PLT Final Project---COLOGO

1. PLT Final Project---COLOGO Lixing Dong, Zhou Ma, Chao Song, Siyuan Lu, Dongyang Jiang

2. Overview of COLOGO • Columbia LOGO • Motivation: For educational use • 1. an effective programming language for drawing 2D graphics • 2. designed in spirit of low threshold, easily implemented.

3. Function Feature • Euclidean Pictures • Creating Functions • Recursive • Iridescent • Simple Data Structure such as Array. • Support direct HTML and Javascript Output

4. COLOGOVS. LOGO • Colorful • Compile together • No list

5. Language Tutorial

6. Some examples of our program • Fibonacci • Recursive

7. Some examples of our program • Olympic Rings (faked)

8. Some examples of our program • Rainbow

9. Language Tutorial • Variable Declaration • Inta,b; • Bool c; • foo d; (:foo is a object:) • Int e[10]; (:array:)

10. Language Tutorial • Expression • Assignment: a = 1; c = True; • Arithmetic Expression: a = b + a; • Comparison Expression: c = a < b; • Logical Expression: c = (a == b); Not c; • Function call: a = testfunc(b); • Comment: (:This is a comment:)

11. Language Tutorial • Loop • Loop(10) { a = a + 1; } • Loop(10) { a = a + 1; Break; } • Loop(10) { a = a + 1; Goon;}

12. Language Tutorial • Condition • If (c) { a = b; } End • If (c) { a = b; } Else { b = a; } End

13. Language Tutorial • Jump • If (c) { a = b; } End • If (c) { a = b; } Else { b = a; } End

14. Language Tutorial • Draw • Move Forward: FD 10; • Move Backward: BK 10; • Turn Left: LF 90; • Turn Right: RT 90;

15. Language Tutorial • Draw • Reset position: RESET; • Clear Screen: CLS; • Pen Operation: PU; PD; PF; • Line Width: WD 10; • Set Line Color: RGB 255, a, e[2]

16. Language Tutorial • Function • Declaration: • Functestfunc(int n) : int { Return n;} • Call: • a = testfunc(b);

17. Language Tutorial • Object • Definition: • Obj foo { int bar; int baz;} • Declaration: • foo d; • Reference: dot operator • d.bar = a; b = d.baz;

18. Implementation

19. Layout

20. Flow Ast:  Abstract Syntax Tree Types Definition   One Rule -> One Type Constructor

21. Flow Scanner:  Generate Tokens Parser: Generate AST Use Type Constructor Defined in AST

22. Flow Scanner:  Generate Tokens Parser: Generate AST  Use Type Constructor Defined in AST Basic Error Recovery

23. Flow Semantic:  Traversal of  AST, Checking Variables, Function Definitions, Type Matching, etc. Generator: Traversal of AST, Generate JS code in HTML file Printer: Traverse and print the AST 

24. Flow Semantic:  Traversal of  AST,  Checking Variables , Redefinition Type Matching: Array Object Function Matching  Parameter Count, Argument Type Return Type Definition Scope Stack faked by List Small Features: infinite loop 

25. Flow Generator: Traversal of AST Generate JS Code in HTML5 file Draw Statement Array in Obj 

26. Flow

27. SUMMARY • Further to develop • Lessons learned