Implement hash fragments in the router (#2320)

* implement hash fragments in the router

* clean up query and search example

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/router-macro/src/hash.rs

@@ -0,0 +1,62 @@
+use quote::quote;
+use syn::{Ident, Type};
+
+use proc_macro2::TokenStream as TokenStream2;
+
+#[derive(Debug)]
+pub struct HashFragment {
+    pub ident: Ident,
+    pub ty: Type,
+}
+
+impl HashFragment {
+    pub fn contains_ident(&self, ident: &Ident) -> bool {
+        self.ident == *ident
+    }
+
+    pub fn parse(&self) -> TokenStream2 {
+        let ident = &self.ident;
+        let ty = &self.ty;
+        quote! {
+            let #ident = <#ty as dioxus_router::routable::FromHashFragment>::from_hash_fragment(&*hash);
+        }
+    }
+
+    pub fn write(&self) -> TokenStream2 {
+        let ident = &self.ident;
+        quote! {
+            write!(f, "#{}", #ident)?;
+        }
+    }
+
+    pub fn parse_from_str<'a>(
+        route_span: proc_macro2::Span,
+        mut fields: impl Iterator<Item = (&'a Ident, &'a Type)>,
+        hash: &str,
+    ) -> syn::Result<Self> {
+        // check if the route has a hash string
+        let Some(hash) = hash.strip_prefix(':') else {
+            return Err(syn::Error::new(
+                route_span,
+                "Failed to parse `:`. Hash fragments must be in the format '#:<field>'",
+            ));
+        };
+
+        let hash_ident = Ident::new(hash, proc_macro2::Span::call_site());
+        let field = fields.find(|(name, _)| *name == &hash_ident);
+
+        let ty = if let Some((_, ty)) = field {
+            ty.clone()
+        } else {
+            return Err(syn::Error::new(
+                route_span,
+                format!("Could not find a field with the name '{}'", hash_ident),
+            ));
+        };
+
+        Ok(Self {
+            ident: hash_ident,
+            ty,
+        })
+    }
+}