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//! Basic syntax highlighting functionality.
//!
//! This module uses librustc_ast's lexer to provide token-based highlighting for
//! the HTML documentation generated by rustdoc.
//!
//! Use the `render_with_highlighting` to highlight some rust code.
use crate::clean::PrimitiveType;
use crate::html::escape::Escape;
use crate::html::render::{Context, LinkFromSrc};
use std::collections::VecDeque;
use std::fmt::{Display, Write};
use rustc_data_structures::fx::FxHashMap;
use rustc_lexer::{Cursor, LiteralKind, TokenKind};
use rustc_span::edition::Edition;
use rustc_span::symbol::Symbol;
use rustc_span::{BytePos, Span, DUMMY_SP};
use super::format::{self, Buffer};
/// This type is needed in case we want to render links on items to allow to go to their definition.
pub(crate) struct HrefContext<'a, 'tcx> {
pub(crate) context: &'a Context<'tcx>,
/// This span contains the current file we're going through.
pub(crate) file_span: Span,
/// This field is used to know "how far" from the top of the directory we are to link to either
/// documentation pages or other source pages.
pub(crate) root_path: &'a str,
/// This field is used to calculate precise local URLs.
pub(crate) current_href: String,
}
/// Decorations are represented as a map from CSS class to vector of character ranges.
/// Each range will be wrapped in a span with that class.
#[derive(Default)]
pub(crate) struct DecorationInfo(pub(crate) FxHashMap<&'static str, Vec<(u32, u32)>>);
#[derive(Eq, PartialEq, Clone, Copy)]
pub(crate) enum Tooltip {
Ignore,
CompileFail,
ShouldPanic,
Edition(Edition),
None,
}
/// Highlights `src` as an inline example, returning the HTML output.
pub(crate) fn render_example_with_highlighting(
src: &str,
out: &mut Buffer,
tooltip: Tooltip,
playground_button: Option<&str>,
extra_classes: &[String],
) {
write_header(out, "rust-example-rendered", None, tooltip, extra_classes);
write_code(out, src, None, None);
write_footer(out, playground_button);
}
/// Highlights `src` as an item-decl, returning the HTML output.
pub(crate) fn render_item_decl_with_highlighting(src: &str, out: &mut Buffer) {
write!(out, "<pre class=\"rust item-decl\">");
write_code(out, src, None, None);
write!(out, "</pre>");
}
fn write_header(
out: &mut Buffer,
class: &str,
extra_content: Option<Buffer>,
tooltip: Tooltip,
extra_classes: &[String],
) {
write!(
out,
"<div class=\"example-wrap{}\">",
match tooltip {
Tooltip::Ignore => " ignore",
Tooltip::CompileFail => " compile_fail",
Tooltip::ShouldPanic => " should_panic",
Tooltip::Edition(_) => " edition",
Tooltip::None => "",
},
);
if tooltip != Tooltip::None {
let edition_code;
write!(
out,
"<a href=\"#\" class=\"tooltip\" title=\"{}\">ⓘ</a>",
match tooltip {
Tooltip::Ignore => "This example is not tested",
Tooltip::CompileFail => "This example deliberately fails to compile",
Tooltip::ShouldPanic => "This example panics",
Tooltip::Edition(edition) => {
edition_code = format!("This example runs with edition {edition}");
&edition_code
}
Tooltip::None => unreachable!(),
},
);
}
if let Some(extra) = extra_content {
out.push_buffer(extra);
}
if class.is_empty() {
write!(
out,
"<pre class=\"rust{}{}\">",
if extra_classes.is_empty() { "" } else { " " },
extra_classes.join(" "),
);
} else {
write!(
out,
"<pre class=\"rust {class}{}{}\">",
if extra_classes.is_empty() { "" } else { " " },
extra_classes.join(" "),
);
}
write!(out, "<code>");
}
/// Check if two `Class` can be merged together. In the following rules, "unclassified" means `None`
/// basically (since it's `Option<Class>`). The following rules apply:
///
/// * If two `Class` have the same variant, then they can be merged.
/// * If the other `Class` is unclassified and only contains white characters (backline,
/// whitespace, etc), it can be merged.
/// * `Class::Ident` is considered the same as unclassified (because it doesn't have an associated
/// CSS class).
fn can_merge(class1: Option<Class>, class2: Option<Class>, text: &str) -> bool {
match (class1, class2) {
(Some(c1), Some(c2)) => c1.is_equal_to(c2),
(Some(Class::Ident(_)), None) | (None, Some(Class::Ident(_))) => true,
(Some(_), None) | (None, Some(_)) => text.trim().is_empty(),
(None, None) => true,
}
}
/// This type is used as a conveniency to prevent having to pass all its fields as arguments into
/// the various functions (which became its methods).
struct TokenHandler<'a, 'tcx, F: Write> {
out: &'a mut F,
/// It contains the closing tag and the associated `Class`.
closing_tags: Vec<(&'static str, Class)>,
/// This is used because we don't automatically generate the closing tag on `ExitSpan` in
/// case an `EnterSpan` event with the same class follows.
pending_exit_span: Option<Class>,
/// `current_class` and `pending_elems` are used to group HTML elements with same `class`
/// attributes to reduce the DOM size.
current_class: Option<Class>,
/// We need to keep the `Class` for each element because it could contain a `Span` which is
/// used to generate links.
pending_elems: Vec<(&'a str, Option<Class>)>,
href_context: Option<HrefContext<'a, 'tcx>>,
}
impl<'a, 'tcx, F: Write> TokenHandler<'a, 'tcx, F> {
fn handle_exit_span(&mut self) {
// We can't get the last `closing_tags` element using `pop()` because `closing_tags` is
// being used in `write_pending_elems`.
let class = self.closing_tags.last().expect("ExitSpan without EnterSpan").1;
// We flush everything just in case...
self.write_pending_elems(Some(class));
exit_span(self.out, self.closing_tags.pop().expect("ExitSpan without EnterSpan").0);
self.pending_exit_span = None;
}
/// Write all the pending elements sharing a same (or at mergeable) `Class`.
///
/// If there is a "parent" (if a `EnterSpan` event was encountered) and the parent can be merged
/// with the elements' class, then we simply write the elements since the `ExitSpan` event will
/// close the tag.
///
/// Otherwise, if there is only one pending element, we let the `string` function handle both
/// opening and closing the tag, otherwise we do it into this function.
///
/// It returns `true` if `current_class` must be set to `None` afterwards.
fn write_pending_elems(&mut self, current_class: Option<Class>) -> bool {
if self.pending_elems.is_empty() {
return false;
}
if let Some((_, parent_class)) = self.closing_tags.last() &&
can_merge(current_class, Some(*parent_class), "")
{
for (text, class) in self.pending_elems.iter() {
string(self.out, Escape(text), *class, &self.href_context, false);
}
} else {
// We only want to "open" the tag ourselves if we have more than one pending and if the
// current parent tag is not the same as our pending content.
let close_tag = if self.pending_elems.len() > 1 && let Some(current_class) = current_class {
Some(enter_span(self.out, current_class, &self.href_context))
} else {
None
};
for (text, class) in self.pending_elems.iter() {
string(self.out, Escape(text), *class, &self.href_context, close_tag.is_none());
}
if let Some(close_tag) = close_tag {
exit_span(self.out, close_tag);
}
}
self.pending_elems.clear();
true
}
}
impl<'a, 'tcx, F: Write> Drop for TokenHandler<'a, 'tcx, F> {
/// When leaving, we need to flush all pending data to not have missing content.
fn drop(&mut self) {
if self.pending_exit_span.is_some() {
self.handle_exit_span();
} else {
self.write_pending_elems(self.current_class);
}
}
}
/// Convert the given `src` source code into HTML by adding classes for highlighting.
///
/// This code is used to render code blocks (in the documentation) as well as the source code pages.
///
/// Some explanations on the last arguments:
///
/// In case we are rendering a code block and not a source code file, `href_context` will be `None`.
/// To put it more simply: if `href_context` is `None`, the code won't try to generate links to an
/// item definition.
///
/// More explanations about spans and how we use them here are provided in the
pub(super) fn write_code(
out: &mut impl Write,
src: &str,
href_context: Option<HrefContext<'_, '_>>,
decoration_info: Option<DecorationInfo>,
) {
// This replace allows to fix how the code source with DOS backline characters is displayed.
let src = src.replace("\r\n", "\n");
let mut token_handler = TokenHandler {
out,
closing_tags: Vec::new(),
pending_exit_span: None,
current_class: None,
pending_elems: Vec::new(),
href_context,
};
Classifier::new(
&src,
token_handler.href_context.as_ref().map(|c| c.file_span).unwrap_or(DUMMY_SP),
decoration_info,
)
.highlight(&mut |highlight| {
match highlight {
Highlight::Token { text, class } => {
// If we received a `ExitSpan` event and then have a non-compatible `Class`, we
// need to close the `<span>`.
let need_current_class_update = if let Some(pending) = token_handler.pending_exit_span &&
!can_merge(Some(pending), class, text) {
token_handler.handle_exit_span();
true
// If the two `Class` are different, time to flush the current content and start
// a new one.
} else if !can_merge(token_handler.current_class, class, text) {
token_handler.write_pending_elems(token_handler.current_class);
true
} else {
token_handler.current_class.is_none()
};
if need_current_class_update {
token_handler.current_class = class.map(Class::dummy);
}
token_handler.pending_elems.push((text, class));
}
Highlight::EnterSpan { class } => {
let mut should_add = true;
if let Some(pending_exit_span) = token_handler.pending_exit_span {
if class.is_equal_to(pending_exit_span) {
should_add = false;
} else {
token_handler.handle_exit_span();
}
} else {
// We flush everything just in case...
if token_handler.write_pending_elems(token_handler.current_class) {
token_handler.current_class = None;
}
}
if should_add {
let closing_tag = enter_span(token_handler.out, class, &token_handler.href_context);
token_handler.closing_tags.push((closing_tag, class));
}
token_handler.current_class = None;
token_handler.pending_exit_span = None;
}
Highlight::ExitSpan => {
token_handler.current_class = None;
token_handler.pending_exit_span =
Some(token_handler.closing_tags.last().as_ref().expect("ExitSpan without EnterSpan").1);
}
};
});
}
fn write_footer(out: &mut Buffer, playground_button: Option<&str>) {
writeln!(out, "</code></pre>{}</div>", playground_button.unwrap_or_default());
}
/// How a span of text is classified. Mostly corresponds to token kinds.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum Class {
Comment,
DocComment,
Attribute,
KeyWord,
/// Keywords that do pointer/reference stuff.
RefKeyWord,
Self_(Span),
Macro(Span),
MacroNonTerminal,
String,
Number,
Bool,
/// `Ident` isn't rendered in the HTML but we still need it for the `Span` it contains.
Ident(Span),
Lifetime,
PreludeTy,
PreludeVal,
QuestionMark,
Decoration(&'static str),
}
impl Class {
/// It is only looking at the variant, not the variant content.
///
/// It is used mostly to group multiple similar HTML elements into one `<span>` instead of
/// multiple ones.
fn is_equal_to(self, other: Self) -> bool {
match (self, other) {
(Self::Self_(_), Self::Self_(_))
| (Self::Macro(_), Self::Macro(_))
| (Self::Ident(_), Self::Ident(_)) => true,
(Self::Decoration(c1), Self::Decoration(c2)) => c1 == c2,
(x, y) => x == y,
}
}
/// If `self` contains a `Span`, it'll be replaced with `DUMMY_SP` to prevent creating links
/// on "empty content" (because of the attributes merge).
fn dummy(self) -> Self {
match self {
Self::Self_(_) => Self::Self_(DUMMY_SP),
Self::Macro(_) => Self::Macro(DUMMY_SP),
Self::Ident(_) => Self::Ident(DUMMY_SP),
s => s,
}
}
/// Returns the css class expected by rustdoc for each `Class`.
fn as_html(self) -> &'static str {
match self {
Class::Comment => "comment",
Class::DocComment => "doccomment",
Class::Attribute => "attr",
Class::KeyWord => "kw",
Class::RefKeyWord => "kw-2",
Class::Self_(_) => "self",
Class::Macro(_) => "macro",
Class::MacroNonTerminal => "macro-nonterminal",
Class::String => "string",
Class::Number => "number",
Class::Bool => "bool-val",
Class::Ident(_) => "",
Class::Lifetime => "lifetime",
Class::PreludeTy => "prelude-ty",
Class::PreludeVal => "prelude-val",
Class::QuestionMark => "question-mark",
Class::Decoration(kind) => kind,
}
}
/// In case this is an item which can be converted into a link to a definition, it'll contain
/// a "span" (a tuple representing `(lo, hi)` equivalent of `Span`).
fn get_span(self) -> Option<Span> {
match self {
Self::Ident(sp) | Self::Self_(sp) | Self::Macro(sp) => Some(sp),
Self::Comment
| Self::DocComment
| Self::Attribute
| Self::KeyWord
| Self::RefKeyWord
| Self::MacroNonTerminal
| Self::String
| Self::Number
| Self::Bool
| Self::Lifetime
| Self::PreludeTy
| Self::PreludeVal
| Self::QuestionMark
| Self::Decoration(_) => None,
}
}
}
enum Highlight<'a> {
Token { text: &'a str, class: Option<Class> },
EnterSpan { class: Class },
ExitSpan,
}
struct TokenIter<'a> {
src: &'a str,
cursor: Cursor<'a>,
}
impl<'a> Iterator for TokenIter<'a> {
type Item = (TokenKind, &'a str);
fn next(&mut self) -> Option<(TokenKind, &'a str)> {
let token = self.cursor.advance_token();
if token.kind == TokenKind::Eof {
return None;
}
let (text, rest) = self.src.split_at(token.len as usize);
self.src = rest;
Some((token.kind, text))
}
}
/// Classifies into identifier class; returns `None` if this is a non-keyword identifier.
fn get_real_ident_class(text: &str, allow_path_keywords: bool) -> Option<Class> {
let ignore: &[&str] =
if allow_path_keywords { &["self", "Self", "super", "crate"] } else { &["self", "Self"] };
if ignore.iter().any(|k| *k == text) {
return None;
}
Some(match text {
"ref" | "mut" => Class::RefKeyWord,
"false" | "true" => Class::Bool,
_ if Symbol::intern(text).is_reserved(|| Edition::Edition2021) => Class::KeyWord,
_ => return None,
})
}
/// This iterator comes from the same idea than "Peekable" except that it allows to "peek" more than
/// just the next item by using `peek_next`. The `peek` method always returns the next item after
/// the current one whereas `peek_next` will return the next item after the last one peeked.
///
/// You can use both `peek` and `peek_next` at the same time without problem.
struct PeekIter<'a> {
stored: VecDeque<(TokenKind, &'a str)>,
/// This position is reinitialized when using `next`. It is used in `peek_next`.
peek_pos: usize,
iter: TokenIter<'a>,
}
impl<'a> PeekIter<'a> {
fn new(iter: TokenIter<'a>) -> Self {
Self { stored: VecDeque::new(), peek_pos: 0, iter }
}
/// Returns the next item after the current one. It doesn't interfere with `peek_next` output.
fn peek(&mut self) -> Option<&(TokenKind, &'a str)> {
if self.stored.is_empty() && let Some(next) = self.iter.next() {
self.stored.push_back(next);
}
self.stored.front()
}
/// Returns the next item after the last one peeked. It doesn't interfere with `peek` output.
fn peek_next(&mut self) -> Option<&(TokenKind, &'a str)> {
self.peek_pos += 1;
if self.peek_pos - 1 < self.stored.len() {
self.stored.get(self.peek_pos - 1)
} else if let Some(next) = self.iter.next() {
self.stored.push_back(next);
self.stored.back()
} else {
None
}
}
}
impl<'a> Iterator for PeekIter<'a> {
type Item = (TokenKind, &'a str);
fn next(&mut self) -> Option<Self::Item> {
self.peek_pos = 0;
if let Some(first) = self.stored.pop_front() { Some(first) } else { self.iter.next() }
}
}
/// Custom spans inserted into the source. Eg --scrape-examples uses this to highlight function calls
struct Decorations {
starts: Vec<(u32, &'static str)>,
ends: Vec<u32>,
}
impl Decorations {
fn new(info: DecorationInfo) -> Self {
// Extract tuples (start, end, kind) into separate sequences of (start, kind) and (end).
let (mut starts, mut ends): (Vec<_>, Vec<_>) = info
.0
.into_iter()
.flat_map(|(kind, ranges)| ranges.into_iter().map(move |(lo, hi)| ((lo, kind), hi)))
.unzip();
// Sort the sequences in document order.
starts.sort_by_key(|(lo, _)| *lo);
ends.sort();
Decorations { starts, ends }
}
}
/// Processes program tokens, classifying strings of text by highlighting
/// category (`Class`).
struct Classifier<'src> {
tokens: PeekIter<'src>,
in_attribute: bool,
in_macro: bool,
in_macro_nonterminal: bool,
byte_pos: u32,
file_span: Span,
src: &'src str,
decorations: Option<Decorations>,
}
impl<'src> Classifier<'src> {
/// Takes as argument the source code to HTML-ify, the rust edition to use and the source code
/// file span which will be used later on by the `span_correspondence_map`.
fn new(src: &str, file_span: Span, decoration_info: Option<DecorationInfo>) -> Classifier<'_> {
let tokens = PeekIter::new(TokenIter { src, cursor: Cursor::new(src) });
let decorations = decoration_info.map(Decorations::new);
Classifier {
tokens,
in_attribute: false,
in_macro: false,
in_macro_nonterminal: false,
byte_pos: 0,
file_span,
src,
decorations,
}
}
/// Convenient wrapper to create a [`Span`] from a position in the file.
fn new_span(&self, lo: u32, text: &str) -> Span {
let hi = lo + text.len() as u32;
let file_lo = self.file_span.lo();
self.file_span.with_lo(file_lo + BytePos(lo)).with_hi(file_lo + BytePos(hi))
}
/// Concatenate colons and idents as one when possible.
fn get_full_ident_path(&mut self) -> Vec<(TokenKind, usize, usize)> {
let start = self.byte_pos as usize;
let mut pos = start;
let mut has_ident = false;
loop {
let mut nb = 0;
while let Some((TokenKind::Colon, _)) = self.tokens.peek() {
self.tokens.next();
nb += 1;
}
// Ident path can start with "::" but if we already have content in the ident path,
// the "::" is mandatory.
if has_ident && nb == 0 {
return vec![(TokenKind::Ident, start, pos)];
} else if nb != 0 && nb != 2 {
if has_ident {
return vec![(TokenKind::Ident, start, pos), (TokenKind::Colon, pos, pos + nb)];
} else {
return vec![(TokenKind::Colon, start, pos + nb)];
}
}
if let Some((None, text)) = self.tokens.peek().map(|(token, text)| {
if *token == TokenKind::Ident {
let class = get_real_ident_class(text, true);
(class, text)
} else {
// Doesn't matter which Class we put in here...
(Some(Class::Comment), text)
}
}) {
// We only "add" the colon if there is an ident behind.
pos += text.len() + nb;
has_ident = true;
self.tokens.next();
} else if nb > 0 && has_ident {
return vec![(TokenKind::Ident, start, pos), (TokenKind::Colon, pos, pos + nb)];
} else if nb > 0 {
return vec![(TokenKind::Colon, start, start + nb)];
} else if has_ident {
return vec![(TokenKind::Ident, start, pos)];
} else {
return Vec::new();
}
}
}
/// Wraps the tokens iteration to ensure that the `byte_pos` is always correct.
///
/// It returns the token's kind, the token as a string and its byte position in the source
/// string.
fn next(&mut self) -> Option<(TokenKind, &'src str, u32)> {
if let Some((kind, text)) = self.tokens.next() {
let before = self.byte_pos;
self.byte_pos += text.len() as u32;
Some((kind, text, before))
} else {
None
}
}
/// Exhausts the `Classifier` writing the output into `sink`.
///
/// The general structure for this method is to iterate over each token,
/// possibly giving it an HTML span with a class specifying what flavor of
/// token is used.
fn highlight(mut self, sink: &mut dyn FnMut(Highlight<'src>)) {
loop {
if let Some(decs) = self.decorations.as_mut() {
let byte_pos = self.byte_pos;
let n_starts = decs.starts.iter().filter(|(i, _)| byte_pos >= *i).count();
for (_, kind) in decs.starts.drain(0..n_starts) {
sink(Highlight::EnterSpan { class: Class::Decoration(kind) });
}
let n_ends = decs.ends.iter().filter(|i| byte_pos >= **i).count();
for _ in decs.ends.drain(0..n_ends) {
sink(Highlight::ExitSpan);
}
}
if self
.tokens
.peek()
.map(|t| matches!(t.0, TokenKind::Colon | TokenKind::Ident))
.unwrap_or(false)
{
let tokens = self.get_full_ident_path();
for (token, start, end) in &tokens {
let text = &self.src[*start..*end];
self.advance(*token, text, sink, *start as u32);
self.byte_pos += text.len() as u32;
}
if !tokens.is_empty() {
continue;
}
}
if let Some((token, text, before)) = self.next() {
self.advance(token, text, sink, before);
} else {
break;
}
}
}
/// Single step of highlighting. This will classify `token`, but maybe also a couple of
/// following ones as well.
///
/// `before` is the position of the given token in the `source` string and is used as "lo" byte
/// in case we want to try to generate a link for this token using the
/// `span_correspondence_map`.
fn advance(
&mut self,
token: TokenKind,
text: &'src str,
sink: &mut dyn FnMut(Highlight<'src>),
before: u32,
) {
let lookahead = self.peek();
let no_highlight = |sink: &mut dyn FnMut(_)| sink(Highlight::Token { text, class: None });
let class = match token {
TokenKind::Whitespace => return no_highlight(sink),
TokenKind::LineComment { doc_style } | TokenKind::BlockComment { doc_style, .. } => {
if doc_style.is_some() {
Class::DocComment
} else {
Class::Comment
}
}
// Consider this as part of a macro invocation if there was a
// leading identifier.
TokenKind::Bang if self.in_macro => {
self.in_macro = false;
sink(Highlight::Token { text, class: None });
sink(Highlight::ExitSpan);
return;
}
// Assume that '&' or '*' is the reference or dereference operator
// or a reference or pointer type. Unless, of course, it looks like
// a logical and or a multiplication operator: `&&` or `* `.
TokenKind::Star => match self.tokens.peek() {
Some((TokenKind::Whitespace, _)) => return no_highlight(sink),
Some((TokenKind::Ident, "mut")) => {
self.next();
sink(Highlight::Token { text: "*mut", class: Some(Class::RefKeyWord) });
return;
}
Some((TokenKind::Ident, "const")) => {
self.next();
sink(Highlight::Token { text: "*const", class: Some(Class::RefKeyWord) });
return;
}
_ => Class::RefKeyWord,
},
TokenKind::And => match self.tokens.peek() {
Some((TokenKind::And, _)) => {
self.next();
sink(Highlight::Token { text: "&&", class: None });
return;
}
Some((TokenKind::Eq, _)) => {
self.next();
sink(Highlight::Token { text: "&=", class: None });
return;
}
Some((TokenKind::Whitespace, _)) => return no_highlight(sink),
Some((TokenKind::Ident, "mut")) => {
self.next();
sink(Highlight::Token { text: "&mut", class: Some(Class::RefKeyWord) });
return;
}
_ => Class::RefKeyWord,
},
// These can either be operators, or arrows.
TokenKind::Eq => match lookahead {
Some(TokenKind::Eq) => {
self.next();
sink(Highlight::Token { text: "==", class: None });
return;
}
Some(TokenKind::Gt) => {
self.next();
sink(Highlight::Token { text: "=>", class: None });
return;
}
_ => return no_highlight(sink),
},
TokenKind::Minus if lookahead == Some(TokenKind::Gt) => {
self.next();
sink(Highlight::Token { text: "->", class: None });
return;
}
// Other operators.
TokenKind::Minus
| TokenKind::Plus
| TokenKind::Or
| TokenKind::Slash
| TokenKind::Caret
| TokenKind::Percent
| TokenKind::Bang
| TokenKind::Lt
| TokenKind::Gt => return no_highlight(sink),
// Miscellaneous, no highlighting.
TokenKind::Dot
| TokenKind::Semi
| TokenKind::Comma
| TokenKind::OpenParen
| TokenKind::CloseParen
| TokenKind::OpenBrace
| TokenKind::CloseBrace
| TokenKind::OpenBracket
| TokenKind::At
| TokenKind::Tilde
| TokenKind::Colon
| TokenKind::Unknown => return no_highlight(sink),
TokenKind::Question => Class::QuestionMark,
TokenKind::Dollar => match lookahead {
Some(TokenKind::Ident) => {
self.in_macro_nonterminal = true;
Class::MacroNonTerminal
}
_ => return no_highlight(sink),
},
// This might be the start of an attribute. We're going to want to
// continue highlighting it as an attribute until the ending ']' is
// seen, so skip out early. Down below we terminate the attribute
// span when we see the ']'.
TokenKind::Pound => {
match lookahead {
// Case 1: #![inner_attribute]
Some(TokenKind::Bang) => {
self.next();
if let Some(TokenKind::OpenBracket) = self.peek() {
self.in_attribute = true;
sink(Highlight::EnterSpan { class: Class::Attribute });
}
sink(Highlight::Token { text: "#", class: None });
sink(Highlight::Token { text: "!", class: None });
return;
}
// Case 2: #[outer_attribute]
Some(TokenKind::OpenBracket) => {
self.in_attribute = true;
sink(Highlight::EnterSpan { class: Class::Attribute });
}
_ => (),
}
return no_highlight(sink);
}
TokenKind::CloseBracket => {
if self.in_attribute {
self.in_attribute = false;
sink(Highlight::Token { text: "]", class: None });
sink(Highlight::ExitSpan);
return;
}
return no_highlight(sink);
}
TokenKind::Literal { kind, .. } => match kind {
// Text literals.
LiteralKind::Byte { .. }
| LiteralKind::Char { .. }
| LiteralKind::Str { .. }
| LiteralKind::ByteStr { .. }
| LiteralKind::RawStr { .. }
| LiteralKind::RawByteStr { .. }
| LiteralKind::CStr { .. }
| LiteralKind::RawCStr { .. } => Class::String,
// Number literals.
LiteralKind::Float { .. } | LiteralKind::Int { .. } => Class::Number,
},
TokenKind::Ident | TokenKind::RawIdent if lookahead == Some(TokenKind::Bang) => {
self.in_macro = true;
sink(Highlight::EnterSpan { class: Class::Macro(self.new_span(before, text)) });
sink(Highlight::Token { text, class: None });
return;
}
TokenKind::Ident => match get_real_ident_class(text, false) {
None => match text {
"Option" | "Result" => Class::PreludeTy,
"Some" | "None" | "Ok" | "Err" => Class::PreludeVal,
// "union" is a weak keyword and is only considered as a keyword when declaring
// a union type.
"union" if self.check_if_is_union_keyword() => Class::KeyWord,
_ if self.in_macro_nonterminal => {
self.in_macro_nonterminal = false;
Class::MacroNonTerminal
}
"self" | "Self" => Class::Self_(self.new_span(before, text)),
_ => Class::Ident(self.new_span(before, text)),
},
Some(c) => c,
},
TokenKind::RawIdent | TokenKind::UnknownPrefix | TokenKind::InvalidIdent => {
Class::Ident(self.new_span(before, text))
}
TokenKind::Lifetime { .. } => Class::Lifetime,
TokenKind::Eof => panic!("Eof in advance"),
};
// Anything that didn't return above is the simple case where we the
// class just spans a single token, so we can use the `string` method.
sink(Highlight::Token { text, class: Some(class) });
}
fn peek(&mut self) -> Option<TokenKind> {
self.tokens.peek().map(|(token_kind, _text)| *token_kind)
}
fn check_if_is_union_keyword(&mut self) -> bool {
while let Some(kind) = self.tokens.peek_next().map(|(token_kind, _text)| token_kind) {
if *kind == TokenKind::Whitespace {
continue;
}
return *kind == TokenKind::Ident;
}
false
}
}
/// Called when we start processing a span of text that should be highlighted.
/// The `Class` argument specifies how it should be highlighted.
fn enter_span(
out: &mut impl Write,
klass: Class,
href_context: &Option<HrefContext<'_, '_>>,
) -> &'static str {
string_without_closing_tag(out, "", Some(klass), href_context, true).expect(
"internal error: enter_span was called with Some(klass) but did not return a \
closing HTML tag",
)
}
/// Called at the end of a span of highlighted text.
fn exit_span(out: &mut impl Write, closing_tag: &str) {
out.write_str(closing_tag).unwrap();
}
/// Called for a span of text. If the text should be highlighted differently
/// from the surrounding text, then the `Class` argument will be a value other
/// than `None`.
///
/// The following sequences of callbacks are equivalent:
/// ```plain
/// enter_span(Foo), string("text", None), exit_span()
/// string("text", Foo)
/// ```
///
/// The latter can be thought of as a shorthand for the former, which is more
/// flexible.
///
/// Note that if `context` is not `None` and that the given `klass` contains a `Span`, the function
/// will then try to find this `span` in the `span_correspondence_map`. If found, it'll then
/// generate a link for this element (which corresponds to where its definition is located).
fn string<T: Display>(
out: &mut impl Write,
text: T,
klass: Option<Class>,
href_context: &Option<HrefContext<'_, '_>>,
open_tag: bool,
) {
if let Some(closing_tag) = string_without_closing_tag(out, text, klass, href_context, open_tag)
{
out.write_str(closing_tag).unwrap();
}
}
/// This function writes `text` into `out` with some modifications depending on `klass`:
///
/// * If `klass` is `None`, `text` is written into `out` with no modification.
/// * If `klass` is `Some` but `klass.get_span()` is `None`, it writes the text wrapped in a
/// `<span>` with the provided `klass`.
/// * If `klass` is `Some` and has a [`rustc_span::Span`], it then tries to generate a link (`<a>`
/// element) by retrieving the link information from the `span_correspondence_map` that was filled
/// in `span_map.rs::collect_spans_and_sources`. If it cannot retrieve the information, then it's
/// the same as the second point (`klass` is `Some` but doesn't have a [`rustc_span::Span`]).
fn string_without_closing_tag<T: Display>(
out: &mut impl Write,
text: T,
klass: Option<Class>,
href_context: &Option<HrefContext<'_, '_>>,
open_tag: bool,
) -> Option<&'static str> {
let Some(klass) = klass else {
write!(out, "{text}").unwrap();
return None;
};
let Some(def_span) = klass.get_span() else {
if !open_tag {
write!(out, "{text}").unwrap();
return None;
}
write!(out, "<span class=\"{klass}\">{text}", klass = klass.as_html()).unwrap();
return Some("</span>");
};
let mut text_s = text.to_string();
if text_s.contains("::") {
text_s = text_s.split("::").intersperse("::").fold(String::new(), |mut path, t| {
match t {
"self" | "Self" => write!(
&mut path,
"<span class=\"{klass}\">{t}</span>",
klass = Class::Self_(DUMMY_SP).as_html(),
),
"crate" | "super" => {
write!(
&mut path,
"<span class=\"{klass}\">{t}</span>",
klass = Class::KeyWord.as_html(),
)
}
t => write!(&mut path, "{t}"),
}
.expect("Failed to build source HTML path");
path
});
}
if let Some(href_context) = href_context {
if let Some(href) =
href_context.context.shared.span_correspondence_map.get(&def_span).and_then(|href| {
let context = href_context.context;
// FIXME: later on, it'd be nice to provide two links (if possible) for all items:
// one to the documentation page and one to the source definition.
// FIXME: currently, external items only generate a link to their documentation,
// a link to their definition can be generated using this:
// https://github.com/rust-lang/rust/blob/60f1a2fc4b535ead9c85ce085fdce49b1b097531/src/librustdoc/html/render/context.rs#L315-L338
match href {
LinkFromSrc::Local(span) => {
context.href_from_span_relative(*span, &href_context.current_href)
}
LinkFromSrc::External(def_id) => {
format::href_with_root_path(*def_id, context, Some(href_context.root_path))
.ok()
.map(|(url, _, _)| url)
}
LinkFromSrc::Primitive(prim) => format::href_with_root_path(
PrimitiveType::primitive_locations(context.tcx())[prim],
context,
Some(href_context.root_path),
)
.ok()
.map(|(url, _, _)| url),
LinkFromSrc::Doc(def_id) => {
format::href_with_root_path(*def_id, context, Some(&href_context.root_path))
.ok()
.map(|(doc_link, _, _)| doc_link)
}
}
})
{
if !open_tag {
// We're already inside an element which has the same klass, no need to give it
// again.
write!(out, "<a href=\"{href}\">{text_s}").unwrap();
} else {
let klass_s = klass.as_html();
if klass_s.is_empty() {
write!(out, "<a href=\"{href}\">{text_s}").unwrap();
} else {
write!(out, "<a class=\"{klass_s}\" href=\"{href}\">{text_s}").unwrap();
}
}
return Some("</a>");
}
}
if !open_tag {
write!(out, "{}", text_s).unwrap();
return None;
}
let klass_s = klass.as_html();
if klass_s.is_empty() {
out.write_str(&text_s).unwrap();
Some("")
} else {
write!(out, "<span class=\"{klass_s}\">{text_s}").unwrap();
Some("</span>")
}
}
#[cfg(test)]
mod tests;