rust/src/stmt.rs
hafiz 6a7824787e Preserve comments in empty statements (#4180)
* Preserve comments in empty statements

Closes #4018

* fixup! Preserve comments in empty statements
2020-10-24 11:13:00 -05:00

117 lines
3.2 KiB
Rust

use rustc_ast::ast;
use rustc_span::Span;
use crate::comment::recover_comment_removed;
use crate::config::Version;
use crate::expr::{format_expr, ExprType};
use crate::rewrite::{Rewrite, RewriteContext};
use crate::shape::Shape;
use crate::source_map::LineRangeUtils;
use crate::spanned::Spanned;
use crate::utils::semicolon_for_stmt;
pub(crate) struct Stmt<'a> {
inner: &'a ast::Stmt,
is_last: bool,
}
impl<'a> Spanned for Stmt<'a> {
fn span(&self) -> Span {
self.inner.span()
}
}
impl<'a> Stmt<'a> {
pub(crate) fn as_ast_node(&self) -> &ast::Stmt {
self.inner
}
pub(crate) fn to_item(&self) -> Option<&ast::Item> {
match self.inner.kind {
ast::StmtKind::Item(ref item) => Some(&**item),
_ => None,
}
}
pub(crate) fn from_ast_node(inner: &'a ast::Stmt, is_last: bool) -> Self {
Stmt { inner, is_last }
}
pub(crate) fn from_ast_nodes<I>(iter: I) -> Vec<Self>
where
I: Iterator<Item = &'a ast::Stmt>,
{
let mut result = vec![];
let mut iter = iter.peekable();
while iter.peek().is_some() {
result.push(Stmt {
inner: iter.next().unwrap(),
is_last: iter.peek().is_none(),
})
}
result
}
pub(crate) fn is_empty(&self) -> bool {
matches!(self.inner.kind, ast::StmtKind::Empty)
}
fn is_last_expr(&self) -> bool {
if !self.is_last {
return false;
}
match self.as_ast_node().kind {
ast::StmtKind::Expr(ref expr) => match expr.kind {
ast::ExprKind::Ret(..) | ast::ExprKind::Continue(..) | ast::ExprKind::Break(..) => {
false
}
_ => true,
},
_ => false,
}
}
}
impl<'a> Rewrite for Stmt<'a> {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
let expr_type = if context.config.version() == Version::Two && self.is_last_expr() {
ExprType::SubExpression
} else {
ExprType::Statement
};
format_stmt(context, shape, self.as_ast_node(), expr_type)
}
}
impl Rewrite for ast::Stmt {
fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
format_stmt(context, shape, self, ExprType::Statement)
}
}
fn format_stmt(
context: &RewriteContext<'_>,
shape: Shape,
stmt: &ast::Stmt,
expr_type: ExprType,
) -> Option<String> {
skip_out_of_file_lines_range!(context, stmt.span());
let result = match stmt.kind {
ast::StmtKind::Local(ref local) => local.rewrite(context, shape),
ast::StmtKind::Expr(ref ex) | ast::StmtKind::Semi(ref ex) => {
let suffix = if semicolon_for_stmt(context, stmt) {
";"
} else {
""
};
let shape = shape.sub_width(suffix.len())?;
format_expr(ex, expr_type, context, shape).map(|s| s + suffix)
}
ast::StmtKind::MacCall(..) | ast::StmtKind::Item(..) | ast::StmtKind::Empty => None,
};
result.and_then(|res| recover_comment_removed(res, stmt.span(), context))
}