patch 8.0.1092: terminal debugger can't evaluate expressions

Problem:    Terminal debugger can't evaluate expressions.
Solution:   Add :Evaluate and K.  Various other improvements.

runtime/doc/terminal.txt

@@ -1,4 +1,4 @@
-*terminal.txt*	For Vim version 8.0.  Last change: 2017 Sep 09
+*terminal.txt*	For Vim version 8.0.  Last change: 2017 Sep 10
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -318,11 +318,12 @@ To start debugging use `:TermDebug` folowed by the command name, for example: >
 	:TermDebug vim
 
 This opens two windows:
-- A terminal window in which "gdb vim" is executed.  Here you can directly
-  interact with gdb.  The buffer name is "!gdb".
-- A terminal window for the executed program.  When "run" is used in gdb the
-  program I/O will happen in this window, so that it does not interfere with
-  controlling gdb.  The buffer name is "gdb program".
+gdb window	A terminal window in which "gdb vim" is executed.  Here you
+		can directly interact with gdb.  The buffer name is "!gdb".
+program window	A terminal window for the executed program.  When "run" is
+		used in gdb the program I/O will happen in this window, so
+		that it does not interfere with controlling gdb.  The buffer
+		name is "gdb program".
 
 The current window is used to show the source code.  When gdb pauses the
 source file location will be displayed, if possible.  A sign is used to
@@ -334,7 +335,8 @@ to display the current gdb position.
 Focus the terminal of the executed program to interact with it.  This works
 the same as any command running in a terminal window.
 
-When the debugger ends the two opened windows are closed.
+When the debugger ends, typically by typing "quit" in the gdb window, the two
+opened windows are closed.
 
 
 Stepping through code ~
@@ -349,13 +351,29 @@ Put focus on the gdb window to type commands there.  Some common ones are:
 - frame N   go to the Nth stack frame
 - continue  continue execution
 
-In the window showing the source code some commands can passed to gdb:
-- Break     set a breakpoint at the current line; a sign will be displayed
-- Delete    delete a breakpoint at the current line
-- Step	    execute the gdb "step" command
-- NNext	    execute the gdb "next" command (:Next is a Vim command)
-- Finish    execute the gdb "finish" command
-- Continue  execute the gdb "continue" command
+In the window showing the source code some commands can used to control gdb:
+ :Break     set a breakpoint at the current line; a sign will be displayed
+ :Delete    delete a breakpoint at the current line
+ :Step	    execute the gdb "step" command
+ :Over      execute the gdb "next" command (:Next is a Vim command)
+ :Finish    execute the gdb "finish" command
+ :Continue  execute the gdb "continue" command
+
+
+Inspecting variables ~
+
+ :Evaluate	    evaluate the expression under the cursor
+ K		    same
+ :Evaluate {expr}   evaluate {expr}
+ :'<,'>Evaluate	    evaluate the Visually selected text
+
+This is similar to using "print" in the gdb window.
+
+
+Other commands ~
+
+ :Gdb	       jump to the gdb window
+ :Program      jump to the window with the running program
 
 
 Communication ~
@@ -386,9 +404,5 @@ When 'background' is "dark":
   hi debugBreakpoint term=reverse ctermbg=red guibg=red
 
 
-NOT WORKING YET: ~
-
-Values of variables can be inspected, etc.
-
 
  vim:tw=78:ts=8:ft=help:norl:

runtime/pack/dist/opt/termdebug/plugin/termdebug.vim

@@ -54,6 +54,7 @@ func s:StartDebug(cmd)
     return
   endif
   let pty = job_info(term_getjob(s:ptybuf))['tty_out']
+  let s:ptywin = win_getid(winnr())
 
   " Create a hidden terminal window to communicate with gdb
   let s:commbuf = term_start('NONE', {
@@ -81,12 +82,15 @@ func s:StartDebug(cmd)
     exe 'bwipe! ' . s:commbuf
     return
   endif
+  let s:gdbwin = win_getid(winnr())
 
   " Connect gdb to the communication pty, using the GDB/MI interface
   call term_sendkeys(gdbbuf, 'new-ui mi ' . commpty . "\r")
 
-  " Install debugger commands.
+  " Install debugger commands in the text window.
+  call win_gotoid(s:startwin)
   call s:InstallCommands()
+  call win_gotoid(s:gdbwin)
 
   let s:breakpoints = {}
 endfunc
@@ -116,10 +120,14 @@ func s:CommOutput(chan, msg)
     if msg != ''
       if msg =~ '^\*\(stopped\|running\)'
 	call s:HandleCursor(msg)
-      elseif msg =~ '^\^done,bkpt='
+      elseif msg =~ '^\^done,bkpt=' || msg =~ '^=breakpoint-created,'
 	call s:HandleNewBreakpoint(msg)
       elseif msg =~ '^=breakpoint-deleted,'
 	call s:HandleBreakpointDelete(msg)
+      elseif msg =~ '^\^done,value='
+	call s:HandleEvaluate(msg)
+      elseif msg =~ '^\^error,msg='
+	call s:HandleError(msg)
       endif
     endif
   endfor
@@ -130,9 +138,15 @@ func s:InstallCommands()
   command Break call s:SetBreakpoint()
   command Delete call s:DeleteBreakpoint()
   command Step call s:SendCommand('-exec-step')
-  command NNext call s:SendCommand('-exec-next')
+  command Over call s:SendCommand('-exec-next')
   command Finish call s:SendCommand('-exec-finish')
   command Continue call s:SendCommand('-exec-continue')
+  command -range -nargs=* Evaluate call s:Evaluate(<range>, <q-args>)
+  command Gdb call win_gotoid(s:gdbwin)
+  command Program call win_gotoid(s:ptywin)
+
+  " TODO: can the K mapping be restored?
+  nnoremap K :Evaluate<CR>
 endfunc
 
 " Delete installed debugger commands in the current window.
@@ -140,9 +154,21 @@ func s:DeleteCommands()
   delcommand Break
   delcommand Delete
   delcommand Step
-  delcommand NNext
+  delcommand Over
   delcommand Finish
   delcommand Continue
+  delcommand Evaluate
+  delcommand Gdb
+  delcommand Program
+
+  nunmap K
+  sign undefine debugPC
+  sign undefine debugBreakpoint
+  exe 'sign unplace ' . s:pc_id
+  for key in keys(s:breakpoints)
+    exe 'sign unplace ' . (s:break_id + key)
+  endfor
+  unlet s:breakpoints
 endfunc
 
 " :Break - Set a breakpoint at the cursor position.
@@ -171,6 +197,35 @@ func s:SendCommand(cmd)
   call term_sendkeys(s:commbuf, a:cmd . "\r")
 endfunc
 
+" :Evaluate - evaluate what is under the cursor
+func s:Evaluate(range, arg)
+  if a:arg != ''
+    let expr = a:arg
+  elseif a:range == 2
+    let pos = getcurpos()
+    let reg = getreg('v', 1, 1)
+    let regt = getregtype('v')
+    normal! gv"vy
+    let expr = @v
+    call setpos('.', pos)
+    call setreg('v', reg, regt)
+  else
+    let expr = expand('<cexpr>')
+  endif
+  call term_sendkeys(s:commbuf, '-data-evaluate-expression "' . expr . "\"\r")
+  let s:evalexpr = expr
+endfunc
+
+" Handle the result of data-evaluate-expression
+func s:HandleEvaluate(msg)
+  echomsg '"' . s:evalexpr . '": ' . substitute(a:msg, '.*value="\(.*\)"', '\1', '')
+endfunc
+
+" Handle an error.
+func s:HandleError(msg)
+  echoerr substitute(a:msg, '.*msg="\(.*\)"', '\1', '')
+endfunc
+
 " Handle stopping and running message from gdb.
 " Will update the sign that shows the current position.
 func s:HandleCursor(msg)

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1092,
 /**/
     1091,
 /**/