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deepakkumarnd/evaluate.ts

Created September 22, 2022 13:04
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  1. deepakkumarnd created this gist Sep 22, 2022.
    82 changes: 82 additions & 0 deletions evaluate.ts
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,82 @@

    interface Expression {
    evaluate(): number
    }

    type UnaryOperator = "+" | "-"
    type BinaryOperator = "+" | "-" | "*" | "/" | "^"

    class Value implements Expression {
    readonly value: number

    constructor(value: number) {
    this.value = value
    }

    evaluate(): number {
    return this.value
    }
    }

    class UnaryExpression implements Expression {
    readonly operator: UnaryOperator
    readonly operand: Expression

    constructor(operator: UnaryOperator, operand: Expression) {
    this.operator = operator
    this.operand = operand
    }

    evaluate(): number {
    const value = this.operand.evaluate()
    if (this.operator === "-") return (-1 * value)
    else return value
    }
    }

    class BinaryExpression implements Expression {
    readonly operator: BinaryOperator
    readonly left: Expression
    readonly right: Expression

    constructor(operator: BinaryOperator, left: Expression, right: Expression) {
    this.operator = operator
    this.left = left
    this.right = right
    }

    evaluate(): number {
    const leftV = this.left.evaluate()
    const rightV = this.right.evaluate()

    if (this.operator === "+") return (leftV + rightV)
    else if (this.operator === "-") return (leftV - rightV)
    else if (this.operator === "*") return (leftV * rightV)
    else if (this.operator === "^") return (leftV ** rightV)
    else {
    if (rightV === 0) throw new Error("Division by zero error")
    else return (leftV / rightV)
    }
    }
    }


    const e1 = new UnaryExpression("+", new Value(10))
    const e2 = new UnaryExpression("-", new Value(20.1))

    console.log(e1.evaluate() === 10)
    console.log(e2.evaluate() === -20.1)

    const e3 = new BinaryExpression("+", new Value(2), new Value(3))
    const e4 = new BinaryExpression("-", new Value(2), new Value(3))
    const e5 = new BinaryExpression("*", new Value(2), new Value(3))
    const e6 = new BinaryExpression("/", new Value(2), new Value(3))
    const e7 = new BinaryExpression("^", new Value(2), new Value(8))
    const e8 = new BinaryExpression("/", new Value(2), new Value(0))

    console.log(e3.evaluate())
    console.log(e4.evaluate())
    console.log(e5.evaluate())
    console.log(e6.evaluate())
    console.log(e7.evaluate())
    console.log(e8.evaluate())