Graphical Slogo Interpreter

This project implements a development environment that helps users write SLogo programs.

Creators: Alex Xu, Amjad Syedibrahim, Max Smith, Grant LoPresti

Timeline

Start Date: 2/13/2020

Finish Date: 3/7/2020

Hours Spent: 200 Hours Total

Primary Roles

Alex Xu:

• Wrote code for the model package (ModelObjects, Turtles, Pens, ModelCollection, etc .), codefilters package for code preprocessing, and worked on the LogicalController and Parser design, as well as creating the command objects, variable objects, and certain exceptions. Started but did not complete XML writing/saving/validation (save workspace functionality) as more work was needed elsewhere.

Amjad Syedibrahim:

• Wrote code for the various functionalities of the Parser's basic implementation. Wrote helper methods in UserInput class to deal with proper creation of command variables. Implemented controlFlowExtractor utility class, worked on user-defined commands and control flow structures.

Max Smith:

• Wrote code for the visualController, implemented and designed the latest iteration of the Parser, redesigned Command object hierarchy and interfaces, wrote exceptions to improve error handling, implemented and designed and multiple turtles.

Grant LoPresti:

• Created the front-end design and implementation of the GUI in the SLogo program. Worked to add splash screen, main screen with CSS implementation, tabs, a tab factory, multiple turtle visualization, movable/changeable tabs, color pickers, a dark mode, and the framework for items that were inevitably and unfortunately not implemented, such as line color and turtle activation.

Resources Used

• Oracle Java Online Documentation
• Computer Science 308 Course Website, Piazza, and Readings
• StackOverflow postings

Running the Program

Main class: Main.java

Data files needed:

• All files in /parser_team10/resources, including /images/, /languages/, and /stylesheets/
• All files in src/properties

Features implemented:

Basic

Front End

• Enter commands to interact with turtle
• See results visually
• See errors from backend (command generation)
• Set background color for display area
• Set image for turtle
• See commands previously run in environment
• Choose language available in environment
• Access help about available commands

Back End

• Recognize basic slogo commands (all in some capacity)
• Throw errors from incorrectly entered commands (formatted)

Complete

Front End

• Current state of turtle (ID, heading, pen state, etc.)
• Palettes of images and colors to select (via GUI, not command)
• Click to execute commands from history
• Move current turtle(s) graphically by fixed amount
• Create multiple, independent workspaces through splash screen
• Preferences for workspaces, setting defaults through splash screen
• Animations on turtles as command executes

Back End

• Additional commands - infrastructure for extensibility (e.g. tell works)
• Support for multiple turtles
• Future expandability to include infinite parameters and recursion

Notes/Assumptions

Assumptions or Simplifications:

• Assumed that user input would be space separated
• Assumed that for the program to have the desired effects, the SLogo syntax will be followed
• Assumption that control flow statements (for, repeat) have brackets on the first line
• Assumed that errors could be combined into a single error for user display (e.g. all reflection exceptions get packaged into one exception)

Interesting data files:

• See data/examples/interesting

Known Bugs:

• Any command that does not cause an error will be displayed as a user input (e.g. blah blah, however these do not get executed)
• Variables can be created, but not used (part of parsing design)

Extra credit:

• slogo/logicalcontroller/codefilters package to "massage" data before parsing (with toggleable filters through properties file)
  • This feature is modular and data-driven, where a user an toggle these filters on or off. This is essentially a "syntax corrector" that makes the program more forgiving to user-errors (and enables the Parser's algorithm to look for new forms of syntax)
• Toggleable DarkMode in view to change style sheet of whole page

Impressions

• Designing the parsing algorithm was a challenge for this project
• Interesting to see how data-driven design and design patterns can be used to create a program that evaluates another "programming language".
• Late night, pair programming sessions were surprisingly productive, many benefits (accountability, perspective, motivation) seen in group programming sessions from design and implementation perspective.
• Design emphasis in the beginning definitely payed off in the end
• EVERYTHING is a tradeoff, cannot be open to everything, must evaluate pros and cons of each decision and decide on the "best" and/or "least bad" option.