Module: Trepan::Frame

Includes:
Util
Defined in:
app/frame.rb

Overview

Call-Stack frame methods

Constant Summary collapse

DEFAULT_STACK_TRACE_SETTINGS = 
{
  :basename     => false,   # Basename only for files?
  :maxstack     => 16,      # How many entries to show? nil means all
  :count        => nil,     # How many entries to show? nil means all
  :current_pos  => 0,       # Where are we in the stack?
  :show_pc      => false,   # Show PC offset?
}

Class Method Summary collapse

Methods included from Util

extract_expression, safe_repr, suppress_warnings, uniq_abbrev

Class Method Details

.all_param_names(iseq, delineate = true) ⇒ Object 



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# File 'app/frame.rb', line 21

def all_param_names(iseq, delineate=true)
  return '' unless iseq
  params = param_names(iseq, 0, iseq.argc-1, '')
  if iseq.arg_opts > 0
    opt_params = param_names(iseq, iseq.argc, 
                             iseq.argc + iseq.arg_opts-2, '')
    opt_params[0] = "optional: #{opt_params[0]}" if delineate
    params += opt_params
  end
  params += param_names(iseq, iseq.arg_rest, iseq.arg_rest, '*') if 
    iseq.arg_rest != -1
  if iseq.arg_post_len > 0
    # Manditory arguments after optional ones - new in Ruby 1.9
    post_params = param_names(iseq, iseq.arg_post_start, 
                              iseq.post_start + iseq.arg_post_len, '')
    post_params[0] = "post: #{post_params[0]}" if delineate
    params += post_params
  end
  params += param_names(iseq, iseq.arg_block, iseq.arg_block, '&') if 
    iseq.arg_block != -1

  return params
end

.c_params(frame, maxstring = 20) ⇒ Object 



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# File 'app/frame.rb', line 45

def c_params(frame, maxstring=20)
  argc = frame.argc
  # FIXME should figure out why exception is raised.
  begin
    args = 
      if 0 == argc
        ''
      elsif frame 
        1.upto(argc).map do 
        |i| 
        safe_repr(frame.sp(argc-i+3).inspect, 10)
      end.join(', ')
      else
        '??'
      end
    safe_repr(args, maxstring)
  rescue NotImplementedError
    '??'
  end
end

.eval_string(frame) ⇒ Object

Return the eval string. We get this as the parameter to the eval C call. A bit of checking is done to make sure everything is okay:

- we have to be in an EVAL type frame which has an iseq
- we have to have a prev frame which is a CFUNC
- the prev method name has to be 'eval'



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# File 'app/frame.rb', line 72

def eval_string(frame)
  return nil unless 'EVAL' == frame.type && frame.iseq
  prev = frame.prev
  return nil unless prev && 'CFUNC' == prev.type && 'eval' == prev.method
  retval = prev.sp 3 
  retval = $1 if retval =~ /^\(eval "(.+)"\)/
  retval
end

.file ⇒ Object 



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# File 'app/frame.rb', line 81

def file
  iseq.source_container[1]
end

.format_stack_call(frame, opts) ⇒ Object 



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# File 'app/frame.rb', line 85

def format_stack_call(frame, opts)
  # FIXME: prettify 
  s = "#{frame.type}"
  s += if opts[:class]
         " #{opts[:class]}#"
       else
         begin 
           obj = eval('self', frame.binding)
         rescue
           ''
         else
           if obj
             " #{obj.class}#" 
           else
             ''
           end
         end
       end
  meth = frame.method
  if meth and frame.type != 'IFUNC'
    iseq = frame.iseq
    args = if 'CFUNC' == frame.type
             c_params(frame)
           elsif iseq
             all_param_names(iseq).join(', ')
           end
    s += meth
    if %w(CFUNC METHOD).member?(frame.type)
      s += "(#{args})"
    elsif %w(BLOCK LAMBDA TOP EVAL).member?(frame.type)
      s += " |#{args}|" unless args.nil? || args.empty?
    else
      s += "(#{all_param_names(iseq)})" 
    end
  end
  s
rescue ThreadFrameError
  'invalid frame'
end

.format_stack_entry(frame, opts = {}) ⇒ Object 



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# File 'app/frame.rb', line 125

def format_stack_entry(frame, opts={})
  return 'invalid frame' if frame.invalid?
  s  = format_stack_call(frame, opts)
  s += " in #{frame.source_container[0]} "
  s += 
    if (eval_str = eval_string(frame))
      safe_repr(eval_str.inspect, 15)
    else
      if 'file' == frame.source_container[0] &&
          opts[:basename]
        File.basename(frame.source_container[1])
      else
        frame.source_container[1]
      end
    end
  if frame.source_location
    s += 
      if opts[:maxwidth] && s.size > opts[:maxwidth]
        "\n\t"
      else
        ' '
      end
    if frame.source_location.size == 1
      s += "at line #{frame.source_location[0]}" if 
        frame.source_location[0] != 0
    else
      s += " at lines #{frame.source_location}"
    end
  end
  s += ", pc: #{frame.pc_offset}" if 
    frame.pc_offset > 0 && opts[:show_pc]
  return s
end

.location_equal(frame1, frame2) ⇒ Object

Return true if frame1 and frame2 are at the same place. We use this for example in detecting tail recursion.



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# File 'app/frame.rb', line 161

def location_equal(frame1, frame2)
  frame1 && frame2 && frame1.source_location == frame2.source_location &&
    frame1.pc_offset == frame2.pc_offset && 
    frame1.source_container == frame2.source_container
end

.offset_for_return(event) ⇒ Object

Raises:

  • (RuntimeError) 


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# File 'app/frame.rb', line 167

def offset_for_return(event)
  raise RuntimeError unless %w(return c-return).member?(event)
  # FIXME: C calls have a RubyVM::Env added to the stack.
  # Where? Why?
  'return' == event ? 1 : 4
end

.param_names(iseq, start, stop, prefix = '') ⇒ Object 



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# File 'app/frame.rb', line 174

def param_names(iseq, start, stop, prefix='')
  start.upto(stop).map do |i| 
    begin
      prefix + iseq.local_name(i)
    rescue
      nil
    end
  end.compact
end

.print_stack_entry(frame, i, prefix = ' ', opts = {}) ⇒ Object 



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# File 'app/frame.rb', line 184

def print_stack_entry(frame, i, prefix='    ', opts={})
  opts[:class] = nil unless i == 0
  msg "%s%s" % [prefix, format_stack_entry(frame, opts)]
end

.print_stack_trace(frame, opts = {}) ⇒ Object

Print ‘count’ frame entries



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# File 'app/frame.rb', line 211

def print_stack_trace(frame, opts={})
  opts    = DEFAULT_STACK_TRACE_SETTINGS.merge(opts)
  halfstack = (opts[:maxstack]+1) / 2
  n       = frame.stack_size
  n       = [n, opts[:count]].min if opts[:count]
  if n > (halfstack * 2)
    print_stack_trace_from_to(0, halfstack-1, frame, opts)
    msg "... %d levels ..." % (n - halfstack*2)
    print_stack_trace_from_to(n - halfstack, n-1, frame, opts)
  else
    print_stack_trace_from_to(0, n-1, frame, opts)
  end
  msg "(More stack frames follow...)" if n < frame.stack_size
end

.print_stack_trace_from_to(from, to, frame, opts) ⇒ Object 



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# File 'app/frame.rb', line 189

def print_stack_trace_from_to(from, to, frame, opts)
  last_frame = nil
  # TODO: handle indirect recursion.
  direct_recursion_count = 0
  from.upto(to) do |i|
    if location_equal(last_frame, frame)
      direct_recursion_count += 1
    else
      if direct_recursion_count > 0
        msg("... above line repeated #{direct_recursion_count} times")
        direct_recursion_count = 0
      end
      prefix = (i == opts[:current_pos]) ? '-->' : '   '
      prefix += ' #%d ' % [i]
      print_stack_entry(frame, i, prefix, opts)
    end
    last_frame = frame
    frame = frame.prev
  end
end

.set_return_value(frame, event, value) ⇒ Object 



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# File 'app/frame.rb', line 226

def set_return_value(frame, event, value)
  offset = offset_for_return(event)
  frame.sp_set(offset, value)
end

.value_returned(frame, event) ⇒ Object 



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# File 'app/frame.rb', line 232

def value_returned(frame, event)
  frame.sp(offset_for_return(event))
end