EZGraphs

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EZGraphs

• A graphs and charts generating language

Vincent Dobrev vd2006_at_columbia.edu Edlira
Kumbarce ek2248_at_columbia.edu
COMS W4115 Programming Languages and
Translators Spring 2007
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Introduction

• Why graphs?
• Graphs are used widely. They communicate
  information more easily and efficiently than
  words or tables.
• Objective
• Provide a language that can be used to create
  charts and graphs, targeting those with a little
  prior programming experience.

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Features

• User-Friendly Syntax
• Very similar to C and Java. Intuitive keywords
  and internal function names. More organized than
  Ploticus.
• Easy Debugging
• Non-cryptic and informative error messages make
  it easy to use and debug. User given exact
  location of error with file name and line and
  column numbers.

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Features (contd)

• Portability
• Based on Java, so it only depends on the
  presence of the Java Runtime Environment.
• Data Types Operators
• Supports boolean, integer, floating-point, and
  string data types, as well as multi-dimensional
  arrays.

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Features (contd)

• File Inclusion
• Allows code reuse and modularity. More organized
  programs.
• Control Flow Statements
• Supports conditionals (if-then-else) and
  iterative statements (loops), which in turn
  enable user to create recursive functions.

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Features (contd)

• Pre-Defined Functions
• Drawing point(), line(), polygon(), etc.
• Transfromation translate(), scale(), shear()
  etc.
• Data Acquiring data()
• Math exp(), log(), pow(), sqrt(), etc.
• Auxiliary strToInt(), strToFloat(), substring(),
  size(), etc.
• Output print(), println() , save(), show()

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Example 1 - Recursion
/ Sierpinski Triangle. / void main()
canvas(600, 600) scale(1, -1)
translate(0, -600) triangles(50, 50, 550,
50, 300, 550, 1) show() void
triangles(int x1, int y1, int x2, int y2,
int x3, int y3, int level) line(x1, y1, x2,
y2) line(x2, y2, x3, y3) line(x3, y3,
x1, y1) int xp1 (x2x1) / 2 int yp1
(y2y1) / 2 int xp2 (x3x2) / 2 int
yp2 (y3y2) / 2 int xp3 (x1x3) / 2
int yp3 (y1y3) / 2 if (level lt 8)
triangles(x1, y1, xp1, yp1, xp3, yp3,
level1) triangles(xp1, yp1, x2, y2,
xp2, yp2, level1) triangles(xp3, yp3,
xp2, yp2, x3, y3, level1)
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Example 2 - A Pie Chart
/ A pie chart illustrating distribution of
income. / void main() int fields 7
/ Colors. / int c new
intfields3 c00 255 c01 50
c02 0 c10 0 c11 255
c12 0 ... c60 255
c61 255 c62 0 / Labels. /
string l new stringfields l0
"Savings" l1 "Insurance" ...
l6 "Housing" / Percentages. /
int p new intfields p0 9 p1
11 ... p6 21 ...
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Example 2 - A Pie Chart (contd)
canvas(400,400) background(244,244,244)
string title "Income Distribution"
font("Arial", 0, 20) int width
width(title) text(title, 200 - width/2,
40) stroke(2) line(50,50,350,50)
translate(100,100) int start 0, end 0
for (int i 0 i lt fields i)
color(ci0,ci1,ci2) start
end end pi 360 / 100
fillArc(0,0,200,200,start,end)
show()
Output
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Language Implementation

• The source code is parsed and executed right away
  with no intermediate code.
• Programs reside in .ezg files, with one file
  containing a main() function and any number of
  other .ezg files containing other functions.

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Language Implementation (contd)

• Three types of output
• Text in the console
• An image in a window on-screen
• An image in a file
• Exception handling mechanism catches, formats,
• and prints out error messages for the user.
• Examples
• Error draw.ezg4810 expecting ID, found '
• Error draw.ezg596 unexpected data type being
  assigned to array
• Error recursion.ezg55 function fact(int)
  expected to return int
• Error recursion.ezg716 variable g not declared

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Architecture
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Interpreter Structure
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Type System
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Type Conversions Operators
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Type Conversions Operators (contd)