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//! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
use rustc_hash::FxHashMap;
use hir::{PathResolution, SemanticsScope};
use ra_ide_db::RootDatabase;
use ra_syntax::ast::{self, AstNode};
pub trait AstTransform<'a> {
fn get_substitution(&self, node: &ra_syntax::SyntaxNode) -> Option<ra_syntax::SyntaxNode>;
fn chain_before(self, other: Box<dyn AstTransform<'a> + 'a>) -> Box<dyn AstTransform<'a> + 'a>;
fn or<T: AstTransform<'a> + 'a>(self, other: T) -> Box<dyn AstTransform<'a> + 'a>
where
Self: Sized + 'a,
{
self.chain_before(Box::new(other))
}
}
struct NullTransformer;
impl<'a> AstTransform<'a> for NullTransformer {
fn get_substitution(&self, _node: &ra_syntax::SyntaxNode) -> Option<ra_syntax::SyntaxNode> {
None
}
fn chain_before(self, other: Box<dyn AstTransform<'a> + 'a>) -> Box<dyn AstTransform<'a> + 'a> {
other
}
}
pub struct SubstituteTypeParams<'a> {
source_scope: &'a SemanticsScope<'a, RootDatabase>,
substs: FxHashMap<hir::TypeParam, ast::TypeRef>,
previous: Box<dyn AstTransform<'a> + 'a>,
}
impl<'a> SubstituteTypeParams<'a> {
pub fn for_trait_impl(
source_scope: &'a SemanticsScope<'a, RootDatabase>,
db: &'a RootDatabase,
// FIXME: there's implicit invariant that `trait_` and `source_scope` match...
trait_: hir::Trait,
impl_def: ast::ImplDef,
) -> SubstituteTypeParams<'a> {
let substs = get_syntactic_substs(impl_def).unwrap_or_default();
let generic_def: hir::GenericDef = trait_.into();
let substs_by_param: FxHashMap<_, _> = generic_def
.params(db)
.into_iter()
// this is a trait impl, so we need to skip the first type parameter -- this is a bit hacky
.skip(1)
.zip(substs.into_iter())
.collect();
return SubstituteTypeParams {
source_scope,
substs: substs_by_param,
previous: Box::new(NullTransformer),
};
// FIXME: It would probably be nicer if we could get this via HIR (i.e. get the
// trait ref, and then go from the types in the substs back to the syntax)
fn get_syntactic_substs(impl_def: ast::ImplDef) -> Option<Vec<ast::TypeRef>> {
let target_trait = impl_def.target_trait()?;
let path_type = match target_trait {
ast::TypeRef::PathType(path) => path,
_ => return None,
};
let type_arg_list = path_type.path()?.segment()?.type_arg_list()?;
let mut result = Vec::new();
for type_arg in type_arg_list.type_args() {
let type_arg: ast::TypeArg = type_arg;
result.push(type_arg.type_ref()?);
}
Some(result)
}
}
fn get_substitution_inner(
&self,
node: &ra_syntax::SyntaxNode,
) -> Option<ra_syntax::SyntaxNode> {
let type_ref = ast::TypeRef::cast(node.clone())?;
let path = match &type_ref {
ast::TypeRef::PathType(path_type) => path_type.path()?,
_ => return None,
};
let path = hir::Path::from_ast(path)?;
let resolution = self.source_scope.resolve_hir_path(&path)?;
match resolution {
hir::PathResolution::TypeParam(tp) => Some(self.substs.get(&tp)?.syntax().clone()),
_ => None,
}
}
}
impl<'a> AstTransform<'a> for SubstituteTypeParams<'a> {
fn get_substitution(&self, node: &ra_syntax::SyntaxNode) -> Option<ra_syntax::SyntaxNode> {
self.get_substitution_inner(node).or_else(|| self.previous.get_substitution(node))
}
fn chain_before(self, other: Box<dyn AstTransform<'a> + 'a>) -> Box<dyn AstTransform<'a> + 'a> {
Box::new(SubstituteTypeParams { previous: other, ..self })
}
}
pub struct QualifyPaths<'a> {
target_scope: &'a SemanticsScope<'a, RootDatabase>,
source_scope: &'a SemanticsScope<'a, RootDatabase>,
db: &'a RootDatabase,
previous: Box<dyn AstTransform<'a> + 'a>,
}
impl<'a> QualifyPaths<'a> {
pub fn new(
target_scope: &'a SemanticsScope<'a, RootDatabase>,
source_scope: &'a SemanticsScope<'a, RootDatabase>,
db: &'a RootDatabase,
) -> Self {
Self { target_scope, source_scope, db, previous: Box::new(NullTransformer) }
}
fn get_substitution_inner(
&self,
node: &ra_syntax::SyntaxNode,
) -> Option<ra_syntax::SyntaxNode> {
// FIXME handle value ns?
let from = self.target_scope.module()?;
let p = ast::Path::cast(node.clone())?;
if p.segment().and_then(|s| s.param_list()).is_some() {
// don't try to qualify `Fn(Foo) -> Bar` paths, they are in prelude anyway
return None;
}
let hir_path = hir::Path::from_ast(p.clone());
let resolution = self.source_scope.resolve_hir_path(&hir_path?)?;
match resolution {
PathResolution::Def(def) => {
let found_path = from.find_use_path(self.db, def)?;
let mut path = path_to_ast(found_path);
let type_args = p
.segment()
.and_then(|s| s.type_arg_list())
.map(|arg_list| apply(self, arg_list));
if let Some(type_args) = type_args {
let last_segment = path.segment().unwrap();
path = path.with_segment(last_segment.with_type_args(type_args))
}
Some(path.syntax().clone())
}
PathResolution::Local(_)
| PathResolution::TypeParam(_)
| PathResolution::SelfType(_) => None,
PathResolution::Macro(_) => None,
PathResolution::AssocItem(_) => None,
}
}
}
pub fn apply<'a, N: AstNode>(transformer: &dyn AstTransform<'a>, node: N) -> N {
let syntax = node.syntax();
let result = ra_syntax::algo::replace_descendants(syntax, |element| match element {
ra_syntax::SyntaxElement::Node(n) => {
let replacement = transformer.get_substitution(&n)?;
Some(replacement.into())
}
_ => None,
});
N::cast(result).unwrap()
}
impl<'a> AstTransform<'a> for QualifyPaths<'a> {
fn get_substitution(&self, node: &ra_syntax::SyntaxNode) -> Option<ra_syntax::SyntaxNode> {
self.get_substitution_inner(node).or_else(|| self.previous.get_substitution(node))
}
fn chain_before(self, other: Box<dyn AstTransform<'a> + 'a>) -> Box<dyn AstTransform<'a> + 'a> {
Box::new(QualifyPaths { previous: other, ..self })
}
}
pub(crate) fn path_to_ast(path: hir::ModPath) -> ast::Path {
let parse = ast::SourceFile::parse(&path.to_string());
parse.tree().syntax().descendants().find_map(ast::Path::cast).unwrap()
}
|
