Merge #5750

5750: Rename ra_ide -> ide
 r=matklad a=matklad

bors r+
🤖

Co-authored-by: Aleksey Kladov <[email protected]>

4 files changed, 932 insertions, 0 deletions

diff --git a/crates/ide/src/syntax_highlighting/html.rs b/crates/ide/src/syntax_highlighting/html.rs
new file mode 100644
index 000000000..249368ff8
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/html.rs
@@ -0,0 +1,97 @@
+//! Renders a bit of code as HTML.
+
+use base_db::SourceDatabase;
+use oorandom::Rand32;
+use syntax::{AstNode, TextRange, TextSize};
+
+use crate::{syntax_highlighting::highlight, FileId, RootDatabase};
+
+pub(crate) fn highlight_as_html(db: &RootDatabase, file_id: FileId, rainbow: bool) -> String {
+    let parse = db.parse(file_id);
+
+    fn rainbowify(seed: u64) -> String {
+        let mut rng = Rand32::new(seed);
+        format!(
+            "hsl({h},{s}%,{l}%)",
+            h = rng.rand_range(0..361),
+            s = rng.rand_range(42..99),
+            l = rng.rand_range(40..91),
+        )
+    }
+
+    let ranges = highlight(db, file_id, None, false);
+    let text = parse.tree().syntax().to_string();
+    let mut prev_pos = TextSize::from(0);
+    let mut buf = String::new();
+    buf.push_str(&STYLE);
+    buf.push_str("<pre><code>");
+    for range in &ranges {
+        if range.range.start() > prev_pos {
+            let curr = &text[TextRange::new(prev_pos, range.range.start())];
+            let text = html_escape(curr);
+            buf.push_str(&text);
+        }
+        let curr = &text[TextRange::new(range.range.start(), range.range.end())];
+
+        let class = range.highlight.to_string().replace('.', " ");
+        let color = match (rainbow, range.binding_hash) {
+            (true, Some(hash)) => {
+                format!(" data-binding-hash=\"{}\" style=\"color: {};\"", hash, rainbowify(hash))
+            }
+            _ => "".into(),
+        };
+        buf.push_str(&format!("<span class=\"{}\"{}>{}</span>", class, color, html_escape(curr)));
+
+        prev_pos = range.range.end();
+    }
+    // Add the remaining (non-highlighted) text
+    let curr = &text[TextRange::new(prev_pos, TextSize::of(&text))];
+    let text = html_escape(curr);
+    buf.push_str(&text);
+    buf.push_str("</code></pre>");
+    buf
+}
+
+//FIXME: like, real html escaping
+fn html_escape(text: &str) -> String {
+    text.replace("<", "&lt;").replace(">", "&gt;")
+}
+
+const STYLE: &str = "
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+";
diff --git a/crates/ide/src/syntax_highlighting/injection.rs b/crates/ide/src/syntax_highlighting/injection.rs
new file mode 100644
index 000000000..43f4e6fea
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/injection.rs
@@ -0,0 +1,187 @@
+//! Syntax highlighting injections such as highlighting of documentation tests.
+
+use std::{collections::BTreeMap, convert::TryFrom};
+
+use ast::{HasQuotes, HasStringValue};
+use hir::Semantics;
+use itertools::Itertools;
+use syntax::{ast, AstToken, SyntaxNode, SyntaxToken, TextRange, TextSize};
+
+use crate::{
+    call_info::ActiveParameter, Analysis, Highlight, HighlightModifier, HighlightTag,
+    HighlightedRange, RootDatabase,
+};
+
+use super::HighlightedRangeStack;
+
+pub(super) fn highlight_injection(
+    acc: &mut HighlightedRangeStack,
+    sema: &Semantics<RootDatabase>,
+    literal: ast::RawString,
+    expanded: SyntaxToken,
+) -> Option<()> {
+    let active_parameter = ActiveParameter::at_token(&sema, expanded)?;
+    if !active_parameter.name.starts_with("ra_fixture") {
+        return None;
+    }
+    let value = literal.value()?;
+    let (analysis, tmp_file_id) = Analysis::from_single_file(value.into_owned());
+
+    if let Some(range) = literal.open_quote_text_range() {
+        acc.add(HighlightedRange {
+            range,
+            highlight: HighlightTag::StringLiteral.into(),
+            binding_hash: None,
+        })
+    }
+
+    for mut h in analysis.highlight(tmp_file_id).unwrap() {
+        if let Some(r) = literal.map_range_up(h.range) {
+            h.range = r;
+            acc.add(h)
+        }
+    }
+
+    if let Some(range) = literal.close_quote_text_range() {
+        acc.add(HighlightedRange {
+            range,
+            highlight: HighlightTag::StringLiteral.into(),
+            binding_hash: None,
+        })
+    }
+
+    Some(())
+}
+
+/// Mapping from extracted documentation code to original code
+type RangesMap = BTreeMap<TextSize, TextSize>;
+
+const RUSTDOC_FENCE: &'static str = "```";
+const RUSTDOC_FENCE_TOKENS: &[&'static str] =
+    &["", "rust", "should_panic", "ignore", "no_run", "compile_fail", "edition2015", "edition2018"];
+
+/// Extracts Rust code from documentation comments as well as a mapping from
+/// the extracted source code back to the original source ranges.
+/// Lastly, a vector of new comment highlight ranges (spanning only the
+/// comment prefix) is returned which is used in the syntax highlighting
+/// injection to replace the previous (line-spanning) comment ranges.
+pub(super) fn extract_doc_comments(
+    node: &SyntaxNode,
+) -> Option<(String, RangesMap, Vec<HighlightedRange>)> {
+    // wrap the doctest into function body to get correct syntax highlighting
+    let prefix = "fn doctest() {\n";
+    let suffix = "}\n";
+    // Mapping from extracted documentation code to original code
+    let mut range_mapping: RangesMap = BTreeMap::new();
+    let mut line_start = TextSize::try_from(prefix.len()).unwrap();
+    let mut is_codeblock = false;
+    let mut is_doctest = false;
+    // Replace the original, line-spanning comment ranges by new, only comment-prefix
+    // spanning comment ranges.
+    let mut new_comments = Vec::new();
+    let doctest = node
+        .children_with_tokens()
+        .filter_map(|el| el.into_token().and_then(ast::Comment::cast))
+        .filter(|comment| comment.kind().doc.is_some())
+        .filter(|comment| {
+            if let Some(idx) = comment.text().find(RUSTDOC_FENCE) {
+                is_codeblock = !is_codeblock;
+                // Check whether code is rust by inspecting fence guards
+                let guards = &comment.text()[idx + RUSTDOC_FENCE.len()..];
+                let is_rust =
+                    guards.split(',').all(|sub| RUSTDOC_FENCE_TOKENS.contains(&sub.trim()));
+                is_doctest = is_codeblock && is_rust;
+                false
+            } else {
+                is_doctest
+            }
+        })
+        .map(|comment| {
+            let prefix_len = comment.prefix().len();
+            let line: &str = comment.text().as_str();
+            let range = comment.syntax().text_range();
+
+            // whitespace after comment is ignored
+            let pos = if let Some(ws) = line.chars().nth(prefix_len).filter(|c| c.is_whitespace()) {
+                prefix_len + ws.len_utf8()
+            } else {
+                prefix_len
+            };
+
+            // lines marked with `#` should be ignored in output, we skip the `#` char
+            let pos = if let Some(ws) = line.chars().nth(pos).filter(|&c| c == '#') {
+                pos + ws.len_utf8()
+            } else {
+                pos
+            };
+
+            range_mapping.insert(line_start, range.start() + TextSize::try_from(pos).unwrap());
+            new_comments.push(HighlightedRange {
+                range: TextRange::new(
+                    range.start(),
+                    range.start() + TextSize::try_from(pos).unwrap(),
+                ),
+                highlight: HighlightTag::Comment | HighlightModifier::Documentation,
+                binding_hash: None,
+            });
+            line_start += range.len() - TextSize::try_from(pos).unwrap();
+            line_start += TextSize::try_from('\n'.len_utf8()).unwrap();
+
+            line[pos..].to_owned()
+        })
+        .join("\n");
+
+    if doctest.is_empty() {
+        return None;
+    }
+
+    let doctest = format!("{}{}{}", prefix, doctest, suffix);
+    Some((doctest, range_mapping, new_comments))
+}
+
+/// Injection of syntax highlighting of doctests.
+pub(super) fn highlight_doc_comment(
+    text: String,
+    range_mapping: RangesMap,
+    new_comments: Vec<HighlightedRange>,
+    stack: &mut HighlightedRangeStack,
+) {
+    let (analysis, tmp_file_id) = Analysis::from_single_file(text);
+
+    stack.push();
+    for mut h in analysis.with_db(|db| super::highlight(db, tmp_file_id, None, true)).unwrap() {
+        // Determine start offset and end offset in case of multi-line ranges
+        let mut start_offset = None;
+        let mut end_offset = None;
+        for (line_start, orig_line_start) in range_mapping.range(..h.range.end()).rev() {
+            // It's possible for orig_line_start - line_start to be negative. Add h.range.start()
+            // here and remove it from the end range after the loop below so that the values are
+            // always non-negative.
+            let offset = h.range.start() + orig_line_start - line_start;
+            if line_start <= &h.range.start() {
+                start_offset.get_or_insert(offset);
+                break;
+            } else {
+                end_offset.get_or_insert(offset);
+            }
+        }
+        if let Some(start_offset) = start_offset {
+            h.range = TextRange::new(
+                start_offset,
+                h.range.end() + end_offset.unwrap_or(start_offset) - h.range.start(),
+            );
+
+            h.highlight |= HighlightModifier::Injected;
+            stack.add(h);
+        }
+    }
+
+    // Inject the comment prefix highlight ranges
+    stack.push();
+    for comment in new_comments {
+        stack.add(comment);
+    }
+    stack.pop_and_inject(None);
+    stack
+        .pop_and_inject(Some(Highlight::from(HighlightTag::Generic) | HighlightModifier::Injected));
+}
diff --git a/crates/ide/src/syntax_highlighting/tags.rs b/crates/ide/src/syntax_highlighting/tags.rs
new file mode 100644
index 000000000..49ec94bdc
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/tags.rs
@@ -0,0 +1,203 @@
+//! Defines token tags we use for syntax highlighting.
+//! A tag is not unlike a CSS class.
+
+use std::{fmt, ops};
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct Highlight {
+    pub tag: HighlightTag,
+    pub modifiers: HighlightModifiers,
+}
+
+#[derive(Default, Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct HighlightModifiers(u32);
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum HighlightTag {
+    Attribute,
+    BoolLiteral,
+    BuiltinType,
+    ByteLiteral,
+    CharLiteral,
+    Comment,
+    Constant,
+    Enum,
+    EnumVariant,
+    EscapeSequence,
+    Field,
+    Function,
+    Generic,
+    Keyword,
+    Lifetime,
+    Macro,
+    Module,
+    NumericLiteral,
+    Punctuation,
+    SelfKeyword,
+    SelfType,
+    Static,
+    StringLiteral,
+    Struct,
+    Trait,
+    TypeAlias,
+    TypeParam,
+    Union,
+    ValueParam,
+    Local,
+    UnresolvedReference,
+    FormatSpecifier,
+    Operator,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[repr(u8)]
+pub enum HighlightModifier {
+    /// Used to differentiate individual elements within attributes.
+    Attribute = 0,
+    /// Used with keywords like `if` and `break`.
+    ControlFlow,
+    /// `foo` in `fn foo(x: i32)` is a definition, `foo` in `foo(90 + 2)` is
+    /// not.
+    Definition,
+    Documentation,
+    Injected,
+    Mutable,
+    Unsafe,
+}
+
+impl HighlightTag {
+    fn as_str(self) -> &'static str {
+        match self {
+            HighlightTag::Attribute => "attribute",
+            HighlightTag::BoolLiteral => "bool_literal",
+            HighlightTag::BuiltinType => "builtin_type",
+            HighlightTag::ByteLiteral => "byte_literal",
+            HighlightTag::CharLiteral => "char_literal",
+            HighlightTag::Comment => "comment",
+            HighlightTag::Constant => "constant",
+            HighlightTag::Enum => "enum",
+            HighlightTag::EnumVariant => "enum_variant",
+            HighlightTag::EscapeSequence => "escape_sequence",
+            HighlightTag::Field => "field",
+            HighlightTag::FormatSpecifier => "format_specifier",
+            HighlightTag::Function => "function",
+            HighlightTag::Generic => "generic",
+            HighlightTag::Keyword => "keyword",
+            HighlightTag::Lifetime => "lifetime",
+            HighlightTag::Punctuation => "punctuation",
+            HighlightTag::Macro => "macro",
+            HighlightTag::Module => "module",
+            HighlightTag::NumericLiteral => "numeric_literal",
+            HighlightTag::Operator => "operator",
+            HighlightTag::SelfKeyword => "self_keyword",
+            HighlightTag::SelfType => "self_type",
+            HighlightTag::Static => "static",
+            HighlightTag::StringLiteral => "string_literal",
+            HighlightTag::Struct => "struct",
+            HighlightTag::Trait => "trait",
+            HighlightTag::TypeAlias => "type_alias",
+            HighlightTag::TypeParam => "type_param",
+            HighlightTag::Union => "union",
+            HighlightTag::ValueParam => "value_param",
+            HighlightTag::Local => "variable",
+            HighlightTag::UnresolvedReference => "unresolved_reference",
+        }
+    }
+}
+
+impl fmt::Display for HighlightTag {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.as_str(), f)
+    }
+}
+
+impl HighlightModifier {
+    const ALL: &'static [HighlightModifier] = &[
+        HighlightModifier::Attribute,
+        HighlightModifier::ControlFlow,
+        HighlightModifier::Definition,
+        HighlightModifier::Documentation,
+        HighlightModifier::Injected,
+        HighlightModifier::Mutable,
+        HighlightModifier::Unsafe,
+    ];
+
+    fn as_str(self) -> &'static str {
+        match self {
+            HighlightModifier::Attribute => "attribute",
+            HighlightModifier::ControlFlow => "control",
+            HighlightModifier::Definition => "declaration",
+            HighlightModifier::Documentation => "documentation",
+            HighlightModifier::Injected => "injected",
+            HighlightModifier::Mutable => "mutable",
+            HighlightModifier::Unsafe => "unsafe",
+        }
+    }
+
+    fn mask(self) -> u32 {
+        1 << (self as u32)
+    }
+}
+
+impl fmt::Display for HighlightModifier {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.as_str(), f)
+    }
+}
+
+impl fmt::Display for Highlight {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.tag)?;
+        for modifier in self.modifiers.iter() {
+            write!(f, ".{}", modifier)?
+        }
+        Ok(())
+    }
+}
+
+impl From<HighlightTag> for Highlight {
+    fn from(tag: HighlightTag) -> Highlight {
+        Highlight::new(tag)
+    }
+}
+
+impl Highlight {
+    pub(crate) fn new(tag: HighlightTag) -> Highlight {
+        Highlight { tag, modifiers: HighlightModifiers::default() }
+    }
+}
+
+impl ops::BitOr<HighlightModifier> for HighlightTag {
+    type Output = Highlight;
+
+    fn bitor(self, rhs: HighlightModifier) -> Highlight {
+        Highlight::new(self) | rhs
+    }
+}
+
+impl ops::BitOrAssign<HighlightModifier> for HighlightModifiers {
+    fn bitor_assign(&mut self, rhs: HighlightModifier) {
+        self.0 |= rhs.mask();
+    }
+}
+
+impl ops::BitOrAssign<HighlightModifier> for Highlight {
+    fn bitor_assign(&mut self, rhs: HighlightModifier) {
+        self.modifiers |= rhs;
+    }
+}
+
+impl ops::BitOr<HighlightModifier> for Highlight {
+    type Output = Highlight;
+
+    fn bitor(mut self, rhs: HighlightModifier) -> Highlight {
+        self |= rhs;
+        self
+    }
+}
+
+impl HighlightModifiers {
+    pub fn iter(self) -> impl Iterator<Item = HighlightModifier> {
+        HighlightModifier::ALL.iter().copied().filter(move |it| self.0 & it.mask() == it.mask())
+    }
+}
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
new file mode 100644
index 000000000..94f37d773
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -0,0 +1,445 @@
+use std::fs;
+
+use expect::{expect_file, ExpectFile};
+use test_utils::project_dir;
+
+use crate::{mock_analysis::single_file, FileRange, TextRange};
+
+#[test]
+fn test_highlighting() {
+    check_highlighting(
+        r#"
+use inner::{self as inner_mod};
+mod inner {}
+
+#[derive(Clone, Debug)]
+struct Foo {
+    pub x: i32,
+    pub y: i32,
+}
+
+trait Bar {
+    fn bar(&self) -> i32;
+}
+
+impl Bar for Foo {
+    fn bar(&self) -> i32 {
+        self.x
+    }
+}
+
+impl Foo {
+    fn baz(mut self) -> i32 {
+        self.x
+    }
+
+    fn qux(&mut self) {
+        self.x = 0;
+    }
+}
+
+static mut STATIC_MUT: i32 = 0;
+
+fn foo<'a, T>() -> T {
+    foo::<'a, i32>()
+}
+
+macro_rules! def_fn {
+    ($($tt:tt)*) => {$($tt)*}
+}
+
+def_fn! {
+    fn bar() -> u32 {
+        100
+    }
+}
+
+macro_rules! noop {
+    ($expr:expr) => {
+        $expr
+    }
+}
+
+// comment
+fn main() {
+    println!("Hello, {}!", 92);
+
+    let mut vec = Vec::new();
+    if true {
+        let x = 92;
+        vec.push(Foo { x, y: 1 });
+    }
+    unsafe {
+        vec.set_len(0);
+        STATIC_MUT = 1;
+    }
+
+    for e in vec {
+        // Do nothing
+    }
+
+    noop!(noop!(1));
+
+    let mut x = 42;
+    let y = &mut x;
+    let z = &y;
+
+    let Foo { x: z, y } = Foo { x: z, y };
+
+    y;
+}
+
+enum Option<T> {
+    Some(T),
+    None,
+}
+use Option::*;
+
+impl<T> Option<T> {
+    fn and<U>(self, other: Option<U>) -> Option<(T, U)> {
+        match other {
+            None => unimplemented!(),
+            Nope => Nope,
+        }
+    }
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlighting.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_rainbow_highlighting() {
+    check_highlighting(
+        r#"
+fn main() {
+    let hello = "hello";
+    let x = hello.to_string();
+    let y = hello.to_string();
+
+    let x = "other color please!";
+    let y = x.to_string();
+}
+
+fn bar() {
+    let mut hello = "hello";
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/rainbow_highlighting.html"],
+        true,
+    );
+}
+
+#[test]
+fn accidentally_quadratic() {
+    let file = project_dir().join("crates/syntax/test_data/accidentally_quadratic");
+    let src = fs::read_to_string(file).unwrap();
+
+    let (analysis, file_id) = single_file(&src);
+
+    // let t = std::time::Instant::now();
+    let _ = analysis.highlight(file_id).unwrap();
+    // eprintln!("elapsed: {:?}", t.elapsed());
+}
+
+#[test]
+fn test_ranges() {
+    let (analysis, file_id) = single_file(
+        r#"
+#[derive(Clone, Debug)]
+struct Foo {
+    pub x: i32,
+    pub y: i32,
+}
+"#,
+    );
+
+    // The "x"
+    let highlights = &analysis
+        .highlight_range(FileRange { file_id, range: TextRange::at(45.into(), 1.into()) })
+        .unwrap();
+
+    assert_eq!(&highlights[0].highlight.to_string(), "field.declaration");
+}
+
+#[test]
+fn test_flattening() {
+    check_highlighting(
+        r##"
+fn fixture(ra_fixture: &str) {}
+
+fn main() {
+    fixture(r#"
+        trait Foo {
+            fn foo() {
+                println!("2 + 2 = {}", 4);
+            }
+        }"#
+    );
+}"##
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_injection.html"],
+        false,
+    );
+}
+
+#[test]
+fn ranges_sorted() {
+    let (analysis, file_id) = single_file(
+        r#"
+#[foo(bar = "bar")]
+macro_rules! test {}
+}"#
+        .trim(),
+    );
+    let _ = analysis.highlight(file_id).unwrap();
+}
+
+#[test]
+fn test_string_highlighting() {
+    // The format string detection is based on macro-expansion,
+    // thus, we have to copy the macro definition from `std`
+    check_highlighting(
+        r#"
+macro_rules! println {
+    ($($arg:tt)*) => ({
+        $crate::io::_print($crate::format_args_nl!($($arg)*));
+    })
+}
+#[rustc_builtin_macro]
+macro_rules! format_args_nl {
+    ($fmt:expr) => {{ /* compiler built-in */ }};
+    ($fmt:expr, $($args:tt)*) => {{ /* compiler built-in */ }};
+}
+
+fn main() {
+    // from https://doc.rust-lang.org/std/fmt/index.html
+    println!("Hello");                 // => "Hello"
+    println!("Hello, {}!", "world");   // => "Hello, world!"
+    println!("The number is {}", 1);   // => "The number is 1"
+    println!("{:?}", (3, 4));          // => "(3, 4)"
+    println!("{value}", value=4);      // => "4"
+    println!("{} {}", 1, 2);           // => "1 2"
+    println!("{:04}", 42);             // => "0042" with leading zerosV
+    println!("{1} {} {0} {}", 1, 2);   // => "2 1 1 2"
+    println!("{argument}", argument = "test");   // => "test"
+    println!("{name} {}", 1, name = 2);          // => "2 1"
+    println!("{a} {c} {b}", a="a", b='b', c=3);  // => "a 3 b"
+    println!("{{{}}}", 2);                       // => "{2}"
+    println!("Hello {:5}!", "x");
+    println!("Hello {:1$}!", "x", 5);
+    println!("Hello {1:0$}!", 5, "x");
+    println!("Hello {:width$}!", "x", width = 5);
+    println!("Hello {:<5}!", "x");
+    println!("Hello {:-<5}!", "x");
+    println!("Hello {:^5}!", "x");
+    println!("Hello {:>5}!", "x");
+    println!("Hello {:+}!", 5);
+    println!("{:#x}!", 27);
+    println!("Hello {:05}!", 5);
+    println!("Hello {:05}!", -5);
+    println!("{:#010x}!", 27);
+    println!("Hello {0} is {1:.5}", "x", 0.01);
+    println!("Hello {1} is {2:.0$}", 5, "x", 0.01);
+    println!("Hello {0} is {2:.1$}", "x", 5, 0.01);
+    println!("Hello {} is {:.*}",    "x", 5, 0.01);
+    println!("Hello {} is {2:.*}",   "x", 5, 0.01);
+    println!("Hello {} is {number:.prec$}", "x", prec = 5, number = 0.01);
+    println!("{}, `{name:.*}` has 3 fractional digits", "Hello", 3, name=1234.56);
+    println!("{}, `{name:.*}` has 3 characters", "Hello", 3, name="1234.56");
+    println!("{}, `{name:>8.*}` has 3 right-aligned characters", "Hello", 3, name="1234.56");
+    println!("Hello {{}}");
+    println!("{{ Hello");
+
+    println!(r"Hello, {}!", "world");
+
+    // escape sequences
+    println!("Hello\nWorld");
+    println!("\u{48}\x65\x6C\x6C\x6F World");
+
+    println!("{\x41}", A = 92);
+    println!("{ничоси}", ничоси = 92);
+}"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_strings.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_unsafe_highlighting() {
+    check_highlighting(
+        r#"
+unsafe fn unsafe_fn() {}
+
+union Union {
+    a: u32,
+    b: f32,
+}
+
+struct HasUnsafeFn;
+
+impl HasUnsafeFn {
+    unsafe fn unsafe_method(&self) {}
+}
+
+struct TypeForStaticMut {
+    a: u8
+}
+
+static mut global_mut: TypeForStaticMut = TypeForStaticMut { a: 0 };
+
+#[repr(packed)]
+struct Packed {
+    a: u16,
+}
+
+trait DoTheAutoref {
+    fn calls_autoref(&self);
+}
+
+impl DoTheAutoref for u16 {
+    fn calls_autoref(&self) {}
+}
+
+fn main() {
+    let x = &5 as *const _ as *const usize;
+    let u = Union { b: 0 };
+    unsafe {
+        // unsafe fn and method calls
+        unsafe_fn();
+        let b = u.b;
+        match u {
+            Union { b: 0 } => (),
+            Union { a } => (),
+        }
+        HasUnsafeFn.unsafe_method();
+
+        // unsafe deref
+        let y = *x;
+
+        // unsafe access to a static mut
+        let a = global_mut.a;
+
+        // unsafe ref of packed fields
+        let packed = Packed { a: 0 };
+        let a = &packed.a;
+        let ref a = packed.a;
+        let Packed { ref a } = packed;
+        let Packed { a: ref _a } = packed;
+
+        // unsafe auto ref of packed field
+        packed.a.calls_autoref();
+    }
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_unsafe.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_highlight_doctest() {
+    check_highlighting(
+        r#"
+/// ```
+/// let _ = "early doctests should not go boom";
+/// ```
+struct Foo {
+    bar: bool,
+}
+
+impl Foo {
+    pub const bar: bool = true;
+
+    /// Constructs a new `Foo`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![allow(unused_mut)]
+    /// let mut foo: Foo = Foo::new();
+    /// ```
+    pub const fn new() -> Foo {
+        Foo { bar: true }
+    }
+
+    /// `bar` method on `Foo`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use x::y;
+    ///
+    /// let foo = Foo::new();
+    ///
+    /// // calls bar on foo
+    /// assert!(foo.bar());
+    ///
+    /// let bar = foo.bar || Foo::bar;
+    ///
+    /// /* multi-line
+    ///        comment */
+    ///
+    /// let multi_line_string = "Foo
+    ///   bar
+    ///          ";
+    ///
+    /// ```
+    ///
+    /// ```rust,no_run
+    /// let foobar = Foo::new().bar();
+    /// ```
+    ///
+    /// ```sh
+    /// echo 1
+    /// ```
+    pub fn foo(&self) -> bool {
+        true
+    }
+}
+
+/// ```
+/// noop!(1);
+/// ```
+macro_rules! noop {
+    ($expr:expr) => {
+        $expr
+    }
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_doctest.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_extern_crate() {
+    check_highlighting(
+        r#"
+        //- /main.rs
+        extern crate std;
+        extern crate alloc as abc;
+        //- /std/lib.rs
+        pub struct S;
+        //- /alloc/lib.rs
+        pub struct A
+        "#,
+        expect_file!["crates/ide/test_data/highlight_extern_crate.html"],
+        false,
+    );
+}
+
+/// Highlights the code given by the `ra_fixture` argument, renders the
+/// result as HTML, and compares it with the HTML file given as `snapshot`.
+/// Note that the `snapshot` file is overwritten by the rendered HTML.
+fn check_highlighting(ra_fixture: &str, expect: ExpectFile, rainbow: bool) {
+    let (analysis, file_id) = single_file(ra_fixture);
+    let actual_html = &analysis.highlight_as_html(file_id, rainbow).unwrap();
+    expect.assert_eq(actual_html)
+}