Programming Languages and Translators

1
CHAD

• Programming Languages and Translators
• Prof. Stephen Edwards, Fall 2003
• Team Members
• Haronil Estevez Diana Jackson Catherine
  MacInnes Adam Rosenzweig

2
CHAD Overview

• An interpreted language
• Interpreter creates a graphical display of the
  program
• 5 native data types
• Integers
• Strings
• Arrays
• Queues
• Stacks
• Types have native operations
• Used to implement most algorithms

3
CHAD Motivation

• Graphic representations are a very powerful
  teaching tool
• Teachers don't want to spend a lot of time coding
  an algorithm just so that their students can see
  what is going on
• There are no current languages which make it
  easy to graphically represent algorithms
• In CHAD you can write a graphical representation
  of simple algorithms in less than 15min.

4
CHAD Tutorial

• Program Order/Structure Declarations,
  Expressions, Functions
• Declarations terminate in semicolon
• Control Statements end in an end keyword for
  appropriate type (e.g. if/endif, else/endelse,
  for/endfor)
• Most CHAD Types have the same syntactical
  structure and typical operations as the most
  common languages
• Supports comments (// / /)

5
CHAD Tutorial

• Integers Typical Operations
  (add,multiply,mod,compare)
• Functions Min(a,b)
  and Max(a,b)
• Strings Operations (assignment ,
  concatenation , comparison)
• Arrays Syntax arrayintstring, size a
• Functions
  a.sortAZ(begin, end), a.sortZA(begin, end),
  a.swap(i,j)
• Queues Syntax queueintstring q
• Functions
  q.enqueue(1) q.dequeue()
• Stacks Syntax stackintstring s
• Functions
  s.push(string) s.pop()
• Functions Syntax
• function
  return type functionName(parameters)
• Body
  of Declarations
• Body
  of Expressions
• 
  Return statement
• 
  endfunction

6
CHAD Tutorial

• Insertion Sort
• Primary Focus(red), Secondary Focus(green)
  handled by Interpreter
• Detailed description/explanation in final report

7
CHAD Implementation

• Lexer (CHADLexer) and Parser (CHADParser) written
  in ANTLR
• Two tree walkers implemented with ANTRL
• StaticCHADWalker performs static semantics
  analysis
• CHADWalker the interpreter

• CHADType class stores built-in types/data
  structures
• CHADType object used by interpreter to evaluate
  binary operations and execute built-in functions

8
CHAD Implementation

• CHAD GUI written with Java Swing and gives users
  the ability to load/run CHAD programs
• GUI uses CHADParser to detect parser errors and
  StaticCHADWalker to perform static semantics
  analysis before allowing user to run CHAD program

• GUI's "Step" button triggers use of CHADWalker to
  step through execution of the program one step at
  a time
• GUI's Run" button triggers use of CHADWalker to
  run through execution of entire program
• GUI only displays data structures that are marked
  "visible" by the interpreter

9
CHAD Summary

• Simple language to implement basic algorithms
  with familiar syntax
• Automatic animations of algorithms
• Excellent instructional tool

10
CHAD Future Paths

• More basic data structures implemented
• Linked lists
• Trees
• Graphs, etc.
• Enhanced simulator functionality
• Variable timed run steps
• More code-control over displayed variables

11
CHAD Lessons Learned

• Multiple paths to all goals
• Every time you think about it, youll find
  something else you didnt handle yet
• So, start early and stay ahead
• Keep all members up to date on each aspect of
  project (especially if its a part theyre not
  working on)
• Provide more descriptive error messages -gt easier
  to debug