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use std::fmt;
use anyhow::Context;
use bimap::BiHashMap;
use guppy::PackageId;
use serde::{Deserializer, Serializer};
use crate::function_pointer::write_fn_pointer_prefix;
use crate::{Lifetime, Type};
/// Configuration for rendering types and generic arguments.
///
/// The two dimensions—[`PathStyle`] and [`LifetimeStyle`]—capture the
/// differences between codegen rendering, inferred-lifetime rendering,
/// and error-message rendering, allowing a single traversal to serve
/// all three use cases.
#[derive(Clone, Copy)]
pub(crate) struct RenderConfig<'a> {
/// How to render the crate-qualified portion of a path type.
pub path: PathStyle<'a>,
/// How to render named lifetime parameters.
pub lifetime: LifetimeStyle,
}
/// Controls how the crate prefix of a [`Type::Path`] is rendered.
#[derive(Clone, Copy)]
pub(crate) enum PathStyle<'a> {
/// Look up the crate name from a package-id-to-name mapping,
/// then join the remaining segments with `::`.
CrateLookup(&'a BiHashMap<PackageId, String>),
/// Join all segments of `base_type` directly with `::`.
Direct,
}
/// Controls how named lifetimes are rendered.
#[derive(Clone, Copy)]
pub(crate) enum LifetimeStyle {
/// Preserve named lifetimes as-is (e.g. `'a` stays `'a`).
Preserve,
/// Replace named and inferred lifetimes with `'_`.
Erase,
}
/// Serialize a [`PackageId`] as its string representation.
pub(crate) fn serialize_package_id<S>(
package_id: &PackageId,
serializer: S,
) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
serializer.serialize_str(package_id.repr())
}
/// Deserialize a [`PackageId`] from its string representation.
pub(crate) fn deserialize_package_id<'de, D>(deserializer: D) -> Result<PackageId, D::Error>
where
D: Deserializer<'de>,
{
let s: &str = serde::de::Deserialize::deserialize(deserializer)?;
Ok(PackageId::new(s))
}
impl Type {
/// Parse this type into a [`syn::Type`], using the provided package-id-to-crate-name mapping.
///
/// Named lifetimes are preserved as-is. Call sites that need `'_` should use
/// [`Type::rename_lifetime_parameters`] beforehand to replace named lifetimes.
pub fn syn_type(&self, id2name: &BiHashMap<PackageId, String>) -> syn::Type {
let type_ = self.render_type(id2name);
syn::parse_str(&type_).unwrap()
}
/// Render this type as a Rust source string, preserving named lifetimes as-is.
pub fn render_type(&self, id2name: &BiHashMap<PackageId, String>) -> String {
let mut buffer = String::new();
self.render_type_into(id2name, &mut buffer);
buffer
}
/// Like [`Type::render_type`], but writes into an existing buffer instead of allocating.
pub fn render_type_into(&self, id2name: &BiHashMap<PackageId, String>, buffer: &mut String) {
let config = RenderConfig {
path: PathStyle::CrateLookup(id2name),
lifetime: LifetimeStyle::Preserve,
};
self.render_into(&config, buffer);
}
/// Render this type as a Rust source string, replacing named lifetimes with `'_`.
///
/// Use this when the type appears in a codegen expression context where the
/// original named lifetimes are not in scope.
pub fn render_with_inferred_lifetimes(&self, id2name: &BiHashMap<PackageId, String>) -> String {
let mut buffer = String::new();
self.render_with_inferred_lifetimes_into(id2name, &mut buffer);
buffer
}
/// Like [`Type::render_with_inferred_lifetimes`], but writes into an existing buffer
/// instead of allocating.
pub fn render_with_inferred_lifetimes_into(
&self,
id2name: &BiHashMap<PackageId, String>,
buffer: &mut String,
) {
let config = RenderConfig {
path: PathStyle::CrateLookup(id2name),
lifetime: LifetimeStyle::Erase,
};
self.render_into(&config, buffer);
}
/// Format this type for display in user-facing error messages.
pub fn display_for_error(&self) -> String {
let mut s = String::new();
self.display_for_error_into(&mut s);
s
}
/// Like [`Type::display_for_error`], but writes into an existing buffer instead of
/// allocating.
pub fn display_for_error_into<W: fmt::Write>(&self, buffer: &mut W) {
let config = RenderConfig {
path: PathStyle::Direct,
lifetime: LifetimeStyle::Preserve,
};
self.render_into(&config, buffer);
}
/// Render this type into `buffer` according to `config`.
///
/// This is the single implementation behind [`Type::render_type_into`],
/// [`Type::render_with_inferred_lifetimes_into`], and [`Type::display_for_error_into`].
pub(crate) fn render_into<W: fmt::Write>(&self, config: &RenderConfig<'_>, buffer: &mut W) {
match self {
Type::Path(t) | Type::TypeAlias(t) => {
match config.path {
PathStyle::CrateLookup(id2name) => {
let crate_name = id2name
.get_by_left(&t.package_id)
.with_context(|| {
format!(
"The package id '{}' is missing from the id<>name mapping for crates.",
t.package_id
)
})
.unwrap();
write!(buffer, "{crate_name}").unwrap();
write!(buffer, "::{}", t.base_type[1..].join("::")).unwrap();
}
PathStyle::Direct => {
write!(buffer, "{}", t.base_type.join("::")).unwrap();
}
}
if !t.generic_arguments.is_empty() {
write!(buffer, "<").unwrap();
let mut arguments = t.generic_arguments.iter().peekable();
while let Some(argument) = arguments.next() {
argument.render_into(config, buffer);
if arguments.peek().is_some() {
write!(buffer, ", ").unwrap();
}
}
write!(buffer, ">").unwrap();
}
}
Type::Reference(r) => {
write!(buffer, "&").unwrap();
match &r.lifetime {
Lifetime::Static => {
write!(buffer, "'static ").unwrap();
}
Lifetime::Named(l) => match config.lifetime {
LifetimeStyle::Preserve => {
write!(buffer, "'{} ", l.as_str()).unwrap();
}
LifetimeStyle::Erase => {
write!(buffer, "'_ ").unwrap();
}
},
Lifetime::Inferred => {
write!(buffer, "'_ ").unwrap();
}
Lifetime::Elided => {}
}
if r.is_mutable {
write!(buffer, "mut ").unwrap();
}
r.inner.render_into(config, buffer);
}
Type::Tuple(t) => {
write!(buffer, "(").unwrap();
let mut elements = t.elements.iter().peekable();
while let Some(element) = elements.next() {
element.render_into(config, buffer);
if elements.peek().is_some() {
write!(buffer, ", ").unwrap();
}
}
write!(buffer, ")").unwrap();
}
Type::ScalarPrimitive(s) => {
write!(buffer, "{s}").unwrap();
}
Type::Slice(s) => {
write!(buffer, "[").unwrap();
s.element_type.render_into(config, buffer);
write!(buffer, "]").unwrap();
}
Type::Array(a) => {
write!(buffer, "[").unwrap();
a.element_type.render_into(config, buffer);
write!(buffer, "; {}]", a.len).unwrap();
}
Type::RawPointer(r) => {
if r.is_mutable {
write!(buffer, "*mut ").unwrap();
} else {
write!(buffer, "*const ").unwrap();
}
r.inner.render_into(config, buffer);
}
Type::FunctionPointer(fp) => {
write_fn_pointer_prefix(buffer, &fp.abi, fp.is_unsafe).unwrap();
write!(buffer, "fn(").unwrap();
let mut inputs = fp.inputs.iter().peekable();
while let Some(input) = inputs.next() {
if let Some(name) = &input.name {
write!(buffer, "{name}: ").unwrap();
}
input.type_.render_into(config, buffer);
if inputs.peek().is_some() {
write!(buffer, ", ").unwrap();
}
}
write!(buffer, ")").unwrap();
if let Some(output) = &fp.output {
write!(buffer, " -> ").unwrap();
output.render_into(config, buffer);
}
}
Type::Generic(t) => {
write!(buffer, "{}", t.name).unwrap();
}
}
}
}
impl fmt::Display for Type {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.display_for_error_into(f);
Ok(())
}
}