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rust/rust/8ae423e5e8db47b8233ad657b8d84247f94de179/./compiler/rustc_ast_pretty/src/pprust/state.rs
blob: 74cbd6682e3143f88249f6eff7fade4dd3f73c61 [file]
//! AST pretty printing.
//!
//! Note that HIR pretty printing is layered on top of this crate.
mod expr;
mod fixup;
mod item;
use std::borrow::Cow;
use std::sync::Arc;
use rustc_ast::attr::AttrIdGenerator;
use rustc_ast::token::{self, CommentKind, Delimiter, DocFragmentKind, Token, TokenKind};
use rustc_ast::tokenstream::{Spacing, TokenStream, TokenTree};
use rustc_ast::util::classify;
use rustc_ast::util::comments::{Comment, CommentStyle};
use rustc_ast::{
self as ast, AttrArgs, BindingMode, BlockCheckMode, ByRef, DelimArgs, GenericArg, GenericBound,
InlineAsmOperand, InlineAsmOptions, InlineAsmRegOrRegClass, InlineAsmTemplatePiece, PatKind,
RangeEnd, RangeSyntax, Safety, SelfKind, Term, attr,
};
use rustc_span::edition::Edition;
use rustc_span::source_map::SourceMap;
use rustc_span::symbol::IdentPrinter;
use rustc_span::{
BytePos, CharPos, DUMMY_SP, FileName, Ident, Pos, Span, Spanned, Symbol, kw, sym,
};
use crate::pp::Breaks::{Consistent, Inconsistent};
use crate::pp::{self, BoxMarker, Breaks};
use crate::pprust::state::fixup::FixupContext;
pub enum MacHeader<'a> {
Path(&'a ast::Path),
Keyword(&'static str),
}
pub enum AnnNode<'a> {
Ident(&'a Ident),
Name(&'a Symbol),
Block(&'a ast::Block),
Item(&'a ast::Item),
SubItem(ast::NodeId),
Expr(&'a ast::Expr),
Pat(&'a ast::Pat),
Crate(&'a ast::Crate),
}
pub trait PpAnn {
fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
}
struct NoAnn;
impl PpAnn for NoAnn {}
pub struct Comments<'a> {
sm: &'a SourceMap,
// Stored in reverse order so we can consume them by popping.
reversed_comments: Vec<Comment>,
}
/// Returns `None` if the first `col` chars of `s` contain a non-whitespace char.
/// Otherwise returns `Some(k)` where `k` is first char offset after that leading
/// whitespace. Note that `k` may be outside bounds of `s`.
fn all_whitespace(s: &str, col: CharPos) -> Option<usize> {
let mut idx = 0;
for (i, ch) in s.char_indices().take(col.to_usize()) {
if !ch.is_whitespace() {
return None;
}
idx = i + ch.len_utf8();
}
Some(idx)
}
fn trim_whitespace_prefix(s: &str, col: CharPos) -> &str {
let len = s.len();
match all_whitespace(s, col) {
Some(col) => {
if col < len {
&s[col..]
} else {
""
}
}
None => s,
}
}
fn split_block_comment_into_lines(text: &str, col: CharPos) -> Vec<String> {
let mut res: Vec<String> = vec![];
let mut lines = text.lines();
// just push the first line
res.extend(lines.next().map(|it| it.to_string()));
// for other lines, strip common whitespace prefix
for line in lines {
res.push(trim_whitespace_prefix(line, col).to_string())
}
res
}
fn gather_comments(sm: &SourceMap, path: FileName, src: String) -> Vec<Comment> {
let sm = SourceMap::new(sm.path_mapping().clone());
let source_file = sm.new_source_file(path, src);
let text = Arc::clone(&(*source_file.src.as_ref().unwrap()));
let text: &str = text.as_str();
let start_bpos = source_file.start_pos;
let mut pos = 0;
let mut comments: Vec<Comment> = Vec::new();
let mut code_to_the_left = false;
if let Some(shebang_len) = rustc_lexer::strip_shebang(text) {
comments.push(Comment {
style: CommentStyle::Isolated,
lines: vec![text[..shebang_len].to_string()],
pos: start_bpos,
});
pos += shebang_len;
}
for token in rustc_lexer::tokenize(&text[pos..], rustc_lexer::FrontmatterAllowed::Yes) {
let token_text = &text[pos..pos + token.len as usize];
match token.kind {
rustc_lexer::TokenKind::Whitespace => {
if let Some(mut idx) = token_text.find('\n') {
code_to_the_left = false;
while let Some(next_newline) = &token_text[idx + 1..].find('\n') {
idx += 1 + next_newline;
comments.push(Comment {
style: CommentStyle::BlankLine,
lines: vec![],
pos: start_bpos + BytePos((pos + idx) as u32),
});
}
}
}
rustc_lexer::TokenKind::BlockComment { doc_style, .. } => {
if doc_style.is_none() {
let code_to_the_right = !matches!(
text[pos + token.len as usize..].chars().next(),
Some('\r' | '\n')
);
let style = match (code_to_the_left, code_to_the_right) {
(_, true) => CommentStyle::Mixed,
(false, false) => CommentStyle::Isolated,
(true, false) => CommentStyle::Trailing,
};
// Count the number of chars since the start of the line by rescanning.
let pos_in_file = start_bpos + BytePos(pos as u32);
let line_begin_in_file = source_file.line_begin_pos(pos_in_file);
let line_begin_pos = (line_begin_in_file - start_bpos).to_usize();
let col = CharPos(text[line_begin_pos..pos].chars().count());
let lines = split_block_comment_into_lines(token_text, col);
comments.push(Comment { style, lines, pos: pos_in_file })
}
}
rustc_lexer::TokenKind::LineComment { doc_style } => {
if doc_style.is_none() {
comments.push(Comment {
style: if code_to_the_left {
CommentStyle::Trailing
} else {
CommentStyle::Isolated
},
lines: vec![token_text.to_string()],
pos: start_bpos + BytePos(pos as u32),
})
}
}
rustc_lexer::TokenKind::Frontmatter { .. } => {
code_to_the_left = false;
comments.push(Comment {
style: CommentStyle::Isolated,
lines: vec![token_text.to_string()],
pos: start_bpos + BytePos(pos as u32),
});
}
_ => {
code_to_the_left = true;
}
}
pos += token.len as usize;
}
comments
}
impl<'a> Comments<'a> {
pub fn new(sm: &'a SourceMap, filename: FileName, input: String) -> Comments<'a> {
let mut comments = gather_comments(sm, filename, input);
comments.reverse();
Comments { sm, reversed_comments: comments }
}
fn peek(&self) -> Option<&Comment> {
self.reversed_comments.last()
}
fn next(&mut self) -> Option<Comment> {
self.reversed_comments.pop()
}
fn trailing_comment(
&mut self,
span: rustc_span::Span,
next_pos: Option<BytePos>,
) -> Option<Comment> {
if let Some(cmnt) = self.peek() {
if cmnt.style != CommentStyle::Trailing {
return None;
}
let span_line = self.sm.lookup_char_pos(span.hi());
let comment_line = self.sm.lookup_char_pos(cmnt.pos);
let next = next_pos.unwrap_or_else(|| cmnt.pos + BytePos(1));
if span.hi() < cmnt.pos && cmnt.pos < next && span_line.line == comment_line.line {
return Some(self.next().unwrap());
}
}
None
}
}
pub struct State<'a> {
pub s: pp::Printer,
comments: Option<Comments<'a>>,
ann: &'a (dyn PpAnn + 'a),
is_sdylib_interface: bool,
}
const INDENT_UNIT: isize = 4;
/// Requires you to pass an input filename and reader so that
/// it can scan the input text for comments to copy forward.
pub fn print_crate<'a>(
sm: &'a SourceMap,
krate: &ast::Crate,
filename: FileName,
input: String,
ann: &'a dyn PpAnn,
is_expanded: bool,
edition: Edition,
g: &AttrIdGenerator,
) -> String {
let mut s = State {
s: pp::Printer::new(),
comments: Some(Comments::new(sm, filename, input)),
ann,
is_sdylib_interface: false,
};
print_crate_inner(&mut s, krate, is_expanded, edition, g);
s.s.eof()
}
pub fn print_crate_as_interface(
krate: &ast::Crate,
edition: Edition,
g: &AttrIdGenerator,
) -> String {
let mut s =
State { s: pp::Printer::new(), comments: None, ann: &NoAnn, is_sdylib_interface: true };
print_crate_inner(&mut s, krate, false, edition, g);
s.s.eof()
}
fn print_crate_inner<'a>(
s: &mut State<'a>,
krate: &ast::Crate,
is_expanded: bool,
edition: Edition,
g: &AttrIdGenerator,
) {
// We need to print shebang before anything else
// otherwise the resulting code will not compile
// and shebang will be useless.
s.maybe_print_shebang();
if is_expanded && !krate.attrs.iter().any(|attr| attr.has_name(sym::no_core)) {
// We need to print `#![no_std]` (and its feature gate) so that
// compiling pretty-printed source won't inject libstd again.
// However, we don't want these attributes in the AST because
// of the feature gate, so we fake them up here.
// `#![feature(prelude_import)]`
let fake_attr = attr::mk_attr_nested_word(
g,
ast::AttrStyle::Inner,
Safety::Default,
sym::feature,
sym::prelude_import,
DUMMY_SP,
);
s.print_attribute(&fake_attr);
// Currently, in Rust 2018 we don't have `extern crate std;` at the crate
// root, so this is not needed, and actually breaks things.
if edition.is_rust_2015() {
// `#![no_std]`
let fake_attr = attr::mk_attr_word(
g,
ast::AttrStyle::Inner,
Safety::Default,
sym::no_std,
DUMMY_SP,
);
s.print_attribute(&fake_attr);
}
}
s.print_inner_attributes(&krate.attrs);
for item in &krate.items {
s.print_item(item);
}
s.print_remaining_comments();
s.ann.post(s, AnnNode::Crate(krate));
}
/// Should two consecutive tokens be printed with a space between them?
///
/// Note: some old proc macros parse pretty-printed output, so changes here can
/// break old code. For example:
/// - #63896: `#[allow(unused,` must be printed rather than `#[allow(unused ,`
/// - #73345: `#[allow(unused)]` must be printed rather than `# [allow(unused)]`
///
/// Returns `true` if both token trees are identifier-like tokens that would
/// merge into a single token if printed without a space between them.
/// E.g. `ident` + `where` would merge into `identwhere`.
fn idents_would_merge(tt1: &TokenTree, tt2: &TokenTree) -> bool {
fn is_ident_like(tt: &TokenTree) -> bool {
matches!(
tt,
TokenTree::Token(Token { kind: token::Ident(..) | token::NtIdent(..), .. }, _,)
)
}
is_ident_like(tt1) && is_ident_like(tt2)
}
fn space_between(tt1: &TokenTree, tt2: &TokenTree) -> bool {
use Delimiter::*;
use TokenTree::{Delimited as Del, Token as Tok};
use token::*;
fn is_punct(tt: &TokenTree) -> bool {
matches!(tt, TokenTree::Token(tok, _) if tok.is_punct())
}
// Each match arm has one or more examples in comments. The default is to
// insert space between adjacent tokens, except for the cases listed in
// this match.
match (tt1, tt2) {
// No space after line doc comments.
(Tok(Token { kind: DocComment(CommentKind::Line, ..), .. }, _), _) => false,
// `.` + NON-PUNCT: `x.y`, `tup.0`
(Tok(Token { kind: Dot, .. }, _), tt2) if !is_punct(tt2) => false,
// `$` + IDENT: `$e`
(Tok(Token { kind: Dollar, .. }, _), Tok(Token { kind: Ident(..), .. }, _)) => false,
// NON-PUNCT + `,`: `foo,`
// NON-PUNCT + `;`: `x = 3;`, `[T; 3]`
// NON-PUNCT + `.`: `x.y`, `tup.0`
(tt1, Tok(Token { kind: Comma | Semi | Dot, .. }, _)) if !is_punct(tt1) => false,
// IDENT + `!`: `println!()`, but `if !x { ... }` needs a space after the `if`
(Tok(Token { kind: Ident(sym, is_raw), span }, _), Tok(Token { kind: Bang, .. }, _))
if !Ident::new(*sym, *span).is_reserved() || matches!(is_raw, IdentIsRaw::Yes) =>
{
false
}
// IDENT|`fn`|`Self`|`pub` + `(`: `f(3)`, `fn(x: u8)`, `Self()`, `pub(crate)`,
// but `let (a, b) = (1, 2)` needs a space after the `let`
(Tok(Token { kind: Ident(sym, is_raw), span }, _), Del(_, _, Parenthesis, _))
if !Ident::new(*sym, *span).is_reserved()
|| *sym == kw::Fn
|| *sym == kw::SelfUpper
|| *sym == kw::Pub
|| matches!(is_raw, IdentIsRaw::Yes) =>
{
false
}
// `#` + `[`: `#[attr]`
(Tok(Token { kind: Pound, .. }, _), Del(_, _, Bracket, _)) => false,
_ => true,
}
}
pub fn doc_comment_to_string(
fragment_kind: DocFragmentKind,
attr_style: ast::AttrStyle,
data: Symbol,
) -> String {
match fragment_kind {
DocFragmentKind::Sugared(comment_kind) => match (comment_kind, attr_style) {
(CommentKind::Line, ast::AttrStyle::Outer) => format!("///{data}"),
(CommentKind::Line, ast::AttrStyle::Inner) => format!("//!{data}"),
(CommentKind::Block, ast::AttrStyle::Outer) => format!("/**{data}*/"),
(CommentKind::Block, ast::AttrStyle::Inner) => format!("/*!{data}*/"),
},
DocFragmentKind::Raw(_) => {
format!(
"#{}[doc = {:?}]",
if attr_style == ast::AttrStyle::Inner { "!" } else { "" },
data.to_string(),
)
}
}
}
fn literal_to_string(lit: token::Lit) -> String {
let token::Lit { kind, symbol, suffix } = lit;
let mut out = match kind {
token::Byte => format!("b'{symbol}'"),
token::Char => format!("'{symbol}'"),
token::Str => format!("\"{symbol}\""),
token::StrRaw(n) => {
format!("r{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = symbol)
}
token::ByteStr => format!("b\"{symbol}\""),
token::ByteStrRaw(n) => {
format!("br{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = symbol)
}
token::CStr => format!("c\"{symbol}\""),
token::CStrRaw(n) => {
format!("cr{delim}\"{symbol}\"{delim}", delim = "#".repeat(n as usize))
}
token::Integer | token::Float | token::Bool | token::Err(_) => symbol.to_string(),
};
if let Some(suffix) = suffix {
out.push_str(suffix.as_str())
}
out
}
impl std::ops::Deref for State<'_> {
type Target = pp::Printer;
fn deref(&self) -> &Self::Target {
&self.s
}
}
impl std::ops::DerefMut for State<'_> {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.s
}
}
/// This trait is used for both AST and HIR pretty-printing.
pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::DerefMut {
fn comments(&self) -> Option<&Comments<'a>>;
fn comments_mut(&mut self) -> Option<&mut Comments<'a>>;
fn ann_post(&mut self, ident: Ident);
fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool);
fn print_ident(&mut self, ident: Ident) {
self.word(IdentPrinter::for_ast_ident(ident, ident.guess_print_mode()).to_string());
self.ann_post(ident)
}
fn strsep<'x, T: 'x, F, I>(
&mut self,
sep: &'static str,
space_before: bool,
b: Breaks,
elts: I,
mut op: F,
) where
F: FnMut(&mut Self, &T),
I: IntoIterator<Item = &'x T>,
{
let mut it = elts.into_iter();
let rb = self.rbox(0, b);
if let Some(first) = it.next() {
op(self, first);
for elt in it {
if space_before {
self.space();
}
self.word_space(sep);
op(self, elt);
}
}
self.end(rb);
}
fn commasep<'x, T: 'x, F, I>(&mut self, b: Breaks, elts: I, op: F)
where
F: FnMut(&mut Self, &T),
I: IntoIterator<Item = &'x T>,
{
self.strsep(",", false, b, elts, op)
}
fn maybe_print_comment(&mut self, pos: BytePos) -> bool {
let mut has_comment = false;
while let Some(cmnt) = self.peek_comment() {
if cmnt.pos >= pos {
break;
}
has_comment = true;
let cmnt = self.next_comment().unwrap();
self.print_comment(cmnt);
}
has_comment
}
fn print_comment(&mut self, cmnt: Comment) {
match cmnt.style {
CommentStyle::Mixed => {
if !self.is_beginning_of_line() {
self.zerobreak();
}
if let Some((last, lines)) = cmnt.lines.split_last() {
let ib = self.ibox(0);
for line in lines {
self.word(line.clone());
self.hardbreak()
}
self.word(last.clone());
self.space();
self.end(ib);
}
self.zerobreak()
}
CommentStyle::Isolated => {
self.hardbreak_if_not_bol();
for line in &cmnt.lines {
// Don't print empty lines because they will end up as trailing
// whitespace.
if !line.is_empty() {
self.word(line.clone());
}
self.hardbreak();
}
}
CommentStyle::Trailing => {
if !self.is_beginning_of_line() {
self.word(" ");
}
if let [line] = cmnt.lines.as_slice() {
self.word(line.clone());
self.hardbreak()
} else {
let vb = self.visual_align();
for line in &cmnt.lines {
if !line.is_empty() {
self.word(line.clone());
}
self.hardbreak();
}
self.end(vb);
}
}
CommentStyle::BlankLine => {
// We need to do at least one, possibly two hardbreaks.
let twice = match self.last_token() {
Some(pp::Token::String(s)) => ";" == s,
Some(pp::Token::Begin(_)) => true,
Some(pp::Token::End) => true,
_ => false,
};
if twice {
self.hardbreak();
}
self.hardbreak();
}
}
}
fn peek_comment<'b>(&'b self) -> Option<&'b Comment>
where
'a: 'b,
{
self.comments().and_then(|c| c.peek())
}
fn next_comment(&mut self) -> Option<Comment> {
self.comments_mut().and_then(|c| c.next())
}
fn maybe_print_trailing_comment(&mut self, span: rustc_span::Span, next_pos: Option<BytePos>) {
if let Some(cmnts) = self.comments_mut()
&& let Some(cmnt) = cmnts.trailing_comment(span, next_pos)
{
self.print_comment(cmnt);
}
}
fn print_remaining_comments(&mut self) {
// If there aren't any remaining comments, then we need to manually
// make sure there is a line break at the end.
if self.peek_comment().is_none() {
self.hardbreak();
}
while let Some(cmnt) = self.next_comment() {
self.print_comment(cmnt)
}
}
fn print_string(&mut self, st: &str, style: ast::StrStyle) {
let st = match style {
ast::StrStyle::Cooked => format!("\"{}\"", st.escape_debug()),
ast::StrStyle::Raw(n) => {
format!("r{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = st)
}
};
self.word(st)
}
fn maybe_print_shebang(&mut self) {
if let Some(cmnt) = self.peek_comment() {
// Comment is a shebang if it's:
// Isolated, starts with #! and doesn't continue with `[`
// See [rustc_lexer::strip_shebang] and [gather_comments] from pprust/state.rs for details
if cmnt.style == CommentStyle::Isolated
&& cmnt.lines.first().map_or(false, |l| l.starts_with("#!"))
{
let cmnt = self.next_comment().unwrap();
self.print_comment(cmnt);
}
}
}
fn print_inner_attributes(&mut self, attrs: &[ast::Attribute]) -> bool {
self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
}
fn print_outer_attributes(&mut self, attrs: &[ast::Attribute]) -> bool {
self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
}
fn print_either_attributes(
&mut self,
attrs: &[ast::Attribute],
kind: ast::AttrStyle,
is_inline: bool,
trailing_hardbreak: bool,
) -> bool {
let mut printed = false;
for attr in attrs {
if attr.style == kind {
if self.print_attribute_inline(attr, is_inline) {
if is_inline {
self.nbsp();
}
printed = true;
}
}
}
if printed && trailing_hardbreak && !is_inline {
self.hardbreak_if_not_bol();
}
printed
}
fn print_attribute_inline(&mut self, attr: &ast::Attribute, is_inline: bool) -> bool {
if attr.has_name(sym::cfg_trace) || attr.has_name(sym::cfg_attr_trace) {
// It's not a valid identifier, so avoid printing it
// to keep the printed code reasonably parse-able.
return false;
}
if !is_inline {
self.hardbreak_if_not_bol();
}
self.maybe_print_comment(attr.span.lo());
match &attr.kind {
ast::AttrKind::Normal(normal) => {
match attr.style {
ast::AttrStyle::Inner => self.word("#!["),
ast::AttrStyle::Outer => self.word("#["),
}
self.print_attr_item(&normal.item, attr.span);
self.word("]");
}
ast::AttrKind::DocComment(comment_kind, data) => {
self.word(doc_comment_to_string(
DocFragmentKind::Sugared(*comment_kind),
attr.style,
*data,
));
self.hardbreak()
}
}
true
}
fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) {
let ib = self.ibox(0);
match item.unsafety {
ast::Safety::Unsafe(_) => {
self.word("unsafe");
self.popen();
}
ast::Safety::Default | ast::Safety::Safe(_) => {}
}
match &item.args.unparsed_ref().expect("Parsed attributes are never printed") {
AttrArgs::Delimited(DelimArgs { dspan: _, delim, tokens }) => self.print_mac_common(
Some(MacHeader::Path(&item.path)),
false,
None,
*delim,
None,
tokens,
true,
span,
),
AttrArgs::Empty => {
self.print_path(&item.path, false, 0);
}
AttrArgs::Eq { expr, .. } => {
self.print_path(&item.path, false, 0);
self.space();
self.word_space("=");
let token_str = self.expr_to_string(expr);
self.word(token_str);
}
}
match item.unsafety {
ast::Safety::Unsafe(_) => self.pclose(),
ast::Safety::Default | ast::Safety::Safe(_) => {}
}
self.end(ib);
}
/// This doesn't deserve to be called "pretty" printing, but it should be
/// meaning-preserving. A quick hack that might help would be to look at the
/// spans embedded in the TTs to decide where to put spaces and newlines.
/// But it'd be better to parse these according to the grammar of the
/// appropriate macro, transcribe back into the grammar we just parsed from,
/// and then pretty-print the resulting AST nodes (so, e.g., we print
/// expression arguments as expressions). It can be done! I think.
fn print_tt(&mut self, tt: &TokenTree, convert_dollar_crate: bool) -> Spacing {
match tt {
TokenTree::Token(token, spacing) => {
let token_str = self.token_to_string_ext(token, convert_dollar_crate);
self.word(token_str);
// Emit hygiene annotations for identity-bearing tokens,
// matching how print_ident() and print_lifetime() call ann_post().
match token.kind {
token::Ident(name, _) => {
self.ann_post(Ident::new(name, token.span));
}
token::NtIdent(ident, _) => {
self.ann_post(ident);
}
token::Lifetime(name, _) => {
self.ann_post(Ident::new(name, token.span));
}
token::NtLifetime(ident, _) => {
self.ann_post(ident);
}
_ => {}
}
if let token::DocComment(..) = token.kind {
self.hardbreak()
}
*spacing
}
TokenTree::Delimited(dspan, spacing, delim, tts) => {
self.print_mac_common(
None,
false,
None,
*delim,
Some(spacing.open),
tts,
convert_dollar_crate,
dspan.entire(),
);
spacing.close
}
}
}
// The easiest way to implement token stream pretty printing would be to
// print each token followed by a single space. But that would produce ugly
// output, so we go to some effort to do better.
//
// First, we track whether each token that appears in source code is
// followed by a space, with `Spacing`, and reproduce that in the output.
// This works well in a lot of cases. E.g. `stringify!(x + y)` produces
// "x + y" and `stringify!(x+y)` produces "x+y".
//
// But this doesn't work for code produced by proc macros (which have no
// original source text representation) nor for code produced by decl
// macros (which are tricky because the whitespace after tokens appearing
// in macro rules isn't always what you want in the produced output). For
// these we mostly use `Spacing::Alone`, which is the conservative choice.
//
// So we have a backup mechanism for when `Spacing::Alone` occurs between a
// pair of tokens: we check if that pair of tokens can obviously go
// together without a space between them. E.g. token `x` followed by token
// `,` is better printed as `x,` than `x ,`. (Even if the original source
// code was `x ,`.)
//
// Finally, we must be careful about changing the output. Token pretty
// printing is used by `stringify!` and `impl Display for
// proc_macro::TokenStream`, and some programs rely on the output having a
// particular form, even though they shouldn't. In particular, some proc
// macros do `format!({stream})` on a token stream and then "parse" the
// output with simple string matching that can't handle whitespace changes.
// E.g. we have seen cases where a proc macro can handle `a :: b` but not
// `a::b`. See #117433 for some examples.
fn print_tts(&mut self, tts: &TokenStream, convert_dollar_crate: bool) {
let mut iter = tts.iter().peekable();
while let Some(tt) = iter.next() {
let spacing = self.print_tt(tt, convert_dollar_crate);
if let Some(next) = iter.peek() {
if spacing == Spacing::Alone && space_between(tt, next) {
self.space();
} else if spacing != Spacing::Alone && idents_would_merge(tt, next) {
// When tokens from macro `tt` captures preserve their
// original `Joint`/`JointHidden` spacing, adjacent
// identifier-like tokens can be concatenated without a
// space (e.g. `$x:identwhere`). Insert a space to
// prevent this.
self.space();
}
}
}
}
fn print_mac_common(
&mut self,
header: Option<MacHeader<'_>>,
has_bang: bool,
ident: Option<Ident>,
delim: Delimiter,
open_spacing: Option<Spacing>,
tts: &TokenStream,
convert_dollar_crate: bool,
span: Span,
) {
let cb = (delim == Delimiter::Brace).then(|| self.cbox(INDENT_UNIT));
match header {
Some(MacHeader::Path(path)) => self.print_path(path, false, 0),
Some(MacHeader::Keyword(kw)) => self.word(kw),
None => {}
}
if has_bang {
self.word("!");
}
if let Some(ident) = ident {
self.nbsp();
self.print_ident(ident);
}
match delim {
Delimiter::Brace => {
if header.is_some() || has_bang || ident.is_some() {
self.nbsp();
}
self.word("{");
// Respect `Alone`, if provided, and print a space. Unless the list is empty.
let open_space = (open_spacing == None || open_spacing == Some(Spacing::Alone))
&& !tts.is_empty();
if open_space {
self.space();
}
let ib = self.ibox(0);
self.print_tts(tts, convert_dollar_crate);
self.end(ib);
// Use `open_space` for the spacing *before* the closing delim.
// Because spacing on delimiters is lost when going through
// proc macros, and otherwise we can end up with ugly cases
// like `{ x}`. Symmetry is better.
self.bclose(span, !open_space, cb.unwrap());
}
delim => {
// `open_spacing` is ignored. We never print spaces after
// non-brace opening delims or before non-brace closing delims.
let token_str = self.token_kind_to_string(&delim.as_open_token_kind());
self.word(token_str);
let ib = self.ibox(0);
self.print_tts(tts, convert_dollar_crate);
self.end(ib);
let token_str = self.token_kind_to_string(&delim.as_close_token_kind());
self.word(token_str);
}
}
}
fn print_mac_def(
&mut self,
macro_def: &ast::MacroDef,
ident: &Ident,
sp: Span,
print_visibility: impl FnOnce(&mut Self),
) {
if let Some(eii_decl) = &macro_def.eii_declaration {
self.word("#[eii_declaration(");
self.print_path(&eii_decl.foreign_item, false, 0);
if eii_decl.impl_unsafe {
self.word(",");
self.space();
self.word("unsafe");
}
self.word(")]");
self.hardbreak();
}
let (kw, has_bang) = if macro_def.macro_rules {
("macro_rules", true)
} else {
print_visibility(self);
("macro", false)
};
self.print_mac_common(
Some(MacHeader::Keyword(kw)),
has_bang,
Some(*ident),
macro_def.body.delim,
None,
&macro_def.body.tokens,
true,
sp,
);
if macro_def.body.need_semicolon() {
self.word(";");
}
}
fn print_path(&mut self, path: &ast::Path, colons_before_params: bool, depth: usize) {
self.maybe_print_comment(path.span.lo());
for (i, segment) in path.segments[..path.segments.len() - depth].iter().enumerate() {
if i > 0 {
self.word("::")
}
self.print_path_segment(segment, colons_before_params);
}
}
fn print_path_segment(&mut self, segment: &ast::PathSegment, colons_before_params: bool) {
if segment.ident.name != kw::PathRoot {
self.print_ident(segment.ident);
if let Some(args) = &segment.args {
self.print_generic_args(args, colons_before_params);
}
}
}
fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) -> (BoxMarker, BoxMarker) {
let w = w.into();
// Outer-box is consistent.
let cb = self.cbox(INDENT_UNIT);
// Head-box is inconsistent.
let ib = self.ibox(0);
// Keyword that starts the head.
if !w.is_empty() {
self.word_nbsp(w);
}
(cb, ib)
}
fn bopen(&mut self, ib: BoxMarker) {
self.word("{");
self.end(ib);
}
fn bclose_maybe_open(&mut self, span: rustc_span::Span, no_space: bool, cb: Option<BoxMarker>) {
let has_comment = self.maybe_print_comment(span.hi());
if !no_space || has_comment {
self.break_offset_if_not_bol(1, -INDENT_UNIT);
}
self.word("}");
if let Some(cb) = cb {
self.end(cb);
}
}
fn bclose(&mut self, span: rustc_span::Span, no_space: bool, cb: BoxMarker) {
let cb = Some(cb);
self.bclose_maybe_open(span, no_space, cb)
}
fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
if !self.is_beginning_of_line() {
self.break_offset(n, off)
} else if off != 0 {
if let Some(last_token) = self.last_token_still_buffered() {
if last_token.is_hardbreak_tok() {
// We do something pretty sketchy here: tuck the nonzero
// offset-adjustment we were going to deposit along with the
// break into the previous hardbreak.
self.replace_last_token_still_buffered(pp::Printer::hardbreak_tok_offset(off));
}
}
}
}
/// Print the token kind precisely, without converting `$crate` into its respective crate name.
fn token_kind_to_string(&self, tok: &TokenKind) -> Cow<'static, str> {
self.token_kind_to_string_ext(tok, None)
}
fn token_kind_to_string_ext(
&self,
tok: &TokenKind,
convert_dollar_crate: Option<Span>,
) -> Cow<'static, str> {
match *tok {
token::Eq => "=".into(),
token::Lt => "<".into(),
token::Le => "<=".into(),
token::EqEq => "==".into(),
token::Ne => "!=".into(),
token::Ge => ">=".into(),
token::Gt => ">".into(),
token::Bang => "!".into(),
token::Tilde => "~".into(),
token::OrOr => "||".into(),
token::AndAnd => "&&".into(),
token::Plus => "+".into(),
token::Minus => "-".into(),
token::Star => "*".into(),
token::Slash => "/".into(),
token::Percent => "%".into(),
token::Caret => "^".into(),
token::And => "&".into(),
token::Or => "|".into(),
token::Shl => "<<".into(),
token::Shr => ">>".into(),
token::PlusEq => "+=".into(),
token::MinusEq => "-=".into(),
token::StarEq => "*=".into(),
token::SlashEq => "/=".into(),
token::PercentEq => "%=".into(),
token::CaretEq => "^=".into(),
token::AndEq => "&=".into(),
token::OrEq => "|=".into(),
token::ShlEq => "<<=".into(),
token::ShrEq => ">>=".into(),
/* Structural symbols */
token::At => "@".into(),
token::Dot => ".".into(),
token::DotDot => "..".into(),
token::DotDotDot => "...".into(),
token::DotDotEq => "..=".into(),
token::Comma => ",".into(),
token::Semi => ";".into(),
token::Colon => ":".into(),
token::PathSep => "::".into(),
token::RArrow => "->".into(),
token::LArrow => "<-".into(),
token::FatArrow => "=>".into(),
token::OpenParen => "(".into(),
token::CloseParen => ")".into(),
token::OpenBracket => "[".into(),
token::CloseBracket => "]".into(),
token::OpenBrace => "{".into(),
token::CloseBrace => "}".into(),
token::OpenInvisible(_) | token::CloseInvisible(_) => "".into(),
token::Pound => "#".into(),
token::Dollar => "$".into(),
token::Question => "?".into(),
token::SingleQuote => "'".into(),
/* Literals */
token::Literal(lit) => literal_to_string(lit).into(),
/* Name components */
token::Ident(name, is_raw) => {
IdentPrinter::new(name, is_raw.to_print_mode_ident(), convert_dollar_crate)
.to_string()
.into()
}
token::NtIdent(ident, is_raw) => {
IdentPrinter::for_ast_ident(ident, is_raw.to_print_mode_ident()).to_string().into()
}
token::Lifetime(name, is_raw) | token::NtLifetime(Ident { name, .. }, is_raw) => {
IdentPrinter::new(name, is_raw.to_print_mode_lifetime(), None).to_string().into()
}
/* Other */
token::DocComment(comment_kind, attr_style, data) => {
doc_comment_to_string(DocFragmentKind::Sugared(comment_kind), attr_style, data)
.into()
}
token::Eof => "<eof>".into(),
}
}
/// Print the token precisely, without converting `$crate` into its respective crate name.
fn token_to_string(&self, token: &Token) -> Cow<'static, str> {
self.token_to_string_ext(token, false)
}
fn token_to_string_ext(&self, token: &Token, convert_dollar_crate: bool) -> Cow<'static, str> {
let convert_dollar_crate = convert_dollar_crate.then_some(token.span);
self.token_kind_to_string_ext(&token.kind, convert_dollar_crate)
}
fn ty_to_string(&self, ty: &ast::Ty) -> String {
Self::to_string(|s| s.print_type(ty))
}
fn pat_to_string(&self, pat: &ast::Pat) -> String {
Self::to_string(|s| s.print_pat(pat))
}
fn expr_to_string(&self, e: &ast::Expr) -> String {
Self::to_string(|s| s.print_expr(e, FixupContext::default()))
}
fn meta_item_lit_to_string(&self, lit: &ast::MetaItemLit) -> String {
Self::to_string(|s| s.print_meta_item_lit(lit))
}
fn stmt_to_string(&self, stmt: &ast::Stmt) -> String {
Self::to_string(|s| s.print_stmt(stmt))
}
fn item_to_string(&self, i: &ast::Item) -> String {
Self::to_string(|s| s.print_item(i))
}
fn assoc_item_to_string(&self, i: &ast::AssocItem) -> String {
Self::to_string(|s| s.print_assoc_item(i))
}
fn foreign_item_to_string(&self, i: &ast::ForeignItem) -> String {
Self::to_string(|s| s.print_foreign_item(i))
}
fn path_to_string(&self, p: &ast::Path) -> String {
Self::to_string(|s| s.print_path(p, false, 0))
}
fn vis_to_string(&self, v: &ast::Visibility) -> String {
Self::to_string(|s| s.print_visibility(v))
}
fn impl_restriction_to_string(&self, r: &ast::ImplRestriction) -> String {
Self::to_string(|s| s.print_impl_restriction(r))
}
fn block_to_string(&self, blk: &ast::Block) -> String {
Self::to_string(|s| {
let (cb, ib) = s.head("");
s.print_block(blk, cb, ib)
})
}
fn attr_item_to_string(&self, ai: &ast::AttrItem) -> String {
Self::to_string(|s| s.print_attr_item(ai, ai.path.span))
}
fn tts_to_string(&self, tokens: &TokenStream) -> String {
Self::to_string(|s| s.print_tts(tokens, false))
}
fn to_string(f: impl FnOnce(&mut State<'_>)) -> String {
let mut printer = State::new();
f(&mut printer);
printer.s.eof()
}
}
impl<'a> PrintState<'a> for State<'a> {
fn comments(&self) -> Option<&Comments<'a>> {
self.comments.as_ref()
}
fn comments_mut(&mut self) -> Option<&mut Comments<'a>> {
self.comments.as_mut()
}
fn ann_post(&mut self, ident: Ident) {
self.ann.post(self, AnnNode::Ident(&ident));
}
fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool) {
if colons_before_params {
self.word("::")
}
match args {
ast::GenericArgs::AngleBracketed(data) => {
self.word("<");
self.commasep(Inconsistent, &data.args, |s, arg| match arg {
ast::AngleBracketedArg::Arg(a) => s.print_generic_arg(a),
ast::AngleBracketedArg::Constraint(c) => s.print_assoc_item_constraint(c),
});
self.word(">")
}
ast::GenericArgs::Parenthesized(data) => {
self.word("(");
self.commasep(Inconsistent, &data.inputs, |s, ty| s.print_type(ty));
self.word(")");
self.print_fn_ret_ty(&data.output);
}
ast::GenericArgs::ParenthesizedElided(_) => {
self.word("(");
self.word("..");
self.word(")");
}
}
}
}
impl<'a> State<'a> {
pub fn new() -> State<'a> {
State { s: pp::Printer::new(), comments: None, ann: &NoAnn, is_sdylib_interface: false }
}
fn commasep_cmnt<T, F, G>(&mut self, b: Breaks, elts: &[T], mut op: F, mut get_span: G)
where
F: FnMut(&mut State<'_>, &T),
G: FnMut(&T) -> rustc_span::Span,
{
let rb = self.rbox(0, b);
let len = elts.len();
let mut i = 0;
for elt in elts {
self.maybe_print_comment(get_span(elt).hi());
op(self, elt);
i += 1;
if i < len {
self.word(",");
self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
self.space_if_not_bol();
}
}
self.end(rb);
}
fn commasep_exprs(&mut self, b: Breaks, exprs: &[Box<ast::Expr>]) {
self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e, FixupContext::default()), |e| e.span)
}
pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
if let Some(lt) = *lifetime {
self.print_lifetime(lt);
self.nbsp();
}
}
pub fn print_assoc_item_constraint(&mut self, constraint: &ast::AssocItemConstraint) {
self.print_ident(constraint.ident);
if let Some(args) = constraint.gen_args.as_ref() {
self.print_generic_args(args, false)
}
self.space();
match &constraint.kind {
ast::AssocItemConstraintKind::Equality { term } => {
self.word_space("=");
match term {
Term::Ty(ty) => self.print_type(ty),
Term::Const(c) => self.print_expr_anon_const(c, &[]),
}
}
ast::AssocItemConstraintKind::Bound { bounds } => {
if !bounds.is_empty() {
self.word_nbsp(":");
self.print_type_bounds(bounds);
}
}
}
}
pub fn print_generic_arg(&mut self, generic_arg: &GenericArg) {
match generic_arg {
GenericArg::Lifetime(lt) => self.print_lifetime(*lt),
GenericArg::Type(ty) => self.print_type(ty),
GenericArg::Const(ct) => self.print_expr(&ct.value, FixupContext::default()),
}
}
pub fn print_ty_pat(&mut self, pat: &ast::TyPat) {
match &pat.kind {
rustc_ast::TyPatKind::Range(start, end, include_end) => {
if let Some(start) = start {
self.print_expr_anon_const(start, &[]);
}
self.word("..");
if let Some(end) = end {
if let RangeEnd::Included(_) = include_end.node {
self.word("=");
}
self.print_expr_anon_const(end, &[]);
}
}
rustc_ast::TyPatKind::NotNull => self.word("!null"),
rustc_ast::TyPatKind::Or(variants) => {
let mut first = true;
for pat in variants {
if first {
first = false
} else {
self.word(" | ");
}
self.print_ty_pat(pat);
}
}
rustc_ast::TyPatKind::Err(_) => {
self.popen();
self.word("/*ERROR*/");
self.pclose();
}
}
}
pub fn print_type(&mut self, ty: &ast::Ty) {
self.maybe_print_comment(ty.span.lo());
let ib = self.ibox(0);
match &ty.kind {
ast::TyKind::Slice(ty) => {
self.word("[");
self.print_type(ty);
self.word("]");
}
ast::TyKind::Ptr(mt) => {
self.word("*");
self.print_mt(mt, true);
}
ast::TyKind::Ref(lifetime, mt) => {
self.word("&");
self.print_opt_lifetime(lifetime);
self.print_mt(mt, false);
}
ast::TyKind::PinnedRef(lifetime, mt) => {
self.word("&");
self.print_opt_lifetime(lifetime);
self.word("pin ");
self.print_mt(mt, true);
}
ast::TyKind::Never => {
self.word("!");
}
ast::TyKind::Tup(elts) => {
self.popen();
self.commasep(Inconsistent, elts, |s, ty| s.print_type(ty));
if elts.len() == 1 {
self.word(",");
}
self.pclose();
}
ast::TyKind::Paren(typ) => {
self.popen();
self.print_type(typ);
self.pclose();
}
ast::TyKind::FnPtr(f) => {
self.print_ty_fn(f.ext, f.safety, &f.decl, None, &f.generic_params);
}
ast::TyKind::UnsafeBinder(f) => {
let ib = self.ibox(INDENT_UNIT);
self.word("unsafe");
self.print_generic_params(&f.generic_params);
self.nbsp();
self.print_type(&f.inner_ty);
self.end(ib);
}
ast::TyKind::Path(None, path) => {
self.print_path(path, false, 0);
}
ast::TyKind::Path(Some(qself), path) => self.print_qpath(path, qself, false),
ast::TyKind::TraitObject(bounds, syntax) => {
match syntax {
ast::TraitObjectSyntax::Dyn => self.word_nbsp("dyn"),
ast::TraitObjectSyntax::None => {}
}
self.print_type_bounds(bounds);
}
ast::TyKind::ImplTrait(_, bounds) => {
self.word_nbsp("impl");
self.print_type_bounds(bounds);
}
ast::TyKind::Array(ty, length) => {
self.word("[");
self.print_type(ty);
self.word("; ");
self.print_expr(&length.value, FixupContext::default());
self.word("]");
}
ast::TyKind::Infer => {
self.word("_");
}
ast::TyKind::Err(_) => {
self.popen();
self.word("/*ERROR*/");
self.pclose();
}
ast::TyKind::Dummy => {
self.popen();
self.word("/*DUMMY*/");
self.pclose();
}
ast::TyKind::ImplicitSelf => {
self.word("Self");
}
ast::TyKind::MacCall(m) => {
self.print_mac(m);
}
ast::TyKind::CVarArgs => {
self.word("...");
}
ast::TyKind::Pat(ty, pat) => {
self.print_type(ty);
self.word(" is ");
self.print_ty_pat(pat);
}
ast::TyKind::FieldOf(ty, variant, field) => {
self.word("builtin # field_of");
self.popen();
let ib = self.ibox(0);
self.print_type(ty);
self.word(",");
self.space();
if let Some(variant) = variant {
self.print_ident(*variant);
self.word(".");
}
self.print_ident(*field);
self.end(ib);
self.pclose();
}
}
self.end(ib);
}
fn print_trait_ref(&mut self, t: &ast::TraitRef) {
self.print_path(&t.path, false, 0)
}
fn print_formal_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
if !generic_params.is_empty() {
self.word("for");
self.print_generic_params(generic_params);
self.nbsp();
}
}
fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) {
if let ast::Parens::Yes = t.parens {
self.popen();
}
self.print_formal_generic_params(&t.bound_generic_params);
let ast::TraitBoundModifiers { constness, asyncness, polarity } = t.modifiers;
match constness {
ast::BoundConstness::Never => {}
ast::BoundConstness::Always(_) | ast::BoundConstness::Maybe(_) => {
self.word_space(constness.as_str());
}
}
match asyncness {
ast::BoundAsyncness::Normal => {}
ast::BoundAsyncness::Async(_) => {
self.word_space(asyncness.as_str());
}
}
match polarity {
ast::BoundPolarity::Positive => {}
ast::BoundPolarity::Negative(_) | ast::BoundPolarity::Maybe(_) => {
self.word(polarity.as_str());
}
}
self.print_trait_ref(&t.trait_ref);
if let ast::Parens::Yes = t.parens {
self.pclose();
}
}
fn print_stmt(&mut self, st: &ast::Stmt) {
self.maybe_print_comment(st.span.lo());
match &st.kind {
ast::StmtKind::Let(loc) => {
self.print_outer_attributes(&loc.attrs);
self.space_if_not_bol();
let ib1 = self.ibox(INDENT_UNIT);
if loc.super_.is_some() {
self.word_nbsp("super");
}
self.word_nbsp("let");
let ib2 = self.ibox(INDENT_UNIT);
self.print_local_decl(loc);
self.end(ib2);
if let Some((init, els)) = loc.kind.init_else_opt() {
self.nbsp();
self.word_space("=");
self.print_expr_cond_paren(
init,
els.is_some() && classify::expr_trailing_brace(init).is_some(),
FixupContext::default(),
);
if let Some(els) = els {
let cb = self.cbox(INDENT_UNIT);
let ib = self.ibox(INDENT_UNIT);
self.word(" else ");
self.print_block(els, cb, ib);
}
}
self.word(";");
self.end(ib1);
}
ast::StmtKind::Item(item) => self.print_item(item),
ast::StmtKind::Expr(expr) => {
self.space_if_not_bol();
self.print_expr_outer_attr_style(expr, false, FixupContext::new_stmt());
if classify::expr_requires_semi_to_be_stmt(expr) {
self.word(";");
}
}
ast::StmtKind::Semi(expr) => {
self.space_if_not_bol();
self.print_expr_outer_attr_style(expr, false, FixupContext::new_stmt());
self.word(";");
}
ast::StmtKind::Empty => {
self.space_if_not_bol();
self.word(";");
}
ast::StmtKind::MacCall(mac) => {
self.space_if_not_bol();
self.print_outer_attributes(&mac.attrs);
self.print_mac(&mac.mac);
if mac.style == ast::MacStmtStyle::Semicolon {
self.word(";");
}
}
}
self.maybe_print_trailing_comment(st.span, None)
}
fn print_block(&mut self, blk: &ast::Block, cb: BoxMarker, ib: BoxMarker) {
self.print_block_with_attrs(blk, &[], cb, ib)
}
fn print_block_unclosed_indent(&mut self, blk: &ast::Block, ib: BoxMarker) {
self.print_block_maybe_unclosed(blk, &[], None, ib)
}
fn print_block_with_attrs(
&mut self,
blk: &ast::Block,
attrs: &[ast::Attribute],
cb: BoxMarker,
ib: BoxMarker,
) {
self.print_block_maybe_unclosed(blk, attrs, Some(cb), ib)
}
fn print_block_maybe_unclosed(
&mut self,
blk: &ast::Block,
attrs: &[ast::Attribute],
cb: Option<BoxMarker>,
ib: BoxMarker,
) {
match blk.rules {
BlockCheckMode::Unsafe(..) => self.word_space("unsafe"),
BlockCheckMode::Default => (),
}
self.maybe_print_comment(blk.span.lo());
self.ann.pre(self, AnnNode::Block(blk));
self.bopen(ib);
let has_attrs = self.print_inner_attributes(attrs);
for (i, st) in blk.stmts.iter().enumerate() {
match &st.kind {
ast::StmtKind::Expr(expr) if i == blk.stmts.len() - 1 => {
self.maybe_print_comment(st.span.lo());
self.space_if_not_bol();
self.print_expr_outer_attr_style(expr, false, FixupContext::new_stmt());
self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
}
_ => self.print_stmt(st),
}
}
let no_space = !has_attrs && blk.stmts.is_empty();
self.bclose_maybe_open(blk.span, no_space, cb);
self.ann.post(self, AnnNode::Block(blk))
}
/// Print a `let pat = expr` expression.
///
/// Parentheses are inserted surrounding `expr` if a round-trip through the
/// parser would otherwise work out the wrong way in a condition position.
///
/// For example each of the following would mean the wrong thing without
/// parentheses.
///
/// ```ignore (illustrative)
/// if let _ = (Struct {}) {}
///
/// if let _ = (true && false) {}
/// ```
///
/// In a match guard, the second case still requires parens, but the first
/// case no longer does because anything until `=>` is considered part of
/// the match guard expression. Parsing of the expression is not terminated
/// by `{` in that position.
///
/// ```ignore (illustrative)
/// match () {
/// () if let _ = Struct {} => {}
/// () if let _ = (true && false) => {}
/// }
/// ```
fn print_let(&mut self, pat: &ast::Pat, expr: &ast::Expr, fixup: FixupContext) {
self.word("let ");
self.print_pat(pat);
self.space();
self.word_space("=");
self.print_expr_cond_paren(
expr,
fixup.needs_par_as_let_scrutinee(expr),
FixupContext::default(),
);
}
fn print_mac(&mut self, m: &ast::MacCall) {
self.print_mac_common(
Some(MacHeader::Path(&m.path)),
true,
None,
m.args.delim,
None,
&m.args.tokens,
true,
m.span(),
);
}
fn print_inline_asm(&mut self, asm: &ast::InlineAsm) {
enum AsmArg<'a> {
Template(String),
Operand(&'a InlineAsmOperand),
ClobberAbi(Symbol),
Options(InlineAsmOptions),
}
let mut args = vec![AsmArg::Template(InlineAsmTemplatePiece::to_string(&asm.template))];
args.extend(asm.operands.iter().map(|(o, _)| AsmArg::Operand(o)));
for (abi, _) in &asm.clobber_abis {
args.push(AsmArg::ClobberAbi(*abi));
}
if !asm.options.is_empty() {
args.push(AsmArg::Options(asm.options));
}
self.popen();
self.commasep(Consistent, &args, |s, arg| match arg {
AsmArg::Template(template) => s.print_string(template, ast::StrStyle::Cooked),
AsmArg::Operand(op) => {
let print_reg_or_class = |s: &mut Self, r: &InlineAsmRegOrRegClass| match r {
InlineAsmRegOrRegClass::Reg(r) => s.print_symbol(*r, ast::StrStyle::Cooked),
InlineAsmRegOrRegClass::RegClass(r) => s.word(r.to_string()),
};
match op {
InlineAsmOperand::In { reg, expr } => {
s.word("in");
s.popen();
print_reg_or_class(s, reg);
s.pclose();
s.space();
s.print_expr(expr, FixupContext::default());
}
InlineAsmOperand::Out { reg, late, expr } => {
s.word(if *late { "lateout" } else { "out" });
s.popen();
print_reg_or_class(s, reg);
s.pclose();
s.space();
match expr {
Some(expr) => s.print_expr(expr, FixupContext::default()),
None => s.word("_"),
}
}
InlineAsmOperand::InOut { reg, late, expr } => {
s.word(if *late { "inlateout" } else { "inout" });
s.popen();
print_reg_or_class(s, reg);
s.pclose();
s.space();
s.print_expr(expr, FixupContext::default());
}
InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
s.word(if *late { "inlateout" } else { "inout" });
s.popen();
print_reg_or_class(s, reg);
s.pclose();
s.space();
s.print_expr(in_expr, FixupContext::default());
s.space();
s.word_space("=>");
match out_expr {
Some(out_expr) => s.print_expr(out_expr, FixupContext::default()),
None => s.word("_"),
}
}
InlineAsmOperand::Const { anon_const } => {
s.word("const");
s.space();
s.print_expr(&anon_const.value, FixupContext::default());
}
InlineAsmOperand::Sym { sym } => {
s.word("sym");
s.space();
if let Some(qself) = &sym.qself {
s.print_qpath(&sym.path, qself, true);
} else {
s.print_path(&sym.path, true, 0);
}
}
InlineAsmOperand::Label { block } => {
let (cb, ib) = s.head("label");
s.print_block(block, cb, ib);
}
}
}
AsmArg::ClobberAbi(abi) => {
s.word("clobber_abi");
s.popen();
s.print_symbol(*abi, ast::StrStyle::Cooked);
s.pclose();
}
AsmArg::Options(opts) => {
s.word("options");
s.popen();
s.commasep(Inconsistent, &opts.human_readable_names(), |s, &opt| {
s.word(opt);
});
s.pclose();
}
});
self.pclose();
}
fn print_local_decl(&mut self, loc: &ast::Local) {
self.print_pat(&loc.pat);
if let Some(ty) = &loc.ty {
self.word_space(":");
self.print_type(ty);
}
}
fn print_name(&mut self, name: Symbol) {
self.word(name.to_string());
self.ann.post(self, AnnNode::Name(&name))
}
fn print_qpath(&mut self, path: &ast::Path, qself: &ast::QSelf, colons_before_params: bool) {
self.word("<");
self.print_type(&qself.ty);
if qself.position > 0 {
self.space();
self.word_space("as");
let depth = path.segments.len() - qself.position;
self.print_path(path, false, depth);
}
self.word(">");
for item_segment in &path.segments[qself.position..] {
self.word("::");
self.print_ident(item_segment.ident);
if let Some(args) = &item_segment.args {
self.print_generic_args(args, colons_before_params)
}
}
}
/// Print a pattern, parenthesizing it if it is an or-pattern (`A | B`).
///
/// Or-patterns have the lowest precedence among patterns, so they need
/// parentheses when nested inside `@` bindings, `&` references, or `box`
/// patterns — otherwise `x @ A | B` parses as `(x @ A) | B`, `&A | B`
/// parses as `(&A) | B`, etc.
fn print_pat_paren_if_or(&mut self, pat: &ast::Pat) {
let needs_paren = matches!(pat.kind, PatKind::Or(..));
if needs_paren {
self.popen();
}
self.print_pat(pat);
if needs_paren {
self.pclose();
}
}
fn print_pat(&mut self, pat: &ast::Pat) {
self.maybe_print_comment(pat.span.lo());
self.ann.pre(self, AnnNode::Pat(pat));
/* Pat isn't normalized, but the beauty of it is that it doesn't matter */
match &pat.kind {
PatKind::Missing => unreachable!(),
PatKind::Wild => self.word("_"),
PatKind::Never => self.word("!"),
PatKind::Ident(BindingMode(by_ref, mutbl), ident, sub) => {
if mutbl.is_mut() {
self.word_nbsp("mut");
}
if let ByRef::Yes(pinnedness, rmutbl) = by_ref {
self.word_nbsp("ref");
if pinnedness.is_pinned() {
self.word_nbsp("pin");
}
if rmutbl.is_mut() {
self.word_nbsp("mut");
} else if pinnedness.is_pinned() {
self.word_nbsp("const");
}
}
self.print_ident(*ident);
if let Some(p) = sub {
self.space();
self.word_space("@");
self.print_pat_paren_if_or(p);
}
}
PatKind::TupleStruct(qself, path, elts) => {
if let Some(qself) = qself {
self.print_qpath(path, qself, true);
} else {
self.print_path(path, true, 0);
}
self.popen();
self.commasep(Inconsistent, elts, |s, p| s.print_pat(p));
self.pclose();
}
PatKind::Or(pats) => {
self.strsep("|", true, Inconsistent, pats, |s, p| s.print_pat(p));
}
PatKind::Path(None, path) => {
self.print_path(path, true, 0);
}
PatKind::Path(Some(qself), path) => {
self.print_qpath(path, qself, false);
}
PatKind::Struct(qself, path, fields, etc) => {
if let Some(qself) = qself {
self.print_qpath(path, qself, true);
} else {
self.print_path(path, true, 0);
}
self.nbsp();
self.word("{");
let empty = fields.is_empty() && *etc == ast::PatFieldsRest::None;
if !empty {
self.space();
}
self.commasep_cmnt(
Consistent,
fields,
|s, f| {
let cb = s.cbox(INDENT_UNIT);
if !f.is_shorthand {
s.print_ident(f.ident);
s.word_nbsp(":");
}
s.print_pat(&f.pat);
s.end(cb);
},
|f| f.pat.span,
);
if let ast::PatFieldsRest::Rest(_) | ast::PatFieldsRest::Recovered(_) = etc {
if !fields.is_empty() {
self.word_space(",");
}
self.word("..");
if let ast::PatFieldsRest::Recovered(_) = etc {
self.word("/* recovered parse error */");
}
}
if !empty {
self.space();
}
self.word("}");
}
PatKind::Tuple(elts) => {
self.popen();
self.commasep(Inconsistent, elts, |s, p| s.print_pat(p));
if elts.len() == 1 {
self.word(",");
}
self.pclose();
}
PatKind::Box(inner) => {
self.word("box ");
self.print_pat_paren_if_or(inner);
}
PatKind::Deref(inner) => {
self.word("deref!");
self.popen();
self.print_pat(inner);
self.pclose();
}
PatKind::Ref(inner, pinned, mutbl) => {
self.word("&");
if pinned.is_pinned() {
self.word("pin ");
if mutbl.is_not() {
self.word("const ");
}
}
if mutbl.is_mut() {
self.word("mut ");
}
if let PatKind::Ident(ast::BindingMode::MUT, ..) = inner.kind {
self.popen();
self.print_pat(inner);
self.pclose();
} else {
self.print_pat_paren_if_or(inner);
}
}
PatKind::Expr(e) => self.print_expr(e, FixupContext::default()),
PatKind::Range(begin, end, Spanned { node: end_kind, .. }) => {
if let Some(e) = begin {
self.print_expr(e, FixupContext::default());
}
match end_kind {
RangeEnd::Included(RangeSyntax::DotDotDot) => self.word("..."),
RangeEnd::Included(RangeSyntax::DotDotEq) => self.word("..="),
RangeEnd::Excluded => self.word(".."),
}
if let Some(e) = end {
self.print_expr(e, FixupContext::default());
}
}
PatKind::Guard(subpat, guard) => {
self.popen();
self.print_pat(subpat);
self.space();
self.word_space("if");
self.print_expr(&guard.cond, FixupContext::default());
self.pclose();
}
PatKind::Slice(elts) => {
self.word("[");
self.commasep(Inconsistent, elts, |s, p| s.print_pat(p));
self.word("]");
}
PatKind::Rest => self.word(".."),
PatKind::Paren(inner) => {
self.popen();
self.print_pat(inner);
self.pclose();
}
PatKind::MacCall(m) => self.print_mac(m),
PatKind::Err(_) => {
self.popen();
self.word("/*ERROR*/");
self.pclose();
}
}
self.ann.post(self, AnnNode::Pat(pat))
}
fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) {
match &explicit_self.node {
SelfKind::Value(m) => {
self.print_mutability(*m, false);
self.word("self")
}
SelfKind::Region(lt, m) => {
self.word("&");
self.print_opt_lifetime(lt);
self.print_mutability(*m, false);
self.word("self")
}
SelfKind::Pinned(lt, m) => {
self.word("&");
self.print_opt_lifetime(lt);
self.word("pin ");
self.print_mutability(*m, true);
self.word("self")
}
SelfKind::Explicit(typ, m) => {
self.print_mutability(*m, false);
self.word("self");
self.word_space(":");
self.print_type(typ)
}
}
}
fn print_coroutine_kind(&mut self, coroutine_kind: ast::CoroutineKind) {
match coroutine_kind {
ast::CoroutineKind::Gen { .. } => {
self.word_nbsp("gen");
}
ast::CoroutineKind::Async { .. } => {
self.word_nbsp("async");
}
ast::CoroutineKind::AsyncGen { .. } => {
self.word_nbsp("async");
self.word_nbsp("gen");
}
}
}
pub fn print_type_bounds(&mut self, bounds: &[ast::GenericBound]) {
let mut first = true;
for bound in bounds {
if first {
first = false;
} else {
self.nbsp();
self.word_space("+");
}
match bound {
GenericBound::Trait(tref) => {
self.print_poly_trait_ref(tref);
}
GenericBound::Outlives(lt) => self.print_lifetime(*lt),
GenericBound::Use(args, _) => {
self.word("use");
self.word("<");
self.commasep(Inconsistent, args, |s, arg| match arg {
ast::PreciseCapturingArg::Arg(p, _) => s.print_path(p, false, 0),
ast::PreciseCapturingArg::Lifetime(lt) => s.print_lifetime(*lt),
});
self.word(">")
}
}
}
}
fn print_lifetime(&mut self, lifetime: ast::Lifetime) {
self.word(lifetime.ident.name.to_string());
self.ann_post(lifetime.ident)
}
fn print_lifetime_bounds(&mut self, bounds: &ast::GenericBounds) {
for (i, bound) in bounds.iter().enumerate() {
if i != 0 {
self.word(" + ");
}
match bound {
ast::GenericBound::Outlives(lt) => self.print_lifetime(*lt),
_ => {
panic!("expected a lifetime bound, found a trait bound")
}
}
}
}
fn print_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
if generic_params.is_empty() {
return;
}
self.word("<");
self.commasep(Inconsistent, generic_params, |s, param| {
s.print_outer_attributes_inline(&param.attrs);
match &param.kind {
ast::GenericParamKind::Lifetime => {
let lt = ast::Lifetime { id: param.id, ident: param.ident };
s.print_lifetime(lt);
if !param.bounds.is_empty() {
s.word_nbsp(":");
s.print_lifetime_bounds(&param.bounds)
}
}
ast::GenericParamKind::Type { default } => {
s.print_ident(param.ident);
if !param.bounds.is_empty() {
s.word_nbsp(":");
s.print_type_bounds(&param.bounds);
}
if let Some(default) = default {
s.space();
s.word_space("=");
s.print_type(default)
}
}
ast::GenericParamKind::Const { ty, default, .. } => {
s.word_space("const");
s.print_ident(param.ident);
s.space();
s.word_space(":");
s.print_type(ty);
if !param.bounds.is_empty() {
s.word_nbsp(":");
s.print_type_bounds(&param.bounds);
}
if let Some(default) = default {
s.space();
s.word_space("=");
s.print_expr(&default.value, FixupContext::default());
}
}
}
});
self.word(">");
}
pub fn print_mutability(&mut self, mutbl: ast::Mutability, print_const: bool) {
match mutbl {
ast::Mutability::Mut => self.word_nbsp("mut"),
ast::Mutability::Not => {
if print_const {
self.word_nbsp("const");
}
}
}
}
fn print_mt(&mut self, mt: &ast::MutTy, print_const: bool) {
self.print_mutability(mt.mutbl, print_const);
self.print_type(&mt.ty)
}
fn print_param(&mut self, input: &ast::Param, is_closure: bool) {
let ib = self.ibox(INDENT_UNIT);
self.print_outer_attributes_inline(&input.attrs);
match input.ty.kind {
ast::TyKind::Infer if is_closure => self.print_pat(&input.pat),
_ => {
if let Some(eself) = input.to_self() {
self.print_explicit_self(&eself);
} else {
if !matches!(input.pat.kind, PatKind::Missing) {
self.print_pat(&input.pat);
self.word(":");
self.space();
}
self.print_type(&input.ty);
}
}
}
self.end(ib);
}
fn print_fn_ret_ty(&mut self, fn_ret_ty: &ast::FnRetTy) {
if let ast::FnRetTy::Ty(ty) = fn_ret_ty {
self.space_if_not_bol();
let ib = self.ibox(INDENT_UNIT);
self.word_space("->");
self.print_type(ty);
self.end(ib);
self.maybe_print_comment(ty.span.lo());
}
}
fn print_ty_fn(
&mut self,
ext: ast::Extern,
safety: ast::Safety,
decl: &ast::FnDecl,
name: Option<Ident>,
generic_params: &[ast::GenericParam],
) {
let ib = self.ibox(INDENT_UNIT);
self.print_formal_generic_params(generic_params);
let generics = ast::Generics::default();
let header = ast::FnHeader { safety, ext, ..ast::FnHeader::default() };
self.print_fn(decl, header, name, &generics);
self.end(ib);
}
fn print_fn_header_info(&mut self, header: ast::FnHeader) {
self.print_constness(header.constness);
header.coroutine_kind.map(|coroutine_kind| self.print_coroutine_kind(coroutine_kind));
self.print_safety(header.safety);
match header.ext {
ast::Extern::None => {}
ast::Extern::Implicit(_) => {
self.word_nbsp("extern");
}
ast::Extern::Explicit(abi, _) => {
self.word_nbsp("extern");
self.print_token_literal(abi.as_token_lit(), abi.span);
self.nbsp();
}
}
self.word("fn")
}
fn print_safety(&mut self, s: ast::Safety) {
match s {
ast::Safety::Default => {}
ast::Safety::Safe(_) => self.word_nbsp("safe"),
ast::Safety::Unsafe(_) => self.word_nbsp("unsafe"),
}
}
fn print_constness(&mut self, s: ast::Const) {
match s {
ast::Const::No => {}
ast::Const::Yes(_) => self.word_nbsp("const"),
}
}
fn print_is_auto(&mut self, s: ast::IsAuto) {
match s {
ast::IsAuto::Yes => self.word_nbsp("auto"),
ast::IsAuto::No => {}
}
}
fn print_meta_item_lit(&mut self, lit: &ast::MetaItemLit) {
self.print_token_literal(lit.as_token_lit(), lit.span)
}
fn print_token_literal(&mut self, token_lit: token::Lit, span: Span) {
self.maybe_print_comment(span.lo());
self.word(token_lit.to_string())
}
fn print_symbol(&mut self, sym: Symbol, style: ast::StrStyle) {
self.print_string(sym.as_str(), style);
}
fn print_inner_attributes_no_trailing_hardbreak(&mut self, attrs: &[ast::Attribute]) -> bool {
self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
}
fn print_outer_attributes_inline(&mut self, attrs: &[ast::Attribute]) -> bool {
self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
}
fn print_attribute(&mut self, attr: &ast::Attribute) {
self.print_attribute_inline(attr, false);
}
fn print_meta_list_item(&mut self, item: &ast::MetaItemInner) {
match item {
ast::MetaItemInner::MetaItem(mi) => self.print_meta_item(mi),
ast::MetaItemInner::Lit(lit) => self.print_meta_item_lit(lit),
}
}
fn print_meta_item(&mut self, item: &ast::MetaItem) {
let ib = self.ibox(INDENT_UNIT);
match item.unsafety {
ast::Safety::Unsafe(_) => {
self.word("unsafe");
self.popen();
}
ast::Safety::Default | ast::Safety::Safe(_) => {}
}
match &item.kind {
ast::MetaItemKind::Word => self.print_path(&item.path, false, 0),
ast::MetaItemKind::NameValue(value) => {
self.print_path(&item.path, false, 0);
self.space();
self.word_space("=");
self.print_meta_item_lit(value);
}
ast::MetaItemKind::List(items) => {
self.print_path(&item.path, false, 0);
self.popen();
self.commasep(Consistent, items, |s, i| s.print_meta_list_item(i));
self.pclose();
}
}
match item.unsafety {
ast::Safety::Unsafe(_) => self.pclose(),
ast::Safety::Default | ast::Safety::Safe(_) => {}
}
self.end(ib);
}
pub(crate) fn bounds_to_string(&self, bounds: &[ast::GenericBound]) -> String {
Self::to_string(|s| s.print_type_bounds(bounds))
}
pub(crate) fn where_bound_predicate_to_string(
&self,
where_bound_predicate: &ast::WhereBoundPredicate,
) -> String {
Self::to_string(|s| s.print_where_bound_predicate(where_bound_predicate))
}
pub(crate) fn tt_to_string(&self, tt: &TokenTree) -> String {
Self::to_string(|s| {
s.print_tt(tt, false);
})
}
pub(crate) fn path_segment_to_string(&self, p: &ast::PathSegment) -> String {
Self::to_string(|s| s.print_path_segment(p, false))
}
pub(crate) fn meta_list_item_to_string(&self, li: &ast::MetaItemInner) -> String {
Self::to_string(|s| s.print_meta_list_item(li))
}
pub(crate) fn attribute_to_string(&self, attr: &ast::Attribute) -> String {
Self::to_string(|s| s.print_attribute(attr))
}
}