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rust/src/string.rs

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// Format string literals.
use regex::Regex;
use unicode_categories::UnicodeCategories;
use unicode_segmentation::UnicodeSegmentation;
use crate::config::Config;
use crate::shape::Shape;
use crate::utils::{unicode_str_width, wrap_str};
const MIN_STRING: usize = 10;
/// Describes the layout of a piece of text.
pub(crate) struct StringFormat<'a> {
/// The opening sequence of characters for the piece of text
pub(crate) opener: &'a str,
/// The closing sequence of characters for the piece of text
pub(crate) closer: &'a str,
/// The opening sequence of characters for a line
pub(crate) line_start: &'a str,
/// The closing sequence of characters for a line
pub(crate) line_end: &'a str,
/// The allocated box to fit the text into
pub(crate) shape: Shape,
/// Trim trailing whitespaces
pub(crate) trim_end: bool,
pub(crate) config: &'a Config,
}
impl<'a> StringFormat<'a> {
pub(crate) fn new(shape: Shape, config: &'a Config) -> StringFormat<'a> {
StringFormat {
opener: "\"",
closer: "\"",
line_start: " ",
line_end: "\\",
shape,
trim_end: false,
config,
}
}
/// Returns the maximum number of graphemes that is possible on a line while taking the
/// indentation into account.
///
/// If we cannot put at least a single character per line, the rewrite won't succeed.
fn max_width_with_indent(&self) -> Option<usize> {
Some(
self.shape
.width
.checked_sub(self.opener.len() + self.line_end.len() + 1)?
+ 1,
)
}
/// Like max_width_with_indent but the indentation is not subtracted.
/// This allows to fit more graphemes from the string on a line when
/// SnippetState::EndWithLineFeed.
fn max_width_without_indent(&self) -> Option<usize> {
self.config.max_width().checked_sub(self.line_end.len())
}
}
pub(crate) fn rewrite_string<'a>(
orig: &str,
fmt: &StringFormat<'a>,
newline_max_chars: usize,
) -> Option<String> {
let max_width_with_indent = fmt.max_width_with_indent()?;
let max_width_without_indent = fmt.max_width_without_indent()?;
let indent_with_newline = fmt.shape.indent.to_string_with_newline(fmt.config);
let indent_without_newline = fmt.shape.indent.to_string(fmt.config);
// Strip line breaks.
// With this regex applied, all remaining whitespaces are significant
let strip_line_breaks_re = Regex::new(r"([^\\](\\\\)*)\\[\n\r][[:space:]]*").unwrap();
let stripped_str = strip_line_breaks_re.replace_all(orig, "$1");
let graphemes = UnicodeSegmentation::graphemes(&*stripped_str, false).collect::<Vec<&str>>();
// `cur_start` is the position in `orig` of the start of the current line.
let mut cur_start = 0;
let mut result = String::with_capacity(
stripped_str
.len()
.checked_next_power_of_two()
.unwrap_or(usize::max_value()),
);
result.push_str(fmt.opener);
// Snip a line at a time from `stripped_str` until it is used up. Push the snippet
// onto result.
let mut cur_max_width = max_width_with_indent;
let is_bareline_ok = fmt.line_start.is_empty() || is_whitespace(fmt.line_start);
loop {
// All the input starting at cur_start fits on the current line
if graphemes_width(&graphemes[cur_start..]) <= cur_max_width {
for (i, grapheme) in graphemes[cur_start..].iter().enumerate() {
if is_new_line(grapheme) {
// take care of blank lines
result = trim_end_but_line_feed(fmt.trim_end, result);
result.push('\n');
if !is_bareline_ok && cur_start + i + 1 < graphemes.len() {
result.push_str(&indent_without_newline);
result.push_str(fmt.line_start);
}
} else {
result.push_str(grapheme);
}
}
result = trim_end_but_line_feed(fmt.trim_end, result);
break;
}
// The input starting at cur_start needs to be broken
match break_string(
cur_max_width,
fmt.trim_end,
fmt.line_end,
&graphemes[cur_start..],
) {
SnippetState::LineEnd(line, len) => {
result.push_str(&line);
result.push_str(fmt.line_end);
result.push_str(&indent_with_newline);
result.push_str(fmt.line_start);
cur_max_width = newline_max_chars;
cur_start += len;
}
SnippetState::EndWithLineFeed(line, len) => {
if line == "\n" && fmt.trim_end {
result = result.trim_end().to_string();
}
result.push_str(&line);
if is_bareline_ok {
// the next line can benefit from the full width
cur_max_width = max_width_without_indent;
} else {
result.push_str(&indent_without_newline);
result.push_str(fmt.line_start);
cur_max_width = max_width_with_indent;
}
cur_start += len;
}
SnippetState::EndOfInput(line) => {
result.push_str(&line);
break;
}
}
}
result.push_str(fmt.closer);
wrap_str(result, fmt.config.max_width(), fmt.shape)
}
/// Returns the index to the end of the URL if the split at index of the given string includes a
/// URL or alike. Otherwise, returns `None`.
fn detect_url(s: &[&str], index: usize) -> Option<usize> {
let start = match s[..=index].iter().rposition(|g| is_whitespace(g)) {
Some(pos) => pos + 1,
None => 0,
};
// 8 = minimum length for a string to contain a URL
if s.len() < start + 8 {
return None;
}
let split = s[start..].concat();
if split.contains("https://")
|| split.contains("http://")
|| split.contains("ftp://")
|| split.contains("file://")
{
match s[index..].iter().position(|g| is_whitespace(g)) {
Some(pos) => Some(index + pos - 1),
None => Some(s.len() - 1),
}
} else {
None
}
}
/// Trims whitespaces to the right except for the line feed character.
fn trim_end_but_line_feed(trim_end: bool, result: String) -> String {
let whitespace_except_line_feed = |c: char| c.is_whitespace() && c != '\n';
if trim_end && result.ends_with(whitespace_except_line_feed) {
result
.trim_end_matches(whitespace_except_line_feed)
.to_string()
} else {
result
}
}
/// Result of breaking a string so it fits in a line and the state it ended in.
/// The state informs about what to do with the snippet and how to continue the breaking process.
#[derive(Debug, PartialEq)]
enum SnippetState {
/// The input could not be broken and so rewriting the string is finished.
EndOfInput(String),
/// The input could be broken and the returned snippet should be ended with a
/// `[StringFormat::line_end]`. The next snippet needs to be indented.
///
/// The returned string is the line to print out and the number is the length that got read in
/// the text being rewritten. That length may be greater than the returned string if trailing
/// whitespaces got trimmed.
LineEnd(String, usize),
/// The input could be broken but a newline is present that cannot be trimmed. The next snippet
/// to be rewritten *could* use more width than what is specified by the given shape. For
/// example with a multiline string, the next snippet does not need to be indented, allowing
/// more characters to be fit within a line.
///
/// The returned string is the line to print out and the number is the length that got read in
/// the text being rewritten.
EndWithLineFeed(String, usize),
}
fn not_whitespace_except_line_feed(g: &str) -> bool {
is_new_line(g) || !is_whitespace(g)
}
/// Break the input string at a boundary character around the offset `max_width`. A boundary
/// character is either a punctuation or a whitespace.
/// FIXME(issue#3281): We must follow UAX#14 algorithm instead of this.
fn break_string(max_width: usize, trim_end: bool, line_end: &str, input: &[&str]) -> SnippetState {
let break_at = |index /* grapheme at index is included */| {
// Take in any whitespaces to the left/right of `input[index]` while
// preserving line feeds
let index_minus_ws = input[0..=index]
.iter()
.rposition(|grapheme| not_whitespace_except_line_feed(grapheme))
.unwrap_or(index);
// Take into account newlines occurring in input[0..=index], i.e., the possible next new
// line. If there is one, then text after it could be rewritten in a way that the available
// space is fully used.
for (i, grapheme) in input[0..=index].iter().enumerate() {
if is_new_line(grapheme) {
if i <= index_minus_ws {
let mut line = &input[0..i].concat()[..];
if trim_end {
line = line.trim_end();
}
return SnippetState::EndWithLineFeed(format!("{}\n", line), i + 1);
}
break;
}
}
let mut index_plus_ws = index;
for (i, grapheme) in input[index + 1..].iter().enumerate() {
if !trim_end && is_new_line(grapheme) {
return SnippetState::EndWithLineFeed(
input[0..=index + 1 + i].concat(),
index + 2 + i,
);
} else if not_whitespace_except_line_feed(grapheme) {
index_plus_ws = index + i;
break;
}
}
if trim_end {
SnippetState::LineEnd(input[0..=index_minus_ws].concat(), index_plus_ws + 1)
} else {
SnippetState::LineEnd(input[0..=index_plus_ws].concat(), index_plus_ws + 1)
}
};
// find a first index where the unicode width of input[0..x] become > max_width
let max_width_index_in_input = {
let mut cur_width = 0;
let mut cur_index = 0;
for (i, grapheme) in input.iter().enumerate() {
cur_width += unicode_str_width(grapheme);
cur_index = i;
if cur_width > max_width {
break;
}
}
cur_index
};
if max_width_index_in_input == 0 {
return SnippetState::EndOfInput(input.concat());
}
// Find the position in input for breaking the string
if line_end.is_empty()
&& trim_end
&& !is_whitespace(input[max_width_index_in_input - 1])
&& is_whitespace(input[max_width_index_in_input])
{
// At a breaking point already
// The line won't invalidate the rewriting because:
// - no extra space needed for the line_end character
// - extra whitespaces to the right can be trimmed
return break_at(max_width_index_in_input - 1);
}
if let Some(url_index_end) = detect_url(input, max_width_index_in_input) {
let index_plus_ws = url_index_end
+ input[url_index_end..]
.iter()
.skip(1)
.position(|grapheme| not_whitespace_except_line_feed(grapheme))
.unwrap_or(0);
return if trim_end {
SnippetState::LineEnd(input[..=url_index_end].concat(), index_plus_ws + 1)
} else {
SnippetState::LineEnd(input[..=index_plus_ws].concat(), index_plus_ws + 1)
};
}
match input[0..max_width_index_in_input]
.iter()
.rposition(|grapheme| is_whitespace(grapheme))
{
// Found a whitespace and what is on its left side is big enough.
Some(index) if index >= MIN_STRING => break_at(index),
// No whitespace found, try looking for a punctuation instead
_ => match (0..max_width_index_in_input)
.rev()
.skip_while(|pos| !is_valid_linebreak(input, *pos))
.next()
{
// Found a punctuation and what is on its left side is big enough.
Some(index) if index >= MIN_STRING => break_at(index),
// Either no boundary character was found to the left of `input[max_chars]`, or the line
// got too small. We try searching for a boundary character to the right.
_ => match (max_width_index_in_input..input.len())
.skip_while(|pos| !is_valid_linebreak(input, *pos))
.next()
{
// A boundary was found after the line limit
Some(index) => break_at(index),
// No boundary to the right, the input cannot be broken
None => SnippetState::EndOfInput(input.concat()),
},
},
}
}
fn is_valid_linebreak(input: &[&str], pos: usize) -> bool {
let is_whitespace = is_whitespace(input[pos]);
if is_whitespace {
return true;
}
let is_punctuation = is_punctuation(input[pos]);
if is_punctuation && !is_part_of_type(input, pos) {
return true;
}
false
}
fn is_part_of_type(input: &[&str], pos: usize) -> bool {
input.get(pos..=pos + 1) == Some(&[":", ":"])
|| input.get(pos.saturating_sub(1)..=pos) == Some(&[":", ":"])
}
fn is_new_line(grapheme: &str) -> bool {
let bytes = grapheme.as_bytes();
bytes.starts_with(b"\n") || bytes.starts_with(b"\r\n")
}
fn is_whitespace(grapheme: &str) -> bool {
grapheme.chars().all(char::is_whitespace)
}
fn is_punctuation(grapheme: &str) -> bool {
grapheme
.chars()
.all(UnicodeCategories::is_punctuation_other)
}
fn graphemes_width(graphemes: &[&str]) -> usize {
graphemes.iter().map(|s| unicode_str_width(s)).sum()
}
#[cfg(test)]
mod test {
use super::{break_string, detect_url, rewrite_string, SnippetState, StringFormat};
use crate::config::Config;
use crate::shape::{Indent, Shape};
use unicode_segmentation::UnicodeSegmentation;
#[test]
fn issue343() {
let config = Default::default();
let fmt = StringFormat::new(Shape::legacy(2, Indent::empty()), &config);
rewrite_string("eq_", &fmt, 2);
}
#[test]
fn line_break_at_valid_points_test() {
let string = "[TheName](Dont::break::my::type::That::would::be::very::nice) break here";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(20, false, "", &graphemes[..]),
SnippetState::LineEnd(
"[TheName](Dont::break::my::type::That::would::be::very::nice) ".to_string(),
62
)
);
}
#[test]
fn should_break_on_whitespace() {
let string = "Placerat felis. Mauris porta ante sagittis purus.";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(20, false, "", &graphemes[..]),
SnippetState::LineEnd("Placerat felis. ".to_string(), 16)
);
assert_eq!(
break_string(20, true, "", &graphemes[..]),
SnippetState::LineEnd("Placerat felis.".to_string(), 16)
);
}
#[test]
fn should_break_on_punctuation() {
let string = "Placerat_felis._Mauris_porta_ante_sagittis_purus.";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(20, false, "", &graphemes[..]),
SnippetState::LineEnd("Placerat_felis.".to_string(), 15)
);
}
#[test]
fn should_break_forward() {
let string = "Venenatis_tellus_vel_tellus. Aliquam aliquam dolor at justo.";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(20, false, "", &graphemes[..]),
SnippetState::LineEnd("Venenatis_tellus_vel_tellus. ".to_string(), 29)
);
assert_eq!(
break_string(20, true, "", &graphemes[..]),
SnippetState::LineEnd("Venenatis_tellus_vel_tellus.".to_string(), 29)
);
}
#[test]
fn nothing_to_break() {
let string = "Venenatis_tellus_vel_tellus";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(20, false, "", &graphemes[..]),
SnippetState::EndOfInput("Venenatis_tellus_vel_tellus".to_string())
);
}
#[test]
fn significant_whitespaces() {
let string = "Neque in sem. \n Pellentesque tellus augue.";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(15, false, "", &graphemes[..]),
SnippetState::EndWithLineFeed("Neque in sem. \n".to_string(), 20)
);
assert_eq!(
break_string(25, false, "", &graphemes[..]),
SnippetState::EndWithLineFeed("Neque in sem. \n".to_string(), 20)
);
assert_eq!(
break_string(15, true, "", &graphemes[..]),
SnippetState::LineEnd("Neque in sem.".to_string(), 19)
);
assert_eq!(
break_string(25, true, "", &graphemes[..]),
SnippetState::EndWithLineFeed("Neque in sem.\n".to_string(), 20)
);
}
#[test]
fn big_whitespace() {
let string = "Neque in sem. Pellentesque tellus augue.";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(20, false, "", &graphemes[..]),
SnippetState::LineEnd("Neque in sem. ".to_string(), 25)
);
assert_eq!(
break_string(20, true, "", &graphemes[..]),
SnippetState::LineEnd("Neque in sem.".to_string(), 25)
);
}
#[test]
fn newline_in_candidate_line() {
let string = "Nulla\nconsequat erat at massa. Vivamus id mi.";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(
break_string(25, false, "", &graphemes[..]),
SnippetState::EndWithLineFeed("Nulla\n".to_string(), 6)
);
assert_eq!(
break_string(25, true, "", &graphemes[..]),
SnippetState::EndWithLineFeed("Nulla\n".to_string(), 6)
);
let mut config: Config = Default::default();
config.set().max_width(27);
let fmt = StringFormat::new(Shape::legacy(25, Indent::empty()), &config);
let rewritten_string = rewrite_string(string, &fmt, 27);
assert_eq!(
rewritten_string,
Some("\"Nulla\nconsequat erat at massa. \\\n Vivamus id mi.\"".to_string())
);
}
#[test]
fn last_line_fit_with_trailing_whitespaces() {
let string = "Vivamus id mi. ";
let config: Config = Default::default();
let mut fmt = StringFormat::new(Shape::legacy(25, Indent::empty()), &config);
fmt.trim_end = true;
let rewritten_string = rewrite_string(string, &fmt, 25);
assert_eq!(rewritten_string, Some("\"Vivamus id mi.\"".to_string()));
fmt.trim_end = false; // default value of trim_end
let rewritten_string = rewrite_string(string, &fmt, 25);
assert_eq!(rewritten_string, Some("\"Vivamus id mi. \"".to_string()));
}
#[test]
fn last_line_fit_with_newline() {
let string = "Vivamus id mi.\nVivamus id mi.";
let config: Config = Default::default();
let fmt = StringFormat {
opener: "",
closer: "",
line_start: "// ",
line_end: "",
shape: Shape::legacy(100, Indent::from_width(&config, 4)),
trim_end: true,
config: &config,
};
let rewritten_string = rewrite_string(string, &fmt, 100);
assert_eq!(
rewritten_string,
Some("Vivamus id mi.\n // Vivamus id mi.".to_string())
);
}
#[test]
fn overflow_in_non_string_content() {
let comment = "Aenean metus.\nVestibulum ac lacus. Vivamus porttitor";
let config: Config = Default::default();
let fmt = StringFormat {
opener: "",
closer: "",
line_start: "// ",
line_end: "",
shape: Shape::legacy(30, Indent::from_width(&config, 8)),
trim_end: true,
config: &config,
};
assert_eq!(
rewrite_string(comment, &fmt, 30),
Some(
"Aenean metus.\n // Vestibulum ac lacus. Vivamus\n // porttitor"
.to_string()
)
);
}
#[test]
fn overflow_in_non_string_content_with_line_end() {
let comment = "Aenean metus.\nVestibulum ac lacus. Vivamus porttitor";
let config: Config = Default::default();
let fmt = StringFormat {
opener: "",
closer: "",
line_start: "// ",
line_end: "@",
shape: Shape::legacy(30, Indent::from_width(&config, 8)),
trim_end: true,
config: &config,
};
assert_eq!(
rewrite_string(comment, &fmt, 30),
Some(
"Aenean metus.\n // Vestibulum ac lacus. Vivamus@\n // porttitor"
.to_string()
)
);
}
#[test]
fn blank_line_with_non_empty_line_start() {
let config: Config = Default::default();
let mut fmt = StringFormat {
opener: "",
closer: "",
line_start: "// ",
line_end: "",
shape: Shape::legacy(30, Indent::from_width(&config, 4)),
trim_end: true,
config: &config,
};
let comment = "Aenean metus. Vestibulum\n\nac lacus. Vivamus porttitor";
assert_eq!(
rewrite_string(comment, &fmt, 30),
Some(
"Aenean metus. Vestibulum\n //\n // ac lacus. Vivamus porttitor".to_string()
)
);
fmt.shape = Shape::legacy(15, Indent::from_width(&config, 4));
let comment = "Aenean\n\nmetus. Vestibulum ac lacus. Vivamus porttitor";
assert_eq!(
rewrite_string(comment, &fmt, 15),
Some(
r#"Aenean
//
// metus. Vestibulum
// ac lacus. Vivamus
// porttitor"#
.to_string()
)
);
}
#[test]
fn retain_blank_lines() {
let config: Config = Default::default();
let fmt = StringFormat {
opener: "",
closer: "",
line_start: "// ",
line_end: "",
shape: Shape::legacy(20, Indent::from_width(&config, 4)),
trim_end: true,
config: &config,
};
let comment = "Aenean\n\nmetus. Vestibulum ac lacus.\n\n";
assert_eq!(
rewrite_string(comment, &fmt, 20),
Some(
"Aenean\n //\n // metus. Vestibulum ac\n // lacus.\n //\n".to_string()
)
);
let comment = "Aenean\n\nmetus. Vestibulum ac lacus.\n";
assert_eq!(
rewrite_string(comment, &fmt, 20),
Some("Aenean\n //\n // metus. Vestibulum ac\n // lacus.\n".to_string())
);
let comment = "Aenean\n \nmetus. Vestibulum ac lacus.";
assert_eq!(
rewrite_string(comment, &fmt, 20),
Some("Aenean\n //\n // metus. Vestibulum ac\n // lacus.".to_string())
);
}
#[test]
fn boundary_on_edge() {
let config: Config = Default::default();
let mut fmt = StringFormat {
opener: "",
closer: "",
line_start: "// ",
line_end: "",
shape: Shape::legacy(13, Indent::from_width(&config, 4)),
trim_end: true,
config: &config,
};
let comment = "Aenean metus. Vestibulum ac lacus.";
assert_eq!(
rewrite_string(comment, &fmt, 13),
Some("Aenean metus.\n // Vestibulum ac\n // lacus.".to_string())
);
fmt.trim_end = false;
let comment = "Vestibulum ac lacus.";
assert_eq!(
rewrite_string(comment, &fmt, 13),
Some("Vestibulum \n // ac lacus.".to_string())
);
fmt.trim_end = true;
fmt.line_end = "\\";
let comment = "Vestibulum ac lacus.";
assert_eq!(
rewrite_string(comment, &fmt, 13),
Some("Vestibulum\\\n // ac lacus.".to_string())
);
}
#[test]
fn detect_urls() {
let string = "aaa http://example.org something";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(detect_url(&graphemes, 8), Some(21));
let string = "https://example.org something";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(detect_url(&graphemes, 0), Some(18));
let string = "aaa ftp://example.org something";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(detect_url(&graphemes, 8), Some(20));
let string = "aaa file://example.org something";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(detect_url(&graphemes, 8), Some(21));
let string = "aaa http not an url";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(detect_url(&graphemes, 6), None);
let string = "aaa file://example.org";
let graphemes = UnicodeSegmentation::graphemes(&*string, false).collect::<Vec<&str>>();
assert_eq!(detect_url(&graphemes, 8), Some(21));
}
}
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