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CMSC 431- Assignment 1

Summer 2004

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Assignment 1

For programming Assignment 1 Part 1 you need to write recursive descent parser / evaluator for the following grammar:

A  -> VARIABLE "=" A | E | EVAL VARIABLE
E  -> “+” E T | “-'” E T | T
T  -> “*” T F | "/" T F | F
F->  EXP “(“ F G “)” | G
G  -> VARIABLE | DOUBLE | “(“ E “)“ | [ INVERSE] TRIG “(“ E “)“ 
  |  rads “(“ E “)” | 
TRIG -> “cos'”| “sin'”| "tan"
INVERSE -> “arc”
EVAL -> “eval”
 

• Assume "+"/ "-" means regular double precision addition/subtraction ,
• Assume "*"  means double precision multiplication
• Assume "/ " means double precision division - don't assume that the denominator is non-zero.
• Assume "^ " means double precision exponentiation
• Assume  Trig operators have their natural meaning and take arguments expressed in radians , and  rads(degrees) converts a double precision degree value to radians.
• Assume a DOUBLE is any valid double  as defined by Java
• A VARIABLE is any string viable variable name in Java and can't be "cos" , "sin" , "rads" , etc

• References to unassigned variables should not generate an error.
• The action associated with A is to print to standard out the value of the expression, if the value of the expression can be computed. If the value can not be computed, print out a symbolic (algebraic) representation as discussed in class.

• Remember that you must build the parse tree first before any semantic actions
• Use JLex  for lexical analysis

Assignment 2

Repeat assignment using javacc for the parser and lexer.

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What You Should Hand In (and when)

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1. Your program - Assignments 1and 2 (h/c)
1. should be well documented
2. should include comments at the top that give the EBNF and a brief explanation of the technique
2. A sample run of your program generated from my input  (h/c)
3. In addition to the hardcopy to be turned in for this first project you need to mail me the following as attachments

•  For 1.1 with subject line "CSMC431 SU04 P1” to spam@nospam.umbc.edu by August 9
•  For 1.2 with subject line "CSMC431 SU04 P2” to spam@nospam.cs.umbc.edu by August 18

1. Your source code file(s) as a jar file
2. A README file that explains how to build and run the executable

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Notes

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Implementation Details

1. Your implementation must be in Java and use JLex and javacc

Input data

Sample data will be posted the week of 26 July.

( Note that there can be more than one expression per line and more than one line per expression, tokens don't span lines.

Due Dates, etc

1. Due Dates- see above
2. You may work in group of up to two.

2. NO LATE PROGRAMS WILL BE ACCEPTED under any circumstance without written approval.
3. Any student caught cheating will receive a zero!

If you have any questions mail me.

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