Started graph builder

src/formula/node/graph_builder.rs

@@ -0,0 +1,24 @@
+use crate::formula::node::Node;
+
+pub struct GraphBuilder(Node);
+
+impl GraphBuilder {
+    pub fn from_hash_maps(mut self) -> GraphBuilder {
+        self
+    }
+    /// Path format: /index0/index1/index2/.../indexn
+    /// For example: /0/1/0/0/1
+    /// The reason for unreadable format is because graph builder, as I ended up realising, doesn't need to be used.
+    pub fn add_at_path(mut self, path: String, func: fn(Vec<f64>) -> f64) -> GraphBuilder {
+        let mut node_lookup = self.0;
+        for i in path.split("/").map(str::parse::<i64>) {
+            if let Ok(index) = i {
+                node_lookup = node_lookup.children[index];
+            }
+        }
+        self
+    }
+    pub fn finish(self) -> Node {
+        self.0
+    }
+}

src/formula/node/graph_constructor.rs

@@ -1 +0,0 @@
-pub struct GraphBuilder;

src/formula/node/graph_modifier.rs

@@ -0,0 +1 @@
+struct GraphModifier;

src/formula/node/mod.rs

@@ -1,6 +1,7 @@
-use crate::formula::node::graph_constructor::GraphBuilder;
+use crate::formula::node::graph_builder::GraphBuilder;
 
-mod graph_constructor;
+mod graph_builder;
+mod graph_modifier;
 
 pub struct Node {
     children: Vec<Node>,