vl_lib_readline

Searches for a readline compatible library. If found, defines `HAVE_LIBREADLINE'. If the found library has the `add_history' function, sets also `HAVE_READLINE_HISTORY'. Also checks for the locations of the necessary include files and sets `HAVE_READLINE_H' or `HAVE_READLINE_READLINE_H' and `HAVE_READLINE_HISTORY_H' or 'HAVE_HISTORY_H' if the corresponding include files exists.

The libraries that may be readline compatible are `libedit', `libeditline' and `libreadline'. Sometimes we need to link a termcap library for readline to work, this macro tests these cases too by trying to link with `libtermcap', `libcurses' or `libncurses' before giving up.

Here is an example of how to use the information provided by this macro to perform the necessary includes or declarations in a C file:

  #ifdef HAVE_LIBREADLINE
  #  if defined(HAVE_READLINE_READLINE_H)
  #    include <readline/readline.h>
  #  elif defined(HAVE_READLINE_H)
  #    include <readline.h>
  #  else /* !defined(HAVE_READLINE_H) */
  extern char *readline ();
  #  endif /* !defined(HAVE_READLINE_H) */
  char *cmdline = NULL;
  #else /* !defined(HAVE_READLINE_READLINE_H) */
    /* no readline */
  #endif /* HAVE_LIBREADLINE */

  #ifdef HAVE_READLINE_HISTORY
  #  if defined(HAVE_READLINE_HISTORY_H)
  #    include <readline/history.h>
  #  elif defined(HAVE_HISTORY_H)
  #    include <history.h>
  #  else /* !defined(HAVE_HISTORY_H) */
  extern void add_history ();
  extern int write_history ();
  extern int read_history ();
  #  endif /* defined(HAVE_READLINE_HISTORY_H) */
    /* no history */
  #endif /* HAVE_READLINE_HISTORY */

AC_DEFUN([VL_LIB_READLINE], [
  AC_CACHE_CHECK([for a readline compatible library],
                 vl_cv_lib_readline, [
    ORIG_LIBS="$LIBS"
    for readline_lib in readline edit editline; do
      for termcap_lib in "" termcap curses ncurses; do
        if test -z "$termcap_lib"; then
          TRY_LIB="-l$readline_lib"
        else
          TRY_LIB="-l$readline_lib -l$termcap_lib"
        fi
        LIBS="$ORIG_LIBS $TRY_LIB"
        AC_TRY_LINK_FUNC(readline, vl_cv_lib_readline="$TRY_LIB")
        if test -n "$vl_cv_lib_readline"; then
          break
        fi
      done
      if test -n "$vl_cv_lib_readline"; then
        break
      fi
    done
    if test -z "$vl_cv_lib_readline"; then
      vl_cv_lib_readline="no"
      LIBS="$ORIG_LIBS"
    fi
  ])

  if test "$vl_cv_lib_readline" != "no"; then
    AC_DEFINE(HAVE_LIBREADLINE, 1,
              [Define if you have a readline compatible library])
    AC_CHECK_HEADERS(readline.h readline/readline.h)
    AC_CACHE_CHECK([whether readline supports history],
                   vl_cv_lib_readline_history, [
      vl_cv_lib_readline_history="no"
      AC_TRY_LINK_FUNC(add_history, vl_cv_lib_readline_history="yes")
    ])
    if test "$vl_cv_lib_readline_history" = "yes"; then
      AC_DEFINE(HAVE_READLINE_HISTORY, 1,
                [Define if your readline library has \`add_history'])
      AC_CHECK_HEADERS(history.h readline/history.h)
    fi
  fi
])dnl

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