% This file is part of CWEB. % This program by Silvio Levy and Donald E. Knuth % is based on a program by Knuth. % It is distributed WITHOUT ANY WARRANTY, express or implied. % Version 4.11 --- December 2023 % Copyright (C) 1987,1990,1993,2000 Silvio Levy and Donald E. Knuth % Permission is granted to make and distribute verbatim copies of this % document provided that the copyright notice and this permission notice % are preserved on all copies. % Permission is granted to copy and distribute modified versions of this % document under the conditions for verbatim copying, provided that the % entire resulting derived work is given a different name and distributed % under the terms of a permission notice identical to this one. % Amendments to 'common.w' resulting in this updated version were created % by numerous collaborators over the course of many years. % Please send comments, suggestions, etc. to tex-k@@tug.org. \def\v{\char'174} % vertical (|) in typewriter font \def\title{Common code for CTANGLE and CWEAVE (Version 4.11)} \def\topofcontents{\null\vfill \centerline{\titlefont Common code for {\ttitlefont CTANGLE} and {\ttitlefont CWEAVE}} \vskip 15pt \centerline{(Version 4.11)} \vfill} \def\botofcontents{\vfill \noindent Copyright \copyright\ 1987, 1990, 1993, 2000 Silvio Levy and Donald E. Knuth \bigskip\noindent Permission is granted to make and distribute verbatim copies of this document provided that the copyright notice and this permission notice are preserved on all copies. \smallskip\noindent Permission is granted to copy and distribute modified versions of this document under the conditions for verbatim copying, provided that the entire resulting derived work is given a different name and distributed under the terms of a permission notice identical to this one. } \pageno=\contentspagenumber \advance\pageno by 1 \let\maybe=\iftrue @* Introduction. This file contains code common to both \.{CTANGLE} and \.{CWEAVE}, which roughly concerns the following problems: character uniformity, input routines, error handling and parsing of command line. We have tried to concentrate in this file all the system dependencies, so as to maximize portability. In the texts below we will sometimes use \.{CWEB} to refer to either of the two component programs, if no confusion can arise. The file begins with a few basic definitions. @c @@/ @h @@/ @@/ @ @ The details will be filled in due course. The interface |"common.h"| of this \.{COMMON} module is included first. It is also used by the main programs. @i common.h @ In certain cases \.{CTANGLE} and \.{CWEAVE} should do almost, but not quite, the same thing. In these cases we've written common code for both, differentiating between the two by means of the global variable |program|. @= boolean program; /* \.{CWEAVE} or \.{CTANGLE}? */ @ \.{CWEAVE} operates in three phases: First it inputs the source file and stores cross-reference data, then it inputs the source once again and produces the \TEX/ output file, and finally it sorts and outputs the index. Similarly, \.{CTANGLE} operates in two phases. The global variable |phase| tells which phase we are in. @= int phase; /* which phase are we in? */ @ There's an initialization procedure that gets both \.{CTANGLE} and \.{CWEAVE} off to a good start. We will fill in the details of this procedure later. @c void common_init(void) { @@; @@; @@; } @* The character set. \.{CWEB} uses the conventions of \CEE/ programs found in the standard \.{ctype.h} header file. A few character pairs are encoded internally as single characters, using the definitions in the interface sections above. These definitions are consistent with an extension of ASCII code originally developed at MIT and explained in Appendix~C of {\sl The \TEX/book\/}; thus, users who have such a character set can type things like \.{\char'32} and \.{\char'4} instead of \.{!=} and \.{\&\&}. (However, their files will not be too portable until more people adopt the extended code.) If the character set is not ASCII, the definitions given may conflict with existing characters; in such cases, other arbitrary codes should be substituted. The indexes to \.{CTANGLE} and \.{CWEAVE} mention every case where similar codes may have to be changed in order to avoid character conflicts. Look for the entry ``ASCII code dependencies'' in those indexes. @^ASCII code dependencies@> @^system dependencies@> @= char section_text[longest_name+1]; /* text being sought for */ char *section_text_end = section_text+longest_name; /* end of |section_text| */ char *id_first; /* where the current identifier begins in the buffer */ char *id_loc; /* just after the current identifier in the buffer */ @* Input routines. The lowest level of input to the \.{CWEB} programs is performed by |input_ln|, which must be told which file to read from. The return value of |input_ln| is |true| if the read is successful and |false| if not (generally this means the file has ended). The conventions of \TEX/ are followed; i.e., the characters of the next line of the file are copied into the |buffer| array, and the global variable |limit| is set to the first unoccupied position. Trailing blanks are ignored. The value of |limit| must be strictly less than |buf_size|, so that |buffer[buf_size-1]| is never filled. Since |buf_size| is strictly less than |long_buf_size|, some of \.{CWEB}'s routines use the fact that it is safe to refer to |*(limit+2)| without overstepping the bounds of the array. @= char buffer[long_buf_size]; /* where each line of input goes */ char *buffer_end=buffer+buf_size-2; /* end of |buffer| */ char *loc=buffer; /* points to the next character to be read from the buffer */ char *limit=buffer; /* points to the last character in the buffer */ @ In the unlikely event that your standard I/O library does not support |feof| and |getc| you may have to change things here. @^system dependencies@> @c static boolean input_ln( /* copies a line into |buffer| or returns |false| */ FILE *fp) /* what file to read from */ { int c=EOF; /* character read; initialized so some compilers won't complain */ char *k; /* where next character goes */ if (feof(fp)) return false; /* we have hit end-of-file */ limit = k = buffer; /* beginning of buffer */ while (k<=buffer_end && (c=getc(fp)) != EOF && c!='\n') if ((*(k++) = c) != ' ') limit = k; if (k>buffer_end) { while ((c=getc(fp))!=EOF && c!='\n'); /* discard rest of line */ loc=buffer; err_print("! Input line too long"); @.Input line too long@> } if (c==EOF && limit==buffer) return false; /* there was nothing after the last newline */ return true; } @ @=@+static boolean input_ln(FILE *); @* File handling. Now comes the problem of deciding which file to read from next. Recall that the actual text that \.{CWEB} should process comes from two streams: a |web_file|, which can contain possibly nested include commands~\.{@@i}, and a |change_file|, which might also contain includes. The |web_file| together with the currently open include files form a stack |file|, whose names are stored in a parallel stack |file_name|. The boolean |changing| tells whether or not we're reading from the |change_file|. The line number of each open file is also kept for error reporting and for the benefit of \.{CTANGLE}. @= int include_depth; /* current level of nesting */ FILE *file[max_include_depth]; /* stack of non-change files */ FILE *change_file; /* change file */ char file_name[max_include_depth][max_file_name_length]; /* stack of non-change file names */ char change_file_name[max_file_name_length]; /* name of change file */ static char alt_web_file_name[max_file_name_length]; /* alternate name to try */ int line[max_include_depth]; /* number of current line in the stacked files */ int change_line; /* number of current line in change file */ int change_depth; /* where \.{@@y} originated during a change */ boolean input_has_ended; /* if there is no more input */ boolean changing; /* if the current line is from |change_file| */ boolean web_file_open=false; /* if the web file is being read */ @ When |changing==false|, the next line of |change_file| is kept in |change_buffer|, for purposes of comparison with the next line of |cur_file|. After the change file has been completely input, we set |change_limit=change_buffer|, so that no further matches will be made. Here's a shorthand expression for inequality between the two lines: @d lines_dont_match (change_limit-change_buffer != limit-buffer @| || strncmp(buffer, change_buffer, (size_t)(limit-buffer)) != 0) @= static char change_buffer[buf_size]; /* next line of |change_file| */ static char *change_limit; /* points to the last character in |change_buffer| */ @ Procedure |prime_the_change_buffer| sets |change_buffer| in preparation for the next matching operation. Since blank lines in the change file are not used for matching, we have |(change_limit==change_buffer && !changing)| if and only if the change file is exhausted. This procedure is called only when |changing| is |true|; hence error messages will be reported correctly. @c static void prime_the_change_buffer(void) { change_limit=change_buffer; /* this value is used if the change file ends */ @@; @@; @@; } @ @=@+static void prime_the_change_buffer(void); @ While looking for a line that begins with \.{@@x} in the change file, we allow lines that begin with \.{@@}, as long as they don't begin with \.{@@y}, \.{@@z}, or \.{@@i} (which would probably mean that the change file is fouled up). @= while(true) { change_line++; if (!input_ln(change_file)) return; if (limit } } @ Here we are looking at lines following the \.{@@x}. @= do { change_line++; if (!input_ln(change_file)) { err_print("! Change file ended after @@x"); @.Change file ended...@> return; } } while (limit==buffer); @ @= change_limit=change_buffer+(ptrdiff_t)(limit-buffer); strncpy(change_buffer,buffer,(size_t)(limit-buffer+1)); @ The following procedure is used to see if the next change entry should go into effect; it is called only when |changing| is |false|. The idea is to test whether or not the current contents of |buffer| matches the current contents of |change_buffer|. If not, there's nothing more to do; but if so, a change is called for: All of the text down to the \.{@@y} is supposed to match. An error message is issued if any discrepancy is found. Then the procedure prepares to read the next line from |change_file|. When a match is found, the current section is marked as changed unless the first line after the \.{@@x} and after the \.{@@y} both start with either `\.{@@*}' or `\.{@@\ }' (possibly preceded by whitespace). This procedure is called only when |buffer change_limit=change_buffer; changing=false; return; } if (limit>buffer+1 && buffer[0]=='@@') { if (xisupper(buffer[1])) buffer[1]=tolower((int)buffer[1]); @@; } @@; changing=false; cur_line++; while (!input_ln(cur_file)) { /* pop the stack or quit */ if (include_depth==0) { err_print("! CWEB file ended during a change"); @.CWEB file ended...@> input_has_ended=true; return; } include_depth--; cur_line++; } if (lines_dont_match) n++; } } @ @=@+static void check_change(void); @ @= if (buffer[1]=='x' || buffer[1]=='z') { loc=buffer+2; err_print("! Where is the matching @@y?"); @.Where is the match...@> } else if (buffer[1]=='y') { if (n>0) { loc=buffer+2; printf("\n! Hmm... %d ",n); err_print("of the preceding lines failed to match"); @.Hmm... n of the preceding...@> } change_depth=include_depth; return; } @ The |get_line| procedure is called when |loc>limit|; it puts the next line of merged input into the buffer and updates the other variables appropriately. A space is placed at the right end of the line. This procedure returns |!input_has_ended| because we often want to check the value of that variable after calling the procedure. If we've just changed from the |cur_file| to the |change_file|, or if the |cur_file| has changed, we tell \.{CTANGLE} to print this information in the \CEE/ file by means of the |print_where| flag. @c boolean get_line(void) /* inputs the next line */ { restart: if (changing && include_depth==change_depth) @@; if (! changing || include_depth>change_depth) { @@; if (changing && include_depth==change_depth) goto restart; } if (input_has_ended) return false; loc=buffer; *limit=' '; if (buffer[0]=='@@' && (buffer[1]=='i' || buffer[1]=='I')) { loc=buffer+2; *limit='"'; while (*loc==' '||*loc=='\t') loc++; if (loc>=limit) { err_print("! Include file name not given"); @.Include file name ...@> goto restart; } if (include_depth>=max_include_depth-1) { err_print("! Too many nested includes"); @.Too many nested includes@> goto restart; } include_depth++; /* push input stack */ @@; } return true; } @ When an \.{@@i} line is found in the |cur_file|, we must temporarily stop reading it and start reading from the named include file. The \.{@@i} line should give a complete file name with or without double quotes. 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;} @= { char temp_file_name[max_file_name_length]; char *cur_file_name_end=cur_file_name+max_file_name_length-1; char *kk, *k=cur_file_name; size_t l; /* length of file name */ if (*loc=='"') { loc++; while (*loc!='"' && k<=cur_file_name_end) *k++=*loc++; if (loc==limit) k=cur_file_name_end+1; /* unmatched quote is `too long' */ } else 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; print_where=true; goto restart; /* success */ } if ((kk=getenv("CWEBINPUTS"))!=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 */ @^system dependencies@> if ((cur_file=fopen(cur_file_name,"r"))!=NULL) { cur_line=0; print_where=true; goto restart; /* success */ } } include_depth--; err_print("! Cannot open include file"); goto restart; } @ @= { cur_line++; while (!input_ln(cur_file)) { /* pop the stack or quit */ print_where=true; if (include_depth==0) {input_has_ended=true; 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(); } @ @= { 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 */ if (change_pending) { if_section_start_make_pending(false); if (change_pending) { changed_section[section_count]=true; change_pending=false; } } *limit=' '; if (buffer[0]=='@@') { if (xisupper(buffer[1])) buffer[1]=tolower((int)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; print_where=true; } } } } @ 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|. @c void check_complete(void) { if (change_limit!=change_buffer) { /* |changing| is |false| */ strncpy(buffer,change_buffer,(size_t)(change_limit-change_buffer+1)); limit=buffer+(ptrdiff_t)(change_limit-change_buffer); changing=true; change_depth=include_depth; loc=buffer; err_print("! Change file entry did not match"); @.Change file entry did not match@> } } @ The |reset_input| procedure, which gets \.{CWEB} ready to read the user's \.{CWEB} input, is used at the beginning of phase one of \.{CTANGLE}, phases one and two of \.{CWEAVE}. @c void reset_input(void) { limit=buffer; loc=buffer+1; buffer[0]=' '; @@; include_depth=cur_line=change_line=0; change_depth=include_depth; changing=true; prime_the_change_buffer(); changing=!changing; limit=buffer; loc=buffer+1; buffer[0]=' '; input_has_ended=false; } @ The following code opens the input files. @^system dependencies@> @= if ((web_file=fopen(web_file_name,"r"))==NULL) { strcpy(web_file_name,alt_web_file_name); if ((web_file=fopen(web_file_name,"r"))==NULL) fatal("! Cannot open input file ", web_file_name); } @.Cannot open input file@> @.Cannot open change file@> web_file_open=true; if ((change_file=fopen(change_file_name,"r"))==NULL) fatal("! Cannot open change file ", change_file_name); @ @= sixteen_bits section_count; /* the current section number */ boolean changed_section[max_sections]; /* is the section changed? */ boolean change_pending; /* if the current change is not yet recorded in |changed_section[section_count]| */ boolean print_where=false; /* should \.{CTANGLE} print line and file info? */ @* Storage of names and strings. Both \.{CWEAVE} and \.{CTANGLE} store identifiers, section names and other strings in a large array of |char|s, called |byte_mem|. Information about the names is kept in the array |name_dir|, whose elements are structures of type |name_info|, containing a pointer into the |byte_mem| array (the address where the name begins) and other data. A |name_pointer| variable is a pointer into |name_dir|. You find the complete layout of |name_info| in the interface sections above. The actual sequence of characters in the name pointed to by a |name_pointer p| appears in positions |p->byte_start| to |(p+1)->byte_start-1|, inclusive. The names of identifiers are found by computing a hash address |h| and then looking at strings of bytes signified by the |name_pointer|s |hash[h]|, |hash[h]->link|, |hash[h]->link->link|, \dots, until either finding the desired name or encountering the null pointer. The names of sections are stored in |byte_mem| together with the identifier names, but a hash table is not used for them because \.{CTANGLE} needs to be able to recognize a section name when given a prefix of that name. A conventional binary search tree is used to retrieve section names, with fields called |llink| and |rlink| (where |llink| takes the place of |link|). The root of this tree is stored in |name_dir->rlink|; this will be the only information in |name_dir[0]|. Since the space used by |rlink| has a different function for identifiers than for section names, we declare it as a |union|. The last component of |name_info| is different for \.{CTANGLE} and \.{CWEAVE}. In \.{CTANGLE}, if |p| is a pointer to a section name, |p->equiv| is a pointer to its replacement text, an element of the array |text_info|. In \.{CWEAVE}, on the other hand, if |p| points to an identifier, |p->xref| is a pointer to its list of cross-references, an element of the array |xmem|. The make-up of |text_info| and |xmem| is discussed in the \.{CTANGLE} and \.{CWEAVE} source files, respectively; here we just declare a common field |equiv_or_xref| as a pointer to |void|. @= char byte_mem[max_bytes]; /* characters of names */ char *byte_mem_end = byte_mem+max_bytes-1; /* end of |byte_mem| */ name_info name_dir[max_names]; /* information about names */ name_pointer name_dir_end = name_dir+max_names-1; /* end of |name_dir| */ @ The first unused position in |byte_mem| and |name_dir| is kept in |byte_ptr| and |name_ptr|, respectively. Thus we usually have |name_ptr->byte_start==byte_ptr|, and certainly we want to keep |name_ptr<=name_dir_end| and |byte_ptr<=byte_mem_end|. @= char *byte_ptr; /* first unused position in |byte_mem| */ name_pointer name_ptr; /* first unused position in |name_dir| */ @ @= name_dir->byte_start=byte_ptr=byte_mem; /* position zero in both arrays */ name_ptr=name_dir+1; /* |name_dir[0]| will be used only for error recovery */ name_ptr->byte_start=byte_mem; /* this makes name 0 of length zero */ root=NULL; /* the binary search tree starts out with nothing in it */ @ The hash table itself consists of |hash_size| entries of type |name_pointer|, and is updated by the |id_lookup| procedure, which finds a given identifier and returns the appropriate |name_pointer|. The matching is done by the function |names_match|, which is slightly different in \.{CWEAVE} and \.{CTANGLE}. If there is no match for the identifier, it is inserted into the table. @d hash_size 353 /* should be prime */ @= name_pointer hash[hash_size]={NULL}; /* heads of hash lists */ hash_pointer hash_end = hash+hash_size-1; /* end of |hash| */ hash_pointer hash_ptr; /* index into hash-head array */ @ Initially all the hash lists are empty. @ Here is the main procedure for finding identifiers: @c name_pointer id_lookup( /* looks up a string in the identifier table */ const char *first, /* first character of string */ const char *last, /* last character of string plus one */ eight_bits t) /* the |ilk|; used by \.{CWEAVE} only */ { const char *i=first; /* position in |buffer| */ int h; /* hash code */ size_t l; /* length of the given identifier */ name_pointer p; /* where the identifier is being sought */ if (last==NULL) for (last=first; *last!='\0'; last++); l=(size_t)(last-first); /* compute the length */ @@; @@; if (p==name_ptr) @@; return p; } @ A simple hash code is used: If the sequence of character codes is $c_1c_2\ldots c_n$, its hash value will be $$(2^{n-1}c_1+2^{n-2}c_2+\cdots+c_n)\,\bmod\,|hash_size|.$$ @= h=(int)((eight_bits)*i); while (++i @ If the identifier is new, it will be placed in position |p=name_ptr|, otherwise |p| will point to its existing location. @= p=hash[h]; while (p && !names_match(p,first,l,t)) p=p->link; if (p==NULL) { p=name_ptr; /* the current identifier is new */ p->link=hash[h]; hash[h]=p; /* insert |p| at beginning of hash list */ } @ The information associated with a new identifier must be initialized in a slightly different way in \.{CWEAVE} than in \.{CTANGLE}. @= { if (byte_ptr+l>byte_mem_end) overflow("byte memory"); if (name_ptr>=name_dir_end) overflow("name"); strncpy(byte_ptr,first,l); (++name_ptr)->byte_start=byte_ptr+=l; if (program==cweave) p->ilk=t, init_node(p); } @ If |p| is a |name_pointer| variable, as we have seen, |p->byte_start| is the beginning of the area where the name corresponding to |p| is stored. However, if |p| refers to a section name, the name may need to be stored in chunks, because it may ``grow'': a prefix of the section name may be encountered before the full name. Furthermore we need to know the length of the shortest prefix of the name that was ever encountered. We solve this problem by inserting two extra bytes at |p->byte_start|, representing the length of the shortest prefix, when |p| is a section name. Furthermore, the last byte of the name will be a blank space if |p| is a prefix. In the latter case, the name pointer |p+1| will allow us to access additional chunks of the name: The second chunk will begin at the name pointer |(p+1)->link|, and if it too is a prefix (ending with blank) its |link| will point to additional chunks in the same way. Null links are represented by |name_dir|. @d first_chunk(p) ((p)->byte_start+2) @d prefix_length(p) (size_t)((eight_bits)*((p)->byte_start)*256 + (eight_bits)*((p)->byte_start+1)) @d set_prefix_length(p,m) (*((p)->byte_start)=(char)((m)/256), *((p)->byte_start+1)=(char)((m)%256)) @c void print_section_name( name_pointer p) { char *ss, *s = first_chunk(p); name_pointer q = p+1; while (p!=name_dir) { ss = (p+1)->byte_start-1; if (*ss==' ' && ss>=s) p=q->link,q=p; else ss++,p=name_dir,q=NULL; term_write(s,(size_t)(ss-s)); s = p->byte_start; } if (q) term_write("...",3); /* complete name not yet known */ } @ @c void sprint_section_name( char *dest, name_pointer p) { char *ss, *s = first_chunk(p); name_pointer q = p+1; while (p!=name_dir) { ss = (p+1)->byte_start-1; if (*ss==' ' && ss>=s) p=q->link,q=p; else ss++,p=name_dir; strncpy(dest,s,(size_t)(ss-s)), dest+=ss-s; s = p->byte_start; } *dest='\0'; } @ @c void print_prefix_name( name_pointer p) { char *s = first_chunk(p); size_t l = prefix_length(p); term_write(s,l); if (s+l<(p+1)->byte_start) term_write("...",3); } @ When we compare two section names, we'll need a function analogous to |strcmp|. But we do not assume the strings are null-terminated, and we keep an eye open for prefixes and extensions. @d less 0 /* the first name is lexicographically less than the second */ @d equal 1 /* the first name is equal to the second */ @d greater 2 /* the first name is lexicographically greater than the second */ @d prefix 3 /* the first name is a proper prefix of the second */ @d extension 4 /* the first name is a proper extension of the second */ @= static int web_strcmp(char *,size_t,char *,size_t);@/ static name_pointer add_section_name(name_pointer,int,char *,char *,boolean);@/ static void extend_section_name(name_pointer,char *,char *,boolean); @ @c static int web_strcmp( /* fuller comparison than |strcmp| */ char *j, /* beginning of first string */ size_t j_len, /* length of first string */ char *k, /* beginning of second string */ size_t k_len) /* length of second string */ { char *j1=j+j_len, *k1=k+k_len; while (kbyte_mem_end) overflow("byte memory"); if (name_ptr+1>=name_dir_end) overflow("name"); (++name_ptr)->byte_start=byte_ptr=s+name_len; if (ispref) { *(byte_ptr-1)=' '; name_len--; name_ptr->link=name_dir; (++name_ptr)->byte_start=byte_ptr; } set_prefix_length(p,name_len); strncpy(s,first,name_len); p->llink=p->rlink=NULL; init_node(p); return par==NULL ? (root=p) : c==less ? (par->llink=p) : (par->rlink=p); } @ @c static void extend_section_name( name_pointer p, /* name to be extended */ char *first, /* beginning of extension text */ char *last, /* one beyond end of extension text */ boolean ispref) /* are we adding a prefix or a full name? */ { char *s; name_pointer q=p+1; size_t name_len=(size_t)(last-first+(int)ispref); if (name_ptr>=name_dir_end) overflow("name"); while (q->link!=name_dir) q=q->link; q->link=name_ptr; s=name_ptr->byte_start; name_ptr->link=name_dir; if (s+name_len>byte_mem_end) overflow("byte memory"); (++name_ptr)->byte_start=byte_ptr=s+name_len; strncpy(s,first,name_len); if (ispref) *(byte_ptr-1)=' '; } @ The |section_lookup| procedure is supposed to find a section name that matches a new name, installing the new name if it doesn't match an existing one. The new name is the string between |first| and |last|; a ``match'' means that the new name exactly equals or is a prefix or extension of a name in the tree. @c name_pointer section_lookup( /* find or install section name in tree */ char *first,char *last, /* first and last characters of new name */ boolean ispref) /* is the new name a prefix or a full name? */ { int c=less; /* comparison between two names; initialized so some compilers won't complain */ name_pointer p=root; /* current node of the search tree */ name_pointer q=NULL; /* another place to look in the tree */ name_pointer r=NULL; /* where a match has been found */ name_pointer par=NULL; /* parent of |p|, if |r| is |NULL|; otherwise parent of |r| */ size_t name_len=(size_t)(last-first+1); @@; @@; @@; } @ A legal new name matches an existing section name if and only if it matches the shortest prefix of that section name. Therefore we can limit our search for matches to shortest prefixes, which eliminates the need for chunk-chasing at this stage. @= while (p) { /* compare shortest prefix of |p| with new name */ c=web_strcmp(first,name_len,first_chunk(p),prefix_length(p)); if (c==less || c==greater) { /* new name does not match |p| */ if (r==NULL) /* no previous matches have been found */ par=p; p=(c==less?p->llink:p->rlink); } else { /* new name matches |p| */ if (r!=NULL) { /* and also |r|: illegal */ printf("%s","\n! Ambiguous prefix: matches <"); @.Ambiguous prefix ... @> print_prefix_name(p); printf("%s",">\n and <"); print_prefix_name(r); err_print(">"); return name_dir; /* the unsection */ } r=p; /* remember match */ p=p->llink; /* try another */ q=r->rlink; /* we'll get back here if the new |p| doesn't match */ } if (p==NULL) p=q, q=NULL; /* |q| held the other branch of |r| */ } @ @= if (r==NULL) /* no matches were found */ return add_section_name(par,c,first,last+1,ispref); @ Although error messages are given in anomalous cases, we do return the unique best match when a discrepancy is found, because users often change a title in one place while forgetting to change it elsewhere. @= switch(section_name_cmp(&first,name_len,r)) { /* compare all of |r| with new name */ case prefix: if (!ispref) { printf("%s","\n! New name is a prefix of <"); @.New name is a prefix...@> print_section_name(r); err_print(">"); } else if (name_len@; case equal: break; case extension: if (!ispref || first<=last) extend_section_name(r,first,last+1,ispref); break; case bad_extension: printf("%s","\n! New name extends <"); @.New name extends...@> print_section_name(r); err_print(">"); break; default: /* no match: illegal */ printf("%s","\n! Section name incompatible with <"); @.Section name incompatible...@> print_prefix_name(r); printf("%s",">,\n which abbreviates <"); print_section_name(r); err_print(">"); } return r; @ The return codes of |section_name_cmp|, which compares a string with the full name of a section, are those of |web_strcmp| plus |bad_extension|, used when the string is an extension of a supposedly already complete section name. This function has a side effect when the comparison string is an extension: It advances the address of the first character of the string by an amount equal to the length of the known part of the section name. The name \.{@@} should be an acceptable ``abbreviation'' for \.{@@}. If such an abbreviation comes after the complete name, there's no trouble recognizing it. If it comes before the complete name, we simply append a null chunk. This logic requires us to regard \.{@@} as an ``extension'' of itself. @d bad_extension 5 @c static int section_name_cmp( char **pfirst, /* pointer to beginning of comparison string */ size_t len, /* length of string */ name_pointer r) /* section name being compared */ { char *first=*pfirst; /* beginning of comparison string */ name_pointer q=r+1; /* access to subsequent chunks */ char *ss, *s=first_chunk(r); int c=less; /* comparison */ boolean ispref; /* is chunk |r| a prefix? */ while (true) { ss=(r+1)->byte_start-1; if (*ss==' ' && ss>=r->byte_start) ispref=true,q=q->link; else ispref=false,ss++,q=name_dir; switch(c=web_strcmp(first,len,s,(size_t)(ss-s))) { case equal: if (q==name_dir) if (ispref) { *pfirst=first+(ptrdiff_t)(ss-s); return extension; /* null extension */ } else return equal; else return length(q)==0? equal: prefix; case extension: if (!ispref) return bad_extension; first += ss-s; if (q!=name_dir) {len -= (int)(ss-s); s=q->byte_start; r=q; continue;} *pfirst=first; return extension; default: return c; } } } @ @=@+static int section_name_cmp(char **,size_t,name_pointer); @* 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. @= 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 |"!"|. @c void err_print( /* prints `\..' and location of error message */ const char *s) { printf(*s=='!' ? "\n%s" : "%s",s); if (web_file_open) @@; 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@> @= {char *k,*l; /* pointers into |buffer| */ if (changing && include_depth==change_depth && change_line>0) printf(". (l. %d of change file)\n", change_line); else if (cur_line>0) { if (include_depth==0) printf(". (l. %d)\n", cur_line); else printf(". (l. %d of include file %s)\n", cur_line, cur_file_name); } l= (loc>=limit? limit: loc); if (l>buffer) { for (k=buffer; k @c int wrap_up(void) { if (show_progress || show_happiness || history != spotless) new_line(); if (show_stats) print_stats(); /* print statistics about memory usage */ @@; if (history > harmless_message) return EXIT_FAILURE; else return EXIT_SUCCESS; } @ @= switch (history) { case spotless: if (show_happiness) puts("(No errors were found.)"); break; case harmless_message: puts("(Did you see the warning message above?)"); break; case error_message: puts("(Pardon me, but I think I spotted something wrong.)"); break; case fatal_message: default: puts("(That was a fatal error, my friend.)"); } @ When there is no way to recover from an error, the |fatal| subroutine is invoked. This happens most often when |overflow| occurs. The two parameters to |fatal| are strings that are essentially concatenated to print the final error message. @c void fatal( const char *s,const char *t) { if (*s) printf("%s",s); err_print(t); history=fatal_message; exit(wrap_up()); } @ An overflow stop occurs if \.{CWEB}'s tables aren't large enough. @c void overflow( const char *t) { printf("\n! Sorry, %s capacity exceeded",t); fatal("",""); } @.Sorry, capacity exceeded@> @ Sometimes the program's behavior is far different from what it should be, and \.{CWEB} prints an error message that is really for the \.{CWEB} maintenance person, not the user. In such cases the program says |confusion("indication of where we are")|. @* Command line arguments. The user calls \.{CWEAVE} and \.{CTANGLE} 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. @= int argc; /* copy of |ac| parameter to |main| */ char **argv; /* copy of |av| parameter to |main| */ char C_file_name[max_file_name_length]; /* name of |C_file| */ char tex_file_name[max_file_name_length]; /* name of |tex_file| */ char idx_file_name[max_file_name_length]; /* name of |idx_file| */ char scn_file_name[max_file_name_length]; /* name of |scn_file| */ boolean flags[128]; /* an option for each 7-bit code */ @ The |flags| will be initially |false|. Some of them are set to~|true| before scanning the arguments; if additional flags are |true| by default they should be set before calling |common_init|. @= show_banner=show_happiness=show_progress=make_xrefs=true; @ We now must look at the command line arguments and set the file names accordingly. At least one file name must be present: the \.{CWEB} file. It may have an extension, or it may omit the extension to get |".w"| or |".web"| added. The \TEX/ output file name is formed by replacing the \.{CWEB} file name extension by |".tex"|, and the \CEE/ file name by replacing the extension by |".c"|, after removing the directory name (if any). If there is a second 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. @c static void scan_args(void) { char *dot_pos; /* position of |'.'| in the argument */ char *name_pos; /* file name beginning, sans directory */ char *s; /* pointer for scanning strings */ boolean found_web=false,found_change=false,found_out=false; /* have these names been seen? */ strcpy(change_file_name,"/dev/null"); while (--argc > 0) { if ((**(++argv)=='-'||**argv=='+')&&*(*argv+1)) @@; else { s=name_pos=*argv;@+dot_pos=NULL; while (*s) if (*s=='.') dot_pos=s++; else if (*s=='/') dot_pos=NULL,name_pos=++s; else s++; if (!found_web) @@; else if (!found_change) @@; else if (!found_out) @@; else @@; } } if (!found_web) @@; } @ @=@+static void scan_args(void); @ 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. @= { if (s-*argv > max_file_name_length-5) @@; 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); sprintf(tex_file_name,"%s.tex",name_pos); /* strip off directory name */ if (make_xrefs) { /* indexes will be generated */ sprintf(idx_file_name,"%s.idx",name_pos); sprintf(scn_file_name,"%s.scn",name_pos); } sprintf(C_file_name,"%s.c",name_pos); found_web=true; } @ @= { if (strcmp(*argv,"-")!=0) { if (s-*argv > max_file_name_length-4) @@; if (dot_pos==NULL) sprintf(change_file_name,"%s.ch",*argv); else strcpy(change_file_name,*argv); } found_change=true; } @ @= { if (s-*argv > max_file_name_length-5) @@; if (dot_pos==NULL) { sprintf(tex_file_name,"%s.tex",*argv); sprintf(C_file_name,"%s.c",*argv); } else { strcpy(tex_file_name,*argv); strcpy(C_file_name,*argv); *dot_pos='\0'; /* string now ends where the dot was */ } if (make_xrefs) { /* indexes will be generated */ sprintf(idx_file_name,"%s.idx",*argv); sprintf(scn_file_name,"%s.scn",*argv); } found_out=true; } @ @d flag_change (**argv!='-') @= for(dot_pos=*argv+1;*dot_pos>'\0';dot_pos++) flags[(eight_bits)*dot_pos]=flag_change; @ @= { if (program==ctangle) fatal( "! Usage: ctangle [options] webfile[.w] [{changefile[.ch]|-} [outfile[.c]]]\n" ,""); @.Usage:@> else fatal( "! Usage: cweave [options] webfile[.w] [{changefile[.ch]|-} [outfile[.tex]]]\n" ,""); } @ @= fatal("! Filename too long\n", *argv); @.Filename too long@> @* Output. Here is the code that opens the output file: @^system dependencies@> @= FILE *C_file; /* where output of \.{CTANGLE} goes */ FILE *tex_file; /* where output of \.{CWEAVE} goes */ FILE *idx_file; /* where index from \.{CWEAVE} goes */ FILE *scn_file; /* where list of sections from \.{CWEAVE} goes */ FILE *active_file; /* currently active file for \.{CWEAVE} output */ @ @= 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); } @* Index.