1 //! Utils for extracting, inspecting or transforming source code
3 #![allow(clippy::module_name_repetitions)]
6 use rustc_errors::Applicability;
7 use rustc_hir::{Expr, ExprKind};
8 use rustc_lint::{LateContext, LintContext};
9 use rustc_span::hygiene;
10 use rustc_span::{BytePos, Pos, Span, SyntaxContext};
13 /// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
14 /// Also takes an `Option<String>` which can be put inside the braces.
15 pub fn expr_block<'a, T: LintContext>(
18 option: Option<String>,
20 indent_relative_to: Option<Span>,
22 let code = snippet_block(cx, expr.span, default, indent_relative_to);
23 let string = option.unwrap_or_default();
24 if expr.span.from_expansion() {
25 Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
26 } else if let ExprKind::Block(_, _) = expr.kind {
27 Cow::Owned(format!("{}{}", code, string))
28 } else if string.is_empty() {
29 Cow::Owned(format!("{{ {} }}", code))
31 Cow::Owned(format!("{{\n{};\n{}\n}}", code, string))
35 /// Returns a new Span that extends the original Span to the first non-whitespace char of the first
41 /// // will be converted to
45 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
46 first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
49 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
50 let line_span = line_span(cx, span);
51 snippet_opt(cx, line_span).and_then(|snip| {
52 snip.find(|c: char| !c.is_whitespace())
53 .map(|pos| line_span.lo() + BytePos::from_usize(pos))
57 /// Returns the indentation of the line of a span
61 /// // ^^ -- will return 0
63 /// // ^^ -- will return 4
65 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
66 snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
69 /// Gets a snippet of the indentation of the line of a span
70 pub fn snippet_indent<T: LintContext>(cx: &T, span: Span) -> Option<String> {
71 snippet_opt(cx, line_span(cx, span)).map(|mut s| {
72 let len = s.len() - s.trim_start().len();
78 // If the snippet is empty, it's an attribute that was inserted during macro
79 // expansion and we want to ignore those, because they could come from external
80 // sources that the user has no control over.
81 // For some reason these attributes don't have any expansion info on them, so
82 // we have to check it this way until there is a better way.
83 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
84 if let Some(snippet) = snippet_opt(cx, span) {
85 if snippet.is_empty() {
92 /// Returns the positon just before rarrow
95 /// fn into(self) -> () {}
97 /// // in case of unformatted code
98 /// fn into2(self)-> () {}
100 /// fn into3(self) -> () {}
103 pub fn position_before_rarrow(s: &str) -> Option<usize> {
104 s.rfind("->").map(|rpos| {
106 let chars: Vec<char> = s.chars().collect();
108 if let Some(c) = chars.get(rpos - 1) {
109 if c.is_whitespace() {
120 /// Reindent a multiline string with possibility of ignoring the first line.
121 #[allow(clippy::needless_pass_by_value)]
122 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
123 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
124 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
125 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
128 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
131 .skip(usize::from(ignore_first))
136 // ignore empty lines
137 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
142 let indent = indent.unwrap_or(0);
146 if (ignore_first && i == 0) || l.is_empty() {
148 } else if x > indent {
149 l.split_at(x - indent).1.to_owned()
151 " ".repeat(indent - x) + l
154 .collect::<Vec<String>>()
158 /// Converts a span to a code snippet if available, otherwise returns the default.
160 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
161 /// to convert a given `Span` to a `str`. To create suggestions consider using
162 /// [`snippet_with_applicability`] to ensure that the applicability stays correct.
166 /// // Given two spans one for `value` and one for the `init` expression.
167 /// let value = Vec::new();
168 /// // ^^^^^ ^^^^^^^^^^
171 /// // The snipped call would return the corresponding code snippet
172 /// snippet(cx, span1, "..") // -> "value"
173 /// snippet(cx, span2, "..") // -> "Vec::new()"
175 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
176 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
179 /// Same as [`snippet`], but it adapts the applicability level by following rules:
181 /// - Applicability level `Unspecified` will never be changed.
182 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
183 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
184 /// `HasPlaceholders`
185 pub fn snippet_with_applicability<'a, T: LintContext>(
189 applicability: &mut Applicability,
191 if *applicability != Applicability::Unspecified && span.from_expansion() {
192 *applicability = Applicability::MaybeIncorrect;
194 snippet_opt(cx, span).map_or_else(
196 if *applicability == Applicability::MachineApplicable {
197 *applicability = Applicability::HasPlaceholders;
199 Cow::Borrowed(default)
205 /// Same as `snippet`, but should only be used when it's clear that the input span is
206 /// not a macro argument.
207 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
208 snippet(cx, span.source_callsite(), default)
211 /// Converts a span to a code snippet. Returns `None` if not available.
212 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
213 cx.sess().source_map().span_to_snippet(span).ok()
216 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
218 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
219 /// things which need to be printed as such.
221 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
222 /// resulting snippet of the given span.
227 /// snippet_block(cx, block.span, "..", None)
228 /// // where, `block` is the block of the if expr
232 /// // will return the snippet
239 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
240 /// // where, `block` is the block of the if expr
244 /// // will return the snippet
247 /// } // aligned with `if`
249 /// Note that the first line of the snippet always has 0 indentation.
250 pub fn snippet_block<'a, T: LintContext>(
254 indent_relative_to: Option<Span>,
256 let snip = snippet(cx, span, default);
257 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
258 reindent_multiline(snip, true, indent)
261 /// Same as `snippet_block`, but adapts the applicability level by the rules of
262 /// `snippet_with_applicability`.
263 pub fn snippet_block_with_applicability<'a, T: LintContext>(
267 indent_relative_to: Option<Span>,
268 applicability: &mut Applicability,
270 let snip = snippet_with_applicability(cx, span, default, applicability);
271 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
272 reindent_multiline(snip, true, indent)
275 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
276 /// will result in the macro call, rather then the expansion, if the span is from a child context.
277 /// If the span is not from a child context, it will be used directly instead.
279 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
280 /// would result in `box []`. If given the context of the address of expression, this function will
281 /// correctly get a snippet of `vec![]`.
283 /// This will also return whether or not the snippet is a macro call.
284 pub fn snippet_with_context<'a>(
285 cx: &LateContext<'_>,
287 outer: SyntaxContext,
289 applicability: &mut Applicability,
290 ) -> (Cow<'a, str>, bool) {
291 let (span, is_macro_call) = walk_span_to_context(span, outer).map_or_else(
293 // The span is from a macro argument, and the outer context is the macro using the argument
294 if *applicability != Applicability::Unspecified {
295 *applicability = Applicability::MaybeIncorrect;
297 // TODO: get the argument span.
300 |outer_span| (outer_span, span.ctxt() != outer),
304 snippet_with_applicability(cx, span, default, applicability),
309 /// Walks the span up to the target context, thereby returning the macro call site if the span is
310 /// inside a macro expansion, or the original span if it is not. Note this will return `None` in the
311 /// case of the span being in a macro expansion, but the target context is from expanding a macro
314 /// Given the following
317 /// macro_rules! m { ($e:expr) => { f($e) }; }
321 /// If called with a span of the call to `f` and a context of the call to `g` this will return a
322 /// span containing `m!(0)`. However, if called with a span of the literal `0` this will give a span
323 /// containing `0` as the context is the same as the outer context.
325 /// This will traverse through multiple macro calls. Given the following:
328 /// macro_rules! m { ($e:expr) => { n!($e, 0) }; }
329 /// macro_rules! n { ($e:expr, $f:expr) => { f($e, $f) }; }
333 /// If called with a span of the call to `f` and a context of the call to `g` this will return a
334 /// span containing `m!(0)`.
335 pub fn walk_span_to_context(span: Span, outer: SyntaxContext) -> Option<Span> {
336 let outer_span = hygiene::walk_chain(span, outer);
337 (outer_span.ctxt() == outer).then(|| outer_span)
340 /// Removes block comments from the given `Vec` of lines.
345 /// without_block_comments(vec!["/*", "foo", "*/"]);
348 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
349 /// // => vec!["bar"]
351 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
352 let mut without = vec![];
354 let mut nest_level = 0;
357 if line.contains("/*") {
360 } else if line.contains("*/") {
375 use super::{reindent_multiline, without_block_comments};
378 fn test_reindent_multiline_single_line() {
379 assert_eq!("", reindent_multiline("".into(), false, None));
380 assert_eq!("...", reindent_multiline("...".into(), false, None));
381 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
382 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
383 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
388 fn test_reindent_multiline_block() {
394 }", reindent_multiline(" if x {
398 }".into(), false, None));
404 }", reindent_multiline(" if x {
408 }".into(), false, None));
413 fn test_reindent_multiline_empty_line() {
420 }", reindent_multiline(" if x {
425 }".into(), false, None));
430 fn test_reindent_multiline_lines_deeper() {
436 }", reindent_multiline("\
441 }".into(), true, Some(8)));
445 fn test_without_block_comments_lines_without_block_comments() {
446 let result = without_block_comments(vec!["/*", "", "*/"]);
447 println!("result: {:?}", result);
448 assert!(result.is_empty());
450 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
451 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
453 let result = without_block_comments(vec!["/* rust", "", "*/"]);
454 assert!(result.is_empty());
456 let result = without_block_comments(vec!["/* one-line comment */"]);
457 assert!(result.is_empty());
459 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
460 assert!(result.is_empty());
462 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
463 assert!(result.is_empty());
465 let result = without_block_comments(vec!["foo", "bar", "baz"]);
466 assert_eq!(result, vec!["foo", "bar", "baz"]);