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Diffstat (limited to '')
-rw-r--r-- | src/tools/rustfmt/src/attr.rs | 541 |
1 files changed, 541 insertions, 0 deletions
diff --git a/src/tools/rustfmt/src/attr.rs b/src/tools/rustfmt/src/attr.rs new file mode 100644 index 000000000..41ba9a847 --- /dev/null +++ b/src/tools/rustfmt/src/attr.rs @@ -0,0 +1,541 @@ +//! Format attributes and meta items. + +use rustc_ast::ast; +use rustc_ast::HasAttrs; +use rustc_span::{symbol::sym, Span, Symbol}; + +use self::doc_comment::DocCommentFormatter; +use crate::comment::{contains_comment, rewrite_doc_comment, CommentStyle}; +use crate::config::lists::*; +use crate::config::IndentStyle; +use crate::expr::rewrite_literal; +use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator}; +use crate::overflow; +use crate::rewrite::{Rewrite, RewriteContext}; +use crate::shape::Shape; +use crate::source_map::SpanUtils; +use crate::types::{rewrite_path, PathContext}; +use crate::utils::{count_newlines, mk_sp}; + +mod doc_comment; + +pub(crate) fn contains_name(attrs: &[ast::Attribute], name: Symbol) -> bool { + attrs.iter().any(|attr| attr.has_name(name)) +} + +pub(crate) fn first_attr_value_str_by_name( + attrs: &[ast::Attribute], + name: Symbol, +) -> Option<Symbol> { + attrs + .iter() + .find(|attr| attr.has_name(name)) + .and_then(|attr| attr.value_str()) +} + +/// Returns attributes on the given statement. +pub(crate) fn get_attrs_from_stmt(stmt: &ast::Stmt) -> &[ast::Attribute] { + stmt.attrs() +} + +pub(crate) fn get_span_without_attrs(stmt: &ast::Stmt) -> Span { + match stmt.kind { + ast::StmtKind::Local(ref local) => local.span, + ast::StmtKind::Item(ref item) => item.span, + ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => expr.span, + ast::StmtKind::MacCall(ref mac_stmt) => mac_stmt.mac.span(), + ast::StmtKind::Empty => stmt.span, + } +} + +/// Returns attributes that are within `outer_span`. +pub(crate) fn filter_inline_attrs( + attrs: &[ast::Attribute], + outer_span: Span, +) -> Vec<ast::Attribute> { + attrs + .iter() + .filter(|a| outer_span.lo() <= a.span.lo() && a.span.hi() <= outer_span.hi()) + .cloned() + .collect() +} + +fn is_derive(attr: &ast::Attribute) -> bool { + attr.has_name(sym::derive) +} + +// The shape of the arguments to a function-like attribute. +fn argument_shape( + left: usize, + right: usize, + combine: bool, + shape: Shape, + context: &RewriteContext<'_>, +) -> Option<Shape> { + match context.config.indent_style() { + IndentStyle::Block => { + if combine { + shape.offset_left(left) + } else { + Some( + shape + .block_indent(context.config.tab_spaces()) + .with_max_width(context.config), + ) + } + } + IndentStyle::Visual => shape + .visual_indent(0) + .shrink_left(left) + .and_then(|s| s.sub_width(right)), + } +} + +fn format_derive( + derives: &[ast::Attribute], + shape: Shape, + context: &RewriteContext<'_>, +) -> Option<String> { + // Collect all items from all attributes + let all_items = derives + .iter() + .map(|attr| { + // Parse the derive items and extract the span for each item; if any + // attribute is not parseable, none of the attributes will be + // reformatted. + let item_spans = attr.meta_item_list().map(|meta_item_list| { + meta_item_list + .into_iter() + .map(|nested_meta_item| nested_meta_item.span()) + })?; + + let items = itemize_list( + context.snippet_provider, + item_spans, + ")", + ",", + |span| span.lo(), + |span| span.hi(), + |span| Some(context.snippet(*span).to_owned()), + // We update derive attribute spans to start after the opening '(' + // This helps us focus parsing to just what's inside #[derive(...)] + context.snippet_provider.span_after(attr.span, "("), + attr.span.hi(), + false, + ); + + Some(items) + }) + // Fail if any attribute failed. + .collect::<Option<Vec<_>>>()? + // Collect the results into a single, flat, Vec. + .into_iter() + .flatten() + .collect::<Vec<_>>(); + + // Collect formatting parameters. + let prefix = attr_prefix(&derives[0]); + let argument_shape = argument_shape( + "[derive()]".len() + prefix.len(), + ")]".len(), + false, + shape, + context, + )?; + let one_line_shape = shape + .offset_left("[derive()]".len() + prefix.len())? + .sub_width("()]".len())?; + let one_line_budget = one_line_shape.width; + + let tactic = definitive_tactic( + &all_items, + ListTactic::HorizontalVertical, + Separator::Comma, + argument_shape.width, + ); + let trailing_separator = match context.config.indent_style() { + // We always add the trailing comma and remove it if it is not needed. + IndentStyle::Block => SeparatorTactic::Always, + IndentStyle::Visual => SeparatorTactic::Never, + }; + + // Format the collection of items. + let fmt = ListFormatting::new(argument_shape, context.config) + .tactic(tactic) + .trailing_separator(trailing_separator) + .ends_with_newline(false); + let item_str = write_list(&all_items, &fmt)?; + + debug!("item_str: '{}'", item_str); + + // Determine if the result will be nested, i.e. if we're using the block + // indent style and either the items are on multiple lines or we've exceeded + // our budget to fit on a single line. + let nested = context.config.indent_style() == IndentStyle::Block + && (item_str.contains('\n') || item_str.len() > one_line_budget); + + // Format the final result. + let mut result = String::with_capacity(128); + result.push_str(prefix); + result.push_str("[derive("); + if nested { + let nested_indent = argument_shape.indent.to_string_with_newline(context.config); + result.push_str(&nested_indent); + result.push_str(&item_str); + result.push_str(&shape.indent.to_string_with_newline(context.config)); + } else if let SeparatorTactic::Always = context.config.trailing_comma() { + // Retain the trailing comma. + result.push_str(&item_str); + } else if item_str.ends_with(',') { + // Remove the trailing comma. + result.push_str(&item_str[..item_str.len() - 1]); + } else { + result.push_str(&item_str); + } + result.push_str(")]"); + + Some(result) +} + +/// Returns the first group of attributes that fills the given predicate. +/// We consider two doc comments are in different group if they are separated by normal comments. +fn take_while_with_pred<'a, P>( + context: &RewriteContext<'_>, + attrs: &'a [ast::Attribute], + pred: P, +) -> &'a [ast::Attribute] +where + P: Fn(&ast::Attribute) -> bool, +{ + let mut len = 0; + let mut iter = attrs.iter().peekable(); + + while let Some(attr) = iter.next() { + if pred(attr) { + len += 1; + } else { + break; + } + if let Some(next_attr) = iter.peek() { + // Extract comments between two attributes. + let span_between_attr = mk_sp(attr.span.hi(), next_attr.span.lo()); + let snippet = context.snippet(span_between_attr); + if count_newlines(snippet) >= 2 || snippet.contains('/') { + break; + } + } + } + + &attrs[..len] +} + +/// Rewrite the any doc comments which come before any other attributes. +fn rewrite_initial_doc_comments( + context: &RewriteContext<'_>, + attrs: &[ast::Attribute], + shape: Shape, +) -> Option<(usize, Option<String>)> { + if attrs.is_empty() { + return Some((0, None)); + } + // Rewrite doc comments + let sugared_docs = take_while_with_pred(context, attrs, |a| a.is_doc_comment()); + if !sugared_docs.is_empty() { + let snippet = sugared_docs + .iter() + .map(|a| context.snippet(a.span)) + .collect::<Vec<_>>() + .join("\n"); + return Some(( + sugared_docs.len(), + Some(rewrite_doc_comment( + &snippet, + shape.comment(context.config), + context.config, + )?), + )); + } + + Some((0, None)) +} + +impl Rewrite for ast::NestedMetaItem { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + match self { + ast::NestedMetaItem::MetaItem(ref meta_item) => meta_item.rewrite(context, shape), + ast::NestedMetaItem::Literal(ref l) => rewrite_literal(context, l, shape), + } + } +} + +fn has_newlines_before_after_comment(comment: &str) -> (&str, &str) { + // Look at before and after comment and see if there are any empty lines. + let comment_begin = comment.find('/'); + let len = comment_begin.unwrap_or_else(|| comment.len()); + let mlb = count_newlines(&comment[..len]) > 1; + let mla = if comment_begin.is_none() { + mlb + } else { + comment + .chars() + .rev() + .take_while(|c| c.is_whitespace()) + .filter(|&c| c == '\n') + .count() + > 1 + }; + (if mlb { "\n" } else { "" }, if mla { "\n" } else { "" }) +} + +impl Rewrite for ast::MetaItem { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + Some(match self.kind { + ast::MetaItemKind::Word => { + rewrite_path(context, PathContext::Type, None, &self.path, shape)? + } + ast::MetaItemKind::List(ref list) => { + let path = rewrite_path(context, PathContext::Type, None, &self.path, shape)?; + let has_trailing_comma = crate::expr::span_ends_with_comma(context, self.span); + overflow::rewrite_with_parens( + context, + &path, + list.iter(), + // 1 = "]" + shape.sub_width(1)?, + self.span, + context.config.attr_fn_like_width(), + Some(if has_trailing_comma { + SeparatorTactic::Always + } else { + SeparatorTactic::Never + }), + )? + } + ast::MetaItemKind::NameValue(ref literal) => { + let path = rewrite_path(context, PathContext::Type, None, &self.path, shape)?; + // 3 = ` = ` + let lit_shape = shape.shrink_left(path.len() + 3)?; + // `rewrite_literal` returns `None` when `literal` exceeds max + // width. Since a literal is basically unformattable unless it + // is a string literal (and only if `format_strings` is set), + // we might be better off ignoring the fact that the attribute + // is longer than the max width and continue on formatting. + // See #2479 for example. + let value = rewrite_literal(context, literal, lit_shape) + .unwrap_or_else(|| context.snippet(literal.span).to_owned()); + format!("{} = {}", path, value) + } + }) + } +} + +impl Rewrite for ast::Attribute { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + let snippet = context.snippet(self.span); + if self.is_doc_comment() { + rewrite_doc_comment(snippet, shape.comment(context.config), context.config) + } else { + let should_skip = self + .ident() + .map(|s| context.skip_context.skip_attribute(s.name.as_str())) + .unwrap_or(false); + let prefix = attr_prefix(self); + + if should_skip || contains_comment(snippet) { + return Some(snippet.to_owned()); + } + + if let Some(ref meta) = self.meta() { + // This attribute is possibly a doc attribute needing normalization to a doc comment + if context.config.normalize_doc_attributes() && meta.has_name(sym::doc) { + if let Some(ref literal) = meta.value_str() { + let comment_style = match self.style { + ast::AttrStyle::Inner => CommentStyle::Doc, + ast::AttrStyle::Outer => CommentStyle::TripleSlash, + }; + + let literal_str = literal.as_str(); + let doc_comment_formatter = + DocCommentFormatter::new(literal_str, comment_style); + let doc_comment = format!("{}", doc_comment_formatter); + return rewrite_doc_comment( + &doc_comment, + shape.comment(context.config), + context.config, + ); + } + } + + // 1 = `[` + let shape = shape.offset_left(prefix.len() + 1)?; + Some( + meta.rewrite(context, shape) + .map_or_else(|| snippet.to_owned(), |rw| format!("{}[{}]", prefix, rw)), + ) + } else { + Some(snippet.to_owned()) + } + } + } +} + +impl Rewrite for [ast::Attribute] { + fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> { + if self.is_empty() { + return Some(String::new()); + } + + // The current remaining attributes. + let mut attrs = self; + let mut result = String::new(); + + // Determine if the source text is annotated with `#[rustfmt::skip::attributes(derive)]` + // or `#![rustfmt::skip::attributes(derive)]` + let skip_derives = context.skip_context.skip_attribute("derive"); + + // This is not just a simple map because we need to handle doc comments + // (where we take as many doc comment attributes as possible) and possibly + // merging derives into a single attribute. + loop { + if attrs.is_empty() { + return Some(result); + } + + // Handle doc comments. + let (doc_comment_len, doc_comment_str) = + rewrite_initial_doc_comments(context, attrs, shape)?; + if doc_comment_len > 0 { + let doc_comment_str = doc_comment_str.expect("doc comments, but no result"); + result.push_str(&doc_comment_str); + + let missing_span = attrs + .get(doc_comment_len) + .map(|next| mk_sp(attrs[doc_comment_len - 1].span.hi(), next.span.lo())); + if let Some(missing_span) = missing_span { + let snippet = context.snippet(missing_span); + let (mla, mlb) = has_newlines_before_after_comment(snippet); + let comment = crate::comment::recover_missing_comment_in_span( + missing_span, + shape.with_max_width(context.config), + context, + 0, + )?; + let comment = if comment.is_empty() { + format!("\n{}", mlb) + } else { + format!("{}{}\n{}", mla, comment, mlb) + }; + result.push_str(&comment); + result.push_str(&shape.indent.to_string(context.config)); + } + + attrs = &attrs[doc_comment_len..]; + + continue; + } + + // Handle derives if we will merge them. + if !skip_derives && context.config.merge_derives() && is_derive(&attrs[0]) { + let derives = take_while_with_pred(context, attrs, is_derive); + let derive_str = format_derive(derives, shape, context)?; + result.push_str(&derive_str); + + let missing_span = attrs + .get(derives.len()) + .map(|next| mk_sp(attrs[derives.len() - 1].span.hi(), next.span.lo())); + if let Some(missing_span) = missing_span { + let comment = crate::comment::recover_missing_comment_in_span( + missing_span, + shape.with_max_width(context.config), + context, + 0, + )?; + result.push_str(&comment); + if let Some(next) = attrs.get(derives.len()) { + if next.is_doc_comment() { + let snippet = context.snippet(missing_span); + let (_, mlb) = has_newlines_before_after_comment(snippet); + result.push_str(mlb); + } + } + result.push('\n'); + result.push_str(&shape.indent.to_string(context.config)); + } + + attrs = &attrs[derives.len()..]; + + continue; + } + + // If we get here, then we have a regular attribute, just handle one + // at a time. + + let formatted_attr = attrs[0].rewrite(context, shape)?; + result.push_str(&formatted_attr); + + let missing_span = attrs + .get(1) + .map(|next| mk_sp(attrs[0].span.hi(), next.span.lo())); + if let Some(missing_span) = missing_span { + let comment = crate::comment::recover_missing_comment_in_span( + missing_span, + shape.with_max_width(context.config), + context, + 0, + )?; + result.push_str(&comment); + if let Some(next) = attrs.get(1) { + if next.is_doc_comment() { + let snippet = context.snippet(missing_span); + let (_, mlb) = has_newlines_before_after_comment(snippet); + result.push_str(mlb); + } + } + result.push('\n'); + result.push_str(&shape.indent.to_string(context.config)); + } + + attrs = &attrs[1..]; + } + } +} + +fn attr_prefix(attr: &ast::Attribute) -> &'static str { + match attr.style { + ast::AttrStyle::Inner => "#!", + ast::AttrStyle::Outer => "#", + } +} + +pub(crate) trait MetaVisitor<'ast> { + fn visit_meta_item(&mut self, meta_item: &'ast ast::MetaItem) { + match meta_item.kind { + ast::MetaItemKind::Word => self.visit_meta_word(meta_item), + ast::MetaItemKind::List(ref list) => self.visit_meta_list(meta_item, list), + ast::MetaItemKind::NameValue(ref lit) => self.visit_meta_name_value(meta_item, lit), + } + } + + fn visit_meta_list( + &mut self, + _meta_item: &'ast ast::MetaItem, + list: &'ast [ast::NestedMetaItem], + ) { + for nm in list { + self.visit_nested_meta_item(nm); + } + } + + fn visit_meta_word(&mut self, _meta_item: &'ast ast::MetaItem) {} + + fn visit_meta_name_value(&mut self, _meta_item: &'ast ast::MetaItem, _lit: &'ast ast::Lit) {} + + fn visit_nested_meta_item(&mut self, nm: &'ast ast::NestedMetaItem) { + match nm { + ast::NestedMetaItem::MetaItem(ref meta_item) => self.visit_meta_item(meta_item), + ast::NestedMetaItem::Literal(ref lit) => self.visit_literal(lit), + } + } + + fn visit_literal(&mut self, _lit: &'ast ast::Lit) {} +} |