2023-11-17 05:45:31 +01:00
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//! # TextChange
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//!
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2023-11-17 05:53:38 +01:00
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//! an editor-friendly representation of a text change in a buffer
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//! to easily interface with codemp from various editors
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2023-11-17 05:45:31 +01:00
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/// an editor-friendly representation of a text change in a buffer
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2023-11-17 05:53:38 +01:00
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///
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/// this represent a range in the previous state of the string and a new content which should be
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/// replaced to it, allowing to represent any combination of deletions, insertions or replacements
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///
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/// bulk and widespread operations will result in a TextChange effectively sending the whole new
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/// buffer, but small changes are efficient and easy to create or apply
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///
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/// ### examples
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/// to insert 'a' after 4th character we should send a
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/// `TextChange { span: 4..4, content: "a".into() }`
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///
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/// to delete a the fourth character we should send a
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/// `TextChange { span: 3..4, content: "".into() }`
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///
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2023-11-17 05:45:31 +01:00
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#[derive(Clone, Debug, Default)]
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pub struct TextChange {
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/// range of text change, as char indexes in buffer previous state
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pub span: std::ops::Range<usize>,
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/// new content of text inside span
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pub content: String,
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}
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impl TextChange {
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/// create a new TextChange from the difference of given strings
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pub fn from_diff(before: &str, after: &str) -> TextChange {
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let diff = similar::TextDiff::from_chars(before, after);
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let mut start = 0;
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let mut end = 0;
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let mut from_beginning = true;
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for op in diff.ops() {
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match op {
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2023-11-30 00:37:57 +01:00
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similar::DiffOp::Equal { len, .. } => {
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2023-11-17 05:45:31 +01:00
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if from_beginning {
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2023-11-30 00:37:57 +01:00
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start += len
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2023-11-17 05:45:31 +01:00
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} else {
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end += len
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2023-11-17 05:45:31 +01:00
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}
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},
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_ => {
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end = 0;
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from_beginning = false;
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}
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}
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}
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let end_before = before.len() - end;
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let end_after = after.len() - end;
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TextChange {
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span: start..end_before,
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content: after[start..end_after].to_string(),
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}
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}
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2023-11-24 11:04:42 +01:00
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2023-11-30 00:38:24 +01:00
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/// returns true if this TextChange deletes existing text
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pub fn is_deletion(&self) -> bool {
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!self.span.is_empty()
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}
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// returns true if this TextChange adds new text
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pub fn is_addition(&self) -> bool {
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!self.content.is_empty()
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}
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/// returns true if this TextChange is effectively as no-op
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pub fn is_empty(&self) -> bool {
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!self.is_deletion() && !self.is_addition()
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}
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pub fn apply(&self, txt: &str) -> String {
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let pre = txt[..self.span.start].to_string();
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let post = txt[self.span.end..].to_string();
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format!("{}{}{}", pre, self.content, post)
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}
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2023-11-24 11:04:42 +01:00
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/// convert from byte index to row and column
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/// txt must be the whole content of the buffer, in order to count lines
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2023-11-30 03:01:59 +01:00
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pub fn index_to_rowcol(txt: &str, index: usize) -> crate::proto::RowCol {
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2023-11-24 11:04:42 +01:00
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let row = txt[..index].matches('\n').count() as i32;
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let col = txt[..index].split('\n').last().unwrap_or("").len() as i32;
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crate::proto::RowCol { row, col }
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}
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2023-11-17 05:45:31 +01:00
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}
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2023-11-30 00:37:57 +01:00
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#[cfg(test)]
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mod tests {
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#[test]
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fn textchange_diff_works_for_deletions() {
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let change = super::TextChange::from_diff(
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"sphinx of black quartz, judge my vow",
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"sphinx of quartz, judge my vow"
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);
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assert_eq!(change.span, 10..16);
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assert_eq!(change.content, "");
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}
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#[test]
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fn textchange_diff_works_for_insertions() {
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let change = super::TextChange::from_diff(
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"sphinx of quartz, judge my vow",
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"sphinx of black quartz, judge my vow"
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);
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assert_eq!(change.span, 10..10);
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assert_eq!(change.content, "black ");
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}
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#[test]
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fn textchange_diff_works_for_changes() {
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let change = super::TextChange::from_diff(
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"sphinx of black quartz, judge my vow",
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"sphinx who watches the desert, judge my vow"
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);
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assert_eq!(change.span, 7..22);
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assert_eq!(change.content, "who watches the desert");
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}
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2023-11-30 00:38:24 +01:00
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#[test]
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fn textchange_apply_works_for_insertions() {
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let change = super::TextChange { span: 5..5, content: " cruel".to_string() };
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let result = change.apply("hello world!");
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assert_eq!(result, "hello cruel world!");
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}
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#[test]
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fn textchange_apply_works_for_deletions() {
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let change = super::TextChange { span: 5..11, content: "".to_string() };
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let result = change.apply("hello cruel world!");
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assert_eq!(result, "hello world!");
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}
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#[test]
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fn textchange_apply_works_for_replacements() {
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let change = super::TextChange { span: 5..11, content: " not very pleasant".to_string() };
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let result = change.apply("hello cruel world!");
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assert_eq!(result, "hello not very pleasant world!");
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}
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2023-11-30 03:01:59 +01:00
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#[test]
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fn textchange_apply_never_panics() {
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let change = super::TextChange { span: 100..110, content: "a very long string \n which totally matters".to_string() };
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let result = change.apply("a short text");
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assert_eq!(result, "a short texta very long string \n which totally matters");
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}
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#[test]
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fn empty_diff_produces_empty_textchange() {
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let change = super::TextChange::from_diff("same \n\n text", "same \n\n text");
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assert!(change.is_empty());
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}
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#[test]
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fn empty_textchange_doesnt_alter_buffer() {
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let change = super::TextChange { span: 42..42, content: "".to_string() };
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let result = change.apply("some important text");
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assert_eq!(result, "some important text");
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}
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2023-11-30 00:37:57 +01:00
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}
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