3 files changed, 14 insertions, 8 deletions
diff --git a/src/modelica_ast.rs b/src/modelica_ast.rs
index 6903900..f97cd0a 100644
--- a/src/modelica_ast.rs
+++ b/src/modelica_ast.rs
@@ -3,7 +3,7 @@ use std::clone::Clone;
 use std::fmt::{Debug, Formatter, Error};
 use std::collections::HashMap;
 
-#[derive(PartialEq)]
+#[derive(Clone, PartialEq)]
 pub struct ModelicaModel {
     pub name: String,
     pub components: Vec<Component>,
@@ -68,12 +68,13 @@ pub enum BinOperator {
 
 impl ModelicaModel {
 
-    pub fn get_constant_vars(&self) -> HashMap<String,Expr> {
+    pub fn get_constant_vars(&self) -> HashMap<String,Option<Expr>> {
         let mut binds = HashMap::new();
+        // XXX: actually implement this...
         for c in &self.components {
             match c.prefix {
-                Some(ComponentPrefix::Constant) => { binds.insert(c.name.clone(), Expr::Integer(123)); },
-                Some(ComponentPrefix::Parameter) => { binds.insert(c.name.clone(), Expr::Float(4.56)); },
+                Some(ComponentPrefix::Constant) => { binds.insert(c.name.clone(), Some(Expr::Integer(123))); },
+                Some(ComponentPrefix::Parameter) => { binds.insert(c.name.clone(), Some(Expr::Float(4.56))); },
                 _ => (),
             }
         }
@@ -127,6 +128,7 @@ fn intersect_strings(a: &Vec<String>, b: &Vec<String>) -> Vec<String> {
 impl Expr {
 
     // Order is undefined
+    // TODO: should return a HashSet, not a Vec
     pub fn identifiers(&self) -> Vec<String> {
         use self::Expr::*;
         match *self {
diff --git a/src/transpile_js.rs b/src/transpile_js.rs
index 1ec9a10..7c8932f 100644
--- a/src/transpile_js.rs
+++ b/src/transpile_js.rs
@@ -10,8 +10,10 @@ impl TranspileJS for ModelicaModel {
     fn repr_js(&self) -> Result<String, String> {
         let mut constants = vec![];
         for (c, e) in self.get_constant_vars() {
-            constants.push(format!("var {} = {};",
-                c, try!(e.repr_js())));
+            if let Some(v) = e {
+                constants.push(format!("var {} = {};",
+                    c, try!(v.repr_js())));
+            }
         }
         let mut binds = vec![];
         let mut outputs = vec![];
diff --git a/src/transpile_scheme.rs b/src/transpile_scheme.rs
index ce66d10..5a88cda 100644
--- a/src/transpile_scheme.rs
+++ b/src/transpile_scheme.rs
@@ -10,8 +10,10 @@ impl TranspileScheme for ModelicaModel {
     fn repr_scheme(&self) -> Result<String, String> {
         let mut constants = vec![];
         for (c, e) in self.get_constant_vars() {
-            constants.push(format!("({} {})",
-                c, try!(e.repr_scheme())));
+            if let Some(v) = e {
+                constants.push(format!("({} {})",
+                    c, try!(v.repr_scheme())));
+            }
         }
         let mut binds = vec![];
         let mut outputs = vec![];