information.

@d spotless 0 /* |history| value for normal jobs */
@d harmless_message 1 /* |history| value when non-serious info was printed */
@d error_message 2 /* |history| value when an error was noted */
@d fatal_message 3 /* |history| value when we had to stop prematurely */
@d mark_harmless {if (history==spotless) history=harmless_message;}
@d mark_error history=error_message

@<Definit...@>=
int history=spotless; /* indicates how bad this run was */

@ The command `|err_print("! Error message")|' will report a syntax error to
the user, by printing the error message at the beginning of a new line and
then giving an indication of where the error was spotted in the source file.
Note that no period follows the error message, since the error routine
will automatically supply a period. A newline is automatically supplied
if the string begins with |"!"|.

The actual error indications are provided by a procedure called |error|.

@<Predecl...@>=
void  err_print();

@
@<Functions...@>=
void
err_print(s) /* prints `\..' and location of error message */
char *s;
{
  char *k,*l; /* pointers into |buffer| */
  fprintf(stderr,*s=='!'? "\n%s" : "%s",s);
  if(web_file_open) @<Print error location based on input buffer@>@;
  else putc('\n',stderr);
  update_terminal; mark_error;
}

@ The error locations can be indicated by using the global variables
|loc|, |cur_line|, |cur_file_name| and |changing|,
which tell respectively the first
unlooked-at position in |buffer|, the current line number, the current
file, and whether the current line is from |change_file| or |cur_file|.
This routine should be modified on systems whose standard text editor
has special line-numbering conventions.
@^system dependencies@>

@<Print error location based on input buffer@>=
{if (changing && include_depth==change_depth)
  fprintf(stderr,". (l. %d of change file)\n", change_line);
else if (include_depth==0) fprintf(stderr,". (l. %d)\n", cur_line);
  else fprintf(stderr,". (l. %d of include file %s)\n", cur_line, cur_file_name);
l= (loc>=limit? limit: loc);
if (l>buffer) {
  for (k=buffer; k<l; k++)
    if (*k=='\t') putc(' ',stderr);
    else putc(*k,stderr); /* print the characters already read */
  putc('\n',stderr);
  for (k=buffer; k<l; k++) putc(' ',stderr); /* space out the next line */
}
for (k=l; k<limit; k++) putc(*k,stderr); /* print the part not yet read */
  putc('\n',stderr);
}

@ When no recovery from some error has been provided, we have to wrap
up and quit as graciously as possible.  This is done by calling the
function |wrap_up| at the end of the code.

@d fatal(s,t) {
  fprintf(stderr,s); err_print(t);
  history=fatal_message; exit(wrap_up());
}

@ Some implementations may wish to pass the |history| value to the
operating system so that it can be used to govern whether or not other
programs are started. Here, for instance, we pass the operating system
a status of 0 if and only if only harmless messages were printed.
@^system dependencies@>

@<Func...@>=
wrap_up() {
  @<Print the job |history|@>;
  if (history > harmless_message) return(1);
  else return(0);
}

@ @<Print the job |history|@>=
switch (history) {
case spotless: if (show_happiness) fprintf(stderr,"(No errors were found.)\n"); break;
case harmless_message:
  fprintf(stderr,"(Did you see the warning message above?)\n"); break;
case error_message:
  fprintf(stderr,"(Pardon me, but I think I spotted something wrong.)\n"); break;
case fatal_message: fprintf(stderr,"(That was a fatal error, my friend.)\n");
} /* there are no other cases */

@* Command line arguments.
The user calls \.{wmerge} with arguments on the command line.
These are either file names or flags to be turned off (beginning with |"-"|)
or flags to be turned on (beginning with |"+"|.
The following globals are for communicating the user's desires to the rest
of the program. The various file name variables contain strings with
the names of those files. Most of the 128 flags are undefined but available
for future extensions.

@d show_banner flags['b'] /* should the banner line be printed? */
@d show_happiness flags['h'] /* should lack of errors be announced? */

@<Defin...@>=
int argc; /* copy of |ac| parameter to |main| */
char **argv; /* copy of |av| parameter to |main| */
char out_file_name[max_file_name_length]; /* name of |out_file| */
boolean flags[128]; /* an option for each 7-bit code */

@ The |flags| will be initially 1.

@<Set the default options@>=
show_banner=show_happiness=1;

@ We now must look at the command line arguments and set the file names
accordingly.  At least one file name must be present: the \.{WEB}
file.  It may have an extension, or it may omit it to get |'.w'|
added.

If there is another file name present among the arguments, it is the
change file, again either with an extension or without one to get |'.ch'|
An omitted change file argument means that |'/dev/null'| should be used,
when no changes are desired.
@^system dependencies@>

If there's a third file name, it will be the output file.

@<Pred...@>=
void scan_args();

@
@<Function...@>=
void
scan_args()
{
  char *dot_pos; /* position of |'.'| in the argument */
  register char *s; /* register for scanning strings */
  boolean found_web=0,found_change=0,found_out=0;
             /* have these names have been seen? */
  boolean flag_change;

  while (--argc > 0) {
    if (**(++argv)=='-' || **argv=='+') @<Handle flag argument@>@;
    else {
      s=*argv;@+dot_pos=NULL;
      while (*s) {
        if (*s=='.') dot_pos=s++;
        else if (*s=='/') dot_pos=NULL,++s;
        else s++;
      }
      if (!found_web) @<Make |web_file_name|@>@;
      else if (!found_change) @<Make |change_file_name| from |fname|@>@;
      else if (!found_out) @<Override output file name@>@;
        else @<Print usage error message and quit@>;
    }
  }
  if (!found_web) @<Print usage error message and quit@>;
  if (!found_change) strcpy(change_file_name,"/dev/null");
}

@ We use all of |*argv| for the |web_file_name| if there is a |'.'| in it,
otherwise we add |".w"|. If this file can't be opened, we prepare an
|alt_web_file_name| by adding |"web"| after the dot.
The other file names come from adding other things
after the dot.  We must check that there is enough room in
|web_file_name| and the other arrays for the argument.

@<Make |web_file_name|...@>=
{
  if (s-*argv > max_file_name_length-5)
    @<Complain about argument length@>;
  if (dot_pos==NULL)
    sprintf(web_file_name,"%s.w",*argv);
  else {
    strcpy(web_file_name,*argv);
    *dot_pos=0; /* string now ends where the dot was */
  }
  sprintf(alt_web_file_name,"%s.web",*argv);
  *out_file_name='\0'; /* this will print to stdout */
  found_web=1;
}

@ @<Make |change_file_name|...@>=
{
  if (s-*argv > max_file_name_length-4)
    @<Complain about argument length@>;
  if (dot_pos==NULL)
    sprintf(change_file_name,"%s.ch",*argv);
  else strcpy(change_file_name,*argv);
  found_change=1;
}

@ @<Override...@>=
{
  if (s-*argv > max_file_name_length-5)
    @<Complain about argument length@>;
  if (dot_pos==NULL) sprintf(out_file_name,"%s.out",*argv);
  else strcpy(out_file_name,*argv);
  found_out=1;
}

@ @<Handle flag...@>=
{
  if (**argv=='-') flag_change=0;
  else flag_change=1;
  for(dot_pos=*argv+1;*dot_pos>'\0';dot_pos++)
    flags[*dot_pos]=flag_change;
}

@ @<Print usage error message and quit@>=
{
  fatal("! Usage: wmerge webfile[.w] [changefile[.ch] [outfile[.out]]]\n","")@;
}

@ @<Complain about arg...@>= fatal("! Filename too long\n", *argv);

@* Output. Here is the code that opens the output file:
@^system dependencies@>

@<Defin...@>=
FILE *out_file; /* where output goes */

@ @<Scan arguments and open output file@>=
scan_args();
if (out_file_name[0]=='\0') out_file=stdout;
else if ((out_file=fopen(out_file_name,"w"))==NULL)
    fatal("! Cannot open output file ", out_file_name);
@.Cannot open output file@>

@ The |update_terminal| procedure is called when we want
to make sure that everything we have output to the terminal so far has
actually left the computer's internal buffers and been sent.
@^system dependencies@>

@d update_terminal fflush(stderr) /* empty the terminal output buffer */

@* Index.