rust-analyzer/crates/ra_fmt/src/lib.rs

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//! This crate provides some utilities for indenting rust code.
//!
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use itertools::Itertools;
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use ra_syntax::{
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ast::{self, AstNode, AstToken},
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SmolStr, SyntaxKind,
SyntaxKind::*,
SyntaxNode, SyntaxToken, T,
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};
use std::iter::successors;
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pub fn reindent(text: &str, indent: &str) -> String {
let indent = format!("\n{}", indent);
text.lines().intersperse(&indent).collect()
}
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/// If the node is on the beginning of the line, calculate indent.
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pub fn leading_indent(node: &SyntaxNode) -> Option<SmolStr> {
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for token in prev_tokens(node.first_token()?) {
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if let Some(ws) = ast::Whitespace::cast(token.clone()) {
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let ws_text = ws.text();
if let Some(pos) = ws_text.rfind('\n') {
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return Some(ws_text[pos + 1..].into());
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}
}
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if token.text().contains('\n') {
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break;
}
}
None
}
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fn prev_tokens(token: SyntaxToken) -> impl Iterator<Item = SyntaxToken> {
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successors(token.prev_token(), |token| token.prev_token())
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}
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pub fn extract_trivial_expression(expr: &ast::BlockExpr) -> Option<ast::Expr> {
let block = expr.block()?;
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let expr = block.expr()?;
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if expr.syntax().text().contains_char('\n') {
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return None;
}
let non_trivial_children = block.syntax().children().filter(|it| match it.kind() {
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WHITESPACE | T!['{'] | T!['}'] => false,
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_ => it != expr.syntax(),
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});
if non_trivial_children.count() > 0 {
return None;
}
Some(expr)
}
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pub fn compute_ws(left: SyntaxKind, right: SyntaxKind) -> &'static str {
match left {
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T!['('] | T!['['] => return "",
T!['{'] => {
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if let USE_TREE = right {
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return "";
}
}
_ => (),
}
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match right {
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T![')'] | T![']'] => return "",
T!['}'] => {
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if let USE_TREE = left {
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return "";
}
}
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T![.] => return "",
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_ => (),
}
" "
}