364 lines
13 KiB
Rust
364 lines
13 KiB
Rust
use rustc_span::{BytePos, Pos, Span};
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use crate::comment::{is_last_comment_block, rewrite_comment, CodeCharKind, CommentCodeSlices};
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use crate::config::file_lines::FileLines;
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use crate::config::FileName;
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use crate::config::Version;
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use crate::coverage::transform_missing_snippet;
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use crate::shape::{Indent, Shape};
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use crate::source_map::LineRangeUtils;
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use crate::utils::{count_lf_crlf, count_newlines, last_line_width, mk_sp};
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use crate::visitor::FmtVisitor;
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struct SnippetStatus {
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/// An offset to the current line from the beginning of the original snippet.
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line_start: usize,
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/// A length of trailing whitespaces on the current line.
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last_wspace: Option<usize>,
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/// The current line number.
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cur_line: usize,
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}
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impl SnippetStatus {
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fn new(cur_line: usize) -> Self {
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SnippetStatus {
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line_start: 0,
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last_wspace: None,
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cur_line,
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}
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}
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}
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impl<'a> FmtVisitor<'a> {
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fn output_at_start(&self) -> bool {
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self.buffer.is_empty()
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}
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pub(crate) fn format_missing(&mut self, end: BytePos) {
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// HACK(topecongiro): we use `format_missing()` to extract a missing comment between
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// a macro (or similar) and a trailing semicolon. Here we just try to avoid calling
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// `format_missing_inner` in the common case where there is no such comment.
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// This is a hack, ideally we should fix a possible bug in `format_missing_inner`
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// or refactor `visit_mac` and `rewrite_macro`, but this should suffice to fix the
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// issue (#2727).
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let missing_snippet = self.snippet(mk_sp(self.last_pos, end));
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if missing_snippet.trim() == ";" {
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self.push_str(";");
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self.last_pos = end;
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return;
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}
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self.format_missing_inner(end, |this, last_snippet, _| this.push_str(last_snippet))
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}
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pub(crate) fn format_missing_with_indent(&mut self, end: BytePos) {
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self.format_missing_indent(end, true)
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}
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pub(crate) fn format_missing_no_indent(&mut self, end: BytePos) {
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self.format_missing_indent(end, false)
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}
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fn format_missing_indent(&mut self, end: BytePos, should_indent: bool) {
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let config = self.config;
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self.format_missing_inner(end, |this, last_snippet, snippet| {
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this.push_str(last_snippet.trim_end());
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if last_snippet == snippet && !this.output_at_start() {
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// No new lines in the snippet.
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this.push_str("\n");
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}
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if should_indent {
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let indent = this.block_indent.to_string(config);
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this.push_str(&indent);
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}
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})
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}
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fn format_missing_inner<F: Fn(&mut FmtVisitor<'_>, &str, &str)>(
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&mut self,
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end: BytePos,
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process_last_snippet: F,
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) {
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let start = self.last_pos;
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if start == end {
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// Do nothing if this is the beginning of the file.
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if !self.output_at_start() {
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process_last_snippet(self, "", "");
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}
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return;
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}
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assert!(
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start < end,
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"Request to format inverted span: {}",
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self.parse_sess.span_to_debug_info(mk_sp(start, end)),
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);
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self.last_pos = end;
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let span = mk_sp(start, end);
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let snippet = self.snippet(span);
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// Do nothing for spaces in the beginning of the file
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if start == BytePos(0) && end.0 as usize == snippet.len() && snippet.trim().is_empty() {
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return;
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}
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if snippet.trim().is_empty() && !out_of_file_lines_range!(self, span) {
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// Keep vertical spaces within range.
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self.push_vertical_spaces(count_newlines(snippet));
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process_last_snippet(self, "", snippet);
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} else {
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self.write_snippet(span, &process_last_snippet);
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}
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}
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fn push_vertical_spaces(&mut self, mut newline_count: usize) {
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let offset = self.buffer.chars().rev().take_while(|c| *c == '\n').count();
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let newline_upper_bound = self.config.blank_lines_upper_bound() + 1;
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let newline_lower_bound = self.config.blank_lines_lower_bound() + 1;
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if newline_count + offset > newline_upper_bound {
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if offset >= newline_upper_bound {
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newline_count = 0;
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} else {
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newline_count = newline_upper_bound - offset;
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}
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} else if newline_count + offset < newline_lower_bound {
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if offset >= newline_lower_bound {
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newline_count = 0;
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} else {
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newline_count = newline_lower_bound - offset;
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}
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}
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let blank_lines = "\n".repeat(newline_count);
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self.push_str(&blank_lines);
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}
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fn write_snippet<F>(&mut self, span: Span, process_last_snippet: F)
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where
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F: Fn(&mut FmtVisitor<'_>, &str, &str),
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{
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// Get a snippet from the file start to the span's hi without allocating.
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// We need it to determine what precedes the current comment. If the comment
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// follows code on the same line, we won't touch it.
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let big_span_lo = self.snippet_provider.start_pos();
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let big_snippet = self.snippet_provider.entire_snippet();
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let big_diff = (span.lo() - big_span_lo).to_usize();
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let snippet = self.snippet(span);
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debug!("write_snippet `{}`", snippet);
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self.write_snippet_inner(big_snippet, snippet, big_diff, span, process_last_snippet);
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}
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fn write_snippet_inner<F>(
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&mut self,
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big_snippet: &str,
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old_snippet: &str,
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big_diff: usize,
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span: Span,
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process_last_snippet: F,
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) where
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F: Fn(&mut FmtVisitor<'_>, &str, &str),
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{
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// Trim whitespace from the right hand side of each line.
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// Annoyingly, the library functions for splitting by lines etc. are not
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// quite right, so we must do it ourselves.
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let line = self.parse_sess.line_of_byte_pos(span.lo());
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let file_name = &self.parse_sess.span_to_filename(span);
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let mut status = SnippetStatus::new(line);
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let snippet = &*transform_missing_snippet(self.config, old_snippet);
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let slice_within_file_lines_range =
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|file_lines: FileLines, cur_line, s| -> (usize, usize, bool) {
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let (lf_count, crlf_count) = count_lf_crlf(s);
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let newline_count = lf_count + crlf_count;
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let within_file_lines_range = file_lines.contains_range(
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file_name,
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cur_line,
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// if a newline character is at the end of the slice, then the number of
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// newlines needs to be decreased by 1 so that the range checked against
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// the file_lines is the visual range one would expect.
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cur_line + newline_count - if s.ends_with('\n') { 1 } else { 0 },
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);
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(lf_count, crlf_count, within_file_lines_range)
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};
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for (kind, offset, subslice) in CommentCodeSlices::new(snippet) {
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debug!("{:?}: {:?}", kind, subslice);
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let (lf_count, crlf_count, within_file_lines_range) =
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slice_within_file_lines_range(self.config.file_lines(), status.cur_line, subslice);
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let newline_count = lf_count + crlf_count;
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if CodeCharKind::Comment == kind && within_file_lines_range {
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// 1: comment.
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self.process_comment(
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&mut status,
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snippet,
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&big_snippet[..(offset + big_diff)],
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offset,
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subslice,
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);
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} else if subslice.trim().is_empty() && newline_count > 0 && within_file_lines_range {
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// 2: blank lines.
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self.push_vertical_spaces(newline_count);
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status.cur_line += newline_count;
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status.line_start = offset + lf_count + crlf_count * 2;
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} else {
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// 3: code which we failed to format or which is not within file-lines range.
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self.process_missing_code(&mut status, snippet, subslice, offset, file_name);
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}
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}
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let last_snippet = &snippet[status.line_start..];
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let (_, _, within_file_lines_range) =
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slice_within_file_lines_range(self.config.file_lines(), status.cur_line, last_snippet);
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if within_file_lines_range {
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process_last_snippet(self, last_snippet, snippet);
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} else {
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// just append what's left
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self.push_str(last_snippet);
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}
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}
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fn process_comment(
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&mut self,
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status: &mut SnippetStatus,
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snippet: &str,
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big_snippet: &str,
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offset: usize,
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subslice: &str,
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) {
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let last_char = big_snippet
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.chars()
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.rev()
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.find(|rev_c| ![' ', '\t'].contains(rev_c));
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let fix_indent = last_char.map_or(true, |rev_c| ['{', '\n'].contains(&rev_c));
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let mut on_same_line = false;
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let comment_indent = if fix_indent {
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if let Some('{') = last_char {
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self.push_str("\n");
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}
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let indent_str = self.block_indent.to_string(self.config);
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self.push_str(&indent_str);
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self.block_indent
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} else if self.config.version() == Version::Two && !snippet.starts_with('\n') {
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// The comment appears on the same line as the previous formatted code.
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// Assuming that comment is logically associated with that code, we want to keep it on
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// the same level and avoid mixing it with possible other comment.
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on_same_line = true;
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self.push_str(" ");
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self.block_indent
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} else {
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self.push_str(" ");
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Indent::from_width(self.config, last_line_width(&self.buffer))
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};
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let comment_width = ::std::cmp::min(
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self.config.comment_width(),
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self.config.max_width() - self.block_indent.width(),
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);
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let comment_shape = Shape::legacy(comment_width, comment_indent);
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if on_same_line {
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match subslice.find('\n') {
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None => {
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self.push_str(subslice);
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}
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Some(offset) if offset + 1 == subslice.len() => {
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self.push_str(&subslice[..offset]);
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}
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Some(offset) => {
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// keep first line as is: if it were too long and wrapped, it may get mixed
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// with the other lines.
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let first_line = &subslice[..offset];
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self.push_str(first_line);
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self.push_str(&comment_indent.to_string_with_newline(self.config));
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let other_lines = &subslice[offset + 1..];
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let comment_str =
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rewrite_comment(other_lines, false, comment_shape, self.config)
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.unwrap_or_else(|| String::from(other_lines));
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self.push_str(&comment_str);
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}
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}
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} else {
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let comment_str = rewrite_comment(subslice, false, comment_shape, self.config)
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.unwrap_or_else(|| String::from(subslice));
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self.push_str(&comment_str);
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}
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status.last_wspace = None;
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status.line_start = offset + subslice.len();
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// Add a newline:
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// - if there isn't one already
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// - otherwise, only if the last line is a line comment
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if status.line_start <= snippet.len() {
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match snippet[status.line_start..]
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.chars()
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// skip trailing whitespaces
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.find(|c| !(*c == ' ' || *c == '\t'))
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{
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Some('\n') | Some('\r') => {
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if !is_last_comment_block(subslice) {
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self.push_str("\n");
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}
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}
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_ => self.push_str("\n"),
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}
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}
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status.cur_line += count_newlines(subslice);
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}
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fn process_missing_code(
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&mut self,
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status: &mut SnippetStatus,
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snippet: &str,
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subslice: &str,
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offset: usize,
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file_name: &FileName,
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) {
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for (mut i, c) in subslice.char_indices() {
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i += offset;
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if c == '\n' {
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let skip_this_line = !self
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.config
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.file_lines()
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.contains_line(file_name, status.cur_line);
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if skip_this_line {
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status.last_wspace = None;
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}
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if let Some(lw) = status.last_wspace {
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self.push_str(&snippet[status.line_start..lw]);
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self.push_str("\n");
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status.last_wspace = None;
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} else {
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self.push_str(&snippet[status.line_start..=i]);
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}
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status.cur_line += 1;
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status.line_start = i + 1;
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} else if c.is_whitespace() && status.last_wspace.is_none() {
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status.last_wspace = Some(i);
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} else {
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status.last_wspace = None;
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}
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}
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let remaining = snippet[status.line_start..subslice.len() + offset].trim();
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if !remaining.is_empty() {
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self.push_str(&self.block_indent.to_string(self.config));
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self.push_str(remaining);
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status.line_start = subslice.len() + offset;
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}
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}
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}
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