Update copyright year range in header of all files managed by GDB

[thirdparty/binutils-gdb.git] / gdb / testsuite / lib / tuiterm.exp

# Copyright 2019-2023 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# An ANSI terminal emulator for expect.

namespace eval Term {
    # Size of the terminal.
    variable _rows
    variable _cols

    # Buffer / contents of the terminal.
    variable _chars

    # Position of the cursor.
    variable _cur_col
    variable _cur_row

    variable _attrs

    variable _last_char

    variable _resize_count

    proc _log { what } {
        verbose "+++ $what"
    }

    # Call BODY, then log WHAT along with the original and new cursor position.
    proc _log_cur { what body } {
        variable _cur_row
        variable _cur_col

        set orig_cur_row $_cur_row
        set orig_cur_col $_cur_col

        uplevel $body

        _log "$what, cursor: ($orig_cur_row, $orig_cur_col) -> ($_cur_row, $_cur_col)"
    }

    # If ARG is empty, return DEF: otherwise ARG.  This is useful for
    # defaulting arguments in CSIs.
    proc _default {arg def} {
        if {$arg == ""} {
            return $def
        }
        return $arg
    }

    # Erase in the line Y from SX to just before EX.
    proc _clear_in_line {sx ex y} {
        variable _attrs
        variable _chars
        set lattr [array get _attrs]
        while {$sx < $ex} {
            set _chars($sx,$y) [list " " $lattr]
            incr sx
        }
    }

    # Erase the lines from SY to just before EY.
    proc _clear_lines {sy ey} {
        variable _cols
        while {$sy < $ey} {
            _clear_in_line 0 $_cols $sy
            incr sy
        }
    }

    # Beep.
    proc _ctl_0x07 {} {
    }

    # Backspace.
    proc _ctl_0x08 {} {
        _log_cur "Backspace" {
            variable _cur_col

            if {$_cur_col > 0} {
                incr _cur_col -1
            }
        }
    }

    # Linefeed.
    proc _ctl_0x0a {} {
        _log_cur "Line feed" {
            variable _cur_row
            variable _rows

            incr _cur_row 1
            if {$_cur_row >= $_rows} {
                error "FIXME scroll"
            }
        }
    }

    # Carriage return.
    proc _ctl_0x0d {} {
        _log_cur "Carriage return" {
            variable _cur_col

            set _cur_col 0
        }
    }

    # Insert Character.
    #
    # https://vt100.net/docs/vt510-rm/ICH.html
    proc _csi_@ {args} {
        set n [_default [lindex $args 0] 1]

        _log_cur "Insert Character ($n)" {
            variable _cur_col
            variable _cur_row
            variable _cols
            variable _chars

            # Move characters right of the cursor right by N positions,
            # starting with the rightmost one.
            for {set in_col [expr $_cols - $n - 1]} {$in_col >= $_cur_col} {incr in_col -1} {
                set out_col [expr $in_col + $n]
                set _chars($out_col,$_cur_row) $_chars($in_col,$_cur_row)
            }

            # Write N blank spaces starting from the cursor.
            _clear_in_line $_cur_col [expr $_cur_col + $n] $_cur_row
        }
    }

    # Cursor Up.
    #
    # https://vt100.net/docs/vt510-rm/CUU.html
    proc _csi_A {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Up ($arg)" {
            variable _cur_row

            set _cur_row [expr {max ($_cur_row - $arg, 0)}]
        }
    }

    # Cursor Down.
    #
    # https://vt100.net/docs/vt510-rm/CUD.html
    proc _csi_B {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Down ($arg)" {
            variable _cur_row
            variable _rows

            set _cur_row [expr {min ($_cur_row + $arg, $_rows - 1)}]
        }
    }

    # Cursor Forward.
    #
    # https://vt100.net/docs/vt510-rm/CUF.html
    proc _csi_C {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Forward ($arg)" {
            variable _cur_col
            variable _cols

            set _cur_col [expr {min ($_cur_col + $arg, $_cols - 1)}]
        }
    }

    # Cursor Backward.
    #
    # https://vt100.net/docs/vt510-rm/CUB.html
    proc _csi_D {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Backward ($arg)" {
            variable _cur_col

            set _cur_col [expr {max ($_cur_col - $arg, 0)}]
        }
    }

    # Cursor Next Line.
    #
    # https://vt100.net/docs/vt510-rm/CNL.html
    proc _csi_E {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Next Line ($arg)" {
            variable _cur_col
            variable _cur_row
            variable _rows

            set _cur_col 0
            set _cur_row [expr {min ($_cur_row + $arg, $_rows - 1)}]
        }
    }

    # Cursor Previous Line.
    #
    # https://vt100.net/docs/vt510-rm/CPL.html
    proc _csi_F {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Previous Line ($arg)" {
            variable _cur_col
            variable _cur_row
            variable _rows

            set _cur_col 0
            set _cur_row [expr {max ($_cur_row - $arg, 0)}]
        }
    }

    # Cursor Horizontal Absolute.
    #
    # https://vt100.net/docs/vt510-rm/CHA.html
    proc _csi_G {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Cursor Horizontal Absolute ($arg)" {
            variable _cur_col
            variable _cols

            set _cur_col [expr {min ($arg - 1, $_cols)}]
        }
    }

    # Cursor Position.
    #
    # https://vt100.net/docs/vt510-rm/CUP.html
    proc _csi_H {args} {
        set row [_default [lindex $args 0] 1]
        set col [_default [lindex $args 1] 1]

        _log_cur "Cursor Position ($row, $col)" {
            variable _cur_col
            variable _cur_row

            set _cur_row [expr {$row - 1}]
            set _cur_col [expr {$col - 1}]
        }
    }

    # Cursor Horizontal Forward Tabulation.
    #
    # https://vt100.net/docs/vt510-rm/CHT.html
    proc _csi_I {args} {
        set n [_default [lindex $args 0] 1]

        _log_cur "Cursor Horizontal Forward Tabulation ($n)" {
            variable _cur_col
            variable _cols

            incr _cur_col [expr {$n * 8 - $_cur_col % 8}]
            if {$_cur_col >= $_cols} {
                set _cur_col [expr {$_cols - 1}]
            }
        }
    }

    # Erase in Display.
    #
    # https://vt100.net/docs/vt510-rm/ED.html
    proc _csi_J {args} {
        set arg [_default [lindex $args 0] 0]

        _log_cur "Erase in Display ($arg)" {
            variable _cur_col
            variable _cur_row
            variable _rows
            variable _cols

            if {$arg == 0} {
                # Cursor (inclusive) to end of display.
                _clear_in_line $_cur_col $_cols $_cur_row
                _clear_lines [expr {$_cur_row + 1}] $_rows
            } elseif {$arg == 1} {
                # Beginning of display to cursor (inclusive).
                _clear_lines 0 $_cur_row
                _clear_in_line 0 [expr $_cur_col + 1] $_cur_row
            } elseif {$arg == 2} {
                # Entire display.
                _clear_lines 0 $_rows
            }
        }
    }

    # Erase in Line.
    #
    # https://vt100.net/docs/vt510-rm/EL.html
    proc _csi_K {args} {
        set arg [_default [lindex $args 0] 0]

        _log_cur "Erase in Line ($arg)" {
            variable _cur_col
            variable _cur_row
            variable _cols

            if {$arg == 0} {
                # Cursor (inclusive) to end of line.
                _clear_in_line $_cur_col $_cols $_cur_row
            } elseif {$arg == 1} {
                # Beginning of line to cursor (inclusive).
                _clear_in_line 0 [expr $_cur_col + 1] $_cur_row
            } elseif {$arg == 2} {
                # Entire line.
                _clear_in_line 0 $_cols $_cur_row
            }
        }
    }

    # Insert Line
    #
    # https://vt100.net/docs/vt510-rm/IL.html
    proc _csi_L {args} {
        set arg [_default [lindex $args 0] 1]

        _log_cur "Insert Line ($arg)" {
            variable _cur_col
            variable _cur_row
            variable _rows
            variable _cols
            variable _chars

            set y [expr $_rows - 2]
            set next_y [expr $y + $arg]
            while {$y >= $_cur_row} {
                for {set x 0} {$x < $_cols} {incr x} {
                    set _chars($x,$next_y) $_chars($x,$y)
                }
                incr y -1
                incr next_y -1
            }

            _clear_lines $_cur_row [expr $_cur_row + $arg]
        }
    }

    # Delete line.
    #
    # https://vt100.net/docs/vt510-rm/DL.html
    proc _csi_M {args} {
        set count [_default [lindex $args 0] 1]

        _log_cur "Delete line ($count)" {
            variable _cur_row
            variable _rows
            variable _cols
            variable _chars

            set y $_cur_row
            set next_y [expr {$y + $count}]
            while {$next_y < $_rows} {
                for {set x 0} {$x < $_cols} {incr x} {
                    set _chars($x,$y) $_chars($x,$next_y)
                }
                incr y
                incr next_y
            }
            _clear_lines $y $_rows
        }
    }

    # Delete Character.
    #
    # https://vt100.net/docs/vt510-rm/DCH.html
    proc _csi_P {args} {
        set count [_default [lindex $args 0] 1]

        _log_cur "Delete character ($count)" {
            variable _cur_row
            variable _cur_col
            variable _chars
            variable _cols

            # Move all characters right of the cursor N positions left.
            set out_col [expr $_cur_col]
            set in_col [expr $_cur_col + $count]

            while {$in_col < $_cols} {
                set _chars($out_col,$_cur_row) $_chars($in_col,$_cur_row)
                incr in_col
                incr out_col
            }

            # Clear the rest of the line.
            _clear_in_line $out_col $_cols $_cur_row
        }
    }

    # Pan Down
    #
    # https://vt100.net/docs/vt510-rm/SU.html
    proc _csi_S {args} {
        set count [_default [lindex $args 0] 1]

        _log_cur "Pan Down ($count)" {
            variable _cur_col
            variable _cur_row
            variable _cols
            variable _rows
            variable _chars

            # The following code is written without consideration for
            # the scroll margins.  At this time this comment was
            # written the tuiterm library doesn't support the scroll
            # margins.  If/when that changes, then the following will
            # need to be updated.

            set dy 0
            set y $count

            while {$y < $_rows} {
                for {set x 0} {$x < $_cols} {incr x} {
                    set _chars($x,$dy) $_chars($x,$y)
                }
                incr y 1
                incr dy 1
            }

            _clear_lines $dy $_rows
        }
    }

    # Pan Up
    #
    # https://vt100.net/docs/vt510-rm/SD.html
    proc _csi_T {args} {
        set count [_default [lindex $args 0] 1]

        _log_cur "Pan Up ($count)" {
            variable _cur_col
            variable _cur_row
            variable _cols
            variable _rows
            variable _chars

            # The following code is written without consideration for
            # the scroll margins.  At this time this comment was
            # written the tuiterm library doesn't support the scroll
            # margins.  If/when that changes, then the following will
            # need to be updated.

            set y [expr $_rows - $count]
            set dy $_rows

            while {$dy >= $count} {
                for {set x 0} {$x < $_cols} {incr x} {
                    set _chars($x,$dy) $_chars($x,$y)
                }
                incr y -1
                incr dy -1
            }

            _clear_lines 0 $count
        }
    }

    # Erase chars.
    #
    # https://vt100.net/docs/vt510-rm/ECH.html
    proc _csi_X {args} {
        set n [_default [lindex $args 0] 1]

        _log_cur "Erase chars ($n)" {
            # Erase characters but don't move cursor.
            variable _cur_col
            variable _cur_row
            variable _attrs
            variable _chars

            set lattr [array get _attrs]
            set x $_cur_col
            for {set i 0} {$i < $n} {incr i} {
                set _chars($x,$_cur_row) [list " " $lattr]
                incr x
            }
        }
    }

    # Cursor Backward Tabulation.
    #
    # https://vt100.net/docs/vt510-rm/CBT.html
    proc _csi_Z {args} {
        set n [_default [lindex $args 0] 1]

        _log_cur "Cursor Backward Tabulation ($n)" {
            variable _cur_col

            set _cur_col [expr {max (int (($_cur_col - 1) / 8) * 8 - ($n - 1) * 8, 0)}]
        }
    }

    # Repeat.
    #
    # https://www.xfree86.org/current/ctlseqs.html (See `(REP)`)
    proc _csi_b {args} {
        set n [_default [lindex $args 0] 1]

        _log_cur "Repeat ($n)" {
            variable _last_char

            _insert [string repeat $_last_char $n]
        }
    }

    # Vertical Line Position Absolute.
    #
    # https://vt100.net/docs/vt510-rm/VPA.html
    proc _csi_d {args} {
        set row [_default [lindex $args 0] 1]

        _log_cur "Vertical Line Position Absolute ($row)" {
            variable _cur_row
            variable _rows

            set _cur_row [expr min ($row - 1, $_rows - 1)]
        }
    }

    # Select Graphic Rendition.
    #
    # https://vt100.net/docs/vt510-rm/SGR.html
    proc _csi_m {args} {
        _log_cur "Select Graphic Rendition ([join $args {, }])" {
          variable _attrs

          foreach item $args {
              switch -exact -- $item {
                  "" - 0 {
                      set _attrs(intensity) normal
                      set _attrs(fg) default
                      set _attrs(bg) default
                      set _attrs(underline) 0
                      set _attrs(reverse) 0
                  }
                  1 {
                      set _attrs(intensity) bold
                  }
                  2 {
                      set _attrs(intensity) dim
                  }
                  4 {
                      set _attrs(underline) 1
                  }
                  7 {
                      set _attrs(reverse) 1
                  }
                  22 {
                      set _attrs(intensity) normal
                  }
                  24 {
                      set _attrs(underline) 0
                  }
                  27 {
                      set _attrs(reverse) 1
                  }
                  30 - 31 - 32 - 33 - 34 - 35 - 36 - 37 {
                      set _attrs(fg) $item
                  }
                  39 {
                      set _attrs(fg) default
                  }
                  40 - 41 - 42 - 43 - 44 - 45 - 46 - 47 {
                      set _attrs(bg) $item
                  }
                  49 {
                      set _attrs(bg) default
                  }
              }
          }
        }
    }

    # Insert string at the cursor location.
    proc _insert {str} {
        _log_cur "Inserted string '$str'" {
            _log "Inserting string '$str'"

            variable _cur_col
            variable _cur_row
            variable _rows
            variable _cols
            variable _attrs
            variable _chars
            set lattr [array get _attrs]
            foreach char [split $str {}] {
                  _log_cur "  Inserted char '$char'" {
                    set _chars($_cur_col,$_cur_row) [list $char $lattr]
                    incr _cur_col
                    if {$_cur_col >= $_cols} {
                        set _cur_col 0
                        incr _cur_row
                        if {$_cur_row >= $_rows} {
                            error "FIXME scroll"
                        }
                    }
                }
            }
        }
    }

    # Move the cursor to the (0-based) COL and ROW positions.
    proc _move_cursor { col row } {
        variable _cols
        variable _rows
        variable _cur_col
        variable _cur_row

        if { $col < 0 || $col >= $_cols } {
            error "_move_cursor: invalid col value: $col"
        }

        if { $row < 0 || $row >= $_rows } {
            error "_move_cursor: invalid row value: $row"
        }


        set _cur_col $col
        set _cur_row $row
    }

    # Initialize.
    proc _setup {rows cols} {
        global stty_init
        set stty_init "rows $rows columns $cols"

        variable _rows
        variable _cols
        variable _cur_col
        variable _cur_row
        variable _attrs
        variable _resize_count

        set _rows $rows
        set _cols $cols
        set _cur_col 0
        set _cur_row 0
        set _resize_count 0
        array set _attrs {
            intensity normal
            fg default
            bg default
            underline 0
            reverse 0
        }

        _clear_lines 0 $_rows
    }

    # Accept some output from gdb and update the screen.
    # Return 1 if successful, or 0 if a timeout occurred.
    proc accept_gdb_output { } {
        global expect_out
        gdb_expect {
            -re "^\[\x07\x08\x0a\x0d\]" {
                scan $expect_out(0,string) %c val
                set hexval [format "%02x" $val]
                _log "wait_for: _ctl_0x${hexval}"
                _ctl_0x${hexval}
            }
            -re "^\x1b(\[0-9a-zA-Z\])" {
                _log "wait_for: unsupported escape"
                error "unsupported escape"
            }
            -re "^\x1b\\\[(\[0-9;\]*)(\[a-zA-Z@\])" {
                set cmd $expect_out(2,string)
                set params [split $expect_out(1,string) ";"]
                _log "wait_for: _csi_$cmd <<<$expect_out(1,string)>>>"
                eval _csi_$cmd $params
            }
            -re "^\[^\x07\x08\x0a\x0d\x1b\]+" {
                _insert $expect_out(0,string)
                variable _last_char
                set _last_char [string index $expect_out(0,string) end]
            }

            timeout {
                # Assume a timeout means we somehow missed the
                # expected result, and carry on.
                return 0
            }
        }

        return 1
    }

    # Accept some output from gdb and update the screen.  WAIT_FOR is
    # a regexp matching the line to wait for.  Return 0 on timeout, 1
    # on success.
    proc wait_for {wait_for} {
        global gdb_prompt
        variable _cur_col
        variable _cur_row

        set prompt_wait_for "$gdb_prompt \$"

        while 1 {
            if { [accept_gdb_output] == 0 } {
                return 0
            }

            # If the cursor appears just after the prompt, return.  It
            # isn't reliable to check this only after an insertion,
            # because curses may make "unusual" redrawing decisions.
            if {$wait_for == "$prompt_wait_for"} {
                set prev [get_line $_cur_row $_cur_col]
            } else {
                set prev [get_line $_cur_row]
            }
            if {[regexp -- $wait_for $prev]} {
                if {$wait_for == "$prompt_wait_for"} {
                    break
                }
                set wait_for $prompt_wait_for
            }
        }

        return 1
    }

    # Accept some output from gdb and update the screen.  Wait for the screen
    # region X/Y/WIDTH/HEIGTH to matches REGEXP.  Return 0 on timeout, 1 on
    # success.
    proc wait_for_region_contents {x y width height regexp} {
        while 1 {
            if { [accept_gdb_output] == 0 } {
                return 0
            }

            if { [check_region_contents_p $x $y $width $height $regexp] } {
                break
            }
        }

        return 1
    }

    # Like ::clean_restart, but ensures that gdb starts in an
    # environment where the TUI can work.  ROWS and COLS are the size
    # of the terminal.  EXECUTABLE, if given, is passed to
    # clean_restart.
    proc clean_restart {rows cols {executable {}}} {
        global env stty_init
        save_vars {env(TERM) stty_init ::GDBFLAGS} {
            setenv TERM ansi
            _setup $rows $cols

            # Make GDB not print the directory names.  Use this setting to
            # remove the differences in test runs due to varying directory
            # names.
            append ::GDBFLAGS " -ex \"set filename-display basename\""

            if {$executable == ""} {
                ::clean_restart
            } else {
                ::clean_restart $executable
            }
            ::gdb_test_no_output "set pagination off"
        }
    }

    # Setup ready for starting the tui, but don't actually start it.
    # Returns 1 on success, 0 if TUI tests should be skipped.
    proc prepare_for_tui {} {
        if {[skip_tui_tests]} {
            return 0
        }

        gdb_test_no_output "set tui border-kind ascii"
        gdb_test_no_output "maint set tui-resize-message on"
        return 1
    }

    # Start the TUI.  Returns 1 on success, 0 if TUI tests should be
    # skipped.
    proc enter_tui {} {
        if {![prepare_for_tui]} {
            return 0
        }

        command_no_prompt_prefix "tui enable"
        return 1
    }

    # Send the command CMD to gdb, then wait for a gdb prompt to be
    # seen in the TUI.  CMD should not end with a newline -- that will
    # be supplied by this function.
    proc command {cmd} {
        global gdb_prompt
        send_gdb "$cmd\n"
        set str [string_to_regexp $cmd]
        set str "^$gdb_prompt $str"
        wait_for $str
    }

    # As proc command, but don't wait for a initial prompt.  This is used for
    # inital terminal commands, where there's no prompt yet.
    proc command_no_prompt_prefix {cmd} {
        send_gdb "$cmd\n"
        set str [string_to_regexp $cmd]
        wait_for "^$str"
    }

    # Return the text of screen line N, without attributes.  Lines are
    # 0-based.  If C is given, stop before column C.  Columns are also
    # zero-based.
    proc get_line {n {c ""}} {
        variable _rows
        # This can happen during resizing, if the cursor seems to
        # temporarily be off-screen.
        if {$n >= $_rows} {
            return ""
        }

        set result ""
        variable _cols
        variable _chars
        set c [_default $c $_cols]
        set x 0
        while {$x < $c} {
            append result [lindex $_chars($x,$n) 0]
            incr x
        }
        return $result
    }

    # Get just the character at (X, Y).
    proc get_char {x y} {
        variable _chars
        return [lindex $_chars($x,$y) 0]
    }

    # Get the entire screen as a string.
    proc get_all_lines {} {
        variable _rows
        variable _cols
        variable _chars

        set result ""
        for {set y 0} {$y < $_rows} {incr y} {
            for {set x 0} {$x < $_cols} {incr x} {
                append result [lindex $_chars($x,$y) 0]
            }
            append result "\n"
        }

        return $result
    }

    # Get the text just before the cursor.
    proc get_current_line {} {
        variable _cur_col
        variable _cur_row
        return [get_line $_cur_row $_cur_col]
    }

    # Helper function for check_box.  Returns empty string if the box
    # is found, description of why not otherwise.
    proc _check_box {x y width height} {
        set x2 [expr {$x + $width - 1}]
        set y2 [expr {$y + $height - 1}]

        verbose -log "_check_box x=$x, y=$y, x2=$x2, y2=$y2, width=$width, height=$height"

        set c [get_char $x $y]
        if {$c != "+"} {
            return "ul corner is $c, not +"
        }

        set c [get_char $x $y2]
        if {$c != "+"} {
            return "ll corner is $c, not +"
        }

        set c [get_char $x2 $y]
        if {$c != "+"} {
            return "ur corner is $c, not +"
        }

        set c [get_char $x2 $y2]
        if {$c != "+"} {
            return "lr corner is $c, not +"
        }

        # Note we do not check the full horizonal borders of the box.
        # The top will contain a title, and the bottom may as well, if
        # it is overlapped by some other border.  However, at most a
        # title should appear as '+-VERY LONG TITLE-+', so we can
        # check for the '+-' on the left, and '-+' on the right.
        set c [get_char [expr {$x + 1}] $y]
        if {$c != "-"} {
            return "ul title padding is $c, not -"
        }

        set c [get_char [expr {$x2 - 1}] $y]
        if {$c != "-"} {
            return "ul title padding is $c, not -"
        }

        # Now check the vertical borders.
        for {set i [expr {$y + 1}]} {$i < $y2 - 1} {incr i} {
            set c [get_char $x $i]
            if {$c != "|"} {
                return "left side $i is $c, not |"
            }

            set c [get_char $x2 $i]
            if {$c != "|"} {
                return "right side $i is $c, not |"
            }
        }

        return ""
    }

    # Check for a box at the given coordinates.
    proc check_box {test_name x y width height} {
        dump_box $x $y $width $height
        set why [_check_box $x $y $width $height]
        if {$why == ""} {
            pass $test_name
        } else {
            fail "$test_name ($why)"
        }
    }

    # Check whether the text contents of the terminal match the
    # regular expression.  Note that text styling is not considered.
    proc check_contents {test_name regexp} {
        dump_screen
        set contents [get_all_lines]
        gdb_assert {[regexp -- $regexp $contents]} $test_name
    }

    # Get the region of the screen described by X, Y, WIDTH,
    # and HEIGHT, and separate the lines using SEP.
    proc get_region { x y width height sep } {
        variable _chars

        # Grab the contents of the box, join each line together
        # using $sep.
        set result ""
        for {set yy $y} {$yy < [expr {$y + $height}]} {incr yy} {
            if {$yy > $y} {
                # Add the end of line sequence only if this isn't the
                # first line.
                append result $sep
            }
            for {set xx $x} {$xx < [expr {$x + $width}]} {incr xx} {
                append result [lindex $_chars($xx,$yy) 0]
            }
        }
        return $result
    }

    # Check that the region of the screen described by X, Y, WIDTH,
    # and HEIGHT match REGEXP.  This is like check_contents except
    # only part of the screen is checked.  This can be used to check
    # the contents within a box (though check_box_contents is a better
    # choice for boxes with a border).  Return 1 if check succeeded.
    proc check_region_contents_p { x y width height regexp } {
        variable _chars
        dump_box $x $y $width $height

        # Now grab the contents of the box, join each line together
        # with a '\r\n' sequence and match against REGEXP.
        set result [get_region $x $y $width $height "\r\n"]
        return [regexp -- $regexp $result]
    }

    # Check that the region of the screen described by X, Y, WIDTH,
    # and HEIGHT match REGEXP.  As check_region_contents_p, but produce
    # a pass/fail message.
    proc check_region_contents { test_name x y width height regexp } {
        set ok [check_region_contents_p $x $y $width $height $regexp]
        gdb_assert {$ok} $test_name
    }

    # Check the contents of a box on the screen.  This is a little
    # like check_contents, but doens't check the whole screen
    # contents, only the contents of a single box.  This procedure
    # includes (effectively) a call to check_box to ensure there is a
    # box where expected, if there is then the contents of the box are
    # matched against REGEXP.
    proc check_box_contents {test_name x y width height regexp} {
        variable _chars

        dump_box $x $y $width $height
        set why [_check_box $x $y $width $height]
        if {$why != ""} {
            fail "$test_name (box check: $why)"
            return
        }

        check_region_contents $test_name [expr {$x + 1}] [expr {$y + 1}] \
            [expr {$width - 2}] [expr {$height - 2}] $regexp
    }

    # A debugging function to dump the current screen, with line
    # numbers.
    proc dump_screen {} {
        variable _rows
        variable _cols
        variable _cur_row
        variable _cur_col

        verbose -log "Screen Dump (size $_cols columns x $_rows rows, cursor at column $_cur_col, row $_cur_row):"

        for {set y 0} {$y < $_rows} {incr y} {
            set fmt [format %5d $y]
            verbose -log "$fmt [get_line $y]"
        }
    }

    # A debugging function to dump a box from the current screen, with line
    # numbers.
    proc dump_box { x y width height } {
        verbose -log "Box Dump ($width x $height) @ ($x, $y):"
        set region [get_region $x $y $width $height "\n"]
        set lines [split $region "\n"]
        set nr $y
        foreach line $lines {
            set fmt [format %5d $nr]
            verbose -log "$fmt $line"
            incr nr
        }
    }

    # Resize the terminal.
    proc _do_resize {rows cols} {
        variable _chars
        variable _rows
        variable _cols

        set old_rows [expr {min ($_rows, $rows)}]
        set old_cols [expr {min ($_cols, $cols)}]

        # Copy locally.
        array set local_chars [array get _chars]
        unset _chars

        set _rows $rows
        set _cols $cols
        _clear_lines 0 $_rows

        for {set x 0} {$x < $old_cols} {incr x} {
            for {set y 0} {$y < $old_rows} {incr y} {
                set _chars($x,$y) $local_chars($x,$y)
            }
        }
    }

    proc resize {rows cols} {
        variable _rows
        variable _cols
        variable _resize_count

        # expect handles each argument to stty separately.  This means
        # that gdb will see SIGWINCH twice.  Rather than rely on this
        # behavior (which, after all, could be changed), we make it
        # explicit here.  This also simplifies waiting for the redraw.
        _do_resize $rows $_cols
        stty rows $_rows < $::gdb_tty_name
        # Due to the strange column resizing behavior, and because we
        # don't care about this intermediate resize, we don't check
        # the size here.
        wait_for "@@ resize done $_resize_count"
        incr _resize_count
        # Somehow the number of columns transmitted to gdb is one less
        # than what we request from expect.  We hide this weird
        # details from the caller.
        _do_resize $_rows $cols
        stty columns [expr {$_cols + 1}] < $::gdb_tty_name
        wait_for "@@ resize done $_resize_count, size = ${_cols}x${rows}"
        incr _resize_count
    }
}