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use super::{GenerateMod, Impl, ImplFor, StreamBuilder};
use crate::parse::{GenericConstraints, Generics};
use crate::prelude::{Ident, TokenStream};
#[must_use]
/// The generator is used to generate code.
///
/// Often you will want to use [`impl_for`] to generate an `impl <trait_name> for <target_name()>`.
///
/// [`impl_for`]: #method.impl_for
pub struct Generator {
pub(crate) name: Ident,
pub(crate) generics: Option<Generics>,
pub(crate) generic_constraints: Option<GenericConstraints>,
pub(crate) stream: StreamBuilder,
}
impl Generator {
pub(crate) fn new(
name: Ident,
generics: Option<Generics>,
generic_constraints: Option<GenericConstraints>,
) -> Self {
Self {
name,
generics,
generic_constraints,
stream: StreamBuilder::new(),
}
}
/// Return the name for the struct or enum that this is going to be implemented on.
pub fn target_name(&self) -> Ident {
self.name.clone()
}
/// Generate an `impl <target_name>` implementation. See [`Impl`] for more information.
pub fn r#impl(&mut self) -> Impl<Self> {
Impl::with_parent_name(self)
}
/// Generate an `impl <target_name>` implementation. See [`Impl`] for more information.
///
/// Alias for [`impl`] which doesn't need a `r#` prefix.
///
/// [`impl`]: #method.impl
pub fn generate_impl(&mut self) -> Impl<Self> {
Impl::with_parent_name(self)
}
/// Generate an `for <trait_name> for <target_name>` implementation. See [ImplFor] for more information.
pub fn impl_for(&mut self, trait_name: impl Into<String>) -> ImplFor<Self> {
ImplFor::new(self, trait_name)
}
/// Generate an `for <..lifetimes> <trait_name> for <target_name>` implementation. See [ImplFor] for more information.
///
/// Note:
/// - Lifetimes should _not_ have the leading apostrophe.
/// - The lifetimes passed to this function will automatically depend on any other lifetime this struct or enum may have. Example:
/// - The struct is `struct Foo<'a> {}`
/// - You call `generator.impl_for_with_lifetime("Bar", &["b"])
/// - The code will be `impl<'a, 'b: 'a> Bar<'b> for Foo<'a> {}`
/// - `trait_name` should _not_ have custom lifetimes. These will be added automatically.
///
/// ```no_run
/// # use virtue::prelude::*;
/// # let mut generator: Generator = unsafe { std::mem::zeroed() };
/// generator.impl_for_with_lifetimes("Foo", ["a", "b"]);
///
/// // will output:
/// // impl<'a, 'b> Foo<'a, 'b> for StructOrEnum { }
/// ```
pub fn impl_for_with_lifetimes<ITER, T>(
&mut self,
trait_name: T,
lifetimes: ITER,
) -> ImplFor<Self>
where
ITER: IntoIterator,
ITER::Item: Into<String>,
T: Into<String>,
{
ImplFor::new_with_lifetimes(self, trait_name, lifetimes)
}
/// Generate a `mod <name> { ... }`. See [`GenerateMod`] for more info.
pub fn generate_mod(&mut self, mod_name: impl Into<String>) -> GenerateMod<Self> {
GenerateMod::new(self, mod_name)
}
/// Export the current stream to a file, making it very easy to debug the output of a derive macro.
/// This will try to find rust's `target` directory, and write `target/generated/<crate_name>/<name>_<file_postfix>.rs`.
///
/// Will return `true` if the file is written, `false` otherwise.
///
/// The outputted file is unformatted. Use `cargo fmt -- target/generated/<crate_name>/<file>.rs` to format the file.
pub fn export_to_file(&self, crate_name: &str, file_postfix: &str) -> bool {
use std::io::Write;
if let Ok(var) = std::env::var("CARGO_MANIFEST_DIR") {
let mut path = std::path::PathBuf::from(var);
loop {
{
let mut path = path.clone();
path.push("target");
if path.exists() {
path.push("generated");
path.push(crate_name);
if std::fs::create_dir_all(&path).is_err() {
return false;
}
path.push(format!("{}_{}.rs", self.target_name(), file_postfix));
if let Ok(mut file) = std::fs::File::create(path) {
let _ = file.write_all(self.stream.stream.to_string().as_bytes());
return true;
}
}
}
if let Some(parent) = path.parent() {
path = parent.to_owned();
} else {
break;
}
}
}
false
}
/// Consume the contents of this generator. This *must* be called, or else the generator will panic on drop.
pub fn finish(mut self) -> crate::prelude::Result<TokenStream> {
Ok(std::mem::take(&mut self.stream).stream)
}
}
impl Drop for Generator {
fn drop(&mut self) {
if !self.stream.stream.is_empty() && !std::thread::panicking() {
eprintln!("WARNING: Generator dropped but the stream is not empty. Please call `.finish()` on the generator");
}
}
}
impl super::Parent for Generator {
fn append(&mut self, builder: StreamBuilder) {
self.stream.append(builder);
}
fn name(&self) -> &Ident {
&self.name
}
fn generics(&self) -> Option<&Generics> {
self.generics.as_ref()
}
fn generic_constraints(&self) -> Option<&GenericConstraints> {
self.generic_constraints.as_ref()
}
}
#[cfg(test)]
mod test {
use proc_macro2::Span;
use crate::token_stream;
use super::*;
#[test]
fn impl_for_with_lifetimes() {
// No generics
let mut generator =
Generator::new(Ident::new("StructOrEnum", Span::call_site()), None, None);
let _ = generator.impl_for_with_lifetimes("Foo", ["a", "b"]);
let output = generator.finish().unwrap();
assert_eq!(
output
.into_iter()
.map(|v| v.to_string())
.collect::<String>(),
token_stream("impl<'a, 'b> Foo<'a, 'b> for StructOrEnum { }")
.map(|v| v.to_string())
.collect::<String>(),
);
//with simple generics
let mut generator = Generator::new(
Ident::new("StructOrEnum", Span::call_site()),
Generics::try_take(&mut token_stream("<T1, T2>")).unwrap(),
None,
);
let _ = generator.impl_for_with_lifetimes("Foo", ["a", "b"]);
let output = generator.finish().unwrap();
assert_eq!(
output
.into_iter()
.map(|v| v.to_string())
.collect::<String>(),
token_stream("impl<'a, 'b, T1, T2> Foo<'a, 'b> for StructOrEnum<T1, T2> { }")
.map(|v| v.to_string())
.collect::<String>()
);
// with lifetimes
let mut generator = Generator::new(
Ident::new("StructOrEnum", Span::call_site()),
Generics::try_take(&mut token_stream("<'alpha, 'beta>")).unwrap(),
None,
);
let _ = generator.impl_for_with_lifetimes("Foo", ["a", "b"]);
let output = generator.finish().unwrap();
assert_eq!(
output
.into_iter()
.map(|v| v.to_string())
.collect::<String>(),
token_stream(
"impl<'a, 'b, 'alpha, 'beta> Foo<'a, 'b> for StructOrEnum<'alpha, 'beta> { }"
)
.map(|v| v.to_string())
.collect::<String>()
);
}
}