Use BindgenLoader for the Python pipeline

I'm liking this BindgenLoader and want to use it in more places, this is
a small step towards that.

Also added the `CrateConfigSupplier::from_cargo_metadata_command` utility
function.

Author: bendk

fixtures/docstring-proc-macro/tests/test_generated_bindings.rs

@@ -52,10 +52,7 @@ mod tests {
 
         let config_supplier = {
             use uniffi_bindgen::cargo_metadata::CrateConfigSupplier;
-            let metadata = cargo_metadata::MetadataCommand::new()
-                .exec()
-                .expect("error running cargo metadata");
-            CrateConfigSupplier::from(metadata)
+            CrateConfigSupplier::from_cargo_metadata_command(false).unwrap()
         };
 
         uniffi_bindgen::library_mode::generate_bindings(

uniffi/src/cli/uniffi_bindgen.rs

@@ -2,12 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use anyhow::{bail, Context, Result};
+use anyhow::{bail, Result};
 use camino::Utf8PathBuf;
 use clap::{Args, Parser, Subcommand, ValueEnum};
 use std::fmt;
 use uniffi_bindgen::bindings::*;
 use uniffi_bindgen::pipeline::initial;
+use uniffi_bindgen::BindgenLoader;
 use uniffi_pipeline::PrintOptions;
 
 /// Enumeration of all foreign language targets currently supported by our CLI.
@@ -187,15 +188,10 @@ fn config_supplier(
     metadata_no_deps: bool,
 ) -> Result<impl uniffi_bindgen::BindgenCrateConfigSupplier> {
     #[cfg(feature = "cargo-metadata")]
-    {
-        use uniffi_bindgen::cargo_metadata::CrateConfigSupplier;
-        let mut cmd = cargo_metadata::MetadataCommand::new();
-        if metadata_no_deps {
-            cmd.no_deps();
-        }
-        let metadata = cmd.exec().context("error running cargo metadata")?;
-        Ok(CrateConfigSupplier::from(metadata))
-    }
+    return uniffi_bindgen::cargo_metadata::CrateConfigSupplier::from_cargo_metadata_command(
+        metadata_no_deps,
+    );
+
     #[cfg(not(feature = "cargo-metadata"))]
     Ok(uniffi_bindgen::EmptyCrateConfigSupplier)
 }
@@ -330,11 +326,14 @@ pub fn run_main() -> anyhow::Result<()> {
                     .as_ref()
                     .expect("--out-dir is required when generating {language} bindings");
                 let config_supplier = config_supplier(metadata_no_deps)?;
-                let initial_root = if library_mode {
-                    initial::Root::from_library(config_supplier, &source, crate_name.clone())?
-                } else {
-                    initial::Root::from_udl(config_supplier, &source, crate_name.clone())?
-                };
+                let loader = BindgenLoader::new(&config_supplier);
+                // Note: we ignore `library_mode` in this case, `BindgenLoader` is smart enough to
+                // auto-detect the source type
+                let mut metadata = loader.load_metadata(&source)?;
+                if let Some(crate_name) = &crate_name {
+                    loader.filter_metadata_by_crate_name(&mut metadata, crate_name);
+                }
+                let initial_root = loader.load_pipeline_initial_root(metadata)?;
 
                 match language {
                     TargetLanguage::Python => python::run_pipeline(initial_root, out_dir)?,

uniffi_bindgen/src/bindings/swift/mod.rs

@@ -146,14 +146,9 @@ impl BindingGenerator for SwiftBindingGenerator {
 pub fn generate_swift_bindings(options: SwiftBindingsOptions) -> Result<()> {
     #[cfg(feature = "cargo-metadata")]
     let config_supplier = {
-        use crate::cargo_metadata::CrateConfigSupplier;
-        use anyhow::Context;
-        let mut cmd = cargo_metadata::MetadataCommand::new();
-        if options.metadata_no_deps {
-            cmd.no_deps();
-        }
-        let metadata = cmd.exec().context("error running cargo metadata")?;
-        CrateConfigSupplier::from(metadata)
+        crate::cargo_metadata::CrateConfigSupplier::from_cargo_metadata_command(
+            options.metadata_no_deps,
+        )?
     };
     #[cfg(not(feature = "cargo-metadata"))]
     let config_supplier = crate::EmptyCrateConfigSupplier;

uniffi_bindgen/src/cargo_metadata.rs

@@ -5,7 +5,7 @@
 //! Helpers for data returned by cargo_metadata. Note that this doesn't
 //! execute cargo_metadata, just parses its output.
 
-use anyhow::{bail, Context};
+use anyhow::{bail, Context, Result};
 use camino::Utf8PathBuf;
 use cargo_metadata::Metadata;
 use std::{collections::HashMap, fs};
@@ -17,16 +17,27 @@ pub struct CrateConfigSupplier {
     paths: HashMap<String, Utf8PathBuf>,
 }
 
+impl CrateConfigSupplier {
+    pub fn from_cargo_metadata_command(no_deps: bool) -> Result<Self> {
+        let mut cmd = cargo_metadata::MetadataCommand::new();
+        if no_deps {
+            cmd.no_deps();
+        }
+        let metadata = cmd.exec().context("error running cargo metadata")?;
+        Ok(Self::from(metadata))
+    }
+}
+
 impl BindgenCrateConfigSupplier for CrateConfigSupplier {
-    fn get_toml(&self, crate_name: &str) -> anyhow::Result<Option<toml::value::Table>> {
+    fn get_toml(&self, crate_name: &str) -> Result<Option<toml::value::Table>> {
         crate::load_toml_file(self.get_toml_path(crate_name).as_deref())
     }
 
     fn get_toml_path(&self, crate_name: &str) -> Option<Utf8PathBuf> {
         self.paths.get(crate_name).map(|p| p.join("uniffi.toml"))
     }
 
-    fn get_udl(&self, crate_name: &str, udl_name: &str) -> anyhow::Result<String> {
+    fn get_udl(&self, crate_name: &str, udl_name: &str) -> Result<String> {
         let path = self
             .paths
             .get(crate_name)

uniffi_bindgen/src/loader.rs

@@ -15,8 +15,8 @@ use uniffi_meta::{
 };
 
 use crate::{
-    crate_name_from_cargo_toml, macro_metadata, BindgenCrateConfigSupplier, Component,
-    ComponentInterface, Result,
+    crate_name_from_cargo_toml, interface, macro_metadata, pipeline, BindgenCrateConfigSupplier,
+    Component, ComponentInterface, Result,
 };
 
 /// Load metadata, component interfaces, configuration, etc. for binding generators.
@@ -61,7 +61,9 @@ impl<'config> BindgenLoader<'config> {
         match source_path.extension() {
             Some(ext) if ext.to_lowercase() == "udl" => {
                 let crate_name = crate_name_from_cargo_toml(source_path)?;
-                let group = uniffi_udl::parse_udl(&fs::read_to_string(source_path)?, &crate_name)?;
+                let mut group =
+                    uniffi_udl::parse_udl(&fs::read_to_string(source_path)?, &crate_name)?;
+                Self::add_checksums(&mut group);
                 Ok(HashMap::from([(crate_name, group)]))
             }
             _ => {
@@ -88,6 +90,39 @@ impl<'config> BindgenLoader<'config> {
         }
     }
 
+    /// Add checksums for metadata parsed from UDL
+    fn add_checksums(metadata_group: &mut MetadataGroup) {
+        // Need to temporarily take items BTree set, since we're technically mutating it's contents
+        // Each item will be added back at the bottom of the for loop.
+        let items = std::mem::take(&mut metadata_group.items);
+        for mut meta in items {
+            // Make sure metadata checksums are set
+            match &mut meta {
+                Metadata::Func(func) => {
+                    func.checksum = Some(uniffi_meta::checksum(&interface::Function::from(
+                        func.clone(),
+                    )));
+                }
+                Metadata::Method(meth) => {
+                    // making a method is mildly tricky as we need a type for self.
+                    // for the purposes of a checksum we ignore self info from udl.
+                    let method_object =
+                        interface::Method::from_metadata(meth.clone(), uniffi_meta::Type::UInt8);
+                    meth.checksum = Some(uniffi_meta::checksum(&method_object));
+                }
+                Metadata::Constructor(cons) => {
+                    cons.checksum = Some(uniffi_meta::checksum(&interface::Constructor::from(
+                        cons.clone(),
+                    )));
+                }
+                // Note: UDL-based callbacks don't have checksum functions, don't set the
+                // checksum for those.
+                _ => (),
+            }
+            metadata_group.items.insert(meta);
+        }
+    }
+
     /// Load a [ComponentInterface] list
     ///
     /// This converts the metadata into `ComponentInterface` instances, which contains additional
@@ -182,6 +217,25 @@ impl<'config> BindgenLoader<'config> {
             .collect()
     }
 
+    /// Load a [pipeline::initial::Root] value from the metadata
+    pub fn load_pipeline_initial_root(
+        &self,
+        metadata: MetadataGroupMap,
+    ) -> Result<pipeline::initial::Root> {
+        let mut metadata_converter = pipeline::initial::UniffiMetaConverter::default();
+        for metadata_group in metadata.into_values() {
+            if let Some(docstring) = metadata_group.namespace_docstring {
+                metadata_converter
+                    .add_module_docstring(metadata_group.namespace.name.clone(), docstring);
+            }
+            metadata_converter.add_metadata_item(Metadata::Namespace(metadata_group.namespace))?;
+            for meta in metadata_group.items {
+                metadata_converter.add_metadata_item(meta)?;
+            }
+        }
+        metadata_converter.try_into_initial_ir()
+    }
+
     /// Get the basename for a source file
     ///
     /// This will remove any file extension.
@@ -206,4 +260,8 @@ impl<'config> BindgenLoader<'config> {
             Some(ext) if ext.to_lowercase() == "udl"
         )
     }
+
+    pub fn filter_metadata_by_crate_name(&self, metadata: &mut MetadataGroupMap, crate_name: &str) {
+        metadata.retain(|_, metadata_group| metadata_group.namespace.crate_name == crate_name)
+    }
 }

uniffi_bindgen/src/pipeline/initial/mod.rs

@@ -17,7 +17,7 @@ use anyhow::Result;
 use camino::Utf8Path;
 
 use crate::{crate_name_from_cargo_toml, interface, macro_metadata, BindgenCrateConfigSupplier};
-use from_uniffi_meta::UniffiMetaConverter;
+pub use from_uniffi_meta::UniffiMetaConverter;
 
 impl Root {
     pub fn from_library(