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|
use arrayvec::ArrayVec;
use ra_text_edit::{TextEdit, TextEditBuilder};
use ra_syntax::{AstNode, TreeArc, ast, SyntaxKind::*, SyntaxElement, SourceFile, InsertPosition, Direction};
pub struct AstEditor<N: AstNode> {
original_ast: TreeArc<N>,
ast: TreeArc<N>,
}
impl<N: AstNode> AstEditor<N> {
pub fn new(node: &N) -> AstEditor<N> {
AstEditor { original_ast: node.to_owned(), ast: node.to_owned() }
}
pub fn into_text_edit(self) -> TextEdit {
// FIXME: compute a more fine-grained diff here.
// If *you* know a nice algorithm to compute diff between two syntax
// tree, tell me about it!
let mut builder = TextEditBuilder::default();
builder.replace(self.original_ast.syntax().range(), self.ast().syntax().text().to_string());
builder.finish()
}
pub fn ast(&self) -> &N {
&*self.ast
}
}
impl AstEditor<ast::NamedFieldList> {
pub fn append_field(&mut self, field: &ast::NamedField) {
self.insert_field(InsertPosition::Last, field)
}
pub fn insert_field(
&mut self,
position: InsertPosition<&'_ ast::NamedField>,
field: &ast::NamedField,
) {
let mut to_insert: ArrayVec<[SyntaxElement; 2]> =
[field.syntax().into(), tokens::comma().into()].into();
let position = match position {
InsertPosition::First => {
let anchor = match self
.ast()
.syntax()
.children_with_tokens()
.find(|it| it.kind() == L_CURLY)
{
Some(it) => it,
None => return,
};
InsertPosition::After(anchor)
}
InsertPosition::Last => {
let anchor = match self
.ast()
.syntax()
.children_with_tokens()
.find(|it| it.kind() == R_CURLY)
{
Some(it) => it,
None => return,
};
InsertPosition::Before(anchor)
}
InsertPosition::Before(anchor) => InsertPosition::Before(anchor.syntax().into()),
InsertPosition::After(anchor) => {
if let Some(comma) = anchor
.syntax()
.siblings_with_tokens(Direction::Next)
.find(|it| it.kind() == COMMA)
{
InsertPosition::After(comma)
} else {
to_insert.insert(0, tokens::comma().into());
InsertPosition::After(anchor.syntax().into())
}
}
};
self.ast = insert_children_into_ast(self.ast(), position, to_insert.iter().cloned());
}
}
fn insert_children_into_ast<'a, N: AstNode>(
node: &N,
position: InsertPosition<SyntaxElement<'_>>,
to_insert: impl Iterator<Item = SyntaxElement<'a>>,
) -> TreeArc<N> {
let new_syntax = node.syntax().insert_children(position, to_insert);
N::cast(&new_syntax).unwrap().to_owned()
}
pub struct AstBuilder<N: AstNode> {
_phantom: std::marker::PhantomData<N>,
}
impl AstBuilder<ast::NamedField> {
pub fn from_text(text: &str) -> TreeArc<ast::NamedField> {
ast_node_from_file_text(&format!("fn f() {{ S {{ {}, }} }}", text))
}
}
fn ast_node_from_file_text<N: AstNode>(text: &str) -> TreeArc<N> {
let file = SourceFile::parse(text);
let res = file.syntax().descendants().find_map(N::cast).unwrap().to_owned();
res
}
mod tokens {
use lazy_static::lazy_static;
use ra_syntax::{AstNode, SourceFile, TreeArc, SyntaxToken, SyntaxKind::*};
lazy_static! {
static ref SOURCE_FILE: TreeArc<SourceFile> = SourceFile::parse(",");
}
pub(crate) fn comma() -> SyntaxToken<'static> {
SOURCE_FILE
.syntax()
.descendants_with_tokens()
.filter_map(|it| it.as_token())
.find(|it| it.kind() == COMMA)
.unwrap()
}
}
#[cfg(test)]
mod tests {
use super::*;
use ra_syntax::SourceFile;
#[test]
fn structure_editing() {
let file = SourceFile::parse(
"\
fn foo() {
let s = S {
original: 92,
}
}
",
);
let field_list = file.syntax().descendants().find_map(ast::NamedFieldList::cast).unwrap();
let mut editor = AstEditor::new(field_list);
let field = AstBuilder::<ast::NamedField>::from_text("first_inserted: 1");
editor.append_field(&field);
let field = AstBuilder::<ast::NamedField>::from_text("second_inserted: 2");
editor.append_field(&field);
eprintln!("{}", editor.ast().syntax());
}
}
|
