feat: add getSimplified to expr class

exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/Expression.kt

@@ -21,6 +21,7 @@ sealed class Expression : Number() {
     // abstract operator fun div(other: Expression): Expression
 
     abstract fun toTerm(): Term
+    abstract fun getSimplified(): Expression
 
     companion object {
         val ZERO: Expression = SimpleExpression(Term.ZERO)

exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/AdditiveExpression.kt

@@ -50,6 +50,8 @@ internal class AdditiveExpression private constructor(private val expressions: C
 
     // TODO
     override fun getValue(): BigDecimal = BigDecimal.ZERO
+    // TODO
+    override fun getSimplified(): Expression = this
 
     override fun hashCode(): Int = createHashCode(listOf(expressions, "AdditiveExpression"))
 

exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/MultiplicativeExpression.kt

@@ -48,7 +48,7 @@ internal class MultiplicativeExpression private constructor(expressions: ConstMu
         }
     }
 
-    fun getSimplified(): Expression = SimpleExpression(toTerm())
+    override fun getSimplified(): Expression = SimpleExpression(toTerm())
     override fun getValue(): BigDecimal = getSimplified().getValue()
 
     override fun hashCode(): Int = createHashCode(listOf(expressions, "MultiplicativeExpression"))

exact-numbers/src/main/kotlin/xyz/lbres/exactnumbers/expressions/expression/SimpleExpression.kt

@@ -19,7 +19,7 @@ internal class SimpleExpression(private val term: Term) : ExpressionImpl() {
     override fun inverse(): Expression = SimpleExpression(term.inverse())
 
     override fun toTerm(): Term = term
-    fun getSimplified(): Expression = getOrSet({ simplified }, { simplified = it }) { SimpleExpression(term.getSimplified()) }
+    override fun getSimplified(): Expression = getOrSet({ simplified }, { simplified = it }) { SimpleExpression(term.getSimplified()) }
     override fun getValue(): BigDecimal = term.getValue()
 
     override fun hashCode(): Int = createHashCode(listOf(term, "Expression"))