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 // If the snippet is empty, it's an attribute that was inserted during macro
70 // expansion and we want to ignore those, because they could come from external
71 // sources that the user has no control over.
72 // For some reason these attributes don't have any expansion info on them, so
73 // we have to check it this way until there is a better way.
74 pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
75 if let Some(snippet) = snippet_opt(cx, span) {
76 if snippet.is_empty() {
83 /// Returns the positon just before rarrow
86 /// fn into(self) -> () {}
88 /// // in case of unformatted code
89 /// fn into2(self)-> () {}
91 /// fn into3(self) -> () {}
94 pub fn position_before_rarrow(s: &str) -> Option<usize> {
95 s.rfind("->").map(|rpos| {
97 let chars: Vec<char> = s.chars().collect();
99 if let Some(c) = chars.get(rpos - 1) {
100 if c.is_whitespace() {
111 /// Reindent a multiline string with possibility of ignoring the first line.
112 #[allow(clippy::needless_pass_by_value)]
113 pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
114 let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
115 let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
116 reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
119 fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
122 .skip(ignore_first as usize)
127 // ignore empty lines
128 Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
133 let indent = indent.unwrap_or(0);
137 if (ignore_first && i == 0) || l.is_empty() {
139 } else if x > indent {
140 l.split_at(x - indent).1.to_owned()
142 " ".repeat(indent - x) + l
145 .collect::<Vec<String>>()
149 /// Converts a span to a code snippet if available, otherwise use default.
151 /// This is useful if you want to provide suggestions for your lint or more generally, if you want
152 /// to convert a given `Span` to a `str`.
156 /// snippet(cx, expr.span, "..")
158 pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
159 snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
162 /// Same as `snippet`, but it adapts the applicability level by following rules:
164 /// - Applicability level `Unspecified` will never be changed.
165 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
166 /// - If the default value is used and the applicability level is `MachineApplicable`, change it to
167 /// `HasPlaceholders`
168 pub fn snippet_with_applicability<'a, T: LintContext>(
172 applicability: &mut Applicability,
174 if *applicability != Applicability::Unspecified && span.from_expansion() {
175 *applicability = Applicability::MaybeIncorrect;
177 snippet_opt(cx, span).map_or_else(
179 if *applicability == Applicability::MachineApplicable {
180 *applicability = Applicability::HasPlaceholders;
182 Cow::Borrowed(default)
188 /// Same as `snippet`, but should only be used when it's clear that the input span is
189 /// not a macro argument.
190 pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
191 snippet(cx, span.source_callsite(), default)
194 /// Converts a span to a code snippet. Returns `None` if not available.
195 pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
196 cx.sess().source_map().span_to_snippet(span).ok()
199 /// Converts a span (from a block) to a code snippet if available, otherwise use default.
201 /// This trims the code of indentation, except for the first line. Use it for blocks or block-like
202 /// things which need to be printed as such.
204 /// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
205 /// resulting snippet of the given span.
210 /// snippet_block(cx, block.span, "..", None)
211 /// // where, `block` is the block of the if expr
215 /// // will return the snippet
222 /// snippet_block(cx, block.span, "..", Some(if_expr.span))
223 /// // where, `block` is the block of the if expr
227 /// // will return the snippet
230 /// } // aligned with `if`
232 /// Note that the first line of the snippet always has 0 indentation.
233 pub fn snippet_block<'a, T: LintContext>(
237 indent_relative_to: Option<Span>,
239 let snip = snippet(cx, span, default);
240 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
241 reindent_multiline(snip, true, indent)
244 /// Same as `snippet_block`, but adapts the applicability level by the rules of
245 /// `snippet_with_applicability`.
246 pub fn snippet_block_with_applicability<'a, T: LintContext>(
250 indent_relative_to: Option<Span>,
251 applicability: &mut Applicability,
253 let snip = snippet_with_applicability(cx, span, default, applicability);
254 let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
255 reindent_multiline(snip, true, indent)
258 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
259 /// will result in the macro call, rather then the expansion, if the span is from a child context.
260 /// If the span is not from a child context, it will be used directly instead.
262 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
263 /// would result in `box []`. If given the context of the address of expression, this function will
264 /// correctly get a snippet of `vec![]`.
266 /// This will also return whether or not the snippet is a macro call.
267 pub fn snippet_with_context(
268 cx: &LateContext<'_>,
270 outer: SyntaxContext,
272 applicability: &mut Applicability,
273 ) -> (Cow<'a, str>, bool) {
274 let outer_span = hygiene::walk_chain(span, outer);
275 let (span, is_macro_call) = if outer_span.ctxt() == outer {
276 (outer_span, span.ctxt() != outer)
278 // The span is from a macro argument, and the outer context is the macro using the argument
279 if *applicability != Applicability::Unspecified {
280 *applicability = Applicability::MaybeIncorrect;
282 // TODO: get the argument span.
287 snippet_with_applicability(cx, span, default, applicability),
292 /// Removes block comments from the given `Vec` of lines.
297 /// without_block_comments(vec!["/*", "foo", "*/"]);
300 /// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
301 /// // => vec!["bar"]
303 pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
304 let mut without = vec![];
306 let mut nest_level = 0;
309 if line.contains("/*") {
312 } else if line.contains("*/") {
327 use super::{reindent_multiline, without_block_comments};
330 fn test_reindent_multiline_single_line() {
331 assert_eq!("", reindent_multiline("".into(), false, None));
332 assert_eq!("...", reindent_multiline("...".into(), false, None));
333 assert_eq!("...", reindent_multiline(" ...".into(), false, None));
334 assert_eq!("...", reindent_multiline("\t...".into(), false, None));
335 assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
340 fn test_reindent_multiline_block() {
346 }", reindent_multiline(" if x {
350 }".into(), false, None));
356 }", reindent_multiline(" if x {
360 }".into(), false, None));
365 fn test_reindent_multiline_empty_line() {
372 }", reindent_multiline(" if x {
377 }".into(), false, None));
382 fn test_reindent_multiline_lines_deeper() {
388 }", reindent_multiline("\
393 }".into(), true, Some(8)));
397 fn test_without_block_comments_lines_without_block_comments() {
398 let result = without_block_comments(vec!["/*", "", "*/"]);
399 println!("result: {:?}", result);
400 assert!(result.is_empty());
402 let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
403 assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
405 let result = without_block_comments(vec!["/* rust", "", "*/"]);
406 assert!(result.is_empty());
408 let result = without_block_comments(vec!["/* one-line comment */"]);
409 assert!(result.is_empty());
411 let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
412 assert!(result.is_empty());
414 let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
415 assert!(result.is_empty());
417 let result = without_block_comments(vec!["foo", "bar", "baz"]);
418 assert_eq!(result, vec!["foo", "bar", "baz"]);