1 /* unlit.c Wed Dec 5 17:16:24 GMT 1990
3 * Literate script filter. In contrast with the format used by most
4 * programming languages, a literate script is a program in which
5 * comments are given the leading role, whilst program text must be
6 * explicitly flagged as such by placing a `>' character in the first
7 * column on each line. It is hoped that this style of programming will
8 * encourage the writing of accurate and clearly documented programs
9 * in which the writer may include motivating arguments, examples
12 * Unlit is a filter that can be used to strip all of the comment lines
13 * out of a literate script file. The command format for unlit is:
14 * unlit [-n] [-q] ifile ofile
15 * where ifile and ofile are the names of the input (literate script) and
16 * output (raw program) files respectively. Either of these names may
17 * be `-' representing the standard input or the standard output resp.
18 * A number of rules are used in an attempt to guard against the most
19 * common errors that are made when writing literate scripts:
20 * 1) Empty script files are not permitted. A file in which no lines
21 * begin with `>' usually indicates a file in which the programmer
22 * has forgotten about the literate script convention.
23 * 2) A line containing part of program definition (i.e. preceeded by `>')
24 * cannot be used immediately before or after a comment line unless
25 * the comment line is blank. This error usually indicates that
26 * the `>' character has been omitted from a line in a section of
27 * program spread over a number of lines.
28 * Using the -q (quiet) flag suppresses the signalling of these error
29 * conditions. The default behaviour can be selected explicitly using
30 * the -n (noisy) option so that any potential errors in the script file
33 * The original idea for the use of literate scripts is due to Richard
34 * Bird of the programming Research Group, Oxford and was initially
35 * adopted for use in the implementation of the functional programming
36 * language Orwell used for teaching in Oxford. This idea has subsequently
37 * been borrowed in a number of other language implementations.
39 * Modified to understand \begin{code} ... \end{code} used in Glasgow. -- LA
40 * And \begin{pseudocode} ... \end{pseudocode}. -- LA
46 #define NULLSTR ((char *)0)
48 #define MISSINGBLANK "unlit: Program line next to comment"
49 #define EMPTYSCRIPT "unlit: No definitions in file (perhaps you forgot the '>'s?)"
50 #define USAGE "usage: unlit [-q] [-n] [-c] file1 file2\n"
51 #define CANNOTOPEN "unlit: cannot open \"%s\"\n"
52 #define DISTINCTNAMES "unlit: input and output filenames must differ\n"
53 #define MISSINGCODE "unlit: missing %s\n"
55 #define BEGINCODE "\\begin{code}"
56 #define LENBEGINCODE 12
57 #define ENDCODE "\\end{code}"
60 /* According to Will Partain, the inventor of pseudocode, this gone now. */
61 #define BEGINPSEUDOCODE "\\begin{pseudocode}"
62 #define LENBEGINPSEUDOCODE 18
63 #define ENDPSEUDOCODE "\\end{pseudocode}"
64 #define LENENDPSEUDOCODE 16
67 typedef enum { START, BLANK, TEXT, DEFN, BEGIN, /*PSEUDO,*/ END, HASH } line;
68 #define isWhitespace(c) (c==' ' || c=='\t')
69 #define isLineTerm(c) (c=='\n' || c==EOF)
71 static int noisy = 1; /* 0 => keep quiet about errors, 1 => report errors */
72 static int errors = 0; /* count the number of errors reported */
73 static int crunchnl = 0; /* don't print \n for removed lines */
74 static int leavecpp = 1; /* leave preprocessor lines */
76 /* complain(file,line,what)
78 * print error message `what' for `file' at `line'. The error is suppressed
79 * if noisy is not set.
82 complain(file, lin, what)
88 fprintf(stderr, "%s ", file);
89 fprintf(stderr,"line %d: %s\n",lin,what);
96 /* As getc, but does TAB expansion */
101 static int spleft = 0;
102 static int linepos = 0;
113 else if (c == '\n' || c == '\f') {
116 } else if (c == '\t') {
117 spleft = TABPOS - linepos % TABPOS;
128 /* readline(istream, ostream)
130 * Read a line from the input stream `istream', and return a value
131 * indicating whether that line was:
132 * BLANK (whitespace only),
133 * DEFN (first character is DEFNCHAR),
134 * TEXT (a line of text)
135 * BEGIN (a \begin{code} line)
136 * PSEUDO (a \begin{pseodocode} line)
137 * HASH (a preprocessor line)
138 * or END (indicating an EOF).
139 * Lines of type DEFN are copied to the output stream `ostream'
140 * (without the leading DEFNCHAR). BLANK and TEXT lines are
141 * replaced by empty (i.e. blank lines) in the output stream, so
142 * that error messages refering to line numbers in the output file
143 * can also be used to locate the corresponding line in the input
147 line readline(istream,ostream)
148 FILE *istream, *ostream; {
149 int c = egetc(istream);
156 if (leavecpp && c=='#') {
158 while (c=egetc(istream), !isLineTerm(c))
165 /* putc(' ',ostream);*/
166 while (c=egetc(istream), !isLineTerm(c))
175 while (isWhitespace(c))
182 while (c=egetc(istream), !isLineTerm(c))
183 if (i < sizeof buf - 1)
185 while(i > 0 && isspace(buf[i-1]))
188 if (strcmp(buf, BEGINCODE) == 0)
191 else if (strcmp(buf, BEGINPSEUDOCODE) == 0)
199 /* unlit(file,istream,ostream)
201 * Copy the file named `file', accessed using the input stream `istream'
202 * to the output stream `ostream', removing any comments and checking
203 * for bad use of literate script features:
204 * - there should be at least one BLANK line between a DEFN and TEXT
205 * - there should be at least one DEFN line in a script.
208 unlit(file, istream, ostream)
212 line last, this=START;
218 this = readline(istream, ostream);
222 if (last==DEFN && this==TEXT)
223 complain(file, linesread-1, MISSINGBLANK);
224 if (last==TEXT && this==DEFN)
225 complain(file, linesread, MISSINGBLANK);
227 /* start of code, copy to end */
230 if (fgets(lineb, sizeof lineb, istream) == NULL) {
231 fprintf(stderr, MISSINGCODE, ENDCODE);
235 if (strncmp(lineb,ENDCODE,LENENDCODE) == 0) {
239 fputs(lineb, ostream);
244 if (this == PSEUDO) {
247 if (fgets(lineb, sizeof lineb, istream) == NULL) {
248 fprintf(stderr, MISSINGCODE, ENDPSEUDOCODE);
253 if (strncmp(lineb,ENDPSEUDOCODE,LENENDPSEUDOCODE) == 0) {
262 complain(file,linesread,EMPTYSCRIPT);
267 * Main program. Processes command line arguments, looking for leading:
268 * -q quiet mode - do not complain about bad literate script files
269 * -n noisy mpde - complain about bad literate script files.
270 * Expects two additional arguments, a file name for the input and a file
271 * name for the output file. These two names must normally be distinct.
272 * An exception is made for the special name "-" which can be used in either
273 * position to specify the standard input or the standard output respectively.
279 FILE *istream, *ostream;
282 for (argc--, argv++; argc > 0; argc--, argv++)
283 if (strcmp(*argv,"-n")==0)
285 else if (strcmp(*argv,"-q")==0)
287 else if (strcmp(*argv,"-c")==0)
293 fprintf(stderr, USAGE);
297 if (strcmp(argv[0],argv[1])==0 && strcmp(argv[0],"-")!=0) {
298 fprintf(stderr, DISTINCTNAMES);
303 if (strcmp(argv[0], "-")==0) {
308 if ((istream=fopen(argv[0], "r")) == NULL) {
309 fprintf(stderr, CANNOTOPEN, argv[0]);
313 if (strcmp(argv[1], "-")==0)
316 if ((ostream=fopen(argv[1], "w")) == NULL) {
317 fprintf(stderr, CANNOTOPEN, argv[1]);
321 unlit(file, istream, ostream);
326 exit(errors==0 ? 0 : 1);