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//! This crate provides some utilities for indenting rust code.
use std::iter::successors;
use syntax::{
ast::{self, AstToken},
SmolStr, SyntaxKind,
SyntaxKind::*,
SyntaxNode, SyntaxToken, T,
};
/// If the node is on the beginning of the line, calculate indent.
pub fn leading_indent(node: &SyntaxNode) -> Option<SmolStr> {
for token in prev_tokens(node.first_token()?) {
if let Some(ws) = ast::Whitespace::cast(token.clone()) {
let ws_text = ws.text();
if let Some(pos) = ws_text.rfind('\n') {
return Some(ws_text[pos + 1..].into());
}
}
if token.text().contains('\n') {
break;
}
}
None
}
fn prev_tokens(token: SyntaxToken) -> impl Iterator<Item = SyntaxToken> {
successors(token.prev_token(), |token| token.prev_token())
}
pub fn compute_ws(left: SyntaxKind, right: SyntaxKind) -> &'static str {
match left {
T!['('] | T!['['] => return "",
T!['{'] => {
if let USE_TREE = right {
return "";
}
}
_ => (),
}
match right {
T![')'] | T![']'] => return "",
T!['}'] => {
if let USE_TREE = left {
return "";
}
}
T![.] => return "",
_ => (),
}
" "
}
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