runtime(termdebug): convert termdebug plugin to Vim9 script

closes: #14903

Signed-off-by: Ubaldo Tiberi <ubaldo.tiberi@volvo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

2 files changed, 1266 insertions, 1190 deletions

diff --git a/runtime/doc/terminal.txt b/runtime/doc/terminal.txt
index c99b882cf9..d7749ff262 100644
--- a/runtime/doc/terminal.txt
+++ b/runtime/doc/terminal.txt
@@ -1,4 +1,4 @@
-*terminal.txt*	For Vim version 9.1.  Last change: 2024 Mar 17
+*terminal.txt*	For Vim version 9.1.  Last change: 2024 Jun 05
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -1332,8 +1332,8 @@ Put focus on the gdb window to type commands there.  Some common ones are:
 						*:Run* *:Arguments*
 In the window showing the source code these commands can be used to control
 gdb:
- `:Run` [args]	    run the program with [args] or the previous arguments
- `:Arguments` {args}  set arguments for the next `:Run`
+ :Run [args]	    run the program with [args] or the previous arguments
+ :Arguments {args}  set arguments for the next `:Run`
 
  *:Break*	set a breakpoint at the cursor position
  :Break {position}
@@ -1379,10 +1379,10 @@ breakpoint, or use the "Clear breakpoint" right-click menu entry.
 
 Inspecting variables ~
 					*termdebug-variables* *:Evaluate*
- `:Evaluate`	    evaluate the expression under the cursor
- `K`		    same (see |termdebug_map_K| to disable)
- `:Evaluate` {expr}   evaluate {expr}
- `:'<,'>Evaluate`     evaluate the Visually selected text
+ :Evaluate	    evaluate the expression under the cursor
+ K		    same (see |termdebug_map_K| to disable)
+ :Evaluate {expr}   evaluate {expr}
+ :'<,'>Evaluate     evaluate the Visually selected text
 
 This is similar to using "print" in the gdb window.
 You can usually shorten `:Evaluate` to `:Ev`.
@@ -1390,14 +1390,14 @@ You can usually shorten `:Evaluate` to `:Ev`.
 
 Navigating stack frames ~
 				*termdebug-frames* *:Frame* *:Up* *:Down*
- `:Frame` [frame]	select frame [frame], which is a frame number,
+ :Frame [frame]	select frame [frame], which is a frame number,
 			address, or function name (default: current frame)
- `:Up` [count]		go up [count] frames (default: 1; the frame that
+ :Up [count]		go up [count] frames (default: 1; the frame that
 			called the current)
- `+`			same (see |termdebug_map_plus| to disable)
- `:Down` [count]	go down [count] frames (default: 1; the frame called
+ +			same (see |termdebug_map_plus| to disable)
+ :Down [count]	go down [count] frames (default: 1; the frame called
 			by the current)
- `-`			same (see |termdebug_map_minus| to disable)
+ -			same (see |termdebug_map_minus| to disable)
 
 
 Other commands ~
diff --git a/runtime/pack/dist/opt/termdebug/plugin/termdebug.vim b/runtime/pack/dist/opt/termdebug/plugin/termdebug.vim
index 8eb3fff694..9d987e350a 100644
--- a/runtime/pack/dist/opt/termdebug/plugin/termdebug.vim
+++ b/runtime/pack/dist/opt/termdebug/plugin/termdebug.vim
@@ -1,419 +1,480 @@
-" Debugger plugin using gdb.
-"
-" Author: Bram Moolenaar
-" Copyright: Vim license applies, see ":help license"
-" Last Change: 2023 Nov 02
-"
-" WORK IN PROGRESS - The basics works stable, more to come
-" Note: In general you need at least GDB 7.12 because this provides the
-" frame= response in MI thread-selected events we need to sync stack to file.
-" The one included with "old" MingW is too old (7.6.1), you may upgrade it or
-" use a newer version from http://www.equation.com/servlet/equation.cmd?fa=gdb
-"
-" There are two ways to run gdb:
-" - In a terminal window; used if possible, does not work on MS-Windows
-"   Not used when g:termdebug_use_prompt is set to 1.
-" - Using a "prompt" buffer; may use a terminal window for the program
-"
-" For both the current window is used to view source code and shows the
-" current statement from gdb.
-"
-" USING A TERMINAL WINDOW
-"
-" Opens two visible terminal windows:
-" 1. runs a pty for the debugged program, as with ":term NONE"
-" 2. runs gdb, passing the pty of the debugged program
-" A third terminal window is hidden, it is used for communication with gdb.
-"
-" USING A PROMPT BUFFER
-"
-" Opens a window with a prompt buffer to communicate with gdb.
-" Gdb is run as a job with callbacks for I/O.
-" On Unix another terminal window is opened to run the debugged program
-" On MS-Windows a separate console is opened to run the debugged program
-"
-" The communication with gdb uses GDB/MI.  See:
-" https://sourceware.org/gdb/current/onlinedocs/gdb/GDB_002fMI.html
-
-" In case this gets sourced twice.
-if exists(':Termdebug')
+vim9script
+
+# Debugger plugin using gdb.
+
+# Author: Bram Moolenaar
+# Copyright: Vim license applies, see ":help license"
+# Last Change: 2024 Jun 03
+# Converted to Vim9: Ubaldo Tiberi <ubaldo.tiberi@volvo.com>
+
+# WORK IN PROGRESS - The basics works stable, more to come
+# Note: In general you need at least GDB 7.12 because this provides the
+# frame= response in MI thread-selected events we need to sync stack to file.
+# The one included with "old" MingW is too old (7.6.1), you may upgrade it or
+# use a newer version from http://www.equation.com/servlet/equation.cmd?fa=gdb
+
+# There are two ways to run gdb:
+# - In a terminal window; used if possible, does not work on MS-Windows
+#   Not used when g:termdebug_use_prompt is set to 1.
+# - Using a "prompt" buffer; may use a terminal window for the program
+
+# For both the current window is used to view source code and shows the
+# current statement from gdb.
+
+# USING A TERMINAL WINDOW
+
+# Opens two visible terminal windows:
+# 1. runs a pty for the debugged program, as with ":term NONE"
+# 2. runs gdb, passing the pty of the debugged program
+# A third terminal window is hidden, it is used for communication with gdb.
+
+# USING A PROMPT BUFFER
+
+# Opens a window with a prompt buffer to communicate with gdb.
+# Gdb is run as a job with callbacks for I/O.
+# On Unix another terminal window is opened to run the debugged program
+# On MS-Windows a separate console is opened to run the debugged program
+
+# The communication with gdb uses GDB/MI.  See:
+# https://sourceware.org/gdb/current/onlinedocs/gdb/GDB_002fMI.html
+
+# In case this gets sourced twice.
+if exists('g:termdebug_loaded')
   finish
 endif
-
-" Need either the +terminal feature or +channel and the prompt buffer.
-" The terminal feature does not work with gdb on win32.
+g:termdebug_loaded = true
+
+var way = 'terminal'
+var err = 'no errors'
+
+var pc_id = 12
+var asm_id = 13
+var break_id = 14  # breakpoint number is added to this
+var stopped = 1
+var running = 0
+
+var parsing_disasm_msg = 0
+var asm_lines = []
+var asm_addr = ''
+
+# These shall be constants but cannot be initialized here
+# They indicate the buffer numbers of the main buffers used
+var gdbbuf = 0
+var varbuf = 0
+var asmbuf = 0
+var promptbuf = 0
+# This is for the "debugged program" thing
+var ptybuf = 0
+var commbuf = 0
+
+var gdbjob = null_job
+var gdb_channel = null_channel
+# These changes because they relate to windows
+var pid = 0
+var gdbwin = 0
+var varwin = 0
+var asmwin = 0
+var ptywin = 0
+var sourcewin = 0
+
+# Contains breakpoints that have been placed, key is a string with the GDB
+# breakpoint number.
+# Each entry is a dict, containing the sub-breakpoints.  Key is the subid.
+# For a breakpoint that is just a number the subid is zero.
+# For a breakpoint "123.4" the id is "123" and subid is "4".
+# Example, when breakpoint "44", "123", "123.1" and "123.2" exist:
+# {'44': {'0': entry}, '123': {'0': entry, '1': entry, '2': entry}}
+var breakpoints = {}
+
+# Contains breakpoints by file/lnum.  The key is "fname:lnum".
+# Each entry is a list of breakpoint IDs at that position.
+var breakpoint_locations = {}
+var BreakpointSigns: list<string> = []
+
+
+var evalFromBalloonExpr = 0
+var evalFromBalloonExprResult = ''
+var ignoreEvalError = 0
+var evalexpr = ''
+# Remember the old value of 'signcolumn' for each buffer that it's set in, so
+# that we can restore the value for all buffers.
+var signcolumn_buflist = [bufnr()]
+var save_columns = 0
+
+var allleft = 0
+# This was s:vertical but I cannot use vertical as variable name
+var vvertical = 0
+
+var winbar_winids = []
+var plus_map_saved = {}
+var minus_map_saved = {}
+var k_map_saved = {}
+var saved_mousemodel = ''
+
+
+# Need either the +terminal feature or +channel and the prompt buffer.
+# The terminal feature does not work with gdb on win32.
 if has('terminal') && !has('win32')
-  let s:way = 'terminal'
+  way = 'terminal'
 elseif has('channel') && exists('*prompt_setprompt')
-  let s:way = 'prompt'
+  way = 'prompt'
 else
   if has('terminal')
-    let s:err = 'Cannot debug, missing prompt buffer support'
+    err = 'Cannot debug, missing prompt buffer support'
   else
-    let s:err = 'Cannot debug, +channel feature is not supported'
+    err = 'Cannot debug, +channel feature is not supported'
   endif
-  command -nargs=* -complete=file -bang Termdebug echoerr s:err
-  command -nargs=+ -complete=file -bang TermdebugCommand echoerr s:err
+  command -nargs=* -complete=file -bang Termdebug echoerr err
+  command -nargs=+ -complete=file -bang TermdebugCommand echoerr err
   finish
 endif
 
-let s:keepcpo = &cpo
-set cpo&vim
-
-" The command that starts debugging, e.g. ":Termdebug vim".
-" To end type "quit" in the gdb window.
-command -nargs=* -complete=file -bang Termdebug call s:StartDebug(<bang>0, <f-args>)
-command -nargs=+ -complete=file -bang TermdebugCommand call s:StartDebugCommand(<bang>0, <f-args>)
-
-let s:pc_id = 12
-let s:asm_id = 13
-let s:break_id = 14  " breakpoint number is added to this
-let s:stopped = 1
-let s:running = 0
-
-let s:parsing_disasm_msg = 0
-let s:asm_lines = []
-let s:asm_addr = ''
-
-" Take a breakpoint number as used by GDB and turn it into an integer.
-" The breakpoint may contain a dot: 123.4 -> 123004
-" The main breakpoint has a zero subid.
-func s:Breakpoint2SignNumber(id, subid)
-  return s:break_id + a:id * 1000 + a:subid
-endfunction
-
-" Define or adjust the default highlighting, using background "new".
-" When the 'background' option is set then "old" has the old value.
-func s:Highlight(init, old, new)
-  let default = a:init ? 'default ' : ''
-  if a:new ==# 'light' && a:old !=# 'light'
-    exe "hi " . default . "debugPC term=reverse ctermbg=lightblue guibg=lightblue"
-  elseif a:new ==# 'dark' && a:old !=# 'dark'
-    exe "hi " . default . "debugPC term=reverse ctermbg=darkblue guibg=darkblue"
-  endif
-endfunc
-
-" Define the default highlighting, using the current 'background' value.
-func s:InitHighlight()
-  call s:Highlight(1, '', &background)
+
+# The command that starts debugging, e.g. ":Termdebug vim".
+# To end type "quit" in the gdb window.
+command -nargs=* -complete=file -bang Termdebug StartDebug(<bang>0, <f-args>)
+command -nargs=+ -complete=file -bang TermdebugCommand StartDebugCommand(<bang>0, <f-args>)
+
+
+# Take a breakpoint number as used by GDB and turn it into an integer.
+# The breakpoint may contain a dot: 123.4 -> 123004
+# The main breakpoint has a zero subid.
+def Breakpoint2SignNumber(id: number, subid: number): number
+  return break_id + id * 1000 + subid
+enddef
+
+# Define or adjust the default highlighting, using background "new".
+# When the 'background' option is set then "old" has the old value.
+def Highlight(init: bool, old: string, new: string)
+  var default = init ? 'default ' : ''
+  if new ==# 'light' && old !=# 'light'
+    exe "hi " .. default .. "debugPC term=reverse ctermbg=lightblue guibg=lightblue"
+  elseif new ==# 'dark' && old !=# 'dark'
+    exe "hi " .. default .. "debugPC term=reverse ctermbg=darkblue guibg=darkblue"
+  endif
+enddef
+
+# Define the default highlighting, using the current 'background' value.
+def InitHighlight()
+  Highlight(1, '', &background)
   hi default debugBreakpoint term=reverse ctermbg=red guibg=red
   hi default debugBreakpointDisabled term=reverse ctermbg=gray guibg=gray
-endfunc
+enddef
 
-" Setup an autocommand to redefine the default highlight when the colorscheme
-" is changed.
-func s:InitAutocmd()
+# Setup an autocommand to redefine the default highlight when the colorscheme
+# is changed.
+def InitAutocmd()
   augroup TermDebug
     autocmd!
-    autocmd ColorScheme * call s:InitHighlight()
+    autocmd ColorScheme * InitHighlight()
   augroup END
-endfunc
+enddef
 
-" Get the command to execute the debugger as a list, defaults to ["gdb"].
-func s:GetCommand()
+# Get the command to execute the debugger as a list, defaults to ["gdb"].
+def GetCommand(): list<string>
+  var cmd = 'gdb'
   if exists('g:termdebug_config')
-    let cmd = get(g:termdebug_config, 'command', 'gdb')
+    cmd = get(g:termdebug_config, 'command', 'gdb')
   elseif exists('g:termdebugger')
-    let cmd = g:termdebugger
-  else
-    let cmd = 'gdb'
+    cmd = g:termdebugger
   endif
 
   return type(cmd) == v:t_list ? copy(cmd) : [cmd]
-endfunc
+enddef
+
+def Echoerr(msg: string)
+  echohl ErrorMsg | echom '[termdebug] ' .. msg | echohl None
+enddef
 
-func s:Echoerr(msg)
-  echohl ErrorMsg | echom '[termdebug] ' .. a:msg | echohl None
-endfunc
+def StartDebug(bang: bool, ...gdb_args: list<string>)
+  # First argument is the command to debug, second core file or process ID.
+  StartDebug_internal({'gdb_args': gdb_args, 'bang': bang})
+enddef
 
-func s:StartDebug(bang, ...)
-  " First argument is the command to debug, second core file or process ID.
-  call s:StartDebug_internal({'gdb_args': a:000, 'bang': a:bang})
-endfunc
+def StartDebugCommand(bang: bool, ...args: list<string>)
+  # First argument is the command to debug, rest are run arguments.
+  StartDebug_internal({'gdb_args': [args[0]], 'proc_args': args[1:], 'bang': bang})
+enddef
 
-func s:StartDebugCommand(bang, ...)
-  " First argument is the command to debug, rest are run arguments.
-  call s:StartDebug_internal({'gdb_args': [a:1], 'proc_args': a:000[1:], 'bang': a:bang})
-endfunc
 
-func s:StartDebug_internal(dict)
-  if exists('s:gdbwin')
-    call s:Echoerr('Terminal debugger already running, cannot run two')
+def StartDebug_internal(dict: dict<any>)
+  if gdbwin > 0
+    Echoerr('Terminal debugger already running, cannot run two')
     return
   endif
-  let gdbcmd = s:GetCommand()
+  var gdbcmd = GetCommand()
   if !executable(gdbcmd[0])
-    call s:Echoerr('Cannot execute debugger program "' .. gdbcmd[0] .. '"')
+    Echoerr('Cannot execute debugger program "' .. gdbcmd[0] .. '"')
     return
   endif
 
-  let s:ptywin = 0
-  let s:pid = 0
-  let s:asmwin = 0
-  let s:asmbuf = 0
-  let s:varwin = 0
-  let s:varbuf = 0
-
   if exists('#User#TermdebugStartPre')
     doauto <nomodeline> User TermdebugStartPre
   endif
 
-  " Uncomment this line to write logging in "debuglog".
-  " call ch_logfile('debuglog', 'w')
-
-  let s:sourcewin = win_getid()
+  # Assume current window is the source code window
+  sourcewin = win_getid()
+  var wide = 0
 
-  " Remember the old value of 'signcolumn' for each buffer that it's set in, so
-  " that we can restore the value for all buffers.
-  let b:save_signcolumn = &signcolumn
-  let s:signcolumn_buflist = [bufnr()]
-
-  let s:save_columns = 0
-  let s:allleft = 0
-  let wide = 0
   if exists('g:termdebug_config')
-    let wide = get(g:termdebug_config, 'wide', 0)
+    wide = get(g:termdebug_config, 'wide', 0)
   elseif exists('g:termdebug_wide')
-    let wide = g:termdebug_wide
+    wide = g:termdebug_wide
   endif
   if wide > 0
     if &columns < wide
-      let s:save_columns = &columns
-      let &columns = wide
-      " If we make the Vim window wider, use the whole left half for the debug
-      " windows.
-      let s:allleft = 1
+      save_columns = &columns
+      &columns = wide
+      # If we make the Vim window wider, use the whole left half for the debug
+      # windows.
+      allleft = 1
     endif
-    let s:vertical = 1
+    vvertical = 1
   else
-    let s:vertical = 0
+    vvertical = 0
   endif
 
-  " Override using a terminal window by setting g:termdebug_use_prompt to 1.
-  let use_prompt = 0
+  # Override using a terminal window by setting g:termdebug_use_prompt to 1.
+  var use_prompt = 0
   if exists('g:termdebug_config')
-    let use_prompt = get(g:termdebug_config, 'use_prompt', 0)
+    use_prompt = get(g:termdebug_config, 'use_prompt', 0)
   elseif exists('g:termdebug_use_prompt')
-    let use_prompt = g:termdebug_use_prompt
+    use_prompt = g:termdebug_use_prompt
   endif
   if has('terminal') && !has('win32') && !use_prompt
-    let s:way = 'terminal'
+    way = 'terminal'
   else
-    let s:way = 'prompt'
+    way = 'prompt'
   endif
 
-  if s:way == 'prompt'
-    call s:StartDebug_prompt(a:dict)
+  if way == 'prompt'
+    StartDebug_prompt(dict)
   else
-    call s:StartDebug_term(a:dict)
+    StartDebug_term(dict)
   endif
 
-  if s:GetDisasmWindow()
-    let curwinid = win_getid()
-    call s:GotoAsmwinOrCreateIt()
-    call win_gotoid(curwinid)
+  if GetDisasmWindow()
+    var curwinid = win_getid()
+    GotoAsmwinOrCreateIt()
+    win_gotoid(curwinid)
   endif
 
-  if s:GetVariablesWindow()
-    let curwinid = win_getid()
-    call s:GotoVariableswinOrCreateIt()
-    call win_gotoid(curwinid)
+  if GetVariablesWindow()
+    var curwinid = win_getid()
+    GotoVariableswinOrCreateIt()
+    win_gotoid(curwinid)
   endif
 
   if exists('#User#TermdebugStartPost')
     doauto <nomodeline> User TermdebugStartPost
   endif
-endfunc
+enddef
 
-" Use when debugger didn't start or ended.
-func s:CloseBuffers()
-  exe 'bwipe! ' . s:ptybuf
-  exe 'bwipe! ' . s:commbuf
-  if s:asmbuf > 0 && bufexists(s:asmbuf)
-    exe 'bwipe! ' . s:asmbuf
+# Use when debugger didn't start or ended.
+def CloseBuffers()
+  exe 'bwipe! ' .. ptybuf
+  exe 'bwipe! ' .. commbuf
+  if asmbuf > 0 && bufexists(asmbuf)
+    exe 'bwipe! ' .. asmbuf
   endif
-  if s:varbuf > 0 && bufexists(s:varbuf)
-    exe 'bwipe! ' . s:varbuf
+  if varbuf > 0 && bufexists(varbuf)
+    exe 'bwipe! ' .. varbuf
   endif
-  let s:running = 0
-  unlet! s:gdbwin
-endfunc
+  running = 0
+  gdbwin = 0
+enddef
 
-func s:CheckGdbRunning()
-  let gdbproc = term_getjob(s:gdbbuf)
-  if gdbproc == v:null || job_status(gdbproc) !=# 'run'
-    call s:Echoerr(string(s:GetCommand()[0]) . ' exited unexpectedly')
-    call s:CloseBuffers()
+# IsGdbRunning(): bool may be a better name?
+def CheckGdbRunning(): string
+  var gdbproc = term_getjob(gdbbuf)
+  var gdbproc_status = 'unknown'
+  if type(gdbproc) == v:t_job
+    gdbproc_status = job_status(gdbproc)
+  endif
+  if gdbproc == v:null || gdbproc_status !=# 'run'
+    Echoerr(string(GetCommand()[0]) .. ' exited unexpectedly')
+    CloseBuffers()
     return ''
   endif
   return 'ok'
-endfunc
-
-" Open a terminal window without a job, to run the debugged program in.
-func s:StartDebug_term(dict)
-  let s:ptybuf = term_start('NONE', {
-	\ 'term_name': 'debugged program',
-	\ 'vertical': s:vertical,
-	\ })
-  if s:ptybuf == 0
-    call s:Echoerr('Failed to open the program terminal window')
+enddef
+
+# Open a terminal window without a job, to run the debugged program in.
+def StartDebug_term(dict: dict<any>)
+  ptybuf = term_start('NONE', {
+        \ 'term_name': 'debugged program',
+        \ 'vertical': vvertical,
+        \ })
+  if ptybuf == 0
+    Echoerr('Failed to open the program terminal window')
     return
   endif
-  let pty = job_info(term_getjob(s:ptybuf))['tty_out']
-  let s:ptywin = win_getid()
-  if s:vertical
-    " Assuming the source code window will get a signcolumn, use two more
-    " columns for that, thus one less for the terminal window.
-    exe (&columns / 2 - 1) . "wincmd |"
-    if s:allleft
-      " use the whole left column
+  var pty = job_info(term_getjob(ptybuf))['tty_out']
+  ptywin = win_getid()
+  if vvertical
+    # Assuming the source code window will get a signcolumn, use two more
+    # columns for that, thus one less for the terminal window.
+    exe ":" .. (&columns / 2 - 1) .. "wincmd |"
+    if allleft
+      # use the whole left column
       wincmd H
     endif
   endif
 
-  " Create a hidden terminal window to communicate with gdb
-  let s:commbuf = term_start('NONE', {
-	\ 'term_name': 'gdb communication',
-	\ 'out_cb': function('s:CommOutput'),
-	\ 'hidden': 1,
-	\ })
-  if s:commbuf == 0
-    call s:Echoerr('Failed to open the communication terminal window')
-    exe 'bwipe! ' . s:ptybuf
+  # Create a hidden terminal window to communicate with gdb
+  commbuf = term_start('NONE', {
+        \ 'term_name': 'gdb communication',
+        \ 'out_cb': function('CommOutput'),
+        \ 'hidden': 1,
+        \ })
+  if commbuf == 0
+    Echoerr('Failed to open the communication terminal window')
+    exe 'bwipe! ' .. ptybuf
     return
   endif
-  let commpty = job_info(term_getjob(s:commbuf))['tty_out']
+  var commpty = job_info(term_getjob(commbuf))['tty_out']
 
-  let gdb_args = get(a:dict, 'gdb_args', [])
-  let proc_args = get(a:dict, 'proc_args', [])
+  var gdb_args = get(dict, 'gdb_args', [])
+  var proc_args = get(dict, 'proc_args', [])
 
-  let gdb_cmd = s:GetCommand()
+  var gdb_cmd = GetCommand()
 
   if exists('g:termdebug_config') && has_key(g:termdebug_config, 'command_add_args')
-    let gdb_cmd = g:termdebug_config.command_add_args(gdb_cmd, pty)
+    gdb_cmd = g:termdebug_config.command_add_args(gdb_cmd, pty)
   else
-    " Add -quiet to avoid the intro message causing a hit-enter prompt.
-    let gdb_cmd += ['-quiet']
-    " Disable pagination, it causes everything to stop at the gdb
-    let gdb_cmd += ['-iex', 'set pagination off']
-    " Interpret commands while the target is running.  This should usually only
-    " be exec-interrupt, since many commands don't work properly while the
-    " target is running (so execute during startup).
-    let gdb_cmd += ['-iex', 'set mi-async on']
-    " Open a terminal window to run the debugger.
-    let gdb_cmd += ['-tty', pty]
-    " Command executed _after_ startup is done, provides us with the necessary
-    " feedback
-    let gdb_cmd += ['-ex', 'echo startupdone\n']
+    # Add -quiet to avoid the intro message causing a hit-enter prompt.
+    gdb_cmd += ['-quiet']
+    # Disable pagination, it causes everything to stop at the gdb
+    gdb_cmd += ['-iex', 'set pagination off']
+    # Interpret commands while the target is running.  This should usually only
+    # be exec-interrupt, since many commands don't work properly while the
+    # target is running (so execute during startup).
+    gdb_cmd += ['-iex', 'set mi-async on']
+    # Open a terminal window to run the debugger.
+    gdb_cmd += ['-tty', pty]
+    # Command executed _after_ startup is done, provides us with the necessary
+    # feedback
+    gdb_cmd += ['-ex', 'echo startupdone\n']
   endif
 
   if exists('g:termdebug_config') && has_key(g:termdebug_config, 'command_filter')
-    let gdb_cmd = g:termdebug_config.command_filter(gdb_cmd)
+    gdb_cmd = g:termdebug_config.command_filter(gdb_cmd)
   endif
 
-  " Adding arguments requested by the user
-  let gdb_cmd += gdb_args
+  # Adding arguments requested by the user
+  gdb_cmd += gdb_args
 
-  call ch_log('executing "' . join(gdb_cmd) . '"')
-  let s:gdbbuf = term_start(gdb_cmd, {
-	\ 'term_finish': 'close',
-	\ })
-  if s:gdbbuf == 0
-    call s:Echoerr('Failed to open the gdb terminal window')
-    call s:CloseBuffers()
+  ch_log('executing "' .. join(gdb_cmd) .. '"')
+  gdbbuf = term_start(gdb_cmd, {
+        \ 'term_name': 'gdb',
+        \ 'term_finish': 'close',
+        \ })
+  if gdbbuf == 0
+    Echoerr('Failed to open the gdb terminal window')
+    CloseBuffers()
     return
   endif
-  let s:gdbwin = win_getid()
+  gdbwin = win_getid()
 
-  " Wait for the "startupdone" message before sending any commands.
-  let try_count = 0
-  while 1
-    if s:CheckGdbRunning() != 'ok'
+  # Wait for the "startupdone" message before sending any commands.
+  var counter = 0
+  var counter_max = 300
+  var success = false
+  while success == false && counter < counter_max
+    if CheckGdbRunning() != 'ok'
+      # Failure. If NOK just return.
       return
     endif
 
     for lnum in range(1, 200)
-      if term_getline(s:gdbbuf, lnum) =~ 'startupdone'
-        let try_count = 9999
-        break
+      if term_getline(gdbbuf, lnum) =~ 'startupdone'
+        success = true
       endif
     endfor
-    let try_count += 1
-    if try_count > 300
-      " done or give up after five seconds
-      break
-    endif
+
+    # Each count is 10ms
+    counter += 1
     sleep 10m
   endwhile
 
-  " Set arguments to be run.
+  if success == false
+    Echoerr('Failed to startup the gdb program.')
+    CloseBuffers()
+    return
+  endif
+
+  # ---- gdb started. Next, let's set the MI interface. ---
+  # Set arguments to be run.
   if len(proc_args)
-    call term_sendkeys(s:gdbbuf, 'server set args ' . join(proc_args) . "\r")
+    term_sendkeys(gdbbuf, 'server set args ' .. join(proc_args) .. "\r")
   endif
 
-  " Connect gdb to the communication pty, using the GDB/MI interface.
-  " Prefix "server" to avoid adding this to the history.
-  call term_sendkeys(s:gdbbuf, 'server new-ui mi ' . commpty . "\r")
+  # Connect gdb to the communication pty, using the GDB/MI interface.
+  # Prefix "server" to avoid adding this to the history.
+  term_sendkeys(gdbbuf, 'server new-ui mi ' .. commpty .. "\r")
 
-  " Wait for the response to show up, users may not notice the error and wonder
-  " why the debugger doesn't work.
-  let try_count = 0
-  while 1
-    if s:CheckGdbRunning() != 'ok'
+  # Wait for the response to show up, users may not notice the error and wonder
+  # why the debugger doesn't work.
+  counter = 0
+  counter_max = 300
+  success = false
+  while success == false && counter < counter_max
+    if CheckGdbRunning() != 'ok'
       return
     endif
 
-    let response = ''
+    var response = ''
     for lnum in range(1, 200)
-      let line1 = term_getline(s:gdbbuf, lnum)
-      let line2 = term_getline(s:gdbbuf, lnum + 1)
+      var line1 = term_getline(gdbbuf, lnum)
+      var line2 = term_getline(gdbbuf, lnum + 1)
       if line1 =~ 'new-ui mi '
-        " response can be in the same line or the next line
-        let response = line1 . line2
+        # response can be in the same line or the next line
+        response = line1 .. line2
         if response =~ 'Undefined command'
-          call s:Echoerr('Sorry, your gdb is too old, gdb 7.12 is required')
-          " CHECKME: possibly send a "server show version" here
-          call s:CloseBuffers()
+          Echoerr('Sorry, your gdb is too old, gdb 7.12 is required')
+          # CHECKME: possibly send a "server show version" here
+          CloseBuffers()
           return
         endif
         if response =~ 'New UI allocated'
-          " Success!
-          break
+          # Success!
+          success = true
         endif
       elseif line1 =~ 'Reading symbols from' && line2 !~ 'new-ui mi '
-        " Reading symbols might take a while, try more times
-        let try_count -= 1
+        # Reading symbols might take a while, try more times
+        counter -= 1
       endif
     endfor
     if response =~ 'New UI allocated'
       break
     endif
-    let try_count += 1
-    if try_count > 100
-      call s:Echoerr('Cannot check if your gdb works, continuing anyway')
-      break
-    endif
+    counter += 1
     sleep 10m
   endwhile
 
-  call job_setoptions(term_getjob(s:gdbbuf), {'exit_cb': function('s:EndTermDebug')})
+  if success == false
+    Echoerr('Cannot check if your gdb works, continuing anyway')
+    return
+  endif
+
+  job_setoptions(term_getjob(gdbbuf), {'exit_cb': function('EndTermDebug')})
 
-  " Set the filetype, this can be used to add mappings.
+  # Set the filetype, this can be used to add mappings.
   set filetype=termdebug
 
-  call s:StartDebugCommon(a:dict)
-endfunc
+  StartDebugCommon(dict)
+enddef
 
-" Open a window with a prompt buffer to run gdb in.
-func s:StartDebug_prompt(dict)
-  if s:vertical
+# Open a window with a prompt buffer to run gdb in.
+def StartDebug_prompt(dict: dict<any>)
+  if vvertical
     vertical new
   else
     new
   endif
-  let s:gdbwin = win_getid()
-  let s:promptbuf = bufnr('')
-  call prompt_setprompt(s:promptbuf, 'gdb> ')
+  gdbwin = win_getid()
+  promptbuf = bufnr('')
+  prompt_setprompt(promptbuf, 'gdb> ')
   set buftype=prompt
 
   if empty(glob('gdb'))
@@ -421,108 +482,108 @@ func s:StartDebug_prompt(dict)
   elseif empty(glob('Termdebug-gdb-console'))
     file Termdebug-gdb-console
   else
-    call s:Echoerr("You have a file/folder named 'gdb'
+    Echoerr("You have a file/folder named 'gdb'
           \ or 'Termdebug-gdb-console'.
           \ Please exit and rename them because Termdebug may not work as expected.")
   endif
 
-  call prompt_setcallback(s:promptbuf, function('s:PromptCallback'))
-  call prompt_setinterrupt(s:promptbuf, function('s:PromptInterrupt'))
-
-  if s:vertical
-    " Assuming the source code window will get a signcolumn, use two more
-    " columns for that, thus one less for the terminal window.
-    exe (&columns / 2 - 1) . "wincmd |"
-  endif
-
-  let gdb_args = get(a:dict, 'gdb_args', [])
-  let proc_args = get(a:dict, 'proc_args', [])
-
-  let gdb_cmd = s:GetCommand()
-  " Add -quiet to avoid the intro message causing a hit-enter prompt.
-  let gdb_cmd += ['-quiet']
-  " Disable pagination, it causes everything to stop at the gdb, needs to be run early
-  let gdb_cmd += ['-iex', 'set pagination off']
-  " Interpret commands while the target is running.  This should usually only
-  " be exec-interrupt, since many commands don't work properly while the
-  " target is running (so execute during startup).
-  let gdb_cmd += ['-iex', 'set mi-async on']
-  " directly communicate via mi2
-  let gdb_cmd += ['--interpreter=mi2']
-
-  " Adding arguments requested by the user
-  let gdb_cmd += gdb_args
-
-  call ch_log('executing "' . join(gdb_cmd) . '"')
-  let s:gdbjob = job_start(gdb_cmd, {
-	\ 'exit_cb': function('s:EndPromptDebug'),
-	\ 'out_cb': function('s:GdbOutCallback'),
-	\ })
-  if job_status(s:gdbjob) != "run"
-    call s:Echoerr('Failed to start gdb')
-    exe 'bwipe! ' . s:promptbuf
+  prompt_setcallback(promptbuf, function('PromptCallback'))
+  prompt_setinterrupt(promptbuf, function('PromptInterrupt'))
+
+  if vvertical
+    # Assuming the source code window will get a signcolumn, use two more
+    # columns for that, thus one less for the terminal window.
+    exe ":" .. (&columns / 2 - 1) .. "wincmd |"
+  endif
+
+  var gdb_args = get(dict, 'gdb_args', [])
+  var proc_args = get(dict, 'proc_args', [])
+
+  var gdb_cmd = GetCommand()
+  # Add -quiet to avoid the intro message causing a hit-enter prompt.
+  gdb_cmd += ['-quiet']
+  # Disable pagination, it causes everything to stop at the gdb, needs to be run early
+  gdb_cmd += ['-iex', 'set pagination off']
+  # Interpret commands while the target is running.  This should usually only
+  # be exec-interrupt, since many commands don't work properly while the
+  # target is running (so execute during startup).
+  gdb_cmd += ['-iex', 'set mi-async on']
+  # directly communicate via mi2
+  gdb_cmd += ['--interpreter=mi2']
+
+  # Adding arguments requested by the user
+  gdb_cmd += gdb_args
+
+  ch_log('executing "' .. join(gdb_cmd) .. '"')
+  gdbjob = job_start(gdb_cmd, {
+        \ 'exit_cb': function('EndPromptDebug'),
+        \ 'out_cb': function('GdbOutCallback'),
+        \ })
+  if job_status(gdbjob) != "run"
+    Echoerr('Failed to start gdb')
+    exe 'bwipe! ' .. promptbuf
     return
   endif
-  exe $'au BufUnload <buffer={s:promptbuf}> ++once ' ..
-	\ 'call job_stop(s:gdbjob, ''kill'')'
-  " Mark the buffer modified so that it's not easy to close.
+  exe $'au BufUnload <buffer={promptbuf}> ++once ' ..
+        \ 'call job_stop(gdbjob, ''kill'')'
+  # Mark the buffer modified so that it's not easy to close.
   set modified
-  let s:gdb_channel = job_getchannel(s:gdbjob)
+  gdb_channel = job_getchannel(gdbjob)
 
-  let s:ptybuf = 0
+  ptybuf = 0
   if has('win32')
-    " MS-Windows: run in a new console window for maximum compatibility
-    call s:SendCommand('set new-console on')
+    # MS-Windows: run in a new console window for maximum compatibility
+    SendCommand('set new-console on')
   elseif has('terminal')
-    " Unix: Run the debugged program in a terminal window.  Open it below the
-    " gdb window.
-    belowright let s:ptybuf = term_start('NONE', {
-	  \ 'term_name': 'debugged program',
-	  \ })
-    if s:ptybuf == 0
-      call s:Echoerr('Failed to open the program terminal window')
-      call job_stop(s:gdbjob)
+    # Unix: Run the debugged program in a terminal window.  Open it below the
+    # gdb window.
+    belowright ptybuf = term_start('NONE', {
+          \ 'term_name': 'debugged program',
+          \ })
+    if ptybuf == 0
+      Echoerr('Failed to open the program terminal window')
+      job_stop(gdbjob)
       return
     endif
-    let s:ptywin = win_getid()
-    let pty = job_info(term_getjob(s:ptybuf))['tty_out']
-    call s:SendCommand('tty ' . pty)
-
-    " Since GDB runs in a prompt window, the environment has not been set to
-    " match a terminal window, need to do that now.
-    call s:SendCommand('set env TERM = xterm-color')
-    call s:SendCommand('set env ROWS = ' . winheight(s:ptywin))
-    call s:SendCommand('set env LINES = ' . winheight(s:ptywin))
-    call s:SendCommand('set env COLUMNS = ' . winwidth(s:ptywin))
-    call s:SendCommand('set env COLORS = ' . &t_Co)
-    call s:SendCommand('set env VIM_TERMINAL = ' . v:version)
+    ptywin = win_getid()
+    var pty = job_info(term_getjob(ptybuf))['tty_out']
+    SendCommand('tty ' .. pty)
+
+    # Since GDB runs in a prompt window, the environment has not been set to
+    # match a terminal window, need to do that now.
+    SendCommand('set env TERM = xterm-color')
+    SendCommand('set env ROWS = ' .. winheight(ptywin))
+    SendCommand('set env LINES = ' .. winheight(ptywin))
+    SendCommand('set env COLUMNS = ' .. winwidth(ptywin))
+    SendCommand('set env COLORS = ' .. &t_Co)
+    SendCommand('set env VIM_TERMINAL = ' .. v:version)
   else
-    " TODO: open a new terminal, get the tty name, pass on to gdb
-    call s:SendCommand('show inferior-tty')
+    # TODO: open a new terminal, get the tty name, pass on to gdb
+    SendCommand('show inferior-tty')
   endif
-  call s:SendCommand('set print pretty on')
-  call s:SendCommand('set breakpoint pending on')
+  SendCommand('set print pretty on')
+  SendCommand('set breakpoint pending on')
 
-  " Set arguments to be run
+  # Set arguments to be run
   if len(proc_args)
-    call s:SendCommand('set args ' . join(proc_args))
+    SendCommand('set args ' .. join(proc_args))
   endif
 
-  call s:StartDebugCommon(a:dict)
+  StartDebugCommon(dict)
   startinsert
-endfunc
+enddef
 
-func s:StartDebugCommon(dict)
-  " Sign used to highlight the line where the program has stopped.
-  " There can be only one.
-  call sign_define('debugPC', #{linehl: 'debugPC'})
+def StartDebugCommon(dict: dict<any>)
+  # Sign used to highlight the line where the program has stopped.
+  # There can be only one.
+  sign_define('debugPC', {'linehl': 'debugPC'})
 
-  " Install debugger commands in the text window.
-  call win_gotoid(s:sourcewin)
-  call s:InstallCommands()
-  call win_gotoid(s:gdbwin)
+  # Install debugger commands in the text window.
+  win_gotoid(sourcewin)
+  InstallCommands()
+  win_gotoid(gdbwin)
 
-  " Enable showing a balloon with eval info
+  # Enable showing a balloon with eval info
   if has("balloon_eval") || has("balloon_eval_term")
     set balloonexpr=TermDebugBalloonExpr()
     if has("balloon_eval")
@@ -533,243 +594,238 @@ func s:StartDebugCommon(dict)
     endif
   endif
 
-  " Contains breakpoints that have been placed, key is a string with the GDB
-  " breakpoint number.
-  " Each entry is a dict, containing the sub-breakpo