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cmdbuf.c

/*
 * Copyright (C) 1984-2002  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.
 */


/*
 * Functions which manipulate the command buffer.
 * Used only by command() and related functions.
 */

#include "less.h"
#include "cmd.h"

extern int sc_width;

static char cmdbuf[CMDBUF_SIZE]; /* Buffer for holding a multi-char command */
static int cmd_col;           /* Current column of the cursor */
static int prompt_col;        /* Column of cursor just after prompt */
static char *cp;        /* Pointer into cmdbuf */
static int cmd_offset;        /* Index into cmdbuf of first displayed char */
static int literal;           /* Next input char should not be interpreted */

#if TAB_COMPLETE_FILENAME
static int cmd_complete();
/*
 * These variables are statics used by cmd_complete.
 */
static int in_completion = 0;
static char *tk_text;
static char *tk_original;
static char *tk_ipoint;
static char *tk_trial;
static struct textlist tk_tlist;
#endif

static int cmd_left();
static int cmd_right();

#if SPACES_IN_FILENAMES
public char openquote = '"';
public char closequote = '"';
#endif

#if CMD_HISTORY
/*
 * A mlist structure represents a command history.
 */
struct mlist
{
      struct mlist *next;
      struct mlist *prev;
      struct mlist *curr_mp;
      char *string;
};

/*
 * These are the various command histories that exist.
 */
struct mlist mlist_search =  
      { &mlist_search,  &mlist_search,  &mlist_search,  NULL };
public void * constant ml_search = (void *) &mlist_search;

struct mlist mlist_examine = 
      { &mlist_examine, &mlist_examine, &mlist_examine, NULL };
public void * constant ml_examine = (void *) &mlist_examine;

#if SHELL_ESCAPE || PIPEC
struct mlist mlist_shell =   
      { &mlist_shell,   &mlist_shell,   &mlist_shell,   NULL };
public void * constant ml_shell = (void *) &mlist_shell;
#endif

#else /* CMD_HISTORY */

/* If CMD_HISTORY is off, these are just flags. */
public void * constant ml_search = (void *)1;
public void * constant ml_examine = (void *)2;
#if SHELL_ESCAPE || PIPEC
public void * constant ml_shell = (void *)3;
#endif

#endif /* CMD_HISTORY */

/*
 * History for the current command.
 */
static struct mlist *curr_mlist = NULL;
static int curr_cmdflags;


/*
 * Reset command buffer (to empty).
 */
      public void
cmd_reset()
{
      cp = cmdbuf;
      *cp = '\0';
      cmd_col = 0;
      cmd_offset = 0;
      literal = 0;
}

/*
 * Clear command line on display.
 */
      public void
clear_cmd()
{
      clear_bot();
      cmd_col = prompt_col = 0;
}

/*
 * Display a string, usually as a prompt for input into the command buffer.
 */
      public void
cmd_putstr(s)
      char *s;
{
      putstr(s);
      cmd_col += strlen(s);
      prompt_col += strlen(s);
}

/*
 * How many characters are in the command buffer?
 */
      public int
len_cmdbuf()
{
      return (strlen(cmdbuf));
}

/*
 * Repaint the line from cp onwards.
 * Then position the cursor just after the char old_cp (a pointer into cmdbuf).
 */
      static void
cmd_repaint(old_cp)
      char *old_cp;
{
      char *p;

      /*
       * Repaint the line from the current position.
       */
      clear_eol();
      for ( ;  *cp != '\0';  cp++)
      {
            p = prchar(*cp);
            if (cmd_col + (int)strlen(p) >= sc_width)
                  break;
            putstr(p);
            cmd_col += strlen(p);
      }

      /*
       * Back up the cursor to the correct position.
       */
      while (cp > old_cp)
            cmd_left();
}

/*
 * Put the cursor at "home" (just after the prompt),
 * and set cp to the corresponding char in cmdbuf.
 */
      static void
cmd_home()
{
      while (cmd_col > prompt_col)
      {
            putbs();
            cmd_col--;
      }

      cp = &cmdbuf[cmd_offset];
}

/*
 * Shift the cmdbuf display left a half-screen.
 */
      static void
cmd_lshift()
{
      char *s;
      char *save_cp;
      int cols;

      /*
       * Start at the first displayed char, count how far to the
       * right we'd have to move to reach the center of the screen.
       */
      s = cmdbuf + cmd_offset;
      cols = 0;
      while (cols < (sc_width - prompt_col) / 2 && *s != '\0')
            cols += strlen(prchar(*s++));

      cmd_offset = s - cmdbuf;
      save_cp = cp;
      cmd_home();
      cmd_repaint(save_cp);
}

/*
 * Shift the cmdbuf display right a half-screen.
 */
      static void
cmd_rshift()
{
      char *s;
      char *p;
      char *save_cp;
      int cols;

      /*
       * Start at the first displayed char, count how far to the
       * left we'd have to move to traverse a half-screen width
       * of displayed characters.
       */
      s = cmdbuf + cmd_offset;
      cols = 0;
      while (cols < (sc_width - prompt_col) / 2 && s > cmdbuf)
      {
            p = prchar(*--s);
            cols += strlen(p);
      }

      cmd_offset = s - cmdbuf;
      save_cp = cp;
      cmd_home();
      cmd_repaint(save_cp);
}

/*
 * Move cursor right one character.
 */
      static int
cmd_right()
{
      char *p;
      
      if (*cp == '\0')
      {
            /* 
             * Already at the end of the line.
             */
            return (CC_OK);
      }
      p = prchar(*cp);
      if (cmd_col + (int)strlen(p) >= sc_width)
            cmd_lshift();
      else if (cmd_col + (int)strlen(p) == sc_width - 1 && cp[1] != '\0')
            cmd_lshift();
      cp++;
      putstr(p);
      cmd_col += strlen(p);
      return (CC_OK);
}

/*
 * Move cursor left one character.
 */
      static int
cmd_left()
{
      char *p;
      
      if (cp <= cmdbuf)
      {
            /* Already at the beginning of the line */
            return (CC_OK);
      }
      p = prchar(cp[-1]);
      if (cmd_col < prompt_col + (int)strlen(p))
            cmd_rshift();
      cp--;
      cmd_col -= strlen(p);
      while (*p++ != '\0')
            putbs();
      return (CC_OK);
}

/*
 * Insert a char into the command buffer, at the current position.
 */
      static int
cmd_ichar(c)
      int c;
{
      char *s;
      
      if (strlen(cmdbuf) >= sizeof(cmdbuf)-2)
      {
            /*
             * No room in the command buffer for another char.
             */
            bell();
            return (CC_ERROR);
      }
            
      /*
       * Insert the character into the buffer.
       */
      for (s = &cmdbuf[strlen(cmdbuf)];  s >= cp;  s--)
            s[1] = s[0];
      *cp = c;
      /*
       * Reprint the tail of the line from the inserted char.
       */
      cmd_repaint(cp);
      cmd_right();
      return (CC_OK);
}

/*
 * Backspace in the command buffer.
 * Delete the char to the left of the cursor.
 */
      static int
cmd_erase()
{
      register char *s;

      if (cp == cmdbuf)
      {
            /*
             * Backspace past beginning of the buffer:
             * this usually means abort the command.
             */
            return (CC_QUIT);
      }
      /*
       * Move cursor left (to the char being erased).
       */
      cmd_left();
      /*
       * Remove the char from the buffer (shift the buffer left).
       */
      for (s = cp;  *s != '\0';  s++)
            s[0] = s[1];
      /*
       * Repaint the buffer after the erased char.
       */
      cmd_repaint(cp);
      
      /*
       * We say that erasing the entire command string causes us
       * to abort the current command, if CF_QUIT_ON_ERASE is set.
       */
      if ((curr_cmdflags & CF_QUIT_ON_ERASE) && cp == cmdbuf && *cp == '\0')
            return (CC_QUIT);
      return (CC_OK);
}

/*
 * Delete the char under the cursor.
 */
      static int
cmd_delete()
{
      if (*cp == '\0')
      {
            /*
             * At end of string; there is no char under the cursor.
             */
            return (CC_OK);
      }
      /*
       * Move right, then use cmd_erase.
       */
      cmd_right();
      cmd_erase();
      return (CC_OK);
}

/*
 * Delete the "word" to the left of the cursor.
 */
      static int
cmd_werase()
{
      if (cp > cmdbuf && cp[-1] == ' ')
      {
            /*
             * If the char left of cursor is a space,
             * erase all the spaces left of cursor (to the first non-space).
             */
            while (cp > cmdbuf && cp[-1] == ' ')
                  (void) cmd_erase();
      } else
      {
            /*
             * If the char left of cursor is not a space,
             * erase all the nonspaces left of cursor (the whole "word").
             */
            while (cp > cmdbuf && cp[-1] != ' ')
                  (void) cmd_erase();
      }
      return (CC_OK);
}

/*
 * Delete the "word" under the cursor.
 */
      static int
cmd_wdelete()
{
      if (*cp == ' ')
      {
            /*
             * If the char under the cursor is a space,
             * delete it and all the spaces right of cursor.
             */
            while (*cp == ' ')
                  (void) cmd_delete();
      } else
      {
            /*
             * If the char under the cursor is not a space,
             * delete it and all nonspaces right of cursor (the whole word).
             */
            while (*cp != ' ' && *cp != '\0')
                  (void) cmd_delete();
      }
      return (CC_OK);
}

/*
 * Delete all chars in the command buffer.
 */
      static int
cmd_kill()
{
      if (cmdbuf[0] == '\0')
      {
            /*
             * Buffer is already empty; abort the current command.
             */
            return (CC_QUIT);
      }
      cmd_offset = 0;
      cmd_home();
      *cp = '\0';
      cmd_repaint(cp);

      /*
       * We say that erasing the entire command string causes us
       * to abort the current command, if CF_QUIT_ON_ERASE is set.
       */
      if (curr_cmdflags & CF_QUIT_ON_ERASE)
            return (CC_QUIT);
      return (CC_OK);
}

/*
 * Select an mlist structure to be the current command history.
 */
      public void
set_mlist(mlist, cmdflags)
      void *mlist;
      int cmdflags;
{
      curr_mlist = (struct mlist *) mlist;
      curr_cmdflags = cmdflags;
}

#if CMD_HISTORY
/*
 * Move up or down in the currently selected command history list.
 */
      static int
cmd_updown(action)
      int action;
{
      char *s;
      
      if (curr_mlist == NULL)
      {
            /*
             * The current command has no history list.
             */
            bell();
            return (CC_OK);
      }
      cmd_home();
      clear_eol();
      /*
       * Move curr_mp to the next/prev entry.
       */
      if (action == EC_UP)
            curr_mlist->curr_mp = curr_mlist->curr_mp->prev;
      else
            curr_mlist->curr_mp = curr_mlist->curr_mp->next;
      /*
       * Copy the entry into cmdbuf and echo it on the screen.
       */
      s = curr_mlist->curr_mp->string;
      if (s == NULL)
            s = "";
      for (cp = cmdbuf;  *s != '\0';  s++)
      {
            *cp = *s;
            cmd_right();
      }
      *cp = '\0';
      return (CC_OK);
}
#endif

/*
 * Add a string to a history list.
 */
      public void
cmd_addhist(mlist, cmd)
      struct mlist *mlist;
      char *cmd;
{
#if CMD_HISTORY
      struct mlist *ml;
      
      /*
       * Don't save a trivial command.
       */
      if (strlen(cmd) == 0)
            return;
      /*
       * Don't save if a duplicate of a command which is already 
       * in the history.
       * But select the one already in the history to be current.
       */
      for (ml = mlist->next;  ml != mlist;  ml = ml->next)
      {
            if (strcmp(ml->string, cmd) == 0)
                  break;
      }
      if (ml == mlist)
      {
            /*
             * Did not find command in history.
             * Save the command and put it at the end of the history list.
             */
            ml = (struct mlist *) ecalloc(1, sizeof(struct mlist));
            ml->string = save(cmd);
            ml->next = mlist;
            ml->prev = mlist->prev;
            mlist->prev->next = ml;
            mlist->prev = ml;
      }
      /*
       * Point to the cmd just after the just-accepted command.
       * Thus, an UPARROW will always retrieve the previous command.
       */
      mlist->curr_mp = ml->next;
#endif
}

/*
 * Accept the command in the command buffer.
 * Add it to the currently selected history list.
 */
      public void
cmd_accept()
{
#if CMD_HISTORY
      /*
       * Nothing to do if there is no currently selected history list.
       */
      if (curr_mlist == NULL)
            return;
      cmd_addhist(curr_mlist, cmdbuf);
#endif
}

/*
 * Try to perform a line-edit function on the command buffer,
 * using a specified char as a line-editing command.
 * Returns:
 *    CC_PASS     The char does not invoke a line edit function.
 *    CC_OK Line edit function done.
 *    CC_QUIT     The char requests the current command to be aborted.
 */
      static int
cmd_edit(c)
      int c;
{
      int action;
      int flags;

#if TAB_COMPLETE_FILENAME
#define     not_in_completion()     in_completion = 0
#else
#define     not_in_completion()
#endif
      
      /*
       * See if the char is indeed a line-editing command.
       */
      flags = 0;
#if CMD_HISTORY
      if (curr_mlist == NULL)
            /*
             * No current history; don't accept history manipulation cmds.
             */
            flags |= EC_NOHISTORY;
#endif
#if TAB_COMPLETE_FILENAME
      if (curr_mlist == ml_search)
            /*
             * In a search command; don't accept file-completion cmds.
             */
            flags |= EC_NOCOMPLETE;
#endif

      action = editchar(c, flags);

      switch (action)
      {
      case EC_RIGHT:
            not_in_completion();
            return (cmd_right());
      case EC_LEFT:
            not_in_completion();
            return (cmd_left());
      case EC_W_RIGHT:
            not_in_completion();
            while (*cp != '\0' && *cp != ' ')
                  cmd_right();
            while (*cp == ' ')
                  cmd_right();
            return (CC_OK);
      case EC_W_LEFT:
            not_in_completion();
            while (cp > cmdbuf && cp[-1] == ' ')
                  cmd_left();
            while (cp > cmdbuf && cp[-1] != ' ')
                  cmd_left();
            return (CC_OK);
      case EC_HOME:
            not_in_completion();
            cmd_offset = 0;
            cmd_home();
            cmd_repaint(cp);
            return (CC_OK);
      case EC_END:
            not_in_completion();
            while (*cp != '\0')
                  cmd_right();
            return (CC_OK);
      case EC_INSERT:
            not_in_completion();
            return (CC_OK);
      case EC_BACKSPACE:
            not_in_completion();
            return (cmd_erase());
      case EC_LINEKILL:
            not_in_completion();
            return (cmd_kill());
      case EC_W_BACKSPACE:
            not_in_completion();
            return (cmd_werase());
      case EC_DELETE:
            not_in_completion();
            return (cmd_delete());
      case EC_W_DELETE:
            not_in_completion();
            return (cmd_wdelete());
      case EC_LITERAL:
            literal = 1;
            return (CC_OK);
#if CMD_HISTORY
      case EC_UP:
      case EC_DOWN:
            not_in_completion();
            return (cmd_updown(action));
#endif
#if TAB_COMPLETE_FILENAME
      case EC_F_COMPLETE:
      case EC_B_COMPLETE:
      case EC_EXPAND:
            return (cmd_complete(action));
#endif
      case EC_NOACTION:
            return (CC_OK);
      default:
            not_in_completion();
            return (CC_PASS);
      }
}

#if TAB_COMPLETE_FILENAME
/*
 * Insert a string into the command buffer, at the current position.
 */
      static int
cmd_istr(str)
      char *str;
{
      char *s;
      int action;
      
      for (s = str;  *s != '\0';  s++)
      {
            action = cmd_ichar(*s);
            if (action != CC_OK)
            {
                  bell();
                  return (action);
            }
      }
      return (CC_OK);
}

/*
 * Find the beginning and end of the "current" word.
 * This is the word which the cursor (cp) is inside or at the end of.
 * Return pointer to the beginning of the word and put the
 * cursor at the end of the word.
 */
      static char *
delimit_word()
{
      char *word;
#if SPACES_IN_FILENAMES
      char *p;
      int delim_quoted = 0;
      int meta_quoted = 0;
      char *esc = get_meta_escape();
      int esclen = strlen(esc);
#endif
      
      /*
       * Move cursor to end of word.
       */
      if (*cp != ' ' && *cp != '\0')
      {
            /*
             * Cursor is on a nonspace.
             * Move cursor right to the next space.
             */
            while (*cp != ' ' && *cp != '\0')
                  cmd_right();
      } else if (cp > cmdbuf && cp[-1] != ' ')
      {
            /*
             * Cursor is on a space, and char to the left is a nonspace.
             * We're already at the end of the word.
             */
            ;
#if 0
      } else
      {
            /*
             * Cursor is on a space and char to the left is a space.
             * Huh? There's no word here.
             */
            return (NULL);
#endif
      }
      /*
       * Find the beginning of the word which the cursor is in.
       */
      if (cp == cmdbuf)
            return (NULL);
#if SPACES_IN_FILENAMES
      /*
       * If we have an unbalanced quote (that is, an open quote
       * without a corresponding close quote), we return everything
       * from the open quote, including spaces.
       */
      for (word = cmdbuf;  word < cp;  word++)
            if (*word != ' ')
                  break;
      if (word >= cp)
            return (cp);
      for (p = cmdbuf;  p < cp;  p++)
      {
            if (meta_quoted)
            {
                  meta_quoted = 0;
            } else if (esclen > 0 && p + esclen < cp &&
                       strncmp(p, esc, esclen) == 0)
            {
                  meta_quoted = 1;
                  p += esclen - 1;
            } else if (delim_quoted)
            {
                  if (*p == closequote)
                        delim_quoted = 0;
            } else /* (!delim_quoted) */
            {
                  if (*p == openquote)
                        delim_quoted = 1;
                  else if (*p == ' ')
                        word = p+1;
            }
      }
#endif
      return (word);
}

/*
 * Set things up to enter completion mode.
 * Expand the word under the cursor into a list of filenames 
 * which start with that word, and set tk_text to that list.
 */
      static void
init_compl()
{
      char *word;
      char c;
      
      /*
       * Get rid of any previous tk_text.
       */
      if (tk_text != NULL)
      {
            free(tk_text);
            tk_text = NULL;
      }
      /*
       * Find the original (uncompleted) word in the command buffer.
       */
      word = delimit_word();
      if (word == NULL)
            return;
      /*
       * Set the insertion point to the point in the command buffer
       * where the original (uncompleted) word now sits.
       */
      tk_ipoint = word;
      /*
       * Save the original (uncompleted) word
       */
      if (tk_original != NULL)
            free(tk_original);
      tk_original = (char *) ecalloc(cp-word+1, sizeof(char));
      strncpy(tk_original, word, cp-word);
      /*
       * Get the expanded filename.
       * This may result in a single filename, or
       * a blank-separated list of filenames.
       */
      c = *cp;
      *cp = '\0';
      if (*word != openquote)
      {
            tk_text = fcomplete(word);
      } else
      {
            char *qword = shell_quote(word+1);
            if (qword == NULL)
                  tk_text = fcomplete(word+1);
            else
            {
                  tk_text = fcomplete(qword);
                  free(qword);
            }
      }
      *cp = c;
}

/*
 * Return the next word in the current completion list.
 */
      static char *
next_compl(action, prev)
      int action;
      char *prev;
{
      switch (action)
      {
      case EC_F_COMPLETE:
            return (forw_textlist(&tk_tlist, prev));
      case EC_B_COMPLETE:
            return (back_textlist(&tk_tlist, prev));
      }
      /* Cannot happen */
      return ("?");
}

/*
 * Complete the filename before (or under) the cursor.
 * cmd_complete may be called multiple times.  The global in_completion
 * remembers whether this call is the first time (create the list),
 * or a subsequent time (step thru the list).
 */
      static int
cmd_complete(action)
      int action;
{
      char *s;

      if (!in_completion || action == EC_EXPAND)
      {
            /*
             * Expand the word under the cursor and 
             * use the first word in the expansion 
             * (or the entire expansion if we're doing EC_EXPAND).
             */
            init_compl();
            if (tk_text == NULL)
            {
                  bell();
                  return (CC_OK);
            }
            if (action == EC_EXPAND)
            {
                  /*
                   * Use the whole list.
                   */
                  tk_trial = tk_text;
            } else
            {
                  /*
                   * Use the first filename in the list.
                   */
                  in_completion = 1;
                  init_textlist(&tk_tlist, tk_text);
                  tk_trial = next_compl(action, (char*)NULL);
            }
      } else
      {
            /*
             * We already have a completion list.
             * Use the next/previous filename from the list.
             */
            tk_trial = next_compl(action, tk_trial);
      }
      
      /*
       * Remove the original word, or the previous trial completion.
       */
      while (cp > tk_ipoint)
            (void) cmd_erase();
      
      if (tk_trial == NULL)
      {
            /*
             * There are no more trial completions.
             * Insert the original (uncompleted) filename.
             */
            in_completion = 0;
            if (cmd_istr(tk_original) != CC_OK)
                  goto fail;
      } else
      {
            /*
             * Insert trial completion.
             */
            if (cmd_istr(tk_trial) != CC_OK)
                  goto fail;
            /*
             * If it is a directory, append a slash.
             */
            if (is_dir(tk_trial))
            {
                  if (cp > cmdbuf && cp[-1] == closequote)
                        (void) cmd_erase();
                  s = lgetenv("LESSSEPARATOR");
                  if (s == NULL)
                        s = PATHNAME_SEP;
                  if (cmd_istr(s) != CC_OK)
                        goto fail;
            }
      }
      
      return (CC_OK);
      
fail:
      in_completion = 0;
      bell();
      return (CC_OK);
}

#endif /* TAB_COMPLETE_FILENAME */

/*
 * Process a single character of a multi-character command, such as
 * a number, or the pattern of a search command.
 * Returns:
 *    CC_OK       The char was accepted.
 *    CC_QUIT           The char requests the command to be aborted.
 *    CC_ERROR    The char could not be accepted due to an error.
 */
      public int
cmd_char(c)
      int c;
{
      int action;

      if (literal)
      {
            /*
             * Insert the char, even if it is a line-editing char.
             */
            literal = 0;
            return (cmd_ichar(c));
      }
            
      /*
       * See if it is a special line-editing character.
       */
      if (in_mca())
      {
            action = cmd_edit(c);
            switch (action)
            {
            case CC_OK:
            case CC_QUIT:
                  return (action);
            case CC_PASS:
                  break;
            }
      }
      
      /*
       * Insert the char into the command buffer.
       */
      return (cmd_ichar(c));
}

/*
 * Return the number currently in the command buffer.
 */
      public LINENUM
cmd_int()
{
      register char *p;
      LINENUM n = 0;

      for (p = cmdbuf;  *p != '\0';  p++)
            n = (10 * n) + (*p - '0');
      return (n);
}

/*
 * Return a pointer to the command buffer.
 */
      public char *
get_cmdbuf()
{
      return (cmdbuf);
}

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