Nikolaos Iliopoulos 1115201800332

Compilers 1

Part1

Use the command make to clean, compile and execute the code.

There are many comments in the code that explain everything.

Grammar

goal -> term exp

exp -> '+' term exp
     | '-' term exp
     | e 

term -> number termTail

termTail -> '*' '*' number termTail
          | e

number -> digit numTail
        | '(' term exp ')'

numTail -> number
         | e

digit -> '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'

In order have precedence for **. I always first check for ** and if the lookahead dont match i go and look for + and -. I achieve this in the term where i always have a termTail after a number. termTail is looking for ** and then is calling expr that is looking for + and -.

I took this logic from the presentations

I treat the () as a number because eventually the () will be evaluated in a number if everything is fine inside them.

In order to have multidigit number i use the logic of the numTail. I made number type of String in my code and the single digits are beeing concatenated with each other and in the end the number is a long String that is beeing parsed into an Integer to make the +, - and ** operations.

Part2

Use the command make to clean, compile, execute the parser and at the end the output Java code will execute.

I have made in the jflex those macros.

• If = (if){WhiteSpace}*[(]

finds an if with any space beetween that ends with (

• Variable = [a-zA-Z][a-zA-Z0-9]*

finds a variable

• Function = {Variable}{WhiteSpace}*[(]

finds a variable with any space beetween that ends (

In the cup all the functions declarations must be before any calls.

Arguments

I have separate the cases where the arguments of an function are valid.

• for the arguments in the declarations of a function can be only variables.
• inside a functions body there can be variables, Strings, function call and an IF as arguments of an function call.
• functions calls in the main can have as arguments Strings, function call and IF.

IF

• An IF can have as operator only a prefix or a suffix.
• Inside an IF can be another IF.

Prefix Suffix

• a prefix b == b.startsWith(a)

• a suffix b == b.endsWith(a)

• left or right from prefix or suffix can be everything that is a string.