From 533b2aa0d5dc82660f83b10d5dbae86da0e64f9f Mon Sep 17 00:00:00 2001
From: Ben Jackson <puremourning@gmail.com>
Date: Sun, 27 May 2018 16:59:06 +0100
Subject: [PATCH] Very basic support for watch expressions

You can currently only add them, not remoove them and you have to pass
the expression in the function call, but once added the variable
breakdown works nicely.
---
 autoload/vimspector.vim             |  4 +++
 python3/vimspector/debug_session.py |  4 +++
 python3/vimspector/variables.py     | 53 ++++++++++++++++++++++++++---
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/autoload/vimspector.vim b/autoload/vimspector.vim
index 942128a..de0c6c8 100644
--- a/autoload/vimspector.vim
+++ b/autoload/vimspector.vim
@@ -69,6 +69,10 @@ function! vimspector#GoToFrame() abort
   py3 _vimspector_session.GoToFrame()
 endfunction
 
+function! vimspector#AddWatch( expr ) abort
+  py3 _vimspector_session.AddWatch( vim.eval( 'a:expr' ) )
+endfunction
+
 " Boilerplate {{{
 let &cpo=s:save_cpo
 unlet s:save_cpo
diff --git a/python3/vimspector/debug_session.py b/python3/vimspector/debug_session.py
index 9a9f1e2..9674412 100644
--- a/python3/vimspector/debug_session.py
+++ b/python3/vimspector/debug_session.py
@@ -180,6 +180,9 @@ class DebugSession( object ):
   def ExpandVariable( self ):
     self._variablesView.ExpandVariable()
 
+  def AddWatch( self, expression ):
+    self._variablesView.AddWatch( self._currentFrame, expression )
+
   def GoToFrame( self ):
     self._stackTraceView.GoToFrame()
 
@@ -221,6 +224,7 @@ class DebugSession( object ):
     self._currentFrame = frame
     self._codeView.SetCurrentFrame( frame )
     self._variablesView.LoadScopes( frame )
+    self._variablesView.EvaluateWatches()
 
   def _StartDebugAdapter( self ):
     self._logger.info( 'Starting debug adapter with: {0}'.format( json.dumps(
diff --git a/python3/vimspector/variables.py b/python3/vimspector/variables.py
index 831e0ab..daa0163 100644
--- a/python3/vimspector/variables.py
+++ b/python3/vimspector/variables.py
@@ -33,6 +33,9 @@ class VariablesView( object ):
     # children. Otherwise, we haven't or shouldn't.
     self._scopes = []
 
+    # This is basically the same as scopes, but the top level is an "expression"
+    self._watches = []
+
     vim.current.buffer = buf
     vim.command(
       'nnoremap <buffer> <CR> :call vimspector#ExpandVariable()<CR>' )
@@ -55,7 +58,7 @@ class VariablesView( object ):
           },
         } )
 
-      self._DrawScopes()
+      self._DrawScopesAndWatches()
 
     self._connection.DoRequest( scopes_consumer, {
       'command': 'scopes',
@@ -64,6 +67,36 @@ class VariablesView( object ):
       },
     } )
 
+  def AddWatch( self, frame, expression ):
+    watch = {
+        'expression': expression,
+        'frameId': frame[ 'id' ],
+        'context': 'watch',
+    }
+    self._watches.append( watch )
+    self.EvaluateWatches()
+
+  def EvaluateWatches( self ):
+    for watch in self._watches:
+      self._connection.DoRequest( partial( self._UpdateWatchExpression,
+                                           watch ), {
+        'command': 'evaluate',
+        'arguments': watch,
+      } )
+
+  def _UpdateWatchExpression( self, watch, message ):
+    watch[ 'result' ] = message[ 'body' ]
+    if 'variablesReference' in watch[ 'result' ]:
+      self._connection.DoRequest(
+        partial( self._ConsumeVariables, watch[ 'result' ] ), {
+          'command': 'variables',
+          'arguments': {
+            'variablesReference': watch[ 'result' ][ 'variablesReference' ]
+          },
+        } )
+
+    self._DrawScopesAndWatches()
+
   def ExpandVariable( self ):
     if vim.current.window.buffer != self._buf:
       return
@@ -75,7 +108,7 @@ class VariablesView( object ):
     variable = self._line_to_variable[ current_line ]
     if '_variables' in variable:
       del variable[ '_variables' ]
-      self._DrawScopes()
+      self._DrawScopesAndWatches()
     else:
       self._connection.DoRequest( partial( self._ConsumeVariables, variable ), {
         'command': 'variables',
@@ -93,13 +126,13 @@ class VariablesView( object ):
                           '_variables' not in variable ) else '-',
           name = variable[ 'name' ],
           type_ = variable.get( 'type', '<unknown type>' ),
-          value = variable[ 'value' ] ) )
+          value = variable[ 'value' ] ).split( '\n' ) )
       self._line_to_variable[ len( self._buf ) ] = variable
 
       if '_variables' in variable:
         self._DrawVariables( variable[ '_variables' ], indent + 2 )
 
-  def _DrawScopes( self ):
+  def _DrawScopesAndWatches( self ):
     self._line_to_variable = {}
     with utils.RestoreCursorPosition():
       with utils.ModifiableScratchBuffer( self._buf ):
@@ -110,6 +143,16 @@ class VariablesView( object ):
             indent = 2
             self._DrawVariables( scope[ '_variables' ], indent )
 
+        self._buf.append( 'Watches: ----' )
+        for watch in self._watches:
+          self._buf.append( 'Expression: ' + watch[ 'expression' ] )
+          if 'result' in watch:
+            result = watch[ 'result' ]
+            line =  '  Result: ' + result[ 'result' ]
+            self._buf.append( line.split( '\n' ) )
+            if '_variables' in result:
+              indent = 4
+              self._DrawVariables( result[ '_variables' ], indent )
 
   def _ConsumeVariables( self, parent, message ):
     for variable in message[ 'body' ][ 'variables' ]:
@@ -118,4 +161,4 @@ class VariablesView( object ):
 
       parent[ '_variables' ].append( variable )
 
-    self._DrawScopes()
+    self._DrawScopesAndWatches()