class Campa::Repl

Attributes

environment[R]

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evaler[R]

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printer[R]

rubocop: enable Metrics/MethodLength

Public Class Methods

new(evaler, context, reader: Reader) click to toggle source

It creates a new {Context} that uses one given as a parameter to this contructor to evaluate expressions typed in the REPL.

@param evaler [Evaler] used to extract value from expressions @param context [Context] against which expressions will be evaled @param reader [Reader] to return expressions to be evaled

# File lib/campa/repl.rb, line 10
def initialize(evaler, context, reader: Reader)
  @reader = reader
  @evaler = evaler
  @context = context
  @environment = @context.push(Context.new)
  @printer = Printer.new
end

Public Instance Methods

run(input, output) click to toggle source

Uses the #getc method from the parameter input to create a (probably blocking) loop to evaluate code “live” creating a REPL session.

Captures the Interrupt exception to break the loop and finish the current REPL session.

@param input [IO] an IO like object from where tokens will be extracted @param output [IO] IO like object to receive the output

from evaluating the forms

rubocop: disable Metrics/MethodLength

# File lib/campa/repl.rb, line 30
def run(input, output)
  output.print "=> "
  reader = @reader.new(input)

  loop do
    begin
      token = reader.next
      break if token.nil?

      show(output, evaler.call(token, environment))
    rescue ExecutionError => e
      handle_exec_error(output, e)
    rescue StandardError => e
      handle_standard_error(output, e)
    end

    output.print "=> "
  end
rescue Interrupt
  output.puts "see you soon"
end

Private Instance Methods

back_trace_to_s(exception) click to toggle source
# File lib/campa/repl.rb, line 85
def back_trace_to_s(exception)
  exception
    .backtrace[0..10]
    .push("...")
    .map { |s| "    #{s}" }
    .join("\n")
end
handle_exec_error(output, exception) click to toggle source
# File lib/campa/repl.rb, line 66
def handle_exec_error(output, exception)
  [
    "Execution Error: #{exception.class}",
    "  message: #{exception.message}",
    "  >> Runtime details:",
    back_trace_to_s(exception),
  ].each { |str| output.puts str }
end
handle_standard_error(output, exception) click to toggle source
# File lib/campa/repl.rb, line 75
def handle_standard_error(output, exception)
  [
    "FATAL!",
    "Exeception error was raised at Runtime level",
    "Runtime Error: #{exception.class}",
    "  message: #{exception.message}",
    back_trace_to_s(exception),
  ].each { |str| output.puts str }
end
show(output, result) click to toggle source
# File lib/campa/repl.rb, line 57
def show(output, result)
  output
    .puts(
      printer.call(
        result
      )
    )
end