comm-output.ch

Changes for COMMON.W by Andreas Scherer, October 2021.

This set of changes modifies the output behaviour of the CWEB system.
Instead of writing directly to the C or TeX file as described in the
manual, the current run is documented in a temporary output file which
is copied to the expected file in the last moment.  In case of an user
abort, previous results are not destroyed.  This feature is activated
with commandline option '+c'.

This change file requires COMM-PATCH.CH and COMM-EXTENSIONS.CH to be
applied as well.

For a complete history of the changes made to COMMON.W see COMM-PATCH.CH.

Section 68.

@x l.1068
  @<Print the job |history|@>@;
@y
  @<Print the job |history|@>@;
  @<Remove the temporary file if not already done@>@;
@z

Section 73.

@x l.1130
char scn_file_name[max_file_name_length]; /* name of |scn_file| */
@y
char scn_file_name[max_file_name_length]; /* name of |scn_file| */
char check_file_name[max_file_name_length]; /* name of |check_file| */
@z

Section 83.

@x l.1272
FILE *active_file; /* currently active file for \.{CWEAVE} output */
@y
FILE *active_file; /* currently active file for \.{CWEAVE} output */
FILE *check_file; /* temporary output file */
@z

Section 84.

@x l.1274
@ @<Scan arguments and open output files@>=
scan_args();
if (program==ctangle) {
  if ((C_file=fopen(C_file_name,"wb"))==NULL)
    fatal("! Cannot open output file ", C_file_name);
@.Cannot open output file@>
}
else {
  if ((tex_file=fopen(tex_file_name,"wb"))==NULL)
    fatal("! Cannot open output file ", tex_file_name);
}
@y
@ @<Scan arguments and open output files@>=
scan_args();
if (program==ctangle) {
  if (check_for_change) @<Open intermediate \CEE/ output file@>@;
  else if ((C_file=fopen(C_file_name,"wb"))==NULL)
    fatal("! Cannot open output file ", C_file_name);
@.Cannot open output file@>
}
else {
  if (check_for_change) @<Open intermediate \TEX/ output file@>@;
  else if ((tex_file=fopen(tex_file_name,"wb"))==NULL)
    fatal("! Cannot open output file ", tex_file_name);
}
@z

New material after section 85.

@x l.1286
@* Index.
@y
@*1 Temporary file output. Most \CEE/ projects are controlled by a \.{Makefile}
that automatically takes care of the temporal dependencies between the different
source modules. It may be convenient that \.{CWEB} doesn't create new output
for all existing files, when there are only changes to some of them. Thus the
\.{make} process will only recompile those modules where necessary. You can
activate this feature with the `\.{+c}' command-line option. The idea and basic
implementation of this mechanism can be found in the program \.{NUWEB} by
Preston Briggs, to whom credit is due.

@<Open intermediate \CEE/ output file@>= {
  if ((C_file=fopen(C_file_name,"a"))==NULL)
    fatal("! Cannot open output file ", C_file_name);
@.Cannot open output file@>
  else fclose(C_file); /* Test accessability */
  strcpy(check_file_name,C_file_name);
  if(check_file_name[0]!='\0') {
    char *dot_pos=strrchr(check_file_name,'.');
    if(dot_pos==NULL) strcat(check_file_name,".ttp");
    else strcpy(dot_pos,".ttp");
  }
  if ((C_file=fopen(check_file_name,"wb"))==NULL)
    fatal("! Cannot open output file ", check_file_name);
}

@ @<Open intermediate \TEX/ output file@>= {
  if ((tex_file=fopen(tex_file_name,"a"))==NULL)
    fatal("! Cannot open output file ", tex_file_name);
@.Cannot open output file@>
  else fclose(tex_file); /* Test accessability */
  strcpy(check_file_name,tex_file_name);
  if(check_file_name[0]!='\0') {
    char *dot_pos=strrchr(check_file_name,'.');
    if(dot_pos==NULL) strcat(check_file_name,".wtp");
    else strcpy(dot_pos,".wtp");
  }
  if ((tex_file=fopen(check_file_name,"wb"))==NULL)
    fatal("! Cannot open output file ", check_file_name);
}

@ Before we leave the program we have to make
sure that the output files are correctly written.

@<Remove the temporary file...@>=
if(C_file) fclose(C_file);
if(tex_file) fclose(tex_file);
if(check_file) fclose(check_file);
if(strlen(check_file_name)) /* Delete the temporary file in case of a break */
   remove(check_file_name);

@* Index.
@z