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prompt.c

/*
 * Copyright (C) 1984-2004  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


/*
 * Prompting and other messages.
 * There are three flavors of prompts, SHORT, MEDIUM and LONG,
 * selected by the -m/-M options.
 * There is also the "equals message", printed by the = command.
 * A prompt is a message composed of various pieces, such as the 
 * name of the file being viewed, the percentage into the file, etc.
 */

#include "less.h"
#include "position.h"

extern int pr_type;
extern int hit_eof;
extern int new_file;
extern int sc_width;
extern int so_s_width, so_e_width;
extern int linenums;
extern int hshift;
extern int sc_height;
extern int jump_sline;
extern IFILE curr_ifile;
#if EDITOR
extern char *editor;
extern char *editproto;
#endif

/*
 * Prototypes for the three flavors of prompts.
 * These strings are expanded by pr_expand().
 */
static constant char s_proto[] =
  "?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\\: %x..%t";
static constant char m_proto[] =
  "?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t";
static constant char M_proto[] =
  "?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?L/%L. :byte %bB?s/%s. .?e(END) ?x- Next\\: %x.:?pB%pB\\%..%t";
static constant char e_proto[] =
  "?f%f .?m(%T %i of %m) .?ltlines %lt-%lb?L/%L. .byte %bB?s/%s. ?e(END) :?pB%pB\\%..%t";
static constant char h_proto[] =
  "HELP -- ?eEND -- Press g to see it again:Press RETURN for more., or q when done";
static constant char w_proto[] =
  "Waiting for data";

public char *prproto[3];
public char constant *eqproto = e_proto;
public char constant *hproto = h_proto;
public char constant *wproto = w_proto;

static char message[PROMPT_SIZE];
static char *mp;

/*
 * Initialize the prompt prototype strings.
 */
      public void
init_prompt()
{
      prproto[0] = save(s_proto);
      prproto[1] = save(m_proto);
      prproto[2] = save(M_proto);
      eqproto = save(e_proto);
      hproto = save(h_proto);
      wproto = save(w_proto);
}

/*
 * Append a string to the end of the message.
 */
      static void
ap_str(s)
      char *s;
{
      int len;

      len = strlen(s);
      if (mp + len >= message + PROMPT_SIZE)
            len = message + PROMPT_SIZE - mp - 1;
      strncpy(mp, s, len);
      mp += len;
      *mp = '\0';
}

/*
 * Append a character to the end of the message.
 */
      static void
ap_char(c)
      char c;
{
      char buf[2];

      buf[0] = c;
      buf[1] = '\0';
      ap_str(buf);
}

/*
 * Append a POSITION (as a decimal integer) to the end of the message.
 */
      static void
ap_pos(pos)
      POSITION pos;
{
      char buf[INT_STRLEN_BOUND(pos) + 2];

      postoa(pos, buf);
      ap_str(buf);
}

/*
 * Append a line number to the end of the message.
 */
      static void
ap_linenum(linenum)
      LINENUM linenum;
{
      char buf[INT_STRLEN_BOUND(linenum) + 2];

      linenumtoa(linenum, buf);
      ap_str(buf);
}

/*
 * Append an integer to the end of the message.
 */
      static void
ap_int(num)
      int num;
{
      char buf[INT_STRLEN_BOUND(num) + 2];

      inttoa(num, buf);
      ap_str(buf);
}

/*
 * Append a question mark to the end of the message.
 */
      static void
ap_quest()
{
      ap_str("?");
}

/*
 * Return the "current" byte offset in the file.
 */
      static POSITION
curr_byte(where)
      int where;
{
      POSITION pos;

      pos = position(where);
      while (pos == NULL_POSITION && where >= 0 && where < sc_height-1)
            pos = position(++where);
      if (pos == NULL_POSITION)
            pos = ch_length();
      return (pos);
}

/*
 * Return the value of a prototype conditional.
 * A prototype string may include conditionals which consist of a 
 * question mark followed by a single letter.
 * Here we decode that letter and return the appropriate boolean value.
 */
      static int
cond(c, where)
      char c;
      int where;
{
      POSITION len;

      switch (c)
      {
      case 'a':   /* Anything in the message yet? */
            return (mp > message);
      case 'b':   /* Current byte offset known? */
            return (curr_byte(where) != NULL_POSITION);
      case 'c':
            return (hshift != 0);
      case 'e':   /* At end of file? */
            return (hit_eof);
      case 'f':   /* Filename known? */
            return (strcmp(get_filename(curr_ifile), "-") != 0);
      case 'l':   /* Line number known? */
      case 'd':   /* Same as l */
            return (linenums);
      case 'L':   /* Final line number known? */
      case 'D':   /* Final page number known? */
            return (linenums && ch_length() != NULL_POSITION);
      case 'm':   /* More than one file? */
#if TAGS
            return (ntags() ? (ntags() > 1) : (nifile() > 1));
#else
            return (nifile() > 1);
#endif
      case 'n':   /* First prompt in a new file? */
#if TAGS
            return (ntags() ? 1 : new_file);
#else
            return (new_file);
#endif
      case 'p':   /* Percent into file (bytes) known? */
            return (curr_byte(where) != NULL_POSITION && 
                        ch_length() > 0);
      case 'P':   /* Percent into file (lines) known? */
            return (currline(where) != 0 &&
                        (len = ch_length()) > 0 &&
                        find_linenum(len) != 0);
      case 's':   /* Size of file known? */
      case 'B':
            return (ch_length() != NULL_POSITION);
      case 'x':   /* Is there a "next" file? */
#if TAGS
            if (ntags())
                  return (0);
#endif
            return (next_ifile(curr_ifile) != NULL_IFILE);
      }
      return (0);
}

/*
 * Decode a "percent" prototype character.
 * A prototype string may include various "percent" escapes;
 * that is, a percent sign followed by a single letter.
 * Here we decode that letter and take the appropriate action,
 * usually by appending something to the message being built.
 */
      static void
protochar(c, where, iseditproto)
      int c;
      int where;
      int iseditproto;
{
      POSITION pos;
      POSITION len;
      int n;
      LINENUM linenum;
      LINENUM last_linenum;
      IFILE h;

#undef  PAGE_NUM
#define PAGE_NUM(linenum)  ((((linenum) - 1) / (sc_height - 1)) + 1)

      switch (c)
      {
      case 'b':   /* Current byte offset */
            pos = curr_byte(where);
            if (pos != NULL_POSITION)
                  ap_pos(pos);
            else
                  ap_quest();
            break;
      case 'c':
            ap_int(hshift);
            break;
      case 'd':   /* Current page number */
            linenum = currline(where);
            if (linenum > 0 && sc_height > 1)
                  ap_linenum(PAGE_NUM(linenum));
            else
                  ap_quest();
            break;
      case 'D':   /* Final page number */
            /* Find the page number of the last byte in the file (len-1). */
            len = ch_length();
            if (len == NULL_POSITION)
                  ap_quest();
            else if (len == 0)
                  /* An empty file has no pages. */
                  ap_linenum(0);
            else
            {
                  linenum = find_linenum(len - 1);
                  if (linenum <= 0)
                        ap_quest();
                  else 
                        ap_linenum(PAGE_NUM(linenum));
            }
            break;
#if EDITOR
      case 'E':   /* Editor name */
            ap_str(editor);
            break;
#endif
      case 'f':   /* File name */
            ap_str(get_filename(curr_ifile));
            break;
      case 'i':   /* Index into list of files */
#if TAGS
            if (ntags())
                  ap_int(curr_tag());
            else
#endif
                  ap_int(get_index(curr_ifile));
            break;
      case 'l':   /* Current line number */
            linenum = currline(where);
            if (linenum != 0)
                  ap_linenum(linenum);
            else
                  ap_quest();
            break;
      case 'L':   /* Final line number */
            len = ch_length();
            if (len == NULL_POSITION || len == ch_zero() ||
                (linenum = find_linenum(len)) <= 0)
                  ap_quest();
            else
                  ap_linenum(linenum-1);
            break;
      case 'm':   /* Number of files */
#if TAGS
            n = ntags();
            if (n)
                  ap_int(n);
            else
#endif
                  ap_int(nifile());
            break;
      case 'p':   /* Percent into file (bytes) */
            pos = curr_byte(where);
            len = ch_length();
            if (pos != NULL_POSITION && len > 0)
                  ap_int(percentage(pos,len));
            else
                  ap_quest();
            break;
      case 'P':   /* Percent into file (lines) */
            linenum = currline(where);
            if (linenum == 0 ||
                (len = ch_length()) == NULL_POSITION || len == ch_zero() ||
                (last_linenum = find_linenum(len)) <= 0)
                  ap_quest();
            else
                  ap_int(percentage(linenum, last_linenum));
            break;
      case 's':   /* Size of file */
      case 'B':
            len = ch_length();
            if (len != NULL_POSITION)
                  ap_pos(len);
            else
                  ap_quest();
            break;
      case 't':   /* Truncate trailing spaces in the message */
            while (mp > message && mp[-1] == ' ')
                  mp--;
            break;
      case 'T':   /* Type of list */
#if TAGS
            if (ntags())
                  ap_str("tag");
            else
#endif
                  ap_str("file");
            break;
      case 'x':   /* Name of next file */
            h = next_ifile(curr_ifile);
            if (h != NULL_IFILE)
                  ap_str(get_filename(h));
            else
                  ap_quest();
            break;
      }
}

/*
 * Skip a false conditional.
 * When a false condition is found (either a false IF or the ELSE part 
 * of a true IF), this routine scans the prototype string to decide
 * where to resume parsing the string.
 * We must keep track of nested IFs and skip them properly.
 */
      static char *
skipcond(p)
      register char *p;
{
      register int iflevel;

      /*
       * We came in here after processing a ? or :,
       * so we start nested one level deep.
       */
      iflevel = 1;

      for (;;) switch (*++p)
      {
      case '?':
            /*
             * Start of a nested IF.
             */
            iflevel++;
            break;
      case ':':
            /*
             * Else.
             * If this matches the IF we came in here with,
             * then we're done.
             */
            if (iflevel == 1)
                  return (p);
            break;
      case '.':
            /*
             * Endif.
             * If this matches the IF we came in here with,
             * then we're done.
             */
            if (--iflevel == 0)
                  return (p);
            break;
      case '\\':
            /*
             * Backslash escapes the next character.
             */
            ++p;
            break;
      case '\0':
            /*
             * Whoops.  Hit end of string.
             * This is a malformed conditional, but just treat it
             * as if all active conditionals ends here.
             */
            return (p-1);
      }
      /*NOTREACHED*/
}

/*
 * Decode a char that represents a position on the screen.
 */
      static char *
wherechar(p, wp)
      char *p;
      int *wp;
{
      switch (*p)
      {
      case 'b': case 'd': case 'l': case 'p': case 'P':
            switch (*++p)
            {
            case 't':   *wp = TOP;              break;
            case 'm':   *wp = MIDDLE;           break;
            case 'b':   *wp = BOTTOM;           break;
            case 'B':   *wp = BOTTOM_PLUS_ONE;  break;
            case 'j':   *wp = adjsline(jump_sline);   break;
            default:    *wp = TOP;  p--;        break;
            }
      }
      return (p);
}

/*
 * Construct a message based on a prototype string.
 */
      public char *
pr_expand(proto, maxwidth)
      char *proto;
      int maxwidth;
{
      register char *p;
      register int c;
      int where;

      mp = message;

      if (*proto == '\0')
            return ("");

      for (p = proto;  *p != '\0';  p++)
      {
            switch (*p)
            {
            default:    /* Just put the character in the message */
                  ap_char(*p);
                  break;
            case '\\':  /* Backslash escapes the next character */
                  p++;
                  ap_char(*p);
                  break;
            case '?':   /* Conditional (IF) */
                  if ((c = *++p) == '\0')
                        --p;
                  else
                  {
                        where = 0;
                        p = wherechar(p, &where);
                        if (!cond(c, where))
                              p = skipcond(p);
                  }
                  break;
            case ':':   /* ELSE */
                  p = skipcond(p);
                  break;
            case '.':   /* ENDIF */
                  break;
            case '%':   /* Percent escape */
                  if ((c = *++p) == '\0')
                        --p;
                  else
                  {
                        where = 0;
                        p = wherechar(p, &where);
                        protochar(c, where,
#if EDITOR
                              (proto == editproto));
#else
                              0);
#endif

                  }
                  break;
            }
      }

      if (mp == message)
            return ("");
      if (maxwidth > 0 && mp >= message + maxwidth)
      {
            /*
             * Message is too long.
             * Return just the final portion of it.
             */
            return (mp - maxwidth);
      }
      return (message);
}

/*
 * Return a message suitable for printing by the "=" command.
 */
      public char *
eq_message()
{
      return (pr_expand(eqproto, 0));
}

/*
 * Return a prompt.
 * This depends on the prompt type (SHORT, MEDIUM, LONG), etc.
 * If we can't come up with an appropriate prompt, return NULL
 * and the caller will prompt with a colon.
 */
      public char *
pr_string()
{
      char *prompt;

      prompt = pr_expand((ch_getflags() & CH_HELPFILE) ?
                        hproto : prproto[pr_type],
                  sc_width-so_s_width-so_e_width-2);
      new_file = 0;
      return (prompt);
}

/*
 * Return a message suitable for printing while waiting in the F command.
 */
      public char *
wait_message()
{
      return (pr_expand(wproto, sc_width-so_s_width-so_e_width-2));
}

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