Welcome to the Elagin Compiler Project

This project is developed during a practical course about compiler development at ITMO University.

Build

./gradlew build

Compile .elg program

java -jar build/libs/compiler-all-1.0.jar Example.elg

Run

java -cp target ElaginProgram 

Language Definition

This is simple jvm-based language with classes support

Types:

• int
• boolean
• void
• classType

Operations:

• arithmetic operations (+,-, /, *, %)
• logical Operations (&&, ||, ==, !=, >, <, >=, <=)

Statements

• block
• conditional (if-else)
• while
• read\print
• variable/Method declaration
• assignments
• return

Classes

• multiple constructors
• private\public fields
• private\public methods
• class inheritance
• super call

Tailrec optimization

• simple tailrec optimization
• accumulator detection

Examples

Functions

/* 
 * simple factorial program
 * with read and some value checks
*/
fun main() {
    var n: int = 1000
    read(n)
    var factorialOfN = fact(n)

    if (n < 7) {
        while(factorialOfN < 1000) {
            n = n + 1
            factorialOfN = fact(n)
        }
    }
    print(n)
}


fun fact(n: int) : int {
    if (n == 1) return 1
    else return n * fact(n - 1)
}

Classes

class Value { 
  private var value: int
  
  constructor(value: int) { 
    this.value = value 
  }
  
  fun getValue() : int { return value }
}


class ValueWithSqr : Value {
    constructor(value: int) { super(value) }
    
    fun getSqr() : int { 
        return getValue() * getValue()
    }
}   
 
class Printer {
    fun printValue(value: ValueWithSqr) {  print(value.getSqr()) }
}

fun main() {
    var value = new ValueWithSqr(10)
    var sqrPrinter = new Printer()
    sqrPrinter.printValue(value)
}

tailrec functions

tailrec fun fact(n: int) : int {
    if (n == 1) return 1
    else return n * fact(n - 1)
}

fun main() {
    print(fact(5))
}