Add pagination to the blog page

No UI to control it yet

src/routes/mod.rs

@@ -1,5 +1,11 @@
-use rocket::response::NamedFile;
-use std::path::{Path, PathBuf};
+use rocket::{
+    http::uri::{FromUriParam, UriDisplay},
+    response::NamedFile
+};
+use std::{
+    fmt,
+    path::{Path, PathBuf}
+};
 
 macro_rules! may_fail {
     ($account:expr, $expr:expr, $template:expr, $msg:expr, | $res:ident | $block:block) => {
@@ -28,6 +34,38 @@ macro_rules! may_fail {
     };
 }
 
+const ITEMS_PER_PAGE: i32 = 10;
+
+#[derive(FromForm)]
+pub struct Page {
+    page: i32
+}
+
+impl UriDisplay for Page {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "page={}", &self.page as &UriDisplay)
+    }
+}
+
+impl FromUriParam<i32> for Page {
+    type Target = Page;
+    fn from_uri_param(num: i32) -> Page {
+        Page { page: num }
+    }
+}
+
+impl Page {
+    pub fn first() -> Page {
+        Page {
+            page: 1
+        }
+    }
+
+    pub fn limits(&self) -> (i32, i32) {
+        ((self.page - 1) * ITEMS_PER_PAGE, self.page * ITEMS_PER_PAGE)
+    }
+}
+
 pub mod blogs;
 pub mod comments;
 pub mod errors;