501 lines
16 KiB
Rust
501 lines
16 KiB
Rust
//! Utils for extracting, inspecting or transforming source code
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#![allow(clippy::module_name_repetitions)]
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use crate::line_span;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LintContext};
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use rustc_span::hygiene;
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use rustc_span::source_map::SourceMap;
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use rustc_span::{BytePos, Pos, Span, SpanData, SyntaxContext};
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use std::borrow::Cow;
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/// Like `snippet_block`, but add braces if the expr is not an `ExprKind::Block`.
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/// Also takes an `Option<String>` which can be put inside the braces.
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pub fn expr_block<'a, T: LintContext>(
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cx: &T,
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expr: &Expr<'_>,
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option: Option<String>,
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default: &'a str,
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indent_relative_to: Option<Span>,
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) -> Cow<'a, str> {
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let code = snippet_block(cx, expr.span, default, indent_relative_to);
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let string = option.unwrap_or_default();
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if expr.span.from_expansion() {
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Cow::Owned(format!("{{ {} }}", snippet_with_macro_callsite(cx, expr.span, default)))
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} else if let ExprKind::Block(_, _) = expr.kind {
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Cow::Owned(format!("{code}{string}"))
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} else if string.is_empty() {
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Cow::Owned(format!("{{ {code} }}"))
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} else {
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Cow::Owned(format!("{{\n{code};\n{string}\n}}"))
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}
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}
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/// Returns a new Span that extends the original Span to the first non-whitespace char of the first
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/// line.
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///
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/// ```rust,ignore
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/// let x = ();
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/// // ^^
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/// // will be converted to
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/// let x = ();
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/// // ^^^^^^^^^^
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/// ```
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pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
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first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
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}
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fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
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let line_span = line_span(cx, span);
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snippet_opt(cx, line_span).and_then(|snip| {
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snip.find(|c: char| !c.is_whitespace())
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.map(|pos| line_span.lo() + BytePos::from_usize(pos))
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})
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}
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/// Returns the indentation of the line of a span
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///
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/// ```rust,ignore
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/// let x = ();
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/// // ^^ -- will return 0
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/// let x = ();
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/// // ^^ -- will return 4
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/// ```
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pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
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snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
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}
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/// Gets a snippet of the indentation of the line of a span
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pub fn snippet_indent<T: LintContext>(cx: &T, span: Span) -> Option<String> {
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snippet_opt(cx, line_span(cx, span)).map(|mut s| {
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let len = s.len() - s.trim_start().len();
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s.truncate(len);
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s
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})
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}
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// If the snippet is empty, it's an attribute that was inserted during macro
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// expansion and we want to ignore those, because they could come from external
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// sources that the user has no control over.
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// For some reason these attributes don't have any expansion info on them, so
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// we have to check it this way until there is a better way.
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pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
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if let Some(snippet) = snippet_opt(cx, span) {
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if snippet.is_empty() {
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return false;
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}
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}
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true
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}
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/// Returns the position just before rarrow
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///
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/// ```rust,ignore
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/// fn into(self) -> () {}
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/// ^
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/// // in case of unformatted code
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/// fn into2(self)-> () {}
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/// ^
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/// fn into3(self) -> () {}
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/// ^
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/// ```
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pub fn position_before_rarrow(s: &str) -> Option<usize> {
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s.rfind("->").map(|rpos| {
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let mut rpos = rpos;
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let chars: Vec<char> = s.chars().collect();
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while rpos > 1 {
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if let Some(c) = chars.get(rpos - 1) {
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if c.is_whitespace() {
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rpos -= 1;
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continue;
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}
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}
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break;
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}
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rpos
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})
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}
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/// Reindent a multiline string with possibility of ignoring the first line.
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#[expect(clippy::needless_pass_by_value)]
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pub fn reindent_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
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let s_space = reindent_multiline_inner(&s, ignore_first, indent, ' ');
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let s_tab = reindent_multiline_inner(&s_space, ignore_first, indent, '\t');
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reindent_multiline_inner(&s_tab, ignore_first, indent, ' ').into()
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}
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fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>, ch: char) -> String {
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let x = s
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.lines()
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.skip(usize::from(ignore_first))
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.filter_map(|l| {
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if l.is_empty() {
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None
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} else {
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// ignore empty lines
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Some(l.char_indices().find(|&(_, x)| x != ch).unwrap_or((l.len(), ch)).0)
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}
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})
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.min()
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.unwrap_or(0);
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let indent = indent.unwrap_or(0);
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s.lines()
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.enumerate()
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.map(|(i, l)| {
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if (ignore_first && i == 0) || l.is_empty() {
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l.to_owned()
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} else if x > indent {
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l.split_at(x - indent).1.to_owned()
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} else {
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" ".repeat(indent - x) + l
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}
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})
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.collect::<Vec<String>>()
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.join("\n")
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}
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/// Converts a span to a code snippet if available, otherwise returns the default.
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///
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/// This is useful if you want to provide suggestions for your lint or more generally, if you want
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/// to convert a given `Span` to a `str`. To create suggestions consider using
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/// [`snippet_with_applicability`] to ensure that the applicability stays correct.
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///
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/// # Example
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/// ```rust,ignore
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/// // Given two spans one for `value` and one for the `init` expression.
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/// let value = Vec::new();
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/// // ^^^^^ ^^^^^^^^^^
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/// // span1 span2
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///
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/// // The snipped call would return the corresponding code snippet
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/// snippet(cx, span1, "..") // -> "value"
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/// snippet(cx, span2, "..") // -> "Vec::new()"
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/// ```
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pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
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snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
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}
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/// Same as [`snippet`], but it adapts the applicability level by following rules:
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///
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/// - Applicability level `Unspecified` will never be changed.
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/// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
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/// - If the default value is used and the applicability level is `MachineApplicable`, change it to
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/// `HasPlaceholders`
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pub fn snippet_with_applicability<'a, T: LintContext>(
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cx: &T,
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span: Span,
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default: &'a str,
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applicability: &mut Applicability,
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) -> Cow<'a, str> {
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if *applicability != Applicability::Unspecified && span.from_expansion() {
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*applicability = Applicability::MaybeIncorrect;
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}
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snippet_opt(cx, span).map_or_else(
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|| {
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if *applicability == Applicability::MachineApplicable {
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*applicability = Applicability::HasPlaceholders;
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}
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Cow::Borrowed(default)
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},
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From::from,
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)
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}
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/// Same as `snippet`, but should only be used when it's clear that the input span is
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/// not a macro argument.
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pub fn snippet_with_macro_callsite<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<'a, str> {
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snippet(cx, span.source_callsite(), default)
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}
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/// Converts a span to a code snippet. Returns `None` if not available.
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pub fn snippet_opt<T: LintContext>(cx: &T, span: Span) -> Option<String> {
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cx.sess().source_map().span_to_snippet(span).ok()
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}
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/// Converts a span (from a block) to a code snippet if available, otherwise use default.
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///
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/// This trims the code of indentation, except for the first line. Use it for blocks or block-like
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/// things which need to be printed as such.
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///
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/// The `indent_relative_to` arg can be used, to provide a span, where the indentation of the
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/// resulting snippet of the given span.
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///
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/// # Example
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///
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/// ```rust,ignore
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/// snippet_block(cx, block.span, "..", None)
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/// // where, `block` is the block of the if expr
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/// if x {
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/// y;
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/// }
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/// // will return the snippet
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/// {
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/// y;
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/// }
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/// ```
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///
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/// ```rust,ignore
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/// snippet_block(cx, block.span, "..", Some(if_expr.span))
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/// // where, `block` is the block of the if expr
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/// if x {
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/// y;
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/// }
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/// // will return the snippet
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/// {
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/// y;
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/// } // aligned with `if`
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/// ```
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/// Note that the first line of the snippet always has 0 indentation.
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pub fn snippet_block<'a, T: LintContext>(
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cx: &T,
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span: Span,
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default: &'a str,
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indent_relative_to: Option<Span>,
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) -> Cow<'a, str> {
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let snip = snippet(cx, span, default);
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let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
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reindent_multiline(snip, true, indent)
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}
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/// Same as `snippet_block`, but adapts the applicability level by the rules of
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/// `snippet_with_applicability`.
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pub fn snippet_block_with_applicability<'a, T: LintContext>(
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cx: &T,
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span: Span,
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default: &'a str,
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indent_relative_to: Option<Span>,
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applicability: &mut Applicability,
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) -> Cow<'a, str> {
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let snip = snippet_with_applicability(cx, span, default, applicability);
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let indent = indent_relative_to.and_then(|s| indent_of(cx, s));
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reindent_multiline(snip, true, indent)
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}
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/// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
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/// will result in the macro call, rather then the expansion, if the span is from a child context.
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/// If the span is not from a child context, it will be used directly instead.
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///
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/// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node
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/// would result in `box []`. If given the context of the address of expression, this function will
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/// correctly get a snippet of `vec![]`.
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///
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/// This will also return whether or not the snippet is a macro call.
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pub fn snippet_with_context<'a>(
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cx: &LateContext<'_>,
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span: Span,
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outer: SyntaxContext,
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default: &'a str,
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applicability: &mut Applicability,
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) -> (Cow<'a, str>, bool) {
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let (span, is_macro_call) = walk_span_to_context(span, outer).map_or_else(
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|| {
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// The span is from a macro argument, and the outer context is the macro using the argument
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if *applicability != Applicability::Unspecified {
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*applicability = Applicability::MaybeIncorrect;
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}
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// TODO: get the argument span.
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(span, false)
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},
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|outer_span| (outer_span, span.ctxt() != outer),
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);
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(
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snippet_with_applicability(cx, span, default, applicability),
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is_macro_call,
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)
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}
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/// Walks the span up to the target context, thereby returning the macro call site if the span is
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/// inside a macro expansion, or the original span if it is not. Note this will return `None` in the
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/// case of the span being in a macro expansion, but the target context is from expanding a macro
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/// argument.
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///
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/// Given the following
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///
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/// ```rust,ignore
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/// macro_rules! m { ($e:expr) => { f($e) }; }
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/// g(m!(0))
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/// ```
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///
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/// If called with a span of the call to `f` and a context of the call to `g` this will return a
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/// span containing `m!(0)`. However, if called with a span of the literal `0` this will give a span
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/// containing `0` as the context is the same as the outer context.
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///
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/// This will traverse through multiple macro calls. Given the following:
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///
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/// ```rust,ignore
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/// macro_rules! m { ($e:expr) => { n!($e, 0) }; }
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/// macro_rules! n { ($e:expr, $f:expr) => { f($e, $f) }; }
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/// g(m!(0))
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/// ```
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///
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/// If called with a span of the call to `f` and a context of the call to `g` this will return a
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/// span containing `m!(0)`.
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pub fn walk_span_to_context(span: Span, outer: SyntaxContext) -> Option<Span> {
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let outer_span = hygiene::walk_chain(span, outer);
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(outer_span.ctxt() == outer).then_some(outer_span)
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}
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/// Removes block comments from the given `Vec` of lines.
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///
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/// # Examples
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///
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/// ```rust,ignore
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/// without_block_comments(vec!["/*", "foo", "*/"]);
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/// // => vec![]
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///
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/// without_block_comments(vec!["bar", "/*", "foo", "*/"]);
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/// // => vec!["bar"]
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/// ```
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pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
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let mut without = vec![];
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let mut nest_level = 0;
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for line in lines {
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if line.contains("/*") {
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nest_level += 1;
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continue;
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} else if line.contains("*/") {
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nest_level -= 1;
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continue;
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}
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if nest_level == 0 {
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without.push(line);
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}
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}
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without
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}
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/// Trims the whitespace from the start and the end of the span.
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pub fn trim_span(sm: &SourceMap, span: Span) -> Span {
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let data = span.data();
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let sf: &_ = &sm.lookup_source_file(data.lo);
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let Some(src) = sf.src.as_deref() else {
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return span;
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};
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let Some(snip) = &src.get((data.lo - sf.start_pos).to_usize()..(data.hi - sf.start_pos).to_usize()) else {
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return span;
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};
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let trim_start = snip.len() - snip.trim_start().len();
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let trim_end = snip.len() - snip.trim_end().len();
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SpanData {
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lo: data.lo + BytePos::from_usize(trim_start),
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hi: data.hi - BytePos::from_usize(trim_end),
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ctxt: data.ctxt,
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parent: data.parent,
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}
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.span()
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}
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/// Expand a span to include a preceding comma
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/// ```rust,ignore
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/// writeln!(o, "") -> writeln!(o, "")
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/// ^^ ^^^^
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/// ```
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pub fn expand_past_previous_comma(cx: &LateContext<'_>, span: Span) -> Span {
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let extended = cx.sess().source_map().span_extend_to_prev_char(span, ',', true);
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extended.with_lo(extended.lo() - BytePos(1))
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}
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#[cfg(test)]
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mod test {
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use super::{reindent_multiline, without_block_comments};
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#[test]
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fn test_reindent_multiline_single_line() {
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assert_eq!("", reindent_multiline("".into(), false, None));
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assert_eq!("...", reindent_multiline("...".into(), false, None));
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assert_eq!("...", reindent_multiline(" ...".into(), false, None));
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assert_eq!("...", reindent_multiline("\t...".into(), false, None));
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assert_eq!("...", reindent_multiline("\t\t...".into(), false, None));
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}
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#[test]
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#[rustfmt::skip]
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fn test_reindent_multiline_block() {
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assert_eq!("\
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if x {
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y
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} else {
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z
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}", reindent_multiline(" if x {
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y
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} else {
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z
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}".into(), false, None));
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assert_eq!("\
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if x {
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\ty
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} else {
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\tz
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}", reindent_multiline(" if x {
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\ty
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} else {
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\tz
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}".into(), false, None));
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}
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#[test]
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#[rustfmt::skip]
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fn test_reindent_multiline_empty_line() {
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assert_eq!("\
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if x {
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y
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} else {
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z
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}", reindent_multiline(" if x {
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y
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} else {
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z
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}".into(), false, None));
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}
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#[test]
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#[rustfmt::skip]
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fn test_reindent_multiline_lines_deeper() {
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assert_eq!("\
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if x {
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y
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} else {
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z
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}", reindent_multiline("\
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if x {
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y
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} else {
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z
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}".into(), true, Some(8)));
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}
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#[test]
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fn test_without_block_comments_lines_without_block_comments() {
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let result = without_block_comments(vec!["/*", "", "*/"]);
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println!("result: {result:?}");
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assert!(result.is_empty());
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let result = without_block_comments(vec!["", "/*", "", "*/", "#[crate_type = \"lib\"]", "/*", "", "*/", ""]);
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assert_eq!(result, vec!["", "#[crate_type = \"lib\"]", ""]);
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let result = without_block_comments(vec!["/* rust", "", "*/"]);
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assert!(result.is_empty());
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|
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let result = without_block_comments(vec!["/* one-line comment */"]);
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assert!(result.is_empty());
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|
|
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let result = without_block_comments(vec!["/* nested", "/* multi-line", "comment", "*/", "test", "*/"]);
|
|
assert!(result.is_empty());
|
|
|
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let result = without_block_comments(vec!["/* nested /* inline /* comment */ test */ */"]);
|
|
assert!(result.is_empty());
|
|
|
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let result = without_block_comments(vec!["foo", "bar", "baz"]);
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|
assert_eq!(result, vec!["foo", "bar", "baz"]);
|
|
}
|
|
}
|