Module: PrettyBacktrace

Defined in:
lib/pretty_backtrace.rb,
lib/pretty_backtrace/version.rb

Constant Summary collapse

CONFIG = 
{
  truncate_length: 20,
  disabled_exception_classes: {},
  effective_lines: 0, # 0 is infinite
  file_contents: true,
  file_contents_lines: 2,

  multi_line: false,
  multi_line_truncate_length: 60,
  multi_line_indent: 10,
}
EXCEPTION_MODIFIER_TRACE = 
TracePoint.new(:raise){|tp|
  begin
    e = tp.raised_exception

    CONFIG[:disabled_exception_classes].each{|klass, _|
      next if e.kind_of?(klass)
    }

    RubyVM::DebugInspector.open{|dc|
      locs = dc.backtrace_locations

      effective_lines = CONFIG[:effective_lines]
      effective_lines = locs.size - 2 if effective_lines == 0

      pretty_backtrace = locs.map.with_index{|loc, i|
        next if i < 2
        next loc.to_s unless (effective_lines -= 1) >= 0

        iseq = dc.frame_iseq(i)

        if iseq
          b = dc.frame_binding(i)
          lvs = iseq_local_variables(iseq)
          lvs_val = lvs.inject({}){|r, lv|
            v = b.local_variable_get(lv).inspect
            r[lv] = v; r
          }
        else
          lvs_val = {}
        end

        modify_trace_line loc, loc.absolute_path, loc.lineno, lvs_val
      }.compact
      e.set_backtrace pretty_backtrace
    }
  rescue => e
    puts e
    puts e.backtrace
    fail "PrettyBacktrace BUG"
  end
}
VERSION = 
"0.1.1"

Class Method Summary collapse

Class Method Details

.disable ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 126

def self.disable
  if block_given?
    EXCEPTION_MODIFIER_TRACE.disable{
      yield
    }
  else
    EXCEPTION_MODIFIER_TRACE.disable
  end
end

.effective_lines=(lines) ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 144

def self.effective_lines=(lines)
  CONFIG[:effective_lines] = lines
end

.enable ⇒ Object

configuration



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# File 'lib/pretty_backtrace.rb', line 116

def self.enable
  if block_given?
    EXCEPTION_MODIFIER_TRACE.enable{
      yield
    }
  else
    EXCEPTION_MODIFIER_TRACE.enable
  end
end

.file_contents=(setting) ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 140

def self.file_contents=(setting)
  CONFIG[:file_contents] = setting
end

.iseq_local_variables(iseq) ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 59

def self.iseq_local_variables iseq
  _,_,_,_,arg_info,name,path,a_path,_,type,lvs, * = iseq.to_a
  lvs
end

.modify_trace_line(backtrace_location, absolute_path, lineno, local_variables_values) ⇒ Object

local_variables_values is a Hash object containing pairs of a local variable name and value of local variable.



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# File 'lib/pretty_backtrace.rb', line 68

def self.modify_trace_line backtrace_location, absolute_path, lineno, local_variables_values
  trace_line = backtrace_location.to_s

  if CONFIG[:multi_line]
    indent = ' ' * CONFIG[:multi_line_indent]
    additional = ''

    # file scope
    if CONFIG[:file_contents] && File.exists?(absolute_path)
      fclines = CONFIG[:file_contents_lines]
      start_line = lineno - 1 - 1 * fclines
      start_line = 0 if start_line < 0

      additional << indent + "[FILE]\n"
      additional << open(absolute_path){|f| f.readlines[start_line, 1 + 2 * fclines]}.map.with_index{|line, i|
        ln = start_line + i + 1
        line = line.chomp
        '%s%4d|%s' % [ln == lineno ? indent[0..-3] + "->" : indent, ln, line]
      }.join("\n")
      additional << "\n"
      additional << "\n"
    end

    # local variables
    unless local_variables_values.empty?
      additional << indent + "[LOCAL VARIABLES]\n"
      additional << local_variables_values.map{|lv, v|
        v = v[0..CONFIG[:multi_line_truncate_length]] + '...' if v.length > CONFIG[:multi_line_truncate_length]
        indent + "  #{lv} = #{v.to_s}"
      }.join("\n") + "\n"
    end

    trace_line = "#{trace_line}\n#{additional}" unless additional.empty?
  else
    unless local_variables_values.empty?
      additional = local_variables_values.map{|lv, v|
        v = v[0..CONFIG[:truncate_length]] + '...' if v.length > CONFIG[:truncate_length]
        "#{lv} = #{v.to_s}"
      }.join(", ")
      trace_line = "#{trace_line} (#{additional})"
    end
  end

  trace_line
end

.multi_line=(setting) ⇒ Object 



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# File 'lib/pretty_backtrace.rb', line 136

def self.multi_line=(setting)
  CONFIG[:multi_line] = setting
end