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Diffstat (limited to 'vendor/similar/src/utils.rs')
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diff --git a/vendor/similar/src/utils.rs b/vendor/similar/src/utils.rs new file mode 100644 index 000000000..1f8fdc989 --- /dev/null +++ b/vendor/similar/src/utils.rs @@ -0,0 +1,415 @@ +//! Utilities for common diff related operations. +//! +//! This module provides specialized utilities and simplified diff operations +//! for common operations. It's useful when you want to work with text diffs +//! and you're interested in getting vectors of these changes directly. +//! +//! # Slice Remapping +//! +//! When working with [`TextDiff`] it's common that one takes advantage of the +//! built-in tokenization of the differ. This for instance lets you do +//! grapheme level diffs. This is implemented by the differ generating rather +//! small slices of strings and running a diff algorithm over them. +//! +//! The downside of this is that all the [`DiffOp`] objects produced by the +//! diffing algorithm encode operations on these rather small slices. For +//! a lot of use cases this is not what one wants which can make this very +//! inconvenient. This module provides a [`TextDiffRemapper`] which lets you +//! map from the ranges that the [`TextDiff`] returns to the original input +//! strings. For more information see [`TextDiffRemapper`]. +//! +//! # Simple Diff Functions +//! +//! This module provides a range of common test diff functions that will +//! produce vectors of `(change_tag, value)` tuples. They will automatically +//! optimize towards returning the most useful slice that one would expect for +//! the type of diff performed. + +use std::hash::Hash; +use std::ops::{Index, Range}; + +use crate::{ + capture_diff_slices, Algorithm, ChangeTag, DiffOp, DiffableStr, DiffableStrRef, TextDiff, +}; + +struct SliceRemapper<'x, T: ?Sized> { + source: &'x T, + indexes: Vec<Range<usize>>, +} + +impl<'x, 'slices, T: DiffableStr + ?Sized> SliceRemapper<'x, T> { + fn new(source: &'x T, slices: &[&'x T]) -> SliceRemapper<'x, T> { + let indexes = slices + .iter() + .scan(0, |state, item| { + let start = *state; + let end = start + item.len(); + *state = end; + Some(start..end) + }) + .collect(); + SliceRemapper { source, indexes } + } + + fn slice(&self, range: Range<usize>) -> Option<&'x T> { + let start = self.indexes.get(range.start)?.start; + let end = self.indexes.get(range.end - 1)?.end; + Some(self.source.slice(start..end)) + } +} + +impl<'x, T: DiffableStr + ?Sized> Index<Range<usize>> for SliceRemapper<'x, T> { + type Output = T; + + fn index(&self, range: Range<usize>) -> &Self::Output { + self.slice(range).expect("out of bounds") + } +} + +/// A remapper that can remap diff ops to the original slices. +/// +/// The idea here is that when a [`TextDiff`](crate::TextDiff) is created from +/// two strings and the internal tokenization is used, this remapper can take +/// a range in the tokenized sequences and remap it to the original string. +/// This is particularly useful when you want to do things like character or +/// grapheme level diffs but you want to not have to iterate over small sequences +/// but large consequitive ones from the source. +/// +/// ```rust +/// use similar::{ChangeTag, TextDiff}; +/// use similar::utils::TextDiffRemapper; +/// +/// let old = "yo! foo bar baz"; +/// let new = "yo! foo bor baz"; +/// let diff = TextDiff::from_words(old, new); +/// let remapper = TextDiffRemapper::from_text_diff(&diff, old, new); +/// let changes: Vec<_> = diff.ops() +/// .iter() +/// .flat_map(move |x| remapper.iter_slices(x)) +/// .collect(); +/// +/// assert_eq!(changes, vec![ +/// (ChangeTag::Equal, "yo! foo "), +/// (ChangeTag::Delete, "bar"), +/// (ChangeTag::Insert, "bor"), +/// (ChangeTag::Equal, " baz") +/// ]); +pub struct TextDiffRemapper<'x, T: ?Sized> { + old: SliceRemapper<'x, T>, + new: SliceRemapper<'x, T>, +} + +impl<'x, 'slices, T: DiffableStr + ?Sized> TextDiffRemapper<'x, T> { + /// Creates a new remapper from strings and slices. + pub fn new( + old_slices: &[&'x T], + new_slices: &[&'x T], + old: &'x T, + new: &'x T, + ) -> TextDiffRemapper<'x, T> { + TextDiffRemapper { + old: SliceRemapper::new(old, old_slices), + new: SliceRemapper::new(new, new_slices), + } + } + + /// Creates a new remapper from a text diff and the original strings. + pub fn from_text_diff<'old, 'new, 'bufs>( + diff: &TextDiff<'old, 'new, 'bufs, T>, + old: &'x T, + new: &'x T, + ) -> TextDiffRemapper<'x, T> + where + 'old: 'x, + 'new: 'x, + { + TextDiffRemapper { + old: SliceRemapper::new(old, diff.old_slices()), + new: SliceRemapper::new(new, diff.new_slices()), + } + } + + /// Slices into the old string. + pub fn slice_old(&self, range: Range<usize>) -> Option<&'x T> { + self.old.slice(range) + } + + /// Slices into the new string. + pub fn slice_new(&self, range: Range<usize>) -> Option<&'x T> { + self.new.slice(range) + } + + /// Given a diffop yields the changes it encodes against the original strings. + /// + /// This is the same as the [`DiffOp::iter_slices`] method. + /// + /// ## Panics + /// + /// This method can panic if the input strings passed to the constructor + /// are incompatible with the input strings passed to the diffing algorithm. + pub fn iter_slices(&self, op: &DiffOp) -> impl Iterator<Item = (ChangeTag, &'x T)> { + // note: this is equivalent to the code in `DiffOp::iter_slices`. It is + // a copy/paste because the slicing currently cannot be well abstracted + // because of lifetime issues caused by the `Index` trait. + match *op { + DiffOp::Equal { old_index, len, .. } => { + Some((ChangeTag::Equal, self.old.slice(old_index..old_index + len))) + .into_iter() + .chain(None.into_iter()) + } + DiffOp::Insert { + new_index, new_len, .. + } => Some(( + ChangeTag::Insert, + self.new.slice(new_index..new_index + new_len), + )) + .into_iter() + .chain(None.into_iter()), + DiffOp::Delete { + old_index, old_len, .. + } => Some(( + ChangeTag::Delete, + self.old.slice(old_index..old_index + old_len), + )) + .into_iter() + .chain(None.into_iter()), + DiffOp::Replace { + old_index, + old_len, + new_index, + new_len, + } => Some(( + ChangeTag::Delete, + self.old.slice(old_index..old_index + old_len), + )) + .into_iter() + .chain( + Some(( + ChangeTag::Insert, + self.new.slice(new_index..new_index + new_len), + )) + .into_iter(), + ), + } + .map(|(tag, opt_val)| (tag, opt_val.expect("slice out of bounds"))) + } +} + +/// Shortcut for diffing two slices. +/// +/// This function produces the diff of two slices and returns a vector +/// with the changes. +/// +/// ```rust +/// use similar::{Algorithm, ChangeTag}; +/// use similar::utils::diff_slices; +/// +/// let old = "foo\nbar\nbaz".lines().collect::<Vec<_>>(); +/// let new = "foo\nbar\nBAZ".lines().collect::<Vec<_>>(); +/// assert_eq!(diff_slices(Algorithm::Myers, &old, &new), vec![ +/// (ChangeTag::Equal, &["foo", "bar"][..]), +/// (ChangeTag::Delete, &["baz"][..]), +/// (ChangeTag::Insert, &["BAZ"][..]), +/// ]); +/// ``` +pub fn diff_slices<'x, T: PartialEq + Hash + Ord>( + alg: Algorithm, + old: &'x [T], + new: &'x [T], +) -> Vec<(ChangeTag, &'x [T])> { + capture_diff_slices(alg, old, new) + .iter() + .flat_map(|op| op.iter_slices(old, new)) + .collect() +} + +/// Shortcut for making a character level diff. +/// +/// This function produces the diff of two strings and returns a vector +/// with the changes. It returns connected slices into the original string +/// rather than character level slices. +/// +/// ```rust +/// use similar::{Algorithm, ChangeTag}; +/// use similar::utils::diff_chars; +/// +/// assert_eq!(diff_chars(Algorithm::Myers, "foobarbaz", "fooBARbaz"), vec![ +/// (ChangeTag::Equal, "foo"), +/// (ChangeTag::Delete, "bar"), +/// (ChangeTag::Insert, "BAR"), +/// (ChangeTag::Equal, "baz"), +/// ]); +/// ``` +pub fn diff_chars<'x, T: DiffableStrRef + ?Sized>( + alg: Algorithm, + old: &'x T, + new: &'x T, +) -> Vec<(ChangeTag, &'x T::Output)> { + let old = old.as_diffable_str(); + let new = new.as_diffable_str(); + let diff = TextDiff::configure().algorithm(alg).diff_chars(old, new); + let remapper = TextDiffRemapper::from_text_diff(&diff, old, new); + diff.ops() + .iter() + .flat_map(move |x| remapper.iter_slices(x)) + .collect() +} + +/// Shortcut for making a word level diff. +/// +/// This function produces the diff of two strings and returns a vector +/// with the changes. It returns connected slices into the original string +/// rather than word level slices. +/// +/// ```rust +/// use similar::{Algorithm, ChangeTag}; +/// use similar::utils::diff_words; +/// +/// assert_eq!(diff_words(Algorithm::Myers, "foo bar baz", "foo bor baz"), vec![ +/// (ChangeTag::Equal, "foo "), +/// (ChangeTag::Delete, "bar"), +/// (ChangeTag::Insert, "bor"), +/// (ChangeTag::Equal, " baz"), +/// ]); +/// ``` +pub fn diff_words<'x, T: DiffableStrRef + ?Sized>( + alg: Algorithm, + old: &'x T, + new: &'x T, +) -> Vec<(ChangeTag, &'x T::Output)> { + let old = old.as_diffable_str(); + let new = new.as_diffable_str(); + let diff = TextDiff::configure().algorithm(alg).diff_words(old, new); + let remapper = TextDiffRemapper::from_text_diff(&diff, old, new); + diff.ops() + .iter() + .flat_map(move |x| remapper.iter_slices(x)) + .collect() +} + +/// Shortcut for making a unicode word level diff. +/// +/// This function produces the diff of two strings and returns a vector +/// with the changes. It returns connected slices into the original string +/// rather than word level slices. +/// +/// ```rust +/// use similar::{Algorithm, ChangeTag}; +/// use similar::utils::diff_unicode_words; +/// +/// let old = "The quick (\"brown\") fox can't jump 32.3 feet, right?"; +/// let new = "The quick (\"brown\") fox can't jump 9.84 meters, right?"; +/// assert_eq!(diff_unicode_words(Algorithm::Myers, old, new), vec![ +/// (ChangeTag::Equal, "The quick (\"brown\") fox can\'t jump "), +/// (ChangeTag::Delete, "32.3"), +/// (ChangeTag::Insert, "9.84"), +/// (ChangeTag::Equal, " "), +/// (ChangeTag::Delete, "feet"), +/// (ChangeTag::Insert, "meters"), +/// (ChangeTag::Equal, ", right?") +/// ]); +/// ``` +/// +/// This requires the `unicode` feature. +#[cfg(feature = "unicode")] +pub fn diff_unicode_words<'x, T: DiffableStrRef + ?Sized>( + alg: Algorithm, + old: &'x T, + new: &'x T, +) -> Vec<(ChangeTag, &'x T::Output)> { + let old = old.as_diffable_str(); + let new = new.as_diffable_str(); + let diff = TextDiff::configure() + .algorithm(alg) + .diff_unicode_words(old, new); + let remapper = TextDiffRemapper::from_text_diff(&diff, old, new); + diff.ops() + .iter() + .flat_map(move |x| remapper.iter_slices(x)) + .collect() +} + +/// Shortcut for making a grapheme level diff. +/// +/// This function produces the diff of two strings and returns a vector +/// with the changes. It returns connected slices into the original string +/// rather than grapheme level slices. +/// +/// ```rust +/// use similar::{Algorithm, ChangeTag}; +/// use similar::utils::diff_graphemes; +/// +/// let old = "The flag of Austria is 🇦🇹"; +/// let new = "The flag of Albania is 🇦🇱"; +/// assert_eq!(diff_graphemes(Algorithm::Myers, old, new), vec![ +/// (ChangeTag::Equal, "The flag of A"), +/// (ChangeTag::Delete, "ustr"), +/// (ChangeTag::Insert, "lban"), +/// (ChangeTag::Equal, "ia is "), +/// (ChangeTag::Delete, "🇦🇹"), +/// (ChangeTag::Insert, "🇦🇱"), +/// ]); +/// ``` +/// +/// This requires the `unicode` feature. +#[cfg(feature = "unicode")] +pub fn diff_graphemes<'x, T: DiffableStrRef + ?Sized>( + alg: Algorithm, + old: &'x T, + new: &'x T, +) -> Vec<(ChangeTag, &'x T::Output)> { + let old = old.as_diffable_str(); + let new = new.as_diffable_str(); + let diff = TextDiff::configure() + .algorithm(alg) + .diff_graphemes(old, new); + let remapper = TextDiffRemapper::from_text_diff(&diff, old, new); + diff.ops() + .iter() + .flat_map(move |x| remapper.iter_slices(x)) + .collect() +} + +/// Shortcut for making a line diff. +/// +/// This function produces the diff of two slices and returns a vector +/// with the changes. Unlike [`diff_chars`] or [`diff_slices`] it returns a +/// change tag for each line. +/// +/// ```rust +/// use similar::{Algorithm, ChangeTag}; +/// use similar::utils::diff_lines; +/// +/// assert_eq!(diff_lines(Algorithm::Myers, "foo\nbar\nbaz\nblah", "foo\nbar\nbaz\nblurgh"), vec![ +/// (ChangeTag::Equal, "foo\n"), +/// (ChangeTag::Equal, "bar\n"), +/// (ChangeTag::Equal, "baz\n"), +/// (ChangeTag::Delete, "blah"), +/// (ChangeTag::Insert, "blurgh"), +/// ]); +/// ``` +pub fn diff_lines<'x, T: DiffableStrRef + ?Sized>( + alg: Algorithm, + old: &'x T, + new: &'x T, +) -> Vec<(ChangeTag, &'x T::Output)> { + TextDiff::configure() + .algorithm(alg) + .diff_lines(old, new) + .iter_all_changes() + .map(|change| (change.tag(), change.value())) + .collect() +} + +#[test] +fn test_remapper() { + let a = "foo bar baz"; + let words = a.tokenize_words(); + dbg!(&words); + let remap = SliceRemapper::new(a, &words); + assert_eq!(remap.slice(0..3), Some("foo bar")); + assert_eq!(remap.slice(1..3), Some(" bar")); + assert_eq!(remap.slice(0..1), Some("foo")); + assert_eq!(remap.slice(0..5), Some("foo bar baz")); + assert_eq!(remap.slice(0..6), None); +} |