update layout macro invocations

layout/src/collection.rs

@@ -5,6 +5,8 @@ mod stack;  pub use self::stack::*;
 
 use crate::*;
 
+use std::sync::RwLock;
+
 /// Conditional rendering, in unary and binary forms.
 pub struct Cond;
 
@@ -17,8 +19,14 @@ impl Cond {
     pub fn either <E: Engine, A: Content<E>, B: Content<E>> (cond: bool, a: A, b: B) -> Either<E, A, B> {
         Either(cond, a, b, Default::default())
     }
+
+    pub fn opt <E: Engine, A, F: Fn(A)->R, R: Content<E>> (option: Option<A>, cb: F) -> Opt<E, A, F, R> {
+        Opt(option, cb, Default::default())
+    }
 }
 
+pub struct Opt<E: Engine, A, F: Fn(A)->R, R: Content<E>>(Option<A>, F, PhantomData<E>);
+
 /// Contents `self.1` when `self.0` is true.
 pub struct When<E: Engine, A>(bool, A, PhantomData<E>);
 
@@ -62,7 +70,6 @@ pub trait Collector<E: Engine>: Send + Sync + Fn(&mut dyn FnMut(&dyn Content<E>)
 impl<E, F> Collector<E> for F
 where E: Engine, F: Send + Sync + Fn(&mut dyn FnMut(&dyn Content<E>)) {}
 
-/*
 /// Rendering of iterable collections, one-to-one and many-to one.
 pub struct Coll;
 
@@ -73,24 +80,25 @@ impl Coll {
         R: Content<E>,
         F: Fn(T, usize)->R + Send + Sync
     {
-        Map(Default::default(), iterator, callback)
-    }
-    pub fn reduce <E, T, I, R, F>(iterator: I, callback: F) -> Reduce<E, T, I, R, F> where
-        E: Engine,
-        I: Iterator<Item = T> + Send + Sync,
-        R: Content<E>,
-        F: Fn(R, T, usize) -> R + Send + Sync
-    {
-        Reduce(Default::default(), iterator, callback)
+        Map(Default::default(), RwLock::new(iterator), callback)
     }
+    //pub fn reduce <E, T, I, R, F>(iterator: I, callback: F) -> Reduce<E, T, I, R, F> where
+        //E: Engine,
+        //I: Iterator<Item = T> + Send + Sync,
+        //R: Content<E>,
+        //F: Fn(R, T, usize) -> R + Send + Sync
+    //{
+        //Reduce(Default::default(), iterator, callback)
+    //}
 }
 
-pub struct Map<'a, E, T, I, R, F>(PhantomData<E>, &'a mut I, F) where
+pub struct Map<E, T, I, R, F>(PhantomData<E>, RwLock<I>, F) where
     E: Engine,
     I: Iterator<Item = T> + Send + Sync,
     R: Content<E>,
     F: Fn(T, usize)->R + Send + Sync;
-impl<'a, E, T, I, R, F> Content<E> for Map<'a, E, T, I, R, F> where
+
+impl<E, T, I, R, F> Content<E> for Map<E, T, I, R, F> where
     E: Engine,
     I: Iterator<Item = T> + Send + Sync,
     R: Content<E>,
@@ -98,13 +106,14 @@ impl<'a, E, T, I, R, F> Content<E> for Map<'a, E, T, I, R, F> where
 {
     fn render (&self, to: &mut E::Output) {
         let mut index = 0;
-        for item in self.1 {
+        for item in &mut*self.1.write().unwrap() {
             (self.2)(item, index).render(to);
             index += 1;
         }
     }
 }
 
+/*
 pub struct Reduce<E, T, I, R, F>(PhantomData<(E, R)>, I, F) where
     E: Engine,
     I: Iterator<Item = T> + Send + Sync,