Allow usage of imported nodes

The existing implementation of the graphity! macro does not allow for
import of an external node. That was due to a limitation caused by
rust-lang/rust#20400.

With this patch, the signature of the macro changes. It now accepts
direct reference to the node and its producer and consumer.

With this change, it is possible to use nodes defined in other crates.

Signed-off-by: Petr Horáček <phoracek@redhat.com>

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Main
+
+* **Breaking change:** The signature of the `graphity!` macro has been changed
+  to allow imports of external nodes. Read documentation of the macro to learn
+  more.
+
 ## 1.0.0
 
 * Full implementation of the core feature-set. Allows users to define their

README.md

@@ -58,13 +58,15 @@ impl Node<i32> for Sum {
    ...
 }
 
-mod g {
-    use super::{Echo, Generator, Sum};
-    graphity!(Graph<i32>; Echo, Generator, Sum);
-}
+graphity!(
+    Graph<i32>;
+    Generator = {Generator, GeneratorConsumer, GeneratorProducer},
+    Sum = {Sum, SumConsumer, SumProducer},
+    Echo = {Echo, EchoConsumer, EchoProducer},
+);
 
 fn main() {
-    let mut graph = g::Graph::new();
+    let mut graph = Graph::new();
 
     let one = graph.add_node(Generator(1));
     let two = graph.add_node(Generator(2));

examples/graph.rs

@@ -1,95 +1,23 @@
 #[macro_use]
 extern crate graphity;
 
-use graphity::{Node, NodeIndex};
+use graphity::NodeIndex;
 
-mod g {
-    use super::{Echo, Generator, Sum};
-    graphity!(Graph<i32>; Echo, Generator, Sum);
-}
-
-#[derive(Default)]
-pub struct Echo {
-    input: i32,
-}
-
-#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
-pub struct EchoConsumer;
-
-#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
-pub enum EchoProducer {}
-
-impl Node<i32> for Echo {
-    type Consumer = EchoConsumer;
-    type Producer = EchoProducer;
-
-    fn tick(&mut self) {
-        println!("Echo: {}", self.input);
-    }
-
-    fn write(&mut self, _consumer: Self::Consumer, input: i32) {
-        self.input = input;
-    }
-}
-
-pub struct Generator(i32);
-
-#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
-pub enum GeneratorConsumer {}
-
-#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
-pub struct GeneratorProducer;
+// See definitions of nodes used here under nodes/src/lib.rs
+use graphity_nodes::*;
 
-impl Node<i32> for Generator {
-    type Consumer = GeneratorConsumer;
-    type Producer = GeneratorProducer;
-
-    fn read(&self, _producer: Self::Producer) -> i32 {
-        self.0
-    }
-}
-
-#[derive(Default)]
-pub struct Sum {
-    input1: i32,
-    input2: i32,
-    output: i32,
-}
-
-#[derive(PartialEq, Eq, Copy, Clone, Hash, Debug)]
-pub enum SumConsumer {
-    In1,
-    In2,
-}
-
-#[derive(PartialEq, Eq, Copy, Clone, Hash, Debug)]
-pub struct SumProducer;
-
-impl Node<i32> for Sum {
-    type Consumer = SumConsumer;
-    type Producer = SumProducer;
-
-    fn tick(&mut self) {
-        self.output = self.input1 + self.input2;
-    }
-
-    fn read(&self, _producer: Self::Producer) -> i32 {
-        self.output
-    }
-
-    fn write(&mut self, consumer: Self::Consumer, input: i32) {
-        match consumer {
-            Self::Consumer::In1 => self.input1 = input,
-            Self::Consumer::In2 => self.input2 = input,
-        }
-    }
-}
+graphity!(
+    Graph<i32>;
+    Generator = {Generator, GeneratorConsumer, GeneratorProducer},
+    Sum = {Sum, SumConsumer, SumProducer},
+    Echo = {Echo, EchoConsumer, EchoProducer},
+);
 
 fn main() {
-    let mut graph = g::Graph::new();
+    let mut graph = Graph::new();
 
-    let one = graph.add_node(Generator(1));
-    let two = graph.add_node(Generator(2));
+    let one = graph.add_node(Generator::new(1));
+    let two = graph.add_node(Generator::new(2));
     let sum = graph.add_node(Sum::default());
     let echo = graph.add_node(Echo::default());