add assign as a part of declaration and add tests for it

Author: Arcelyth

src/env.rs

@@ -0,0 +1,33 @@
+use std::sync::Arc;
+use std::collections::HashMap;
+
+#[derive(Debug)]
+pub enum Value {
+    Number(u16), 
+    RGB(u16, u16, u16)
+}
+
+#[derive(Debug)]
+pub struct Env {
+    values: HashMap<Arc<str>, Value>    
+}
+
+impl Env {
+    pub fn new() -> Self {
+        let mut vs = Self {
+            values: HashMap::new()
+        };
+
+        // inner variables
+        vs.insert("border_color", Value::RGB(176, 176, 176));
+        vs
+    }
+
+    pub fn insert(&mut self, name: &str, value: Value) {
+        self.values.insert(name.into(), value);
+    }
+
+    pub fn get(&self, k: &str) -> Option<&Value> {
+        self.values.get(k.into())
+    }
+}

src/error.rs

@@ -1,11 +1,14 @@
 use thiserror::Error;
+use std::num::ParseIntError;
 
 #[derive(Error, Debug)]
 pub enum ParserError{
     #[error("IO error: {0}")]
     IOError(#[from] std::io::Error),
     #[error("{0}")]
     Err(String),
+    #[error("IO error: {0}")]
+    ParseIntError(#[from] ParseIntError),
 }
 
 #[derive(Error, Debug)]