Add list flag support.

If a field has a list of primitive values in it expand it to multiples
of that flag for each value in the list.

examples/test.ucg

@@ -24,5 +24,6 @@ let server_config = {
     tmpldir = "./templates",
     prefix = {
         foo = "bar"
-    }
+    },
+    l = ["foo", "bar"]
 };

src/build.rs

@@ -126,6 +126,13 @@ impl Val {
         return false;
     }
 
+    pub fn is_empty(&self) -> bool {
+        if let &Val::Empty = self {
+            return true;
+        }
+        return false;
+    }
+
     pub fn is_float(&self) -> bool {
         if let &Val::Float(_) = self {
             return true;
@@ -148,7 +155,14 @@ impl Val {
     }
 
     pub fn is_list(&self) -> bool {
-        if let &Val::Tuple(_) = self {
+        if let &Val::List(_) = self {
+            return true;
+        }
+        return false;
+    }
+
+    pub fn is_macro(&self) -> bool {
+        if let &Val::Macro(_) = self {
             return true;
         }
         return false;

src/convert/flags.rs

@@ -37,6 +37,27 @@ impl FlagConverter {
         return Ok(());
     }
 
+    fn write_list_flag(&self, pfx: &str, name: &str, v: &Val, w: &mut Write) -> Result<()> {
+        if let &Val::List(ref def) = v {
+            // first of all we need to make sure that each &Val is only a primitive type.
+            for v in def.iter() {
+                let vref = v.as_ref();
+                if vref.is_list() || vref.is_tuple() || vref.is_macro() {
+                    eprintln!(
+                        "Skipping non primitive val in list for flag {}{}",
+                        pfx, name
+                    );
+                } else {
+                    try!(self.write_flag_name(pfx, name, w));
+                    try!(self.write(pfx, vref, w));
+                }
+            }
+        } else {
+            panic!("Impossible call happened. Somebody messed up.")
+        }
+        return Ok(());
+    }
+
     fn write(&self, pfx: &str, v: &Val, w: &mut Write) -> Result<()> {
         match v {
             &Val::Empty => {
@@ -56,8 +77,7 @@ impl FlagConverter {
                 // FIXME(jwall): Fill this in?
                 eprintln!("Skipping List...");
             }
-            &Val::Tuple(ref flds) => {
-                for &(ref name, ref val) in flds.iter() {
+            &Val::Tuple(ref flds) => for &(ref name, ref val) in flds.iter() {
                 if let &Val::Empty = val.as_ref() {
                     try!(self.write_flag_name(pfx, &name.val, w));
                     continue;
@@ -65,13 +85,13 @@ impl FlagConverter {
                 if val.is_tuple() {
                     let new_pfx = format!("{}{}.", pfx, name);
                     try!(self.write(&new_pfx, val, w));
+                } else if val.is_list() {
+                    try!(self.write_list_flag(pfx, &name.val, &val, w));
                 } else {
                     try!(self.write_flag_name(pfx, &name.val, w));
-                        // TODO(jwall): What if the value is a tuple?
                     try!(self.write(pfx, &val, w));
                 }
-                }
-            }
+            },
             &Val::Macro(ref _def) => {
                 // This is ignored
                 eprintln!("Skipping macro...");