1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Format string literals.
14 use unicode_segmentation::UnicodeSegmentation;
20 const MIN_STRING: usize = 10;
22 pub struct StringFormat<'a> {
25 pub line_start: &'a str,
26 pub line_end: &'a str,
29 pub config: &'a Config,
32 impl<'a> StringFormat<'a> {
33 pub fn new(shape: Shape, config: &'a Config) -> StringFormat<'a> {
46 // FIXME: simplify this!
47 pub fn rewrite_string<'a>(orig: &str, fmt: &StringFormat<'a>) -> Option<String> {
49 let re = Regex::new(r"([^\\](\\\\)*)\\[\n\r][[:space:]]*").unwrap();
50 let stripped_str = re.replace_all(orig, "$1");
52 let graphemes = UnicodeSegmentation::graphemes(&*stripped_str, false).collect::<Vec<&str>>();
53 let shape = fmt.shape.visual_indent(0);
54 let indent = shape.indent.to_string(fmt.config);
55 let punctuation = ":,;.";
57 // `cur_start` is the position in `orig` of the start of the current line.
58 let mut cur_start = 0;
59 let mut result = String::with_capacity(
62 .checked_next_power_of_two()
63 .unwrap_or(usize::max_value()),
65 result.push_str(fmt.opener);
67 let ender_length = fmt.line_end.len();
68 // If we cannot put at least a single character per line, the rewrite won't
70 let max_chars = shape.width.checked_sub(fmt.opener.len() + ender_length + 1)? + 1;
72 // Snip a line at a time from `orig` until it is used up. Push the snippet
75 // `cur_end` will be where we break the line, as an offset into `orig`.
76 // Initialised to the maximum it could be (which may be beyond `orig`).
77 let mut cur_end = cur_start + max_chars;
79 // We can fit the rest of the string on this line, so we're done.
80 if cur_end >= graphemes.len() {
81 let line = &graphemes[cur_start..].join("");
82 result.push_str(line);
86 // Push cur_end left until we reach whitespace (or the line is too small).
87 while !graphemes[cur_end - 1].trim().is_empty() {
89 if cur_end < cur_start + MIN_STRING {
90 // We couldn't find whitespace before the string got too small.
91 // So start again at the max length and look for punctuation.
92 cur_end = cur_start + max_chars;
93 while !punctuation.contains(graphemes[cur_end - 1]) {
96 // If we can't break at whitespace or punctuation, grow the string instead.
97 if cur_end < cur_start + MIN_STRING {
98 cur_end = cur_start + max_chars;
99 while !(punctuation.contains(graphemes[cur_end - 1])
100 || graphemes[cur_end - 1].trim().is_empty())
102 if cur_end >= graphemes.len() {
103 let line = &graphemes[cur_start..].join("");
104 result.push_str(line);
115 // Make sure there is no whitespace to the right of the break.
116 while cur_end < stripped_str.len() && graphemes[cur_end].trim().is_empty() {
120 // Make the current line and add it on to result.
121 let raw_line = graphemes[cur_start..cur_end].join("");
122 let line = if fmt.trim_end {
128 result.push_str(line);
129 result.push_str(fmt.line_end);
131 result.push_str(&indent);
132 result.push_str(fmt.line_start);
134 // The next line starts where the current line ends.
138 result.push_str(fmt.closer);
139 wrap_str(result, fmt.config.max_width(), fmt.shape)
144 use super::{rewrite_string, StringFormat};
145 use shape::{Indent, Shape};
149 let config = Default::default();
150 let fmt = StringFormat::new(Shape::legacy(2, Indent::empty()), &config);
151 rewrite_string("eq_", &fmt);