1 files changed, 81 insertions, 0 deletions
diff --git a/macros/src/injectable/dependency.rs b/macros/src/injectable/dependency.rs
new file mode 100644
index 0000000..2c5e0fd
--- /dev/null
+++ b/macros/src/injectable/dependency.rs
@@ -0,0 +1,81 @@
+use std::error::Error;
+
+use proc_macro2::Ident;
+use syn::{parse2, FnArg, GenericArgument, LitStr, PathArguments, Type};
+
+use crate::injectable::named_attr_input::NamedAttrInput;
+use crate::util::syn_path::syn_path_to_string;
+
+pub struct Dependency
+{
+    pub interface: Type,
+    pub ptr: Ident,
+    pub name: Option<LitStr>,
+}
+
+impl Dependency
+{
+    pub fn build(new_method_arg: &FnArg) -> Result<Self, Box<dyn Error>>
+    {
+        let typed_new_method_arg = match new_method_arg {
+            FnArg::Typed(typed_arg) => Ok(typed_arg),
+            FnArg::Receiver(_) => Err("Unexpected self argument in 'new' method"),
+        }?;
+
+        let ptr_type_path = match typed_new_method_arg.ty.as_ref() {
+            Type::Path(arg_type_path) => Ok(arg_type_path),
+            Type::Reference(ref_type_path) => match ref_type_path.elem.as_ref() {
+                Type::Path(arg_type_path) => Ok(arg_type_path),
+                &_ => Err("Unexpected reference to non-path type"),
+            },
+            &_ => Err("Expected a path or a reference type"),
+        }?;
+
+        let ptr_path_segment = ptr_type_path.path.segments.last().map_or_else(
+            || Err("Expected pointer type path to have a last segment"),
+            Ok,
+        )?;
+
+        let ptr = ptr_path_segment.ident.clone();
+
+        let ptr_path_generic_args = &match &ptr_path_segment.arguments {
+            PathArguments::AngleBracketed(generic_args) => Ok(generic_args),
+            &_ => Err("Expected pointer type to have a generic type argument"),
+        }?
+        .args;
+
+        let interface = if let Some(GenericArgument::Type(interface)) =
+            ptr_path_generic_args.first()
+        {
+            Ok(interface.clone())
+        } else {
+            Err("Expected pointer type to have a generic type argument")
+        }?;
+
+        let arg_attrs = &typed_new_method_arg.attrs;
+
+        let opt_named_attr = arg_attrs.iter().find(|attr| {
+            attr.path.get_ident().map_or_else(
+                || false,
+                |attr_ident| attr_ident.to_string().as_str() == "named",
+            ) || syn_path_to_string(&attr.path) == "syrette::named"
+        });
+
+        let opt_named_attr_tokens = opt_named_attr.map(|attr| &attr.tokens);
+
+        let opt_named_attr_input =
+            if let Some(named_attr_tokens) = opt_named_attr_tokens {
+                Some(parse2::<NamedAttrInput>(named_attr_tokens.clone()).map_err(
+                    |err| format!("Invalid input for 'named' attribute. {}", err),
+                )?)
+            } else {
+                None
+            };
+
+        Ok(Self {
+            interface,
+            ptr,
+            name: opt_named_attr_input.map(|named_attr_input| named_attr_input.name),
+        })
+    }
+}