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

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.

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

COLOGO VS. LOGO Colorful Compile together No list

Language Tutorial

Some examples of our program Fibonacci Recursive

Some examples of our program Olympic Rings (faked)

Rainbow Some examples of our program

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

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:)

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

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

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

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

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]

Language Tutorial Function Declaration: Func testfunc(int n) : int { Return n;} Call: a = testfunc(b);

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

Implementation

Layout

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

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

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

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

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

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

Flow

SUMMARY Further to develop Lessons learned