90 lines
2.9 KiB
Rust
90 lines
2.9 KiB
Rust
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Format string literals.
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use utils::{make_indent, next_char, prev_char, round_up_to_power_of_two};
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use MIN_STRING;
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pub struct StringFormat<'a> {
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pub opener: &'a str,
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pub closer: &'a str,
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pub line_start: &'a str,
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pub line_end: &'a str,
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pub width: usize,
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pub offset: usize,
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pub trim_end: bool,
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}
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// TODO: simplify this!
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pub fn rewrite_string<'a>(s: &str, fmt: &StringFormat<'a>) -> String {
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// FIXME I bet this stomps unicode escapes in the source string
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// TODO if lo.col > IDEAL - 10, start a new line (need cur indent for that)
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let indent = make_indent(fmt.offset);
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let indent = &indent;
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let mut cur_start = 0;
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let mut result = String::with_capacity(round_up_to_power_of_two(s.len()));
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result.push_str(fmt.opener);
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let ender_length = fmt.line_end.len();
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let max_chars = fmt.width.checked_sub(fmt.opener.len()).unwrap_or(0)
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.checked_sub(ender_length).unwrap_or(1);
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loop {
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let mut cur_end = cur_start + max_chars;
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if cur_end >= s.len() {
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result.push_str(&s[cur_start..]);
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break;
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}
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// Make sure we're on a char boundary.
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cur_end = next_char(&s, cur_end);
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// Push cur_end left until we reach whitespace.
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while !s.char_at(cur_end - 1).is_whitespace() {
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cur_end = prev_char(&s, cur_end);
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if cur_end - cur_start < MIN_STRING {
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// We can't break at whitespace, fall back to splitting
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// anywhere that doesn't break an escape sequence.
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cur_end = next_char(&s, cur_start + max_chars);
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while s.char_at(prev_char(&s, cur_end)) == '\\' {
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cur_end = prev_char(&s, cur_end);
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}
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break;
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}
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}
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// Make sure there is no whitespace to the right of the break.
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while cur_end < s.len() && s.char_at(cur_end).is_whitespace() {
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cur_end = next_char(&s, cur_end + 1);
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}
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let line: &str = if fmt.trim_end {
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&s[cur_start..cur_end].trim_right_matches(char::is_whitespace)
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} else {
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&s[cur_start..cur_end]
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};
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result.push_str(line);
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result.push_str(fmt.line_end);
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result.push('\n');
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result.push_str(indent);
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result.push_str(fmt.line_start);
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cur_start = cur_end;
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}
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result.push_str(fmt.closer);
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result
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}
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