plt final project---cologo

PLT Final Project---COLOGO

Lixing Dong, Zhou Ma, Chao Song, Siyuan Lu, Dongyang Jiang

Overview of COLOGO

Columbia LOGOMotivation: For educational use

1. an effective programming language for drawing 2D graphics2. designed in spirit of low threshold, easily implemented.

Function Feature

Euclidean PicturesCreating FunctionsRecursiveIridescentSimple Data Structure such as Array.Support direct HTML and Javascript Output

COLOGO VS. LOGO

ColorfulCompile togetherNo 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 ASTUse Type Constructor Defined in AST

FlowScanner:  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