src/debugger.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2013 Lucas Bajolet <lucas.bajolet@gmail.com>
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16
  17 # Debugging of a nit program using the NaiveInterpreter
  18 module debugger
  19
  20 import breakpoint
  21 intrude import naive_interpreter
  22 import nitx
  23 intrude import local_var_init
  24 intrude import scope
  25 intrude import toolcontext
  26
  27 redef class Model
  28         # Cleans the model to remove a module and what it defines when semantic analysis fails on injected code
  29         private fun try_remove_module(m: MModule): Bool
  30         do
  31                 var index = -1
  32                 for i in [0 .. mmodules.length[ do
  33                         if mmodules[i] == m then
  34                                 index = i
  35                                 break
  36                         end
  37                 end
  38                 if index == -1 then return false
  39                 var mmodule = mmodules[index]
  40                 mmodules.remove_at(index)
  41                 for classdef in mmodule.mclassdefs do
  42                         var mclass = classdef.mclass
  43                         for i in [0 .. mclass.mclassdefs.length[ do
  44                                 if mclass.mclassdefs[i] == classdef then
  45                                         index = i
  46                                         break
  47                                 end
  48                         end
  49                         mclass.mclassdefs.remove_at(index)
  50                         var propdefs = classdef.mpropdefs
  51                         for propdef in propdefs do
  52                                 var prop = propdef.mproperty
  53                                 for i in [0..prop.mpropdefs.length[ do
  54                                         if prop.mpropdefs[i] == propdef then
  55                                                 index = i
  56                                                 break
  57                                         end
  58                                 end
  59                                 prop.mpropdefs.remove_at(index)
  60                         end
  61                 end
  62                 return true
  63         end
  64 end
  65
  66 redef class ScopeVisitor
  67
  68         redef init(toolcontext)
  69         do
  70                 super
  71                 if toolcontext.dbg != null then
  72                         var localvars = toolcontext.dbg.frame.map
  73                         for i in localvars.keys do
  74                                 scopes.first.variables[i.to_s] = i
  75                         end
  76                 end
  77         end
  78
  79 end
  80
  81 redef class LocalVarInitVisitor
  82         redef fun mark_is_unset(node: AExpr, variable: nullable Variable)
  83         do
  84                 super
  85                 if toolcontext.dbg != null then
  86                         var varname = variable.to_s
  87                         var instmap = toolcontext.dbg.frame.map
  88                         for i in instmap.keys do
  89                                 if i.to_s == varname then
  90                                         mark_is_set(node, variable)
  91                                 end
  92                         end
  93                 end
  94         end
  95
  96 end
  97
  98 redef class ToolContext
  99         private var dbg: nullable Debugger = null
 100
 101         private var had_error: Bool = false
 102
 103         redef fun check_errors
 104         do
 105                 if dbg == null then
 106                         super
 107                 else
 108                         if messages.length > 0 then
 109                                 message_sorter.sort(messages)
 110
 111                                 for m in messages do
 112                                         if "Warning".search_in(m.text, 0) == null then had_error = true
 113                                         stderr.write("{m.to_color_string}\n")
 114                                 end
 115                         end
 116
 117                         messages.clear
 118                 end
 119         end
 120
 121         # -d
 122         var opt_debugger_mode: OptionBool = new OptionBool("Launches the target program with the debugger attached to it", "-d")
 123         # -c
 124         var opt_debugger_autorun: OptionBool = new OptionBool("Launches the target program with the interpreter, such as when the program fails, the debugging prompt is summoned", "-c")
 125
 126         redef init
 127         do
 128                 super
 129                 self.option_context.add_option(self.opt_debugger_mode)
 130                 self.option_context.add_option(self.opt_debugger_autorun)
 131         end
 132 end
 133
 134 redef class ModelBuilder
 135         # Execute the program from the entry point (Sys::main) of the `mainmodule`
 136         # `arguments` are the command-line arguments in order
 137         # REQUIRE that:
 138         #   1. the AST is fully loaded.
 139         #   2. the model is fully built.
 140         #   3. the instructions are fully analysed.
 141         fun run_debugger(mainmodule: MModule, arguments: Array[String])
 142         do
 143                 var time0 = get_time
 144                 self.toolcontext.info("*** START INTERPRETING ***", 1)
 145
 146                 var interpreter = new Debugger(self, mainmodule, arguments)
 147
 148                 init_naive_interpreter(interpreter, mainmodule)
 149
 150                 var time1 = get_time
 151                 self.toolcontext.info("*** END INTERPRETING: {time1-time0} ***", 2)
 152         end
 153
 154         fun run_debugger_autorun(mainmodule: MModule, arguments: Array[String])
 155         do
 156                 var time0 = get_time
 157                 self.toolcontext.info("*** START INTERPRETING ***", 1)
 158
 159                 var interpreter = new Debugger(self, mainmodule, arguments)
 160                 interpreter.autocontinue = true
 161
 162                 init_naive_interpreter(interpreter, mainmodule)
 163
 164                 var time1 = get_time
 165                 self.toolcontext.info("*** END INTERPRETING: {time1-time0} ***", 2)
 166         end
 167 end
 168
 169 # The class extending `NaiveInterpreter` by adding debugging methods
 170 class Debugger
 171         super NaiveInterpreter
 172
 173         # Keeps the frame count in memory to find when to stop
 174         # and launch the command prompt after a step out call
 175         var step_stack_count = 1
 176
 177         # Triggers a step over an instruction in a nit program
 178         var stop_after_step_over_trigger = true
 179
 180         # Triggers a step out of an instruction
 181         var stop_after_step_out_trigger= false
 182
 183         # Triggers a step in a instruction (enters a function
 184         # if the instruction is a function call)
 185         var step_in_trigger = false
 186
 187         # HashMap containing the breakpoints bound to a file
 188         var breakpoints = new HashMap[String, HashSet[Breakpoint]]
 189
 190         # Contains the current file
 191         var curr_file = ""
 192
 193         # Aliases hashmap (maps an alias to a variable name)
 194         var aliases = new HashMap[String, String]
 195
 196         # Set containing all the traced variables and their related frame
 197         private var traces = new HashSet[TraceObject]
 198
 199         # Map containing all the positions for the positions of the arguments traced
 200         # In a function call
 201         private var fun_call_arguments_positions = new HashMap[Int, TraceObject]
 202
 203         # Triggers the remapping of a trace object in the local context after a function call
 204         var aftermath = false
 205
 206         # Used to prevent the case when the body of the function called is empty
 207         # If it is not, then, the remapping won't be happening
 208         var frame_count_aftermath = 1
 209
 210         # Auto continues the execution until the end or until an error is encountered
 211         var autocontinue = false
 212
 213         #######################################################################
 214         ##                  Execution of statement function                  ##
 215         #######################################################################
 216
 217         # Main loop, every call to a debug command is done here
 218         redef fun stmt(n: nullable AExpr)
 219         do
 220                 if n == null then return
 221
 222                 var frame = self.frame
 223                 var old = frame.current_node
 224                 frame.current_node = n
 225
 226                 if not self.autocontinue then
 227                         if not n isa ABlockExpr then
 228                                 steps_fun_call(n)
 229
 230                                 breakpoint_check(n)
 231
 232                                 check_funcall_and_traced_args(n)
 233
 234                                 remap(n)
 235
 236                                 check_if_vars_are_traced(n)
 237                         end
 238                 end
 239
 240                 n.stmt(self)
 241                 frame.current_node = old
 242         end
 243
 244         # Does the same as an usual send, except it will modify the call chain on the first call when injecting code at Runtime using the debugger.
 245         # Instead of creating a pristine Frame, it will copy the actual values of the frame, and re-inject them after execution in the current context.
 246         fun rt_send(mproperty: MMethod, args: Array[Instance]): nullable Instance
 247         do
 248                 var recv = args.first
 249                 var mtype = recv.mtype
 250                 var ret = send_commons(mproperty, args, mtype)
 251                 if ret != null then return ret
 252                 var propdef = mproperty.lookup_first_definition(self.mainmodule, mtype)
 253                 return self.rt_call(propdef, args)
 254         end
 255
 256         # Same as a regular call but for a runtime injected module
 257         #
 258         fun rt_call(mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 259         do
 260                 args = call_commons(mpropdef, args)
 261                 return rt_call_without_varargs(mpropdef, args)
 262         end
 263
 264         # Common code to call and this function
 265         #
 266         # Call only executes the variadic part, this avoids
 267         # double encapsulation of variadic parameters into an Array
 268         fun rt_call_without_varargs(mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 269         do
 270                 if self.modelbuilder.toolcontext.opt_discover_call_trace.value and not self.discover_call_trace.has(mpropdef) then
 271                         self.discover_call_trace.add mpropdef
 272                         self.debug("Discovered {mpropdef}")
 273                 end
 274                 if args.length < mpropdef.msignature.arity + 1 or args.length > mpropdef.msignature.arity + 1 then
 275                         fatal("NOT YET IMPLEMENTED: Invalid arity for {mpropdef}. {args.length} arguments given.")
 276                 end
 277                 if args.length < mpropdef.msignature.arity + 1 then
 278                         fatal("NOT YET IMPLEMENTED: default closures")
 279                 end
 280
 281                 # Look for the AST node that implements the property
 282                 var mproperty = mpropdef.mproperty
 283                 if self.modelbuilder.mpropdef2npropdef.has_key(mpropdef) then
 284                         var npropdef = self.modelbuilder.mpropdef2npropdef[mpropdef]
 285                         self.parameter_check(npropdef, mpropdef, args)
 286                         if npropdef isa AConcreteMethPropdef then
 287                                 return npropdef.rt_call(self, mpropdef, args)
 288                         else
 289                                 print "Error, invalid propdef to call at runtime !"
 290                                 return null
 291                         end
 292                 else if mproperty.name == "init" then
 293                         var nclassdef = self.modelbuilder.mclassdef2nclassdef[mpropdef.mclassdef]
 294                         self.parameter_check(nclassdef, mpropdef, args)
 295                         return nclassdef.call(self, mpropdef, args)
 296                 else
 297                         fatal("Fatal Error: method {mpropdef} not found in the AST")
 298                         abort
 299                 end
 300         end
 301
 302         # Evaluates dynamically a snippet of Nit code
 303         # `nit_code` : Nit code to be executed
 304         fun eval(nit_code: String)
 305         do
 306                 var local_toolctx = modelbuilder.toolcontext
 307                 local_toolctx.dbg = self
 308                 var e = local_toolctx.parse_something(nit_code)
 309                 if e isa AExpr then
 310                         nit_code = "print " + nit_code
 311                         e = local_toolctx.parse_something(nit_code)
 312                 end
 313                 if e isa AModule then
 314                         local_toolctx.had_error = false
 315                         modelbuilder.load_rt_module(self.mainmodule, e, "rt_module")
 316                         local_toolctx.run_phases([e])
 317                         if local_toolctx.had_error then
 318                                 modelbuilder.model.try_remove_module(e.mmodule.as(not null))
 319                                 local_toolctx.dbg = null
 320                                 return
 321                         end
 322                         var mmod = e.mmodule
 323                         if mmod != null then
 324                                 self.mainmodule = mmod
 325                                 var local_classdefs = mmod.mclassdefs
 326                                 var sys_type = mmod.sys_type
 327                                 if sys_type == null then
 328                                         print "Fatal error, cannot find Class Sys !\nAborting"
 329                                         abort
 330                                 end
 331                                 var mobj = new MutableInstance(sys_type)
 332                                 init_instance(mobj)
 333                                 var initprop = mmod.try_get_primitive_method("init", sys_type.mclass)
 334                                 if initprop != null then
 335                                         self.send(initprop, [mobj])
 336                                 end
 337                                 self.check_init_instance(mobj)
 338                                 var mainprop = mmod.try_get_primitive_method("main", sys_type.mclass)
 339                                 if mainprop != null then
 340                                         self.rt_send(mainprop, [mobj])
 341                                 end
 342                         else
 343                                 print "Error while loading_rt_module"
 344                         end
 345                 else
 346                         print "Error when parsing, e = {e.class_name}"
 347                 end
 348                 local_toolctx.dbg = null
 349         end
 350
 351         # Encpasulates the behaviour for step over/out
 352         private fun steps_fun_call(n: AExpr)
 353         do
 354                 if self.stop_after_step_over_trigger then
 355                         if self.frames.length <= self.step_stack_count then
 356                                 n.debug("Execute stmt {n.to_s}")
 357                                 while read_cmd do end
 358                         end
 359                 else if self.stop_after_step_out_trigger then
 360                         if frames.length < self.step_stack_count then
 361                                 n.debug("Execute stmt {n.to_s}")
 362                                 while read_cmd do end
 363                         end
 364                 else if step_in_trigger then
 365                         n.debug("Execute stmt {n.to_s}")
 366                         while read_cmd do end
 367                 end
 368         end
 369
 370         # Checks if a breakpoint is encountered, and launches the debugging prompt if true
 371         private fun breakpoint_check(n: AExpr)
 372         do
 373                 var currFileNameSplit = self.frame.current_node.location.file.filename.to_s.split_with("/")
 374
 375                 self.curr_file = currFileNameSplit[currFileNameSplit.length-1]
 376
 377                 var breakpoint = find_breakpoint(curr_file, n.location.line_start)
 378
 379                 if breakpoints.keys.has(curr_file) and breakpoint != null then
 380
 381                         breakpoint.check_in
 382
 383                         if not breakpoint.is_valid
 384                         then
 385                                 remove_breakpoint(curr_file, n.location.line_start)
 386                         end
 387
 388                         n.debug("Execute stmt {n.to_s}")
 389                         while read_cmd do end
 390                 end
 391         end
 392
 393         # Check if a variable of current expression is traced
 394         # Then prints and/or breaks for command prompt
 395         private fun check_if_vars_are_traced(n: AExpr)
 396         do
 397                 var identifiers_in_instruction = get_identifiers_in_current_instruction(n.location.text)
 398
 399                 for i in identifiers_in_instruction do
 400                         var variable = seek_variable(i, frame)
 401                         for j in self.traces do
 402                                 if j.is_variable_traced_in_frame(i, frame) then
 403                                         n.debug("Traced variable {i} used")
 404                                         if j.break_on_encounter then while read_cmd do end
 405                                         break
 406                                 end
 407                         end
 408                 end
 409         end
 410
 411         # Function remapping all the traced objects to match their name in the local context
 412         private fun remap(n: AExpr)
 413         do
 414                 if self.aftermath then
 415
 416                         # Trace every argument variable pre-specified
 417                         if self.frame_count_aftermath < frames.length and fun_call_arguments_positions.length > 0 then
 418
 419                                 var ids_in_fun_def = get_identifiers_in_current_instruction(get_function_arguments(frame.mpropdef.location.text))
 420
 421                                 for i in fun_call_arguments_positions.keys do
 422                                         self.fun_call_arguments_positions[i].add_frame_variable(frame, ids_in_fun_def[i])
 423                                 end
 424                         end
 425
 426                         self.aftermath = false
 427                 end
 428         end
 429
 430         # If the current instruction is a function call
 431         # We analyse its signature and the position of traced arguments if the call
 432         # For future remapping when inside the function
 433         private fun check_funcall_and_traced_args(n: AExpr) do
 434                 # If we have a function call, we need to see if any of the arguments is traced (including the caller)
 435                 # if it is, next time we face an instruction, we'll trace the local version on the traced variable in the next frame
 436                 if n isa ACallExpr then
 437                         self.aftermath = true
 438                         self.frame_count_aftermath = frames.length
 439                         fun_call_arguments_positions.clear
 440                         var fun_arguments = get_identifiers_in_current_instruction(get_function_arguments(n.location.text))
 441
 442                         for i in self.traces do
 443                                 for j in [0 .. fun_arguments.length - 1] do
 444                                         if i.is_variable_traced_in_frame(fun_arguments[j],frame) then
 445                                                 fun_call_arguments_positions[j] = i
 446                                         end
 447                                 end
 448                         end
 449                 end
 450         end
 451
 452         #######################################################################
 453         ##                   Processing commands functions                   ##
 454         #######################################################################
 455
 456         fun read_cmd: Bool
 457         do
 458                 printn "> "
 459                 return process_debug_command(gets)
 460         end
 461
 462         # Takes a user command as a parameter
 463         #
 464         # Returns a boolean value, representing whether or not to
 465         # continue reading commands from the console input
 466         fun process_debug_command(command:String): Bool
 467         do
 468                 # Step-out command
 469                 if command == "finish"
 470                 then
 471                         return step_out
 472                 # Step-in command
 473                 else if command == "s"
 474                 then
 475                         return step_in
 476                 # Step-over command
 477                 else if command == "n" then
 478                         return step_over
 479                 # Opens a new NitIndex prompt on current model
 480                 else if command == "nitx" then
 481                         new NitIndex.with_infos(modelbuilder, self.mainmodule).prompt
 482                         return true
 483                 # Continues execution until the end
 484                 else if command == "c" then
 485                         return continue_exec
 486                 else if command == "nit" then
 487                         printn "$~> "
 488                         command = gets
 489                         var nit_buf = new Buffer
 490                         while not command == ":q" do
 491                                 nit_buf.append(command)
 492                                 nit_buf.append("\n")
 493                                 printn "$~> "
 494                                 command = gets
 495                         end
 496                         step_in
 497                         eval(nit_buf.to_s)
 498                 else if command == "quit" then
 499                         exit(0)
 500                 else if command == "abort" then
 501                         print stack_trace
 502                         exit(0)
 503                 else
 504                         var parts_of_command = command.split_with(' ')
 505                         # Shows the value of a variable in the current frame
 506                         if parts_of_command[0] == "p" or parts_of_command[0] == "print" then
 507                                 print_command(parts_of_command)
 508                         # Places a breakpoint on line x of file y
 509                         else if parts_of_command[0] == "break" or parts_of_command[0] == "b"
 510                         then
 511                                 process_place_break_fun(parts_of_command)
 512                         # Places a temporary breakpoint on line x of file y
 513                         else if parts_of_command[0] == "tbreak" and (parts_of_command.length == 2 or parts_of_command.length == 3)
 514                         then
 515                                 process_place_tbreak_fun(parts_of_command)
 516                         # Removes a breakpoint on line x of file y
 517                         else if parts_of_command[0] == "d" or parts_of_command[0] == "delete" then
 518                                 process_remove_break_fun(parts_of_command)
 519                         # Sets an alias for a variable
 520                         else if parts_of_command.length == 3 and parts_of_command[1] == "as"
 521                         then
 522                                 add_alias(parts_of_command[0], parts_of_command[2])
 523                         # Modifies the value of a variable in the current frame
 524                         else if parts_of_command.length >= 3 and parts_of_command[1] == "=" then
 525                                 process_mod_function(parts_of_command)
 526                         # Traces the modifications on a variable
 527                         else if parts_of_command.length >= 2 and parts_of_command[0] == "trace" then
 528                                 process_trace_command(parts_of_command)
 529                         # Untraces the modifications on a variable
 530                         else if parts_of_command.length == 2 and parts_of_command[0] == "untrace" then
 531                                 process_untrace_command(parts_of_command)
 532                         else
 533                                 print "Unknown command \"{command}\""
 534                         end
 535                 end
 536                 return true
 537         end
 538
 539         #######################################################################
 540         ##               Processing specific command functions               ##
 541         #######################################################################
 542
 543         # Sets the flags to step-over an instruction in the current file
 544         fun step_over: Bool
 545         do
 546                 self.step_stack_count = frames.length
 547                 self.stop_after_step_over_trigger = true
 548                 self.stop_after_step_out_trigger = false
 549                 self.step_in_trigger = false
 550                 return false
 551         end
 552
 553         #Sets the flags to step-out of a function
 554         fun step_out: Bool
 555         do
 556                 self.stop_after_step_over_trigger = false
 557                 self.stop_after_step_out_trigger = true
 558                 self.step_in_trigger = false
 559                 self.step_stack_count = frames.length
 560                 return false
 561         end
 562
 563         # Sets the flags to step-in an instruction
 564         fun step_in: Bool
 565         do
 566                 self.step_in_trigger = true
 567                 self.stop_after_step_over_trigger = false
 568                 self.stop_after_step_out_trigger = false
 569                 return false
 570         end
 571
 572         # Sets the flags to continue execution
 573         fun continue_exec: Bool
 574         do
 575                 self.stop_after_step_over_trigger = false
 576                 self.stop_after_step_out_trigger = false
 577                 self.step_in_trigger = false
 578                 return false
 579         end
 580
 581         # Prints the demanded variable in the command
 582         #
 583         # The name of the variable in in position 1 of the array 'parts_of_command'
 584         fun print_command(parts_of_command: Array[String])
 585         do
 586                 if parts_of_command[1] == "*" then
 587                         var map_of_instances = frame.map
 588
 589                         var keys = map_of_instances.iterator
 590
 591                         print "Variables collection : \n"
 592
 593                         for instance in map_of_instances.keys do
 594                                 print "Variable {instance.to_s}, Instance {map_of_instances[instance].to_s}"
 595                         end
 596
 597                         print "\nEnd of current instruction \n"
 598                 else if parts_of_command[1] == "stack" then
 599                         print self.stack_trace
 600                 else if parts_of_command[1].has('[') and parts_of_command[1].has(']') then
 601                         process_array_command(parts_of_command)
 602                 else
 603                         var instance = seek_variable(get_real_variable_name(parts_of_command[1]), frame)
 604
 605                         if instance != null
 606                         then
 607                                 print_instance(instance)
 608                         else
 609                                 print "Cannot find variable {parts_of_command[1]}"
 610                         end
 611                 end
 612         end
 613
 614         # Processes the input string to know where to put a breakpoint
 615         fun process_place_break_fun(parts_of_command: Array[String])
 616         do
 617                 var bp = get_breakpoint_from_command(parts_of_command)
 618                 if bp != null then
 619                         place_breakpoint(bp)
 620                 end
 621         end
 622
 623         # Returns a breakpoint containing the informations stored in the command
 624         fun get_breakpoint_from_command(parts_of_command: Array[String]): nullable Breakpoint
 625         do
 626                 if parts_of_command[1].is_numeric then
 627                         return new Breakpoint(parts_of_command[1].to_i, curr_file)
 628                 else if parts_of_command.length >= 3 and parts_of_command[2].is_numeric then
 629                         return new Breakpoint(parts_of_command[2].to_i, parts_of_command[1])
 630                 else
 631                         return null
 632                 end
 633         end
 634
 635         # Processes the command of removing a breakpoint on specified line and file
 636         fun process_remove_break_fun(parts_of_command: Array[String])
 637         do
 638                 if parts_of_command[1].is_numeric then
 639                         remove_breakpoint(self.curr_file, parts_of_command[1].to_i)
 640                 else if parts_of_command.length >= 3 and parts_of_command[2].is_numeric then
 641                         remove_breakpoint(parts_of_command[1], parts_of_command[2].to_i)
 642                 end
 643         end
 644
 645         # Processes an array print command
 646         fun process_array_command(parts_of_command: Array[String])
 647         do
 648                 var index_of_first_brace = parts_of_command[1].index_of('[')
 649                 var variable_name = get_real_variable_name(parts_of_command[1].substring(0,index_of_first_brace))
 650                 var braces = parts_of_command[1].substring_from(index_of_first_brace)
 651
 652                 var indexes = remove_braces(braces)
 653
 654                 var index_array = new Array[Array[Int]]
 655
 656                 if indexes != null then
 657                         for index in indexes do
 658                                 var temp_indexes_array = process_index(index)
 659                                 if temp_indexes_array != null then
 660                                         index_array.push(temp_indexes_array)
 661                                         #print index_array.last
 662                                 end
 663                         end
 664                 end
 665
 666                 var instance = seek_variable(variable_name, frame)
 667
 668                 if instance != null then
 669                         print_nested_collection(instance, index_array, 0, variable_name, "")
 670                 else
 671                         print "Cannot find variable {variable_name}"
 672                 end
 673         end
 674
 675         # Processes the modification function to modify a variable dynamically
 676         #
 677         # Command of type variable = value
 678         fun process_mod_function(parts_of_command: Array[String])
 679         do
 680                 parts_of_command[0] = get_real_variable_name(parts_of_command[0])
 681                 var parts_of_variable = parts_of_command[0].split_with(".")
 682
 683                 if parts_of_variable.length > 1 then
 684                         var last_part = parts_of_variable.pop
 685                         var first_part = parts_of_command[0].substring(0,parts_of_command[0].length - last_part.length - 1)
 686                         var papa = seek_variable(first_part, frame)
 687
 688                         if papa != null and papa isa MutableInstance then
 689                                 var attribute = get_attribute_in_mutable_instance(papa, last_part)
 690
 691                                 if attribute != null then
 692                                         modify_argument_of_complex_type(papa, attribute, parts_of_command[2])
 693                                 end
 694                         end
 695                 else
 696                         var target = seek_variable(parts_of_variable[0], frame)
 697                         if target != null then
 698                                 modify_in_frame(target, parts_of_command[2])
 699                         end
 700                 end
 701         end
 702
 703         # Processes the untrace variable command
 704         #
 705         # Command pattern : "untrace variable"
 706         fun process_untrace_command(parts_of_command: Array[String])
 707         do
 708                 var variable_name = get_real_variable_name(parts_of_command[1])
 709                 if untrace_variable(variable_name) then
 710                         print "Untraced variable {parts_of_command[1]}"
 711                 else
 712                         print "{parts_of_command[1]} is not traced"
 713                 end
 714         end
 715
 716         # Processes the trace variable command
 717         #
 718         # Command pattern : "trace variable [break/print]"
 719         fun process_trace_command(parts_of_command: Array[String])
 720         do
 721                 var variable_name = get_real_variable_name(parts_of_command[1])
 722                 var breaker:Bool
 723
 724                 if seek_variable(variable_name, frame) == null then
 725                         print "Cannot find a variable called {parts_of_command[1]}"
 726                         return
 727                 end
 728
 729                 if parts_of_command.length == 3 then
 730                         if parts_of_command[2] == "break" then
 731                                 breaker = true
 732                         else
 733                                 breaker = false
 734                         end
 735                 else
 736                         breaker = false
 737                 end
 738
 739                 trace_variable(variable_name, breaker)
 740
 741                 print "Successfully tracing {parts_of_command[1]}"
 742         end
 743
 744         #######################################################################
 745         ##                    Trace Management functions                     ##
 746         #######################################################################
 747
 748         # Effectively untraces the variable called *variable_name*
 749         #
 750         # Returns true if the variable exists, false otherwise
 751         private fun untrace_variable(variable_name: String): Bool
 752         do
 753                 var to_remove: nullable TraceObject = null
 754                 for i in self.traces do
 755                         if i.is_variable_traced_in_frame(variable_name, frame) then
 756                                 to_remove = i
 757                         end
 758                 end
 759
 760                 if to_remove != null then
 761                         self.traces.remove(to_remove)
 762                         return true
 763                 else
 764                         return false
 765                 end
 766         end
 767
 768         # Effectively traces the variable *variable_name* either in print or break mode depending on the value of breaker (break if true, print if false)
 769         #
 770         private fun trace_variable(variable_name: String, breaker: Bool)
 771         do
 772                 for i in self.traces do
 773                         if i.is_variable_traced_in_frame(variable_name, frame) then
 774                                 print "This variable is already traced"
 775                                 return
 776                         end
 777                 end
 778
 779                 var trace_object: TraceObject
 780
 781                 if breaker then
 782                         trace_object = new TraceObject(true)
 783                 else
 784                         trace_object = new TraceObject(false)
 785                 end
 786
 787                 # We trace the current variable found for the current frame
 788                 trace_object.add_frame_variable(self.frame, variable_name)
 789
 790                 var position_of_variable_in_arguments = get_position_of_variable_in_arguments(frame, variable_name)
 791
 792                 # Start parsing the frames starting with the parent of the current one, until the highest
 793                 # When the variable traced is declared locally, the loop stops
 794                 for i in [1 .. frames.length-1] do
 795
 796                         # If the variable was reported to be an argument of the previous frame
 797                         if position_of_variable_in_arguments != -1 then
 798
 799                                 var local_name = get_identifiers_in_current_instruction(get_function_arguments(frames[i].current_node.location.text))[position_of_variable_in_arguments]
 800
 801                                 position_of_variable_in_arguments = get_position_of_variable_in_arguments(frames[i], local_name)
 802
 803                                 trace_object.add_frame_variable(frames[i], local_name)
 804                         else
 805                                 break
 806                         end
 807                 end
 808
 809                 self.traces.add(trace_object)
 810         end
 811
 812         # If the variable *variable_name* is an argument of the function being executed in the frame *frame*
 813         # The function returns its position in the arguments
 814         # Else, it returns -1
 815         private fun get_position_of_variable_in_arguments(frame: Frame, variable_name: String): Int
 816         do
 817                 var identifiers = get_identifiers_in_current_instruction(get_function_arguments(frame.mpropdef.location.text))
 818                 for i in [0 .. identifiers.length-1] do
 819                         # If the current traced variable is an argument of the current function, we trace its parent (at least)
 820                         if identifiers[i] == variable_name then return i
 821                 end
 822                 return -1
 823         end
 824
 825         # Gets all the identifiers of an instruction (uses the rules of Nit as of Mar 05 2013)
 826         #
 827         fun get_identifiers_in_current_instruction(instruction: AbstractString): Array[String]
 828         do
 829                 var result_array = new Array[String]
 830                 var instruction_buffer = new Buffer
 831
 832                 var trigger_char_escape = false
 833                 var trigger_string_escape = false
 834                 var trigger_concat_in_string = false
 835
 836                 for i in instruction do
 837                         if trigger_char_escape then
 838                                 if i == '\'' then trigger_char_escape = false
 839                         else if trigger_string_escape then
 840                                 if i == '{' then
 841                                         trigger_concat_in_string = true
 842                                         trigger_string_escape = false
 843                                 else if i == '\"' then trigger_string_escape = false
 844                         else
 845                                 if i.is_alphanumeric or i == '_' then
 846                                         instruction_buffer.add(i)
 847                                 else if i == '.' then
 848                                         if instruction_buffer.is_numeric or (instruction_buffer[0] >= 'A' and instruction_buffer[0] <= 'Z') then
 849                                                 instruction_buffer.clear
 850                                         else
 851                                                 result_array.push(instruction_buffer.to_s)
 852                                                 instruction_buffer.add(i)
 853                                         end
 854                                 else if i == '\'' then
 855                                         trigger_char_escape = true
 856                                 else if i == '\"' then
 857                                         trigger_string_escape = true
 858                                 else if i == '}' then
 859                                         trigger_concat_in_string = false
 860                                         trigger_string_escape = true
 861                                 else
 862                                         if instruction_buffer.length > 0 and not instruction_buffer.is_numeric and not (instruction_buffer[0] >= 'A' and instruction_buffer[0] <= 'Z') then result_array.push(instruction_buffer.to_s)
 863                                         instruction_buffer.clear
 864                                 end
 865                         end
 866                 end
 867
 868                 if instruction_buffer.length > 0 and not instruction_buffer.is_numeric and not (instruction_buffer[0] >= 'A' and instruction_buffer[0] <= 'Z') then result_array.push(instruction_buffer.to_s)
 869
 870                 return result_array
 871         end
 872
 873         # Takes a function call or declaration and strips all but the arguments
 874         #
 875         fun get_function_arguments(function: AbstractString): String
 876         do
 877                 var buf = new Buffer
 878                 var trigger_copy = false
 879
 880                 for i in function do
 881                         if i == ')' then break
 882                         if trigger_copy then buf.add(i)
 883                         if i == '(' then trigger_copy = true
 884                 end
 885
 886                 return buf.to_s
 887         end
 888
 889         #######################################################################
 890         ##                    Alias management functions                     ##
 891         #######################################################################
 892
 893         # Adds a new alias to the tables
 894         fun add_alias(var_represented: String, alias: String)
 895         do
 896                 self.aliases[alias] = var_represented
 897         end
 898
 899         # Gets the real name of a variable hidden by an alias
 900         fun get_variable_name_by_alias(alias: String): nullable String
 901         do
 902                 if self.aliases.keys.has(alias) then
 903                         return self.aliases[alias]
 904                 end
 905
 906                 return null
 907         end
 908
 909         # Gets the variable named by name, whether it is an alias or not
 910         fun get_real_variable_name(name: String): String
 911         do
 912                 var explode_string = name.split_with(".")
 913                 var final_string = new Buffer
 914                 for i in explode_string do
 915                         var alias_resolved = get_variable_name_by_alias(i)
 916                         if alias_resolved != null then
 917                                 final_string.append(get_real_variable_name(alias_resolved))
 918                         else
 919                                 final_string.append(i)
 920                         end
 921                         final_string.append(".")
 922                 end
 923
 924                 return final_string.substring(0,final_string.length-1).to_s
 925         end
 926
 927         #######################################################################
 928         ##                         Print functions                           ##
 929         #######################################################################
 930
 931         # Prints an object instance and its attributes if it has some
 932         #
 933         # If it is a primitive type, its value is directly printed
 934         fun print_instance(instance: Instance)
 935         do
 936                 print "Printing innards of a variable"
 937
 938                 if instance isa MutableInstance then
 939                         var attributes = instance.attributes
 940                         print "Object : {instance}"
 941
 942                         for current_attribute in attributes.keys do
 943                                 print "Attribute : {current_attribute.to_s} \nValeur : {attributes[current_attribute].to_s}"
 944                         end
 945                 else
 946                         print "Found variable {instance}"
 947                 end
 948
 949                 print "Stopping printing innards of a variable"
 950         end
 951
 952         # Prints the attributes demanded in a SequenceRead
 953         # Used recursively to print nested collections
 954         fun print_nested_collection(instance: Instance, indexes: Array[Array[Int]], depth: Int, variable_name: String, depth_string: String)
 955         do
 956                 var collection: nullable SequenceRead[Object] = null
 957                 var real_collection_length: nullable Int = null
 958
 959                 if instance isa MutableInstance then
 960                         real_collection_length = get_collection_instance_real_length(instance)
 961                         collection = get_primary_collection(instance)
 962                 end
 963
 964                 if collection != null and real_collection_length != null then
 965                         for i in indexes[depth] do
 966                                 if i >= 0 and i < real_collection_length then
 967                                         if depth == indexes.length-1 then
 968                                                 print "{variable_name}{depth_string}[{i}] = {collection[i]}"
 969                                         else
 970                                                 var item_i = collection[i]
 971
 972                                                 if item_i isa MutableInstance then
 973                                                         print_nested_collection(item_i, indexes, depth+1, variable_name, depth_string+"[{i}]")
 974                                                 else
 975                                                         print "The item at {variable_name}{depth_string}[{i}] is not a collection"
 976                                                         print item_i
 977                                                 end
 978                                         end
 979                                 else
 980                                         print "Out of bounds exception : i = {i} and collection_length = {real_collection_length.to_s}"
 981
 982                                         if i < 0 then
 983                                                 continue
 984                                         else if i >= real_collection_length then
 985                                                 break
 986                                         end
 987                                 end
 988                         end
 989                 else
 990                         if collection == null then
 991                                 print "Cannot find {variable_name}{depth_string}"
 992                         else if real_collection_length != null then
 993                                 print "Cannot find attribute length in {instance}"
 994                         else
 995                                 print "Unknown error."
 996                                 abort
 997                         end
 998                 end
 999         end
1000
1001         #######################################################################
1002         ##                  Variable Exploration functions                   ##
1003         #######################################################################
1004
1005         # Seeks a variable from the current frame called 'variable_path', can introspect complex objects using function get_variable_in_mutable_instance
1006         private fun seek_variable(variable_path: String, frame: Frame): nullable Instance
1007         do
1008                 var full_variable = variable_path.split_with(".")
1009
1010                 var full_variable_iterator = full_variable.iterator
1011
1012                 var first_instance = get_variable_in_frame(full_variable_iterator.item, frame)
1013
1014                 if first_instance == null then  return null
1015
1016                 if full_variable.length <= 1 then return first_instance
1017
1018                 full_variable_iterator.next
1019
1020                 if not (first_instance isa MutableInstance and full_variable_iterator.is_ok) then return null
1021
1022                 return get_variable_in_mutable_instance(first_instance, full_variable_iterator)
1023         end
1024
1025         # Gets a variable 'variable_name' contained in the frame 'frame'
1026         private fun get_variable_in_frame(variable_name: String, frame: Frame): nullable Instance
1027         do
1028                 if variable_name == "self" then
1029                         if frame.arguments.length >= 1 then return frame.arguments.first
1030                 end
1031
1032                 var map_of_instances = frame.map
1033
1034                 for key in map_of_instances.keys do
1035                         if key.to_s == variable_name then
1036                                 return map_of_instances[key]
1037                         end
1038                 end
1039
1040                 return null
1041         end
1042
1043         # Gets an attribute 'attribute_name' contained in variable 'variable'
1044         fun get_attribute_in_mutable_instance(variable: MutableInstance, attribute_name: String): nullable MAttribute
1045         do
1046                 var map_of_attributes = variable.attributes
1047
1048                 for key in map_of_attributes.keys do
1049                         if key.to_s.substring_from(1) == attribute_name then
1050                                 return key
1051                         end
1052                 end
1053
1054                 return null
1055         end
1056
1057         # Recursive function, returns the variable described by 'total_chain'
1058         fun get_variable_in_mutable_instance(variable: MutableInstance, iterator: Iterator[String]): nullable Instance
1059         do
1060                 var attribute = get_attribute_in_mutable_instance(variable, iterator.item)
1061
1062                 if attribute == null then return null
1063
1064                 iterator.next
1065
1066                 if iterator.is_ok then
1067                         var new_variable = variable.attributes[attribute]
1068                         if new_variable isa MutableInstance then
1069                                 return get_variable_in_mutable_instance(new_variable, iterator)
1070                         else
1071                                 return null
1072                         end
1073                 else
1074                         return variable.attributes[attribute]
1075                 end
1076         end
1077
1078         #######################################################################
1079         ##                     Array exploring functions                     ##
1080         #######################################################################
1081
1082         # Gets the length of a collection
1083         # Used by the debugger, else if we call Collection.length, it returns the capacity instead
1084         fun get_collection_instance_real_length(collection: MutableInstance): nullable Int
1085         do
1086                 var collection_length_attribute = get_attribute_in_mutable_instance(collection, "length")
1087
1088                 var real_collection_length: nullable Int = null
1089
1090                 if collection_length_attribute != null then
1091                         var primitive_length_instance = collection.attributes[collection_length_attribute]
1092                         if primitive_length_instance isa PrimitiveInstance[Int] then
1093                                 return primitive_length_instance.val
1094                         end
1095                 end
1096
1097                 return null
1098         end
1099
1100         # Processes the indexes of a print array call
1101         # Returns an array containing all the indexes demanded
1102         fun process_index(index_string: String): nullable Array[Int]
1103         do
1104                 var from_end_index = index_string.index_of('.')
1105                 var to_start_index = index_string.last_index_of('.')
1106
1107                 if from_end_index != -1 and to_start_index != -1 then
1108                         var index_from_string = index_string.substring(0,from_end_index)
1109                         var index_to_string = index_string.substring_from(to_start_index+1)
1110
1111                         if index_from_string.is_numeric and index_to_string.is_numeric then
1112                                 var result_array = new Array[Int]
1113
1114                                 var index_from = index_from_string.to_i
1115                                 var index_to = index_to_string.to_i
1116
1117                                 for i in [index_from..index_to] do
1118                                         result_array.push(i)
1119                                 end
1120
1121                                 return result_array
1122                         end
1123                 else
1124                         if index_string.is_numeric
1125                         then
1126                                 var result_array = new Array[Int]
1127
1128                                 result_array.push(index_string.to_i)
1129
1130                                 return result_array
1131                         else
1132                                 return null
1133                         end
1134                 end
1135
1136                 return null
1137         end
1138
1139         # Gets a collection in a MutableInstance
1140         fun get_primary_collection(container: MutableInstance): nullable SequenceRead[Object]
1141         do
1142                 var items_of_array = get_attribute_in_mutable_instance(container, "items")
1143                 if items_of_array != null then
1144                         var array = container.attributes[items_of_array]
1145
1146                         if array isa PrimitiveInstance[Object] then
1147                                 var sequenceRead_final = array.val
1148                                 if sequenceRead_final isa SequenceRead[Object] then
1149                                         return sequenceRead_final
1150                                 end
1151                         end
1152                 end
1153
1154                 return null
1155         end
1156
1157         # Removes the braces '[' ']' in a print array command
1158         # Returns an array containing their content
1159         fun remove_braces(braces: String): nullable Array[String]
1160         do
1161                 var buffer = new Buffer
1162
1163                 var result_array = new Array[String]
1164
1165                 var number_of_opening_brackets = 0
1166                 var number_of_closing_brackets = 0
1167
1168                 var last_was_opening_bracket = false
1169
1170                 for i in braces do
1171                         if i == '[' then
1172                                 if last_was_opening_bracket then
1173                                         return null
1174                                 end
1175
1176                                 number_of_opening_brackets += 1
1177                                 last_was_opening_bracket = true
1178                         else if i == ']' then
1179                                 if not last_was_opening_bracket then
1180                                         return null
1181                                 end
1182
1183                                 result_array.push(buffer.to_s)
1184                                 buffer.clear
1185                                 number_of_closing_brackets += 1
1186                                 last_was_opening_bracket = false
1187                         else if i.is_numeric or i == '.' then
1188                                 buffer.append(i.to_s)
1189                         else if not i == ' ' then
1190                                 return null
1191                         end
1192                 end
1193
1194                 if number_of_opening_brackets != number_of_closing_brackets then
1195                         return null
1196                 end
1197
1198                 return result_array
1199         end
1200
1201         #######################################################################
1202         ##                   Breakpoint placing functions                    ##
1203         #######################################################################
1204
1205         # Places a breakpoint on line 'line_to_break' for file 'file_to_break'
1206         fun place_breakpoint(breakpoint: Breakpoint)
1207         do
1208                 if not self.breakpoints.keys.has(breakpoint.file) then
1209                         self.breakpoints[breakpoint.file] = new HashSet[Breakpoint]
1210                 end
1211                 if find_breakpoint(breakpoint.file, breakpoint.line) == null then
1212                         self.breakpoints[breakpoint.file].add(breakpoint)
1213                         print "Breakpoint added on line {breakpoint.line} for file {breakpoint.file}"
1214                 else
1215                         print "Breakpoint already present on line {breakpoint.line} for file {breakpoint.file}"
1216                 end
1217         end
1218
1219         #Places a breakpoint that will trigger once and be destroyed afterwards
1220         fun process_place_tbreak_fun(parts_of_command: Array[String])
1221         do
1222                 var bp = get_breakpoint_from_command(parts_of_command)
1223                 if bp != null
1224                 then
1225                         bp.set_max_breaks(1)
1226                         place_breakpoint(bp)
1227                 end
1228         end
1229
1230         #######################################################################
1231         ##                  Breakpoint removing functions                    ##
1232         #######################################################################
1233
1234         # Removes a breakpoint on line 'line_to_break' for file 'file_to_break'
1235         fun remove_breakpoint(file_to_break: String, line_to_break: Int)
1236         do
1237                 if self.breakpoints.keys.has(file_to_break) then
1238                         var bp = find_breakpoint(file_to_break, line_to_break)
1239
1240                         if bp != null then
1241                                 self.breakpoints[file_to_break].remove(bp)
1242                                 print "Breakpoint removed on line {line_to_break} for file {file_to_break}"
1243                                 return
1244                         end
1245                 end
1246
1247                 print "No breakpoint existing on line {line_to_break} for file {file_to_break}"
1248         end
1249
1250         #######################################################################
1251         ##                  Breakpoint searching functions                   ##
1252         #######################################################################
1253
1254         # Finds a breakpoint for 'file' and 'line' in the class HashMap
1255         fun find_breakpoint(file: String, line: Int): nullable Breakpoint
1256         do
1257                 if self.breakpoints.keys.has(file)
1258                 then
1259                         for i in self.breakpoints[file]
1260                         do
1261                                 if i.line == line
1262                                 then
1263                                         return i
1264                                 end
1265                         end
1266                 end
1267
1268                 return null
1269         end
1270
1271         #######################################################################
1272         ##                  Runtime modification functions                   ##
1273         #######################################################################
1274
1275         # Modifies the value of a variable contained in a frame
1276         fun modify_in_frame(variable: Instance, value: String)
1277         do
1278                 var new_variable = get_variable_of_type_with_value(variable.mtype.to_s, value)
1279                 if new_variable != null
1280                 then
1281                         var keys = frame.map.keys
1282                         for key in keys
1283                         do
1284                                 if frame.map[key] == variable
1285                                 then
1286                                         frame.map[key] = new_variable
1287                                 end
1288                         end
1289                 end
1290         end
1291
1292         # Modifies the value of a variable contained in a MutableInstance
1293         fun modify_argument_of_complex_type(papa: MutableInstance, attribute: MAttribute, value: String)
1294         do
1295                 var final_variable = papa.attributes[attribute]
1296                 var type_of_variable = final_variable.mtype.to_s
1297                 var new_variable = get_variable_of_type_with_value(type_of_variable, value)
1298                 if new_variable != null
1299                 then
1300                         papa.attributes[attribute] = new_variable
1301                 end
1302         end
1303
1304         #######################################################################
1305         ##                   Variable generator functions                    ##
1306         #######################################################################
1307
1308         # Returns a new variable of the type 'type_of_variable' with a value of 'value'
1309         fun get_variable_of_type_with_value(type_of_variable: String, value: String): nullable Instance
1310         do
1311                 if type_of_variable == "Int" then
1312                         return get_int(value)
1313                 else if type_of_variable == "Float" then
1314                         return get_float(value)
1315                 else if type_of_variable == "Bool" then
1316                         return get_bool(value)
1317                 else if type_of_variable == "Char" then
1318                         return get_char(value)
1319                 end
1320
1321                 return null
1322         end
1323
1324         # Returns a new int instance with value 'value'
1325         fun get_int(value: String): nullable Instance
1326         do
1327                 if value.is_numeric then
1328                         return int_instance(value.to_i)
1329                 else
1330                         return null
1331                 end
1332         end
1333
1334         # Returns a new float instance with value 'value'
1335         fun get_float(value:String): nullable Instance
1336         do
1337                 if value.is_numeric then
1338                         return float_instance(value.to_f)
1339                 else
1340                         return null
1341                 end
1342         end
1343
1344         # Returns a new char instance with value 'value'
1345         fun get_char(value: String): nullable Instance
1346         do
1347                 if value.length >= 1 then
1348                         return char_instance(value[0])
1349                 else
1350                         return null
1351                 end
1352         end
1353
1354         # Returns a new bool instance with value 'value'
1355         fun get_bool(value: String): nullable Instance
1356         do
1357                 if value.to_lower == "true" then
1358                         return self.true_instance
1359                 else if value.to_lower == "false" then
1360                         return self.false_instance
1361                 else
1362                         print "Invalid value, a boolean must be set at \"true\" or \"false\""
1363                         return null
1364                 end
1365         end
1366
1367 end
1368
1369 redef class AConcreteMethPropdef
1370
1371         # Same as call except it will copy local variables of the parent frame to the frame defined in this call.
1372         # Not supposed to be used by anyone else than the Debugger.
1373         private fun rt_call(v: Debugger, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
1374         do
1375                 var f = new Frame(self, self.mpropdef.as(not null), args)
1376                 var curr_instances = v.frame.map
1377                 for i in curr_instances.keys do
1378                         f.map[i] = curr_instances[i]
1379                 end
1380                 call_commons(v,mpropdef,args,f)
1381                 var currFra = v.frames.shift
1382                 for i in curr_instances.keys do
1383                         if currFra.map.keys.has(i) then
1384                                 curr_instances[i] = currFra.map[i]
1385                         end
1386                 end
1387                 if v.returnmark == f then
1388                         v.returnmark = null
1389                         var res = v.escapevalue
1390                         v.escapevalue = null
1391                         return res
1392                 end
1393                 return null
1394
1395         end
1396 end
1397
1398 # Traces the modifications of an object linked to a certain frame
1399 private class TraceObject
1400
1401         # Map of the local names bound to a frame
1402         var trace_map: HashMap[Frame, String]
1403         # Decides if breaking or printing statement when the variable is encountered
1404         var break_on_encounter: Bool
1405
1406         init(break_on_encounter: Bool)
1407         do
1408                 trace_map = new HashMap[Frame, String]
1409                 self.break_on_encounter = break_on_encounter
1410         end
1411
1412         # Adds the local alias for a variable and the frame bound to it
1413         fun add_frame_variable(frame: Frame, variable_name: String)
1414         do
1415                 self.trace_map[frame] = variable_name
1416         end
1417
1418         # Checks if the prompted variable is traced in the specified frame
1419         fun is_variable_traced_in_frame(variable_name: String, frame: Frame): Bool
1420         do
1421                 if self.trace_map.has_key(frame) then
1422                         if self.trace_map[frame] == variable_name then
1423                                 return true
1424                         end
1425                 end
1426
1427                 return false
1428         end
1429
1430 end
1431
1432 redef class ANode
1433
1434         # Breaks automatically when encountering an error
1435         # Permits the injunction of commands before crashing
1436         redef private fun fatal(v: NaiveInterpreter, message: String)
1437         do
1438                 if v isa Debugger then
1439                         print "An error was encountered, the program will stop now."
1440                         self.debug(message)
1441                         while v.process_debug_command(gets) do end
1442                 end
1443
1444                 super
1445         end
1446 end