first push, simple setup to use opengl

It's all insired in copy/paste style by: https://github.com/Nercury/rust-and-opengl-lessons

lib/config/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "config"
+version = "0.1.0"
+authors = []
+edition = "2018"
+
+[dependencies]
+failure = "0.1.3"
+slab = "0.4"
+metrohash = "1.0.6"
+resources = { path = "../resources" }

lib/config/src/lib.rs

@@ -0,0 +1,76 @@
+use std::rc::Rc;
+use std::cell::RefCell;
+
+pub struct Config {
+    shared: Rc<RefCell<shared::InnerConfig>>,
+}
+
+impl Config {
+    pub fn new(res: resources::Resource) -> Config {
+        Config {
+            shared: Rc::new(RefCell::new(shared::InnerConfig::new(res)))
+        }
+    }
+
+    pub fn pick<T>(&self, name: &str) -> Pick<T>
+        where T: Default
+    {
+        let (index, mut data) = self.shared.borrow_mut().pick(name)
+            .unwrap_or_else(|| panic!("config section {:?} is already in use", name));
+
+        let value = if data.is_none() {
+            T::default()
+        } else {
+            unimplemented!("parse value from data")
+        };
+
+        Pick {
+            value,
+            shared: self.shared.clone(),
+        }
+    }
+}
+
+pub struct Pick<T> {
+    value: T,
+    shared: Rc<RefCell<shared::InnerConfig>>,
+}
+
+mod shared {
+    use slab::Slab;
+    use resources::Resource;
+    use metrohash::MetroHashMap;
+
+    struct SlabData {
+    }
+
+    pub struct InnerConfig {
+        sections: Slab<SlabData>,
+        section_name_index: MetroHashMap<String, usize>,
+        res: resources::Resource,
+    }
+
+    impl InnerConfig {
+        pub fn new(res: Resource) -> InnerConfig {
+            InnerConfig {
+                sections: Slab::new(),
+                section_name_index: MetroHashMap::default(),
+                res
+            }
+        }
+
+        pub fn pick(&mut self, section_name: &str) -> Option<(usize, Option<String>)> {
+            let existing_section = self.section_name_index.get(section_name).map(|v| *v);
+
+            match existing_section {
+                Some(_) => None,
+                None => {
+                    let index = self.sections.insert(SlabData {});
+                    self.section_name_index.insert(section_name.to_string(), index);
+
+                    Some((index, None)) // TODO: load and return section config
+                }
+            }
+        }
+    }
+}