Update the BindingGenerator trait and remove BindingsConfig.

This is a breaking change for BindingGenerators, and follows up on
other breaking changes made for this release (#2078). Between them,
it is intended to offer a better framework for binding generators
for future versions and break unintentional coupling between
uniffi_bindgen and the builtin bindings.

This patch updates the `BindingGenerator` trait to give binding generators
more control over the binding generation process and to simplify the
interactions between the generator and `uniffi_bindgen`.

The trait `BindingsConfig` has been removed and replaced with a new
method on `BindingGenerator` which passes the generator the entire
list of all `ComponentInterface` and `Config` objects to be used in the
generation, which the generator can modify as necessary. The binding
generator is also passed the entire list of items to generate rather
than called once per item - this gives the generator more flexibility
in how the items are generated.

A new `Component` struct has been introduced which holds all necessary
information for a single crate/namespace, including the `ComponentInterface`
and `Config`. These structs are passed to the `BindingGenerator`

A new `GenerationSettings` struct is defined to pass options to the generators.

CHANGELOG.md

@@ -21,9 +21,9 @@
 
 ### What's changed?
 - The internal bindings generation has changed to make it friendlier for external language bindings.
-  However, this is likely to be a small **breaking change** for these bindings.
+  However, this a **breaking change** for these bindings.
   No consumers of any languages are impacted, only the maintainers of these language bindings.
-  ([#2066](https://github.com/mozilla/uniffi-rs/issues/2066))
+  ([#2066](https://github.com/mozilla/uniffi-rs/issues/2066)), ([#2094](https://github.com/mozilla/uniffi-rs/pull/2094))
 
 - The async runtime can be specified for constructors/methods, this will override the runtime specified at the impl block level.
 

uniffi/src/cli.rs

@@ -141,6 +141,14 @@ fn gen_library_mode(
 ) -> anyhow::Result<()> {
     use uniffi_bindgen::library_mode::generate_bindings;
     for language in languages {
+        // to help avoid mistakes we check the library is actually a cdylib, except
+        // for swift where static libs are often used to extract the metadata.
+        if !matches!(language, TargetLanguage::Swift) && !uniffi_bindgen::is_cdylib(library_path) {
+            anyhow::bail!(
+                "Generate bindings for {language} requires a cdylib, but {library_path} was given"
+            );
+        }
+
         // Type-bounds on trait implementations makes selecting between languages a bit tedious.
         match language {
             TargetLanguage::Kotlin => generate_bindings(

uniffi_bindgen/src/bindings/kotlin/gen_kotlin/mod.rs

@@ -16,7 +16,6 @@ use serde::{Deserialize, Serialize};
 use crate::backend::TemplateExpression;
 
 use crate::interface::*;
-use crate::BindingsConfig;
 
 mod callback_interface;
 mod compounds;
@@ -72,13 +71,13 @@ trait CodeType: Debug {
 // config options to customize the generated Kotlin.
 #[derive(Debug, Default, Clone, Serialize, Deserialize)]
 pub struct Config {
-    package_name: Option<String>,
-    cdylib_name: Option<String>,
+    pub(super) package_name: Option<String>,
+    pub(super) cdylib_name: Option<String>,
     generate_immutable_records: Option<bool>,
     #[serde(default)]
     custom_types: HashMap<String, CustomTypeConfig>,
     #[serde(default)]
-    external_packages: HashMap<String, String>,
+    pub(super) external_packages: HashMap<String, String>,
     #[serde(default)]
     android: bool,
     #[serde(default)]
@@ -122,29 +121,6 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.package_name
-            .get_or_insert_with(|| format!("uniffi.{}", ci.namespace()));
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-
-    fn update_from_dependency_configs(&mut self, config_map: HashMap<&str, &Self>) {
-        for (crate_name, config) in config_map {
-            if !self.external_packages.contains_key(crate_name) {
-                self.external_packages
-                    .insert(crate_name.to_string(), config.package_name());
-            }
-        }
-    }
-}
-
 // Generate kotlin bindings for the given ComponentInterface, as a string.
 pub fn generate_bindings(config: &Config, ci: &ComponentInterface) -> Result<String> {
     KotlinWrapper::new(config.clone(), ci)

uniffi_bindgen/src/bindings/kotlin/mod.rs

@@ -2,10 +2,11 @@
  * 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 crate::{BindingGenerator, ComponentInterface};
+use crate::{BindingGenerator, Component, GenerationSettings};
 use anyhow::Result;
 use camino::{Utf8Path, Utf8PathBuf};
 use fs_err as fs;
+use std::collections::HashMap;
 use std::process::Command;
 
 mod gen_kotlin;
@@ -26,33 +27,58 @@ impl BindingGenerator for KotlinBindingGenerator {
         )
     }
 
-    fn write_bindings(
+    fn update_component_configs(
         &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
     ) -> Result<()> {
-        let mut kt_file = full_bindings_path(config, out_dir);
-        fs::create_dir_all(&kt_file)?;
-        kt_file.push(format!("{}.kt", ci.namespace()));
-        fs::write(&kt_file, generate_bindings(config, ci)?)?;
-        if try_format_code {
-            if let Err(e) = Command::new("ktlint").arg("-F").arg(&kt_file).output() {
-                println!(
-                    "Warning: Unable to auto-format {} using ktlint: {e:?}",
-                    kt_file.file_name().unwrap(),
-                );
+        for c in &mut *components {
+            c.config
+                .package_name
+                .get_or_insert_with(|| format!("uniffi.{}", c.ci.namespace()));
+            c.config.cdylib_name.get_or_insert_with(|| {
+                settings.cdylib.clone()
+                    .unwrap_or_else(|| format!("uniffi_{}", c.ci.namespace()))
+            });
+        }
+        // We need to update package names
+        let packages = HashMap::<String, String>::from_iter(
+            components
+                .iter()
+                .map(|c| (c.ci.crate_name().to_string(), c.config.package_name())),
+        );
+        for c in components {
+            for (ext_crate, ext_package) in &packages {
+                if ext_crate != c.ci.crate_name()
+                    && !c.config.external_packages.contains_key(ext_crate)
+                {
+                    c.config
+                        .external_packages
+                        .insert(ext_crate.to_string(), ext_package.clone());
+                }
             }
         }
         Ok(())
     }
 
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        if cdylib_name.is_none() {
-            anyhow::bail!(
-                "Generate bindings for Kotlin requires a cdylib, but {library_path} was given"
-            );
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let mut kt_file = full_bindings_path(config, &settings.out_dir);
+            fs::create_dir_all(&kt_file)?;
+            kt_file.push(format!("{}.kt", ci.namespace()));
+            fs::write(&kt_file, generate_bindings(config, ci)?)?;
+            if settings.try_format_code {
+                if let Err(e) = Command::new("ktlint").arg("-F").arg(&kt_file).output() {
+                    println!(
+                        "Warning: Unable to auto-format {} using ktlint: {e:?}",
+                        kt_file.file_name().unwrap(),
+                    );
+                }
+            }
         }
         Ok(())
     }

uniffi_bindgen/src/bindings/python/gen_python/mod.rs

@@ -16,7 +16,6 @@ use std::fmt::Debug;
 use crate::backend::TemplateExpression;
 
 use crate::interface::*;
-use crate::BindingsConfig;
 
 mod callback_interface;
 mod compounds;
@@ -112,7 +111,7 @@ static KEYWORDS: Lazy<HashSet<String>> = Lazy::new(|| {
 // Config options to customize the generated python.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct Config {
-    cdylib_name: Option<String>,
+    pub(super) cdylib_name: Option<String>,
     #[serde(default)]
     custom_types: HashMap<String, CustomTypeConfig>,
     #[serde(default)]
@@ -148,18 +147,6 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-}
-
 // Generate python bindings for the given ComponentInterface, as a string.
 pub fn generate_python_bindings(config: &Config, ci: &ComponentInterface) -> Result<String> {
     PythonWrapper::new(config.clone(), ci)

uniffi_bindgen/src/bindings/python/mod.rs

@@ -5,12 +5,11 @@
 use std::process::Command;
 
 use anyhow::Result;
-use camino::Utf8Path;
 use fs_err as fs;
 
 mod gen_python;
 mod test;
-use super::super::interface::ComponentInterface;
+use crate::{Component, GenerationSettings};
 use gen_python::{generate_python_bindings, Config};
 pub use test::{run_script, run_test};
 
@@ -28,34 +27,39 @@ impl crate::BindingGenerator for PythonBindingGenerator {
         )
     }
 
-    fn write_bindings(
+    fn update_component_configs(
         &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
     ) -> Result<()> {
-        let py_file = out_dir.join(format!("{}.py", ci.namespace()));
-        fs::write(&py_file, generate_python_bindings(config, ci)?)?;
-
-        if try_format_code {
-            if let Err(e) = Command::new("yapf").arg(&py_file).output() {
-                println!(
-                    "Warning: Unable to auto-format {} using yapf: {e:?}",
-                    py_file.file_name().unwrap(),
-                )
-            }
+        for c in &mut *components {
+            c.config.cdylib_name.get_or_insert_with(|| {
+                settings.cdylib.clone()
+                    .unwrap_or_else(|| format!("uniffi_{}", c.ci.namespace()))
+            });
         }
-
         Ok(())
     }
 
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        if cdylib_name.is_none() {
-            anyhow::bail!(
-                "Generate bindings for Python requires a cdylib, but {library_path} was given"
-            );
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let py_file = settings.out_dir.join(format!("{}.py", ci.namespace()));
+            fs::write(&py_file, generate_python_bindings(config, ci)?)?;
+
+            if settings.try_format_code {
+                if let Err(e) = Command::new("yapf").arg(&py_file).output() {
+                    println!(
+                        "Warning: Unable to auto-format {} using yapf: {e:?}",
+                        py_file.file_name().unwrap(),
+                    )
+                }
+            }
         }
+
         Ok(())
     }
 }

uniffi_bindgen/src/bindings/ruby/gen_ruby/mod.rs

@@ -10,7 +10,6 @@ use serde::{Deserialize, Serialize};
 use std::borrow::Borrow;
 
 use crate::interface::*;
-use crate::BindingsConfig;
 
 const RESERVED_WORDS: &[&str] = &[
     "alias", "and", "BEGIN", "begin", "break", "case", "class", "def", "defined?", "do", "else",
@@ -82,7 +81,7 @@ pub fn canonical_name(t: &Type) -> String {
 // since the details of the underlying component are entirely determined by the `ComponentInterface`.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct Config {
-    cdylib_name: Option<String>,
+    pub(super) cdylib_name: Option<String>,
     cdylib_path: Option<String>,
 }
 
@@ -102,18 +101,6 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-}
-
 #[derive(Template)]
 #[template(syntax = "rb", escape = "none", path = "wrapper.rb")]
 pub struct RubyWrapper<'a> {

uniffi_bindgen/src/bindings/ruby/mod.rs

@@ -4,9 +4,8 @@
 
 use std::process::Command;
 
-use crate::{BindingGenerator, ComponentInterface};
+use crate::{BindingGenerator, Component, ComponentInterface, GenerationSettings};
 use anyhow::{Context, Result};
-use camino::Utf8Path;
 use fs_err as fs;
 
 mod gen_ruby;
@@ -27,33 +26,37 @@ impl BindingGenerator for RubyBindingGenerator {
         )
     }
 
-    fn write_bindings(
+    fn update_component_configs(
         &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
     ) -> Result<()> {
-        let rb_file = out_dir.join(format!("{}.rb", ci.namespace()));
-        fs::write(&rb_file, generate_ruby_bindings(config, ci)?)?;
-
-        if try_format_code {
-            if let Err(e) = Command::new("rubocop").arg("-A").arg(&rb_file).output() {
-                println!(
-                    "Warning: Unable to auto-format {} using rubocop: {e:?}",
-                    rb_file.file_name().unwrap(),
-                )
-            }
+        for c in &mut *components {
+            c.config.cdylib_name.get_or_insert_with(|| {
+                settings.cdylib.clone()
+                    .unwrap_or_else(|| format!("uniffi_{}", c.ci.namespace()))
+            });
         }
-
         Ok(())
     }
 
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        if cdylib_name.is_none() {
-            anyhow::bail!(
-                "Generate bindings for Ruby requires a cdylib, but {library_path} was given"
-            );
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let rb_file = settings.out_dir.join(format!("{}.rb", ci.namespace()));
+            fs::write(&rb_file, generate_ruby_bindings(config, ci)?)?;
+
+            if settings.try_format_code {
+                if let Err(e) = Command::new("rubocop").arg("-A").arg(&rb_file).output() {
+                    println!(
+                        "Warning: Unable to auto-format {} using rubocop: {e:?}",
+                        rb_file.file_name().unwrap(),
+                    )
+                }
+            }
         }
         Ok(())
     }