troff.c

   1 /*
   2  * The main challenge in troff backend is managing unnecessary spaces:
   3  * + no newline should appear in the output, except in blocks
   4  * + no excess whitespace should appear after inline dot commands
   5  *   like footnotes
   6  *
   7  * troff_put() manages white spaces:
   8  * + gotnl: is set when the last character is a newline
   9  * + eatspc: when one, ignore as much space as possible
  10  * + inblk: we are in a block and no whitespace processing should be done
  11  *
  12  * After printing an inline macro, eatspc_on() is called which forces
  13  * troff_put() to ignore all whitespaces until the first
  14  * non-space character.  Some care is necessary when handling dots; if
  15  * a dot appears just after a newline, it is a troff macro, otherwise
  16  * it is a printable dot and should be escaped.
  17  */
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <stdio.h>
  21 #include "ctxt.h"
  22
  23 static int eatspc;      /* jump space chars */
  24 static int gotnl;       /* last output char was a newline */
  25 static int inblk;       /* inside a block */
  26
  27 static void eatspc_on(void)
  28 {
  29         gotnl = 0;
  30         eatspc = 1;
  31 }
  32
  33 static void troff_doc_beg(struct doc *doc)
  34 {
  35 }
  36
  37 static void troff_doc_end(struct doc *doc)
  38 {
  39 }
  40
  41 static void troff_put(struct doc *doc, char *s)
  42 {
  43         if (!*s)
  44                 return;
  45         if (inblk) {
  46                 doc_write(doc, s);
  47                 return;
  48         }
  49         if (eatspc) {
  50                 while (*s == ' ' || *s == '\t' || *s == '\n')
  51                         gotnl = *s++ == '\n';
  52                 eatspc = *s == '\0';    /* more eatspc if s was space */
  53                 if (!gotnl && *s == '.')
  54                         doc_write(doc, "\\&");
  55                 else if (!eatspc)       /* exiting eatspc; set gotnl */
  56                         gotnl = 1;
  57         }
  58         while (gotnl && *s == '\n')
  59                 s++;
  60         while (*s) {
  61                 char *r = strchr(s, '\n');
  62                 r = r ? r + 1 : strchr(s, '\0');
  63                 doc_memcat(doc, s, r - s);
  64                 s = r;
  65                 while (*s == '\n')
  66                         s++;
  67         }
  68         gotnl = s[-1] == '\n';
  69 }
  70
  71 static void troff_head_beg(struct doc *doc, int level)
  72 {
  73         switch (level) {
  74         case 0:
  75                 troff_put(doc, ".NH 1\n");
  76                 break;
  77         case 1:
  78                 troff_put(doc, ".NH 2\n");
  79                 break;
  80         default:
  81                 troff_put(doc, ".SH\n");
  82         }
  83 }
  84
  85 static void troff_head_end(struct doc *doc, int level)
  86 {
  87 }
  88
  89 static void troff_par_beg(struct doc *doc)
  90 {
  91         troff_put(doc, ".PP\n");
  92 }
  93
  94 static void troff_par_end(struct doc *doc)
  95 {
  96 }
  97
  98 static int ldepth;
  99
 100 static void troff_list_beg(struct doc *doc, int mark)
 101 {
 102         troff_put(doc, "\n.br\n");
 103         eatspc_on();
 104         ldepth++;
 105         if (ldepth > 1)
 106                 doc_write(doc, ".RS\n");
 107 }
 108
 109 static void troff_list_end(struct doc *doc)
 110 {
 111         if (ldepth > 1)
 112                 doc_write(doc, ".RE\n");
 113         ldepth--;
 114 }
 115
 116 static void troff_item_beg(struct doc *doc, char *head)
 117 {
 118         char b[1024];
 119         if (head) {
 120                 sprintf(b, ".IP \"%s\" 1i\n", head);
 121                 doc_write(doc, b);
 122         } else {
 123                 doc_write(doc, ".IP \\(bu 2\n");
 124         }
 125         eatspc_on();
 126 }
 127
 128 static void troff_item_end(struct doc *doc)
 129 {
 130 }
 131
 132 static void troff_block_beg(struct doc *doc, char *beg)
 133 {
 134         inblk = 1;
 135         troff_put(doc, beg ? beg : ".DS");
 136         troff_put(doc, "\n");
 137 }
 138
 139 static void troff_block_end(struct doc *doc, char *end)
 140 {
 141         troff_put(doc, end ? end : ".DE");
 142         troff_put(doc, "\n");
 143         inblk = 0;
 144 }
 145
 146 static void troff_put_txt(struct doc *doc, char *s, char *m)
 147 {
 148         char b[1024];
 149         switch(m[0]) {
 150         case '*':
 151                 troff_put(doc, "\\f3");
 152                 troff_put(doc, s);
 153                 troff_put(doc, "\\fP");
 154                 break;
 155         case '/':
 156                 troff_put(doc, "\\f2");
 157                 troff_put(doc, s);
 158                 troff_put(doc, "\\fP");
 159                 break;
 160         case '%':
 161                 troff_put(doc, s);
 162                 break;
 163         case '|':
 164                 troff_put(doc, "\n.[[\n");
 165                 troff_put(doc, s);
 166                 troff_put(doc, "\n.]]\n");
 167                 eatspc_on();
 168                 break;
 169         case '[':
 170                 troff_put(doc, "\n.FS\n");
 171                 troff_put(doc, s);
 172                 troff_put(doc, "\n.FE\n");
 173                 eatspc_on();
 174                 break;
 175         default:
 176                 sprintf(b, "%c%s%c", m[0], s, m[1]);
 177                 troff_put(doc, b);
 178         }
 179 }
 180
 181 static void troff_table_beg(struct doc *doc, int columns)
 182 {
 183         int i;
 184         troff_put(doc, ".TS\n");
 185         if (columns) {
 186                 troff_put(doc, "allbox;\n");
 187                 for (i = 0; i < columns; i++)
 188                         troff_put(doc, "c ");
 189                 troff_put(doc, ".\n");
 190         }
 191 }
 192
 193 static void troff_table_end(struct doc *doc)
 194 {
 195         troff_put(doc, ".TE\n");
 196 }
 197
 198 /* a hack to identify the first entry in each row */
 199 static int entcol;
 200
 201 static void troff_row_beg(struct doc *doc)
 202 {
 203         entcol = 0;
 204 }
 205
 206 static void troff_row_end(struct doc *doc)
 207 {
 208         troff_put(doc, "\n");
 209 }
 210
 211 static void troff_entry_beg(struct doc *doc)
 212 {
 213         if (entcol++)
 214                 troff_put(doc, "\t");
 215         troff_put(doc, "T{\n");
 216 }
 217
 218 static void troff_entry_end(struct doc *doc)
 219 {
 220         troff_put(doc, "\nT}");
 221 }
 222
 223 struct fmt_ops troff_ops = {
 224         .doc_beg        = troff_doc_beg,
 225         .doc_end        = troff_doc_end,
 226         .head_beg       = troff_head_beg,
 227         .head_end       = troff_head_end,
 228         .par_beg        = troff_par_beg,
 229         .par_end        = troff_par_end,
 230         .list_beg       = troff_list_beg,
 231         .list_end       = troff_list_end,
 232         .item_beg       = troff_item_beg,
 233         .item_end       = troff_item_end,
 234         .table_beg      = troff_table_beg,
 235         .table_end      = troff_table_end,
 236         .row_beg        = troff_row_beg,
 237         .row_end        = troff_row_end,
 238         .entry_beg      = troff_entry_beg,
 239         .entry_end      = troff_entry_end,
 240         .block_beg      = troff_block_beg,
 241         .block_end      = troff_block_end,
 242         .put            = troff_put,
 243         .put_txt        = troff_put_txt
 244 };