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LegoLang

-----------------------------------------------------------

                          By Gerard Canal Camprodon
                          &  Siegfried-A. Gevatter Pujals

                          Spring 2012 - FIB / BarcelonaTech

-----------------------------------------------------------

INTRODUCTION

 LegoLang is a simple programming language for NXT 2.0 Lego
 Mindstorms running Lejos (Java for LEGO Mindstorms).

 LegoLang's syntax is inspired by Python, but it features
 static typing (with coercion) and lexical scoping.

 **********************************************************
 NOTE: LegoLang was a university project for our Compilers
       course and is no longer maintained.
 **********************************************************

-----------------------------------------------------------

STRUCTURE

 The following example illustrates the structure of a
 LegoLang program:

  default light S1
  default ultrasonic S2
  // supported sensor types: ultrasonic, light & touch

  global int speed = 500

  print "Hi!"
  move_forward()

  def move_forward():
      setLamp(GREEN)
      move(speed, motorA); move(speed, motorB)

  on signal escape_button_pressed:
      abort()

  on signal onRange40:
      // There's an obstacle, avoid it
      setLamp(RED)

      if random(0, 1):
          move(300, motorA); move(-300, motorB)
      else:
          move(-300, motorA); move(300, motorB)
      while rangeScan(40) != -1:
          /* wait until we've turned enough to avoid
             the obstacle */
          pass
      move_forward()

  while true:
      pass

 The program starts with a defaults declaration section,
 followed by a global variable section. After that, the
 main code block follows.
 
 Code blocks are executed in sequential order, and may
 contain function (or signal) declarations in any place
 (predeclarations aren't necessary - nor supported).

 As you can see, blocks are indented by either exactly 1
 tab or 4 spaces.

 Functions can be nested, and will be visible in sister
 and child functions. Variables are only visible in the
 block where they are declared (with the exception of
 global variables, which are visible everywhere).

-----------------------------------------------------------

TYPES

 - string                   - color
 - int                      - sensor
 - float                    - motor
 - bool                     - button

 Arrays of all basic types are supported. Their syntax is
 as follows:
  int[] numbers = int[21, 42]
  print "The array has has " + #numbers + " elements."
  print "The first element is: " + numbers[0]
  print "The entire array looks liek this: " + numbers

 The sensor, motor and button variables must take one of
 the following values:
  sensor: S1, S2, S3, S4
  motor: motorA, motorB, motorC
  button: ENTER, LEFT, RIGHT, ESCAPE
 
 The following colors are predefined: RED, GREEN, BLUE, WHITE and
 BLACK. Other colors can be specified in hexadecimal format (eg.
 #123456 or #ccc).

-----------------------------------------------------------

INSTRUCTIONS

 LOOPS

  while <expr>:
      <body>
 
  for <variable> in <start> .. <end>:
      <body>
 
  foreach <variable> in <array>:
      <body>

  break (inside while, for or foreach loops)

  pass (do nothing)

 CONDITIONALS

  if <expr>:
      <body-if>
  else if <expr>:
      <body-else-if>
  else:
      <body-else>

 FUNCTIONS

  def <name> (<parameters>) [returns <type>]:
      <body>

 SIGNALS

  on signal <name>:
      <body>

  The signal name may be any of the following:
  {any,enter,left,right,escape}_button_pressed,
  onTouch or onRange[<dist>].

  If the signal type is onRange, a special variable named
  `signal_data' will be available, containing the distance
  to the detected object.

 OTHER INSTRUCTIONS

  ↑<variable>, <variable>↑
  pre- and post-increment

  ↓<variable>, <variable>↓
  pre- and post-decrement

  print <expression> [at [<X>,] <Y>]
 
 STANDARD LIBRARY

  LegoLang includes a standard library with functions
  wrapping some of the most important functionalities
  in Lejos.

-----------------------------------------------------------

USAGE EXAMPLES

 $ ./bin/llcc -h
 usage: llcc [options] 
  -C,--code		don't delete the generated code
  -d,--debug		create debugging file (.nxd)
  -h,--help		show this message
  -o,--output-file		output file
  -q,--quiet		don't show any output on success
  -R,--restricted		build into a standard .jar (for testing purposes)
  -S,--source-only	only generate code (don't build)
  -U,--upload-only	upload program (doesn't generate .nxj)
  -u,--upload		upload program
  -v,--verbose		show debugging information

 $ ./bin/llcc -R examples/fibonacci.ll
 Code written.
 Code compiled.
 Program built into fibonacci.jar.

 $ java -jar fibonacci.jar
 1
 1
 2
 3
 5
 [...]

-----------------------------------------------------------

LICENSE

 All code (other than the external dependencies in libs/) is
 released under the ISC License:

 Permission to use, copy, modify, and/or distribute this software for
 any purpose with or without fee is hereby granted, provided that the
 above copyright notice and this permission notice appear in all copies.

 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.