include new files

sample/nothing.pl.xml

@@ -0,0 +1,12 @@
+<program name="nothing">
+    <main>
+        <real>
+            <integer value="5"/>
+        </real>
+        <return>
+            <integer>
+                <real value="3.0"/>
+            </integer>
+        </return>
+    </main>
+</program>

src/compiler/context.rs

@@ -0,0 +1,21 @@
+pub struct Context {
+    variables: Vec<String>,
+}
+
+impl Context {
+    pub fn new() -> Self {
+        Context {
+            variables: Vec::new(),
+        }
+    }
+
+    pub fn variable_offset(&mut self, var: &String) -> usize {
+        self.variables
+            .iter()
+            .position(|p| p == var)
+            .unwrap_or_else(|| {
+                self.variables.push(var.clone());
+                self.variables.len() - 1
+            })
+    }
+}

src/compiler/value_type.rs

@@ -0,0 +1,8 @@
+pub enum ValueType {
+    Integer,
+    Real,
+    String,
+    Array,
+    Function,
+    None
+}