diff --git a/src/gui.rs b/src/gui.rs
new file mode 100644
index 0000000..5fd2a9a
--- /dev/null
+++ b/src/gui.rs
@@ -0,0 +1,63 @@
+use imgui::{TableFlags, Ui};
+use thousands::Separable;
+use crate::state::{State, Variable};
+
+pub fn draw_main_menu_bar(state: &mut State, ui: &Ui) {
+    if let Some(t) = ui.begin_main_menu_bar() {
+        if ui.menu_item("Clear") {
+            *state = State::default();
+        }
+        if ui.menu_item("Open") {
+            if let Some(f) = rfd::FileDialog::new().add_filter("json", &["json"]).pick_file() {
+                let data =  std::fs::read_to_string(f).unwrap_or("}{".to_string());
+                let vars: Result<Vec<Variable>, _> = serde_json::from_str(&data);
+                match vars {
+                    Ok(v) => {
+                        *state = State::default();
+                        state.variables = v;
+                        state.eval_vars();
+                    },
+                    Err(e) => println!("Error while loading:\n{:#?}", e)
+                }
+            }
+        }
+        if ui.menu_item("Save") {
+            if let Some(f) = rfd::FileDialog::new().add_filter("json", &["json"]).save_file() {
+                if let Err(e) = std::fs::write(f, serde_json::to_string(&state.variables).unwrap()) {
+                    println!("Error while saving:\n{:#?}", e);
+                }
+            }
+        }
+        t.end();
+    }
+}
+
+pub fn draw_table(state: &mut State, ui: &Ui) {
+    if let Some(t) = ui.begin_table_with_flags("VariableTable", 4, TableFlags::BORDERS | TableFlags::ROW_BG | TableFlags::RESIZABLE) {
+        ui.table_setup_column("Name");
+        ui.table_setup_column("Value");
+        ui.table_setup_column("Expression");
+        ui.table_setup_column("Actions");
+        ui.table_headers_row();
+
+        let mut to_remove = vec![];
+        for v in &state.variables {
+            ui.table_next_row();
+            ui.table_next_column();
+            ui.text(&v.name);
+            ui.table_next_column();
+            ui.text(v.value.map_or("-".to_string(), |v| v.separate_with_spaces()));
+            ui.table_next_column();
+            ui.text(&v.expr);
+            ui.table_next_column();
+            if ui.button(format!("Remove##{}", v.name)) {
+                to_remove.push(v.name.clone());
+            }
+        }
+        if !to_remove.is_empty() {
+            state.variables.retain(|v| !to_remove.contains(&v.name));
+            state.eval_vars();
+        }
+        t.end();
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 69c31eb..f5c333f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,136 +1,16 @@
 mod parser;
+mod gui;
+mod state;
 
 use glium::Surface;
-use imgui::{Condition, Context, FocusedWidget, TableFlags, Ui, WindowFlags};
+use imgui::{Condition, Context, FocusedWidget, Ui, WindowFlags};
 use lalrpop_util::lalrpop_mod;
-use thousands::Separable;
-use crate::parser::Node;
+use crate::state::State;
 
 lalrpop_mod!(grammar);
 
-#[derive(Debug, serde::Deserialize, serde::Serialize)]
-struct Variable {
-    name: String,
-    expr: String,
-
-    #[serde(skip)]
-    value: Option<f64>,
-
-    parsed_expr: Node,
-    used: Vec<String>
-}
-
-#[derive(Debug, Default)]
-struct State {
-    inputs: Vec<String>,
-    input_buf: String,
-    error_msg: Option<String>,
-    variables: Vec<Variable>,
-    last_eval: Option<std::time::Duration>
-}
-
-fn eval_vars(state: &mut State) {
-    let start = std::time::Instant::now();
-
-    let var_map = state.variables.iter()
-        .map(|v| (v.name.clone(), v.parsed_expr.clone()))
-        .collect();
-
-    for v in &mut state.variables {
-        let val = v.parsed_expr.eval(&var_map);
-        v.value = val;
-    }
-
-    state.last_eval = Some(start.elapsed());
-}
-
-fn handle_input(input: String, state: &mut State) -> bool {
-    state.error_msg.take();
-
-    let node: Result<(String, Node), lalrpop_util::ParseError<usize, lalrpop_util::lexer::Token<'_>, &str>>
-        = grammar::AssignParser::new().parse(&input);
-    match node  {
-        Ok((name, expr)) => {
-            let used_vars = expr.used_vars();
-            if used_vars.contains(&name) {
-                state.error_msg = Some("Variable can't depend on itself".to_string());
-                return false;
-            }
-            let seen = vec![name.clone()];
-            if let Some(mut e) = used_vars.iter().filter_map(|v| find_dependency_recursive(state, v, seen.clone()).err()).next() {
-                e.push(name.clone());
-                e.reverse();
-                e.push(name.clone());
-                state.error_msg = Some(format!("Found recursive dependency:\n{}", e.join(" -> ")));
-                return false;
-            }
-            if let Some(v) = state.variables.iter_mut().filter(|v| v.name == name).next() {
-                v.parsed_expr = expr;
-                v.expr = input.clone();
-                v.used = used_vars;
-            } else {
-                state.variables.push(Variable {
-                    name,
-                    expr: input.clone(),
-                    value: None,
-                    parsed_expr: expr,
-                    used: used_vars
-                });
-            }
-        }
-        Err(e) => {
-            state.error_msg = Some(e.to_string());
-            return false;
-        }
-    }
-
-    eval_vars(state);
-    state.inputs.push(input);
-    true
-}
-
-fn find_dependency_recursive(state: &State, name: &String, mut seen: Vec<String>) -> Result<(), Vec<String>> {
-    if let Some(var) = state.variables.iter().filter(|v| v.name == *name).next() {
-        seen.push(name.clone());
-        if var.used.iter().any(|v| seen.contains(v)) {
-            return Err(vec![name.clone()]);
-        }
-        if let Some(mut e) = var.used.iter().filter_map(|v| find_dependency_recursive(state, v, seen.clone()).err()).next() {
-            e.push(name.clone());
-            return Err(e);
-        }
-    }
-    Ok(())
-}
-
 fn render(main_pos_size: ([f32; 2], [f32; 2]), state: &mut State, ui: &mut Ui) {
-    if let Some(t) = ui.begin_main_menu_bar() {
-        if ui.menu_item("Clear") {
-            *state = State::default();
-        }
-        if ui.menu_item("Open") {
-            if let Some(f) = rfd::FileDialog::new().add_filter("json", &["json"]).pick_file() {
-                let data =  std::fs::read_to_string(f).unwrap_or("}{".to_string());
-                let vars: Result<Vec<Variable>, _> = serde_json::from_str(&data);
-                match vars {
-                    Ok(v) => {
-                        *state = State::default();
-                        state.variables = v;
-                        eval_vars(state);
-                    },
-                    Err(e) => println!("Error while loading:\n{:#?}", e)
-                }
-            }
-        }
-        if ui.menu_item("Save") {
-            if let Some(f) = rfd::FileDialog::new().add_filter("json", &["json"]).save_file() {
-                if let Err(e) = std::fs::write(f, serde_json::to_string(&state.variables).unwrap()) {
-                    println!("Error while saving:\n{:#?}", e);
-                }
-            }
-        }
-        t.end();
-    }
+    gui::draw_main_menu_bar(state, ui);
 
     let wflags = WindowFlags::NO_SCROLLBAR | WindowFlags::NO_MOVE | WindowFlags::NO_DECORATION | WindowFlags::NO_RESIZE | WindowFlags::NO_TITLE_BAR | WindowFlags::NO_COLLAPSE | WindowFlags::NO_DOCKING;
     if let Some(t) = ui.window("MainWindow")
@@ -155,9 +35,7 @@ fn render(main_pos_size: ([f32; 2], [f32; 2]), state: &mut State, ui: &mut Ui) {
         if ui.input_text("##Input", &mut state.input_buf)
             .enter_returns_true(true)
             .build() {
-            if handle_input(state.input_buf.clone(), state) {
-                state.input_buf.clear();
-            }
+            state.handle_input_buf();
             ui.set_keyboard_focus_here_with_offset(FocusedWidget::Previous);
         }
         if let Some(last_eval) = &state.last_eval {
@@ -170,33 +48,7 @@ fn render(main_pos_size: ([f32; 2], [f32; 2]), state: &mut State, ui: &mut Ui) {
         ui.spacing();
 
         if let Some(t) = ui.child_window("Variables").begin() {
-            if let Some(t) = ui.begin_table_with_flags("VariableTable", 4, TableFlags::BORDERS | TableFlags::ROW_BG | TableFlags::RESIZABLE) {
-                ui.table_setup_column("Name");
-                ui.table_setup_column("Value");
-                ui.table_setup_column("Expression");
-                ui.table_setup_column("Actions");
-                ui.table_headers_row();
-
-                let mut to_remove = vec![];
-                for v in &state.variables {
-                    ui.table_next_row();
-                    ui.table_next_column();
-                    ui.text(&v.name);
-                    ui.table_next_column();
-                    ui.text(v.value.map_or("-".to_string(), |v| v.separate_with_spaces()));
-                    ui.table_next_column();
-                    ui.text(&v.expr);
-                    ui.table_next_column();
-                    if ui.button(format!("Remove##{}", v.name)) {
-                        to_remove.push(v.name.clone());
-                    }
-                }
-                if !to_remove.is_empty() {
-                    state.variables.retain(|v| !to_remove.contains(&v.name));
-                    eval_vars(state);
-                }
-                t.end();
-            }
+            gui::draw_table(state, ui);
             t.end();
         }
         t.end();
diff --git a/src/state.rs b/src/state.rs
new file mode 100644
index 0000000..49ca564
--- /dev/null
+++ b/src/state.rs
@@ -0,0 +1,105 @@
+use crate::parser::Node;
+
+#[derive(Debug, serde::Deserialize, serde::Serialize)]
+pub struct Variable {
+    pub name: String,
+    pub expr: String,
+
+    #[serde(skip)]
+    pub value: Option<f64>,
+
+    pub parsed_expr: Node,
+    pub used: Vec<String>
+}
+
+#[derive(Debug, Default)]
+pub struct State {
+    pub inputs: Vec<String>,
+    pub input_buf: String,
+    pub error_msg: Option<String>,
+    pub variables: Vec<Variable>,
+    pub last_eval: Option<std::time::Duration>
+}
+
+impl State {
+    pub fn eval_vars(&mut self) {
+        let start = std::time::Instant::now();
+
+        let var_map = self.variables.iter()
+            .map(|v| (v.name.clone(), v.parsed_expr.clone()))
+            .collect();
+
+        for v in &mut self.variables {
+            let val = v.parsed_expr.eval(&var_map);
+            v.value = val;
+        }
+
+        self.last_eval = Some(start.elapsed());
+    }
+
+    pub fn handle_input_buf(&mut self) {
+        let input = std::mem::take(&mut self.input_buf);
+        if !self.handle_input(&input) {
+            self.input_buf = input;
+        }
+    }
+
+    pub fn handle_input(&mut self, input: &String) -> bool {
+        self.error_msg.take();
+
+        let node: Result<(String, Node), lalrpop_util::ParseError<usize, lalrpop_util::lexer::Token<'_>, &str>>
+            = crate::grammar::AssignParser::new().parse(&input);
+        match node {
+            Ok((name, expr)) => {
+                let used_vars = expr.used_vars();
+                if used_vars.contains(&name) {
+                    self.error_msg = Some("Variable can't depend on itself".to_string());
+                    return false;
+                }
+                let seen = vec![name.clone()];
+                if let Some(mut e) = used_vars.iter().filter_map(|v| self.find_dependency_recursive(v, seen.clone()).err()).next() {
+                    e.push(name.clone());
+                    e.reverse();
+                    e.push(name.clone());
+                    self.error_msg = Some(format!("Found recursive dependency:\n{}", e.join(" -> ")));
+                    return false;
+                }
+                if let Some(v) = self.variables.iter_mut().filter(|v| v.name == name).next() {
+                    v.parsed_expr = expr;
+                    v.expr = input.clone();
+                    v.used = used_vars;
+                } else {
+                    self.variables.push(Variable {
+                        name,
+                        expr: input.clone(),
+                        value: None,
+                        parsed_expr: expr,
+                        used: used_vars
+                    });
+                }
+            }
+            Err(e) => {
+                self.error_msg = Some(e.to_string());
+                return false;
+            }
+        }
+
+        self.eval_vars();
+        self.inputs.push(input.clone());
+        true
+    }
+
+    fn find_dependency_recursive(&self, name: &String, mut seen: Vec<String>) -> Result<(), Vec<String>> {
+        if let Some(var) = self.variables.iter().filter(|v| v.name == *name).next() {
+            seen.push(name.clone());
+            if var.used.iter().any(|v| seen.contains(v)) {
+                return Err(vec![name.clone()]);
+            }
+            if let Some(mut e) = var.used.iter().filter_map(|v| self.find_dependency_recursive(v, seen.clone()).err()).next() {
+                e.push(name.clone());
+                return Err(e);
+            }
+        }
+        Ok(())
+    }
+}