Write a base Graph class that does some parsing of expressions.

fx/src/main/kotlin/org/nwapw/abacus/fx/graphing/Graph.kt

@@ -0,0 +1,33 @@
+package org.nwapw.abacus.fx.graphing
+
+import org.nwapw.abacus.Abacus
+import org.nwapw.abacus.config.Configuration
+import org.nwapw.abacus.number.NaiveNumber
+import org.nwapw.abacus.number.NumberInterface
+import org.nwapw.abacus.plugin.StandardPlugin
+import org.nwapw.abacus.tree.TreeNode
+
+class Graph(val abacus: Abacus,
+            expression: String, pointExpression: String,
+            var domain: ClosedRange<NumberInterface>, var range: ClosedRange<NumberInterface>,
+            var inputVariable: String = "x", var pointInputVariable: String = "n") {
+
+    private var expressionTree: TreeNode? = null
+    private var pointExpressionTree: TreeNode? = null
+
+    var expression: String = ""
+        set(value) {
+            expressionTree = abacus.parseString(value)
+            field = value
+        }
+    var pointExpression: String = ""
+        set(value) {
+            pointExpressionTree = abacus.parseString(value)
+            field = value
+        }
+
+    init {
+        this.expression = expression
+        this.pointExpression = pointExpression
+    }
+}