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|
use std::cmp::{max, min};
use syntect::highlighting::StyleModifier;
use crate::edits::string_pair::StringPair;
/// Create background style sections for a region of removed/added lines.
/*
This function is called iff a region of n minus lines followed
by n plus lines is encountered, e.g. n successive lines have
been partially changed.
Consider the i-th such line and let m, p be the i-th minus and
i-th plus line, respectively. The following cases exist:
1. Whitespace deleted at line beginning.
=> The deleted section is highlighted in m; p is unstyled.
2. Whitespace inserted at line beginning.
=> The inserted section is highlighted in p; m is unstyled.
3. An internal section of the line containing a non-whitespace character has been deleted.
=> The deleted section is highlighted in m; p is unstyled.
4. An internal section of the line containing a non-whitespace character has been changed.
=> The original section is highlighted in m; the replacement is highlighted in p.
5. An internal section of the line containing a non-whitespace character has been inserted.
=> The inserted section is highlighted in p; m is unstyled.
Note that whitespace can be neither deleted nor inserted at the
end of the line: the line by definition has no trailing
whitespace.
*/
pub fn get_diff_style_sections(
minus_lines: &Vec<String>,
plus_lines: &Vec<String>,
minus_style_modifier: StyleModifier,
minus_emph_style_modifier: StyleModifier,
plus_style_modifier: StyleModifier,
plus_emph_style_modifier: StyleModifier,
) -> (
Vec<Vec<(StyleModifier, String)>>,
Vec<Vec<(StyleModifier, String)>>,
) {
let mut minus_line_sections = Vec::new();
let mut plus_line_sections = Vec::new();
for (minus, plus) in minus_lines.iter().zip(plus_lines.iter()) {
let string_pair = StringPair::new(minus, plus);
// We require that (right-trimmed length) >= (common prefix length). Consider:
// minus = "a "
// plus = "a b "
// Here, the right-trimmed length of minus is 1, yet the common prefix length is
// 2. We resolve this by taking the following maxima:
let minus_length = max(string_pair.lengths[0], string_pair.common_prefix_length);
let plus_length = max(string_pair.lengths[1], string_pair.common_prefix_length);
// Work backwards from the end of the strings. The end of the
// change region is equal to the start of their common
// suffix. To find the start of the change region, start with
// the end of their common prefix, and then move leftwards
// until it is before the start of the common suffix in both
// strings.
let minus_change_end = minus_length - string_pair.common_suffix_length;
let plus_change_end = plus_length - string_pair.common_suffix_length;
let change_begin = min(
string_pair.common_prefix_length,
min(minus_change_end, plus_change_end),
);
minus_line_sections.push(vec![
(minus_style_modifier, minus[0..change_begin].to_string()),
(
minus_emph_style_modifier,
minus[change_begin..minus_change_end].to_string(),
),
(minus_style_modifier, minus[minus_change_end..].to_string()),
]);
plus_line_sections.push(vec![
(plus_style_modifier, plus[0..change_begin].to_string()),
(
plus_emph_style_modifier,
plus[change_begin..plus_change_end].to_string(),
),
(plus_style_modifier, plus[plus_change_end..].to_string()),
]);
}
(minus_line_sections, plus_line_sections)
}
#[cfg(test)]
mod tests {
use super::*;
use syntect::highlighting::{Color, FontStyle};
#[test]
fn test_get_diff_style_sections_1() {
let actual_edits = get_diff_style_sections(
&vec!["aaa\n".to_string()],
&vec!["aba\n".to_string()],
MINUS,
MINUS_EMPH,
PLUS,
PLUS_EMPH,
);
let expected_edits = (
vec![as_strings(vec![
(MINUS, "a"),
(MINUS_EMPH, "a"),
(MINUS, "a\n"),
])],
vec![as_strings(vec![
(PLUS, "a"),
(PLUS_EMPH, "b"),
(PLUS, "a\n"),
])],
);
assert_consistent(&expected_edits);
assert_consistent(&actual_edits);
assert_eq!(actual_edits, expected_edits);
}
#[test]
fn test_get_diff_style_sections_2() {
let actual_edits = get_diff_style_sections(
&vec!["d.iteritems()\n".to_string()],
&vec!["d.items()\n".to_string()],
MINUS,
MINUS_EMPH,
PLUS,
PLUS_EMPH,
);
let expected_edits = (
vec![as_strings(vec![
(MINUS, "d."),
(MINUS_EMPH, "iter"),
(MINUS, "items()\n"),
])],
vec![as_strings(vec![
(PLUS, "d."),
(PLUS_EMPH, ""),
(PLUS, "items()\n"),
])],
);
assert_consistent(&expected_edits);
assert_consistent(&actual_edits);
assert_eq!(actual_edits, expected_edits);
}
type StyleSection = (StyleModifier, String);
type StyleSections = Vec<StyleSection>;
type LineStyleSections = Vec<StyleSections>;
type Edits = (LineStyleSections, LineStyleSections);
fn assert_consistent(edits: &Edits) {
let (minus_line_style_sections, plus_line_style_sections) = edits;
for (minus_style_sections, plus_style_sections) in minus_line_style_sections
.iter()
.zip(plus_line_style_sections)
{
let (minus_total, minus_delta) = summarize_style_sections(minus_style_sections);
let (plus_total, plus_delta) = summarize_style_sections(plus_style_sections);
assert_eq!(minus_total - minus_delta, plus_total - plus_delta);
}
}
fn summarize_style_sections(sections: &StyleSections) -> (usize, usize) {
let mut total = 0;
let mut delta = 0;
for (style, s) in sections {
total += s.len();
if is_emph(style) {
delta += s.len();
}
}
(total, delta)
}
const RED: Color = Color::BLACK;
const GREEN: Color = Color::WHITE;
const MINUS: StyleModifier = StyleModifier {
foreground: None,
background: Some(RED),
font_style: None,
};
const MINUS_EMPH: StyleModifier = StyleModifier {
foreground: None,
background: Some(RED),
font_style: Some(FontStyle::BOLD),
};
const PLUS: StyleModifier = StyleModifier {
foreground: None,
background: Some(GREEN),
font_style: None,
};
const PLUS_EMPH: StyleModifier = StyleModifier {
foreground: None,
background: Some(GREEN),
font_style: Some(FontStyle::BOLD),
};
fn as_strings(sections: Vec<(StyleModifier, &str)>) -> StyleSections {
let mut
|