Adding BindgenLoader

This is a new way for binding generators to load the CIs, Configs,
metadata, etc.  I'm hoping that this can replace the `generate_bindings`
and `generate_external_bindings` functions, as well some other functions
like `library_mode::find_components`.

The goal for the new design is to let bindings generators drive the
process instead of a function like `generate_external_bindings`.  The
advantage of this is that it's easier to customize and we don't need to
keep adding new hook methods.  It also feels simpler overall to me.  See
mozilla#2640 for a discussion of this.

If we adopt this new system, then I think we can use it to remove a
bunch of duplicate code.  We can keep around the old functions for
backwards-compatibility, but I think they can just be wrappers around
`BindgenLoader`.  Also, we should figure out a nice way to hook this up
to the pipeline code.

Made `uniffi-bindgen-swift` use the new system.  This was mostly to test
the code and to serve as an example, but a nice side-benefit is that
`uniffi-bindgen-swift` now can handle UDL files.  I also added a
`uniffi-bindgen-swift` binary file to go with the `uniffi-bindgen`
binary.

Author: bendk

uniffi/Cargo.toml

@@ -68,3 +68,9 @@ name = "uniffi-bindgen"
 path = "uniffi-bindgen.rs"
 required-features = ["cli"]
 doc = false
+
+[[bin]]
+name = "uniffi-bindgen-swift"
+path = "uniffi-bindgen-swift.rs"
+required-features = ["cli"]
+doc = false

uniffi/src/cli/swift.rs

@@ -13,8 +13,9 @@ use uniffi_bindgen::bindings::{generate_swift_bindings, SwiftBindingsOptions};
 struct Cli {
     #[command(flatten)]
     kinds: Kinds,
-    /// Library path to generate bindings for
-    library_path: Utf8PathBuf,
+    #[clap(name = "PATH_TO_LIBRARY_OR_UDL")]
+    /// UDL File / path to generate bindings for
+    source: Utf8PathBuf,
     /// Directory to generate files in
     out_dir: Utf8PathBuf,
     /// Generate a XCFramework-compatible modulemap
@@ -65,7 +66,7 @@ impl From<Cli> for SwiftBindingsOptions {
             generate_swift_sources: cli.kinds.swift_sources,
             generate_headers: cli.kinds.headers,
             generate_modulemap: cli.kinds.modulemap,
-            library_path: cli.library_path,
+            source: cli.source,
             out_dir: cli.out_dir,
             xcframework: cli.xcframework,
             module_name: cli.module_name,

uniffi/uniffi-bindgen-swift.rs

@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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 uniffi::uniffi_bindgen_swift;
+
+fn main() {
+    uniffi_bindgen_swift();
+}

uniffi_bindgen/src/bindings/swift/mod.rs

@@ -29,8 +29,8 @@
 //!  * How to read from and write into a byte buffer.
 //!
 
-use crate::{BindingGenerator, Component, GenerationSettings};
-use anyhow::{Context, Result};
+use crate::{BindgenLoader, BindingGenerator, Component, ComponentInterface, GenerationSettings};
+use anyhow::Result;
 use camino::Utf8PathBuf;
 use fs_err as fs;
 use std::process::Command;
@@ -147,6 +147,7 @@ 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();
@@ -159,17 +160,10 @@ pub fn generate_swift_bindings(options: SwiftBindingsOptions) -> Result<()> {
 
     fs::create_dir_all(&options.out_dir)?;
 
-    let mut components =
-        crate::library_mode::find_components(&options.library_path, &config_supplier)?
-            // map the TOML configs into a our Config struct
-            .into_iter()
-            .map(|Component { ci, config }| {
-                let config = SwiftBindingGenerator.new_config(&config.into())?;
-                Ok(Component { ci, config })
-            })
-            .collect::<Result<Vec<_>>>()?;
-    SwiftBindingGenerator
-        .update_component_configs(&GenerationSettings::default(), &mut components)?;
+    let loader = BindgenLoader::new(&config_supplier);
+    let metadata = loader.load_metadata(&options.source)?;
+    let cis = loader.load_cis(metadata)?;
+    let components = loader.load_components(cis, parse_config)?;
 
     for Component { ci, config } in &components {
         if options.generate_swift_sources {
@@ -185,24 +179,15 @@ pub fn generate_swift_bindings(options: SwiftBindingsOptions) -> Result<()> {
         }
     }
 
-    // find the library name by stripping the extension and leading `lib` from the library path
-    let library_name = {
-        let stem = options
-            .library_path
-            .file_stem()
-            .with_context(|| format!("Invalid library path {}", options.library_path))?;
-        match stem.strip_prefix("lib") {
-            Some(name) => name,
-            None => stem,
-        }
-    };
+    // Derive the default module_name/modulemap_filename from the source filename.
+    let source_basename = loader.source_basename(&options.source);
 
     let module_name = options
         .module_name
-        .unwrap_or_else(|| library_name.to_string());
+        .unwrap_or_else(|| source_basename.to_string());
     let modulemap_filename = options
         .modulemap_filename
-        .unwrap_or_else(|| format!("{library_name}.modulemap"));
+        .unwrap_or_else(|| format!("{source_basename}.modulemap"));
 
     if options.generate_modulemap {
         let mut header_filenames: Vec<_> = components
@@ -223,12 +208,23 @@ pub fn generate_swift_bindings(options: SwiftBindingsOptions) -> Result<()> {
     Ok(())
 }
 
+fn parse_config(ci: &ComponentInterface, root_toml: toml::Value) -> Result<Config> {
+    let mut config: Config = match root_toml.get("bindings").and_then(|b| b.get("swift")) {
+        Some(v) => v.clone().try_into()?,
+        None => Default::default(),
+    };
+    config
+        .module_name
+        .get_or_insert_with(|| ci.namespace().into());
+    Ok(config)
+}
+
 #[derive(Debug, Default)]
 pub struct SwiftBindingsOptions {
     pub generate_swift_sources: bool,
     pub generate_headers: bool,
     pub generate_modulemap: bool,
-    pub library_path: Utf8PathBuf,
+    pub source: Utf8PathBuf,
     pub out_dir: Utf8PathBuf,
     pub xcframework: bool,
     pub module_name: Option<String>,

uniffi_bindgen/src/lib.rs

@@ -104,6 +104,7 @@ use std::process::Command;
 pub mod bindings;
 pub mod interface;
 pub mod library_mode;
+mod loader;
 pub mod macro_metadata;
 pub mod pipeline;
 pub mod scaffolding;
@@ -120,6 +121,8 @@ pub use library_mode::find_components;
 use scaffolding::RustScaffolding;
 use uniffi_meta::Type;
 
+pub use loader::BindgenLoader;
+
 /// The options used when creating bindings. Named such
 /// it doesn't cause confusion that it's settings specific to
 /// the generator itself.

uniffi_bindgen/src/library_mode.rs

@@ -107,10 +107,10 @@ pub fn calc_cdylib_name(library_path: &Utf8Path) -> Option<&str> {
 /// calls.
 ///
 /// `config_supplier` is used to find UDL files on disk and load config data.
-pub fn find_components(
+pub fn find_cis(
     library_path: &Utf8Path,
     config_supplier: &dyn BindgenCrateConfigSupplier,
-) -> Result<Vec<Component<TomlTable>>> {
+) -> Result<Vec<ComponentInterface>> {
     let items = macro_metadata::extract_from_library(library_path)?;
     let mut metadata_groups = create_metadata_groups(&items);
     group_metadata(&mut metadata_groups, items)?;
@@ -137,10 +137,29 @@ pub fn find_components(
             let crate_name = &group.namespace.crate_name;
             let mut ci = ComponentInterface::new(crate_name);
             ci.add_metadata(group)?;
+            ci.set_crate_to_namespace_map(crate_to_namespace_map.clone());
+            Ok(ci)
+        })
+        .collect()
+}
+
+/// Find UniFFI components from a shared library file
+///
+/// This method inspects the library file and creates [ComponentInterface] instances for each
+/// component used to build it.  It parses the UDL files from `uniffi::include_scaffolding!` macro
+/// calls.
+///
+/// `config_supplier` is used to find UDL files on disk and load config data.
+pub fn find_components(
+    library_path: &Utf8Path,
+    config_supplier: &dyn BindgenCrateConfigSupplier,
+) -> Result<Vec<Component<TomlTable>>> {
+    find_cis(library_path, config_supplier)?
+        .into_iter()
+        .map(|ci| {
             let config = config_supplier
                 .get_toml(ci.crate_name())?
                 .unwrap_or_default();
-            ci.set_crate_to_namespace_map(crate_to_namespace_map.clone());
             Ok(Component { ci, config })
         })
         .collect()