fix(ecs-macros): allow for using derive macros via the engine crate

3 files changed, 156 insertions, 6 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 3b32a48..6a88454 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -137,6 +137,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn",
+ "toml",
 ]
 
 [[package]]
@@ -154,6 +155,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
+[[package]]
 name = "fdeflate"
 version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -218,6 +225,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
 
 [[package]]
+name = "hashbrown"
+version = "0.14.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "290f1a1d9242c78d09ce40a5e87e7554ee637af1351968159f4952f028f75604"
+
+[[package]]
 name = "image"
 version = "0.24.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -232,6 +245,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "indexmap"
+version = "2.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+]
+
+[[package]]
 name = "khronos_api"
 version = "3.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -446,6 +469,35 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a3f0bf26fd526d2a95683cd0f87bf103b8539e2ca1ef48ce002d67aad59aa0b4"
 
 [[package]]
+name = "serde"
+version = "1.0.197"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fb1c873e1b9b056a4dc4c0c198b24c3ffa059243875552b2bd0933b1aee4ce2"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.197"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7eb0b34b42edc17f6b7cac84a52a1c5f0e1bb2227e997ca9011ea3dd34e8610b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_spanned"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb3622f419d1296904700073ea6cc23ad690adbd66f13ea683df73298736f0c1"
+dependencies = [
+ "serde",
+]
+
+[[package]]
 name = "sharded-slab"
 version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -514,6 +566,40 @@ dependencies = [
 ]
 
 [[package]]
+name = "toml"
+version = "0.8.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e9dd1545e8208b4a5af1aa9bbd0b4cf7e9ea08fabc5d0a5c67fcaafa17433aa3"
+dependencies = [
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "toml_edit",
+]
+
+[[package]]
+name = "toml_datetime"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3550f4e9685620ac18a50ed434eb3aec30db8ba93b0287467bca5826ea25baf1"
+dependencies = [
+ "serde",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.22.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e40bb779c5187258fd7aad0eb68cb8706a0a81fa712fbea808ab43c4b8374c4"
+dependencies = [
+ "indexmap",
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "winnow",
+]
+
+[[package]]
 name = "tracing"
 version = "0.1.39"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -613,6 +699,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
 [[package]]
+name = "winnow"
+version = "0.6.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0c976aaaa0e1f90dbb21e9587cdaf1d9679a1cde8875c0d6bd83ab96a208352"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
 name = "xml-rs"
 version = "0.8.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/ecs-macros/Cargo.toml b/ecs-macros/Cargo.toml
index 792ca34..cf323fc 100644
--- a/ecs-macros/Cargo.toml
+++ b/ecs-macros/Cargo.toml
@@ -10,4 +10,5 @@ proc-macro = true
 quote = "1.0.35"
 syn = { version = "2.0.51", features = ["full"] }
 proc-macro2 = "1.0.78"
+toml = "0.8.12"
 
diff --git a/ecs-macros/src/lib.rs b/ecs-macros/src/lib.rs
index 17a9be6..73709e4 100644
--- a/ecs-macros/src/lib.rs
+++ b/ecs-macros/src/lib.rs
@@ -1,7 +1,34 @@
+use std::path::PathBuf as FsPathBuf;
+
 use proc_macro::TokenStream;
 use quote::{quote, ToTokens};
 use syn::spanned::Spanned;
-use syn::{parse, Attribute, Ident, Item, ItemEnum, ItemStruct, ItemUnion};
+use syn::{parse, Attribute, Ident, Item, ItemEnum, ItemStruct, ItemUnion, Path};
+use toml::value::{Table as TomlTable, Value as TomlValue};
+
+macro_rules! syn_path {
+    ($first_segment: ident $(::$segment: ident)*) => {
+        ::syn::Path {
+            leading_colon: None,
+            segments: ::syn::punctuated::Punctuated::from_iter([
+                syn_path_segment!($first_segment),
+                $(syn_path_segment!($segment),)*
+            ])
+        }
+    };
+}
+
+macro_rules! syn_path_segment {
+    ($segment: ident) => {
+        ::syn::PathSegment {
+            ident: ::proc_macro2::Ident::new(
+                stringify!($segment),
+                ::proc_macro2::Span::call_site(),
+            ),
+            arguments: ::syn::PathArguments::None,
+        }
+    };
+}
 
 #[proc_macro_derive(Component, attributes(component))]
 pub fn component_derive(input: TokenStream) -> TokenStream
@@ -14,8 +41,10 @@ pub fn component_derive(input: TokenStream) -> TokenStream
 
     let drop_last = component_attr.drop_last;
 
+    let ecs_path = find_engine_ecs_crate_path().unwrap_or_else(|| syn_path!(ecs));
+
     quote! {
-        impl ecs::component::Component for #item_ident
+        impl #ecs_path::component::Component for #item_ident
         {
             fn drop_last(&self) -> bool {
                 #drop_last
@@ -32,9 +61,9 @@ pub fn component_derive(input: TokenStream) -> TokenStream
             }
         }
 
-        impl ecs::system::Input for #item_ident {}
+        impl #ecs_path::system::Input for #item_ident {}
 
-        impl ecs::type_name::TypeName for #item_ident
+        impl #ecs_path::type_name::TypeName for #item_ident
         {
             fn type_name(&self) -> &'static str
             {
@@ -52,8 +81,10 @@ pub fn sole_derive(input: TokenStream) -> TokenStream
 
     let item_ident = item.ident();
 
+    let ecs_path = find_engine_ecs_crate_path().unwrap_or_else(|| syn_path!(ecs));
+
     quote! {
-        impl ecs::sole::Sole for #item_ident
+        impl #ecs_path::sole::Sole for #item_ident
         {
             fn as_any_mut(&mut self) -> &mut dyn std::any::Any
             {
@@ -66,7 +97,7 @@ pub fn sole_derive(input: TokenStream) -> TokenStream
             }
         }
 
-        impl ecs::type_name::TypeName for #item_ident
+        impl #ecs_path::type_name::TypeName for #item_ident
         {
             fn type_name(&self) -> &'static str
             {
@@ -178,3 +209,26 @@ impl ComponentAttribute
         Ok(Self { drop_last })
     }
 }
+
+fn find_engine_ecs_crate_path() -> Option<Path>
+{
+    let cargo_manifest_dir = FsPathBuf::from(std::env::var("CARGO_MANIFEST_DIR").ok()?);
+
+    let crate_manifest = std::fs::read_to_string(cargo_manifest_dir.join("Cargo.toml"))
+        .ok()?
+        .parse::<TomlTable>()
+        .expect("Failed to parse crate manifest file");
+
+    let crate_dependencies = match crate_manifest.get("dependencies")? {
+        TomlValue::Table(dependencies) => Some(dependencies),
+        _ => None,
+    }?;
+
+    crate_dependencies.iter().find_map(|(crate_dep_name, _)| {
+        if crate_dep_name == "engine" {
+            return Some(syn_path!(engine::ecs));
+        }
+
+        None
+    })
+}