337 lines
13 KiB
Rust
337 lines
13 KiB
Rust
use std::fmt::Debug;
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#[cfg(feature = "serde")]
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use serde::{Deserialize, Serialize};
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use crate::{
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BuiltinTokenizer, CursorPosition, TextWithCursors,
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operation_transformation::{
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Operation,
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utils::{cook_operations::cook_operations, elongate_operations::elongate_operations},
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},
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raw_operation::RawOperation,
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tokenizer::Tokenizer,
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types::{history::History, side::Side, span_with_history::SpanWithHistory},
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utils::string_builder::StringBuilder,
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};
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/// A text document and a sequence of operations that can be applied to the text
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/// document. `EditedText` supports merging two sequences of operations using
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/// the principles of Operational Transformation.
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///
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/// It's mainly created through the `from_strings` method, then merged with
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/// another `EditedText` derived from the same original text and then applied to
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/// the original text to get the reconciled text of concurrent edits.
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///
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/// In addition to text and operations, it also keeps track of cursor positions
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/// in the original text. The cursor positions are updated when the operations
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/// are applied, so that the cursor positions can be used to restore the
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/// cursor positions in the updated text.
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#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
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#[derive(Debug, Clone, PartialEq, Default)]
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pub struct EditedText<'a, T>
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where
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T: PartialEq + Clone + Debug,
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{
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text: &'a str,
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operations: Vec<Operation<T>>,
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cursors: Vec<CursorPosition>,
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}
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impl<'a> EditedText<'a, String> {
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/// Create an `EditedText` from the given original (old) and updated (new)
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/// strings. The returned `EditedText` represents the changes from the
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/// original to the updated text. When the return value is applied to
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/// the original text, it will result in the updated text. The default
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/// word tokenizer is used to tokenize the text which splits the text on
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/// whitespaces.
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#[must_use]
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pub fn from_strings(original: &'a str, updated: &TextWithCursors, side: Side) -> Self {
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Self::from_strings_with_tokenizer(original, updated, &*BuiltinTokenizer::Word, side)
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}
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}
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impl<'a, T> EditedText<'a, T>
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where
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T: PartialEq + Clone + Debug,
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{
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/// Create an `EditedText` from the given original (old) and updated (new)
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/// strings. The returned `EditedText` represents the changes from the
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/// original to the updated text. When the return value is applied to
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/// the original text, it will result in the updated text. The tokenizer
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/// function is used to tokenize the text.
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pub fn from_strings_with_tokenizer(
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original: &'a str,
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updated: &TextWithCursors,
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tokenizer: &Tokenizer<T>,
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side: Side,
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) -> Self {
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let original_tokens = (tokenizer)(original);
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let updated_tokens = (tokenizer)(&updated.text());
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let diff: Vec<RawOperation<T>> = RawOperation::vec_from(&original_tokens, &updated_tokens);
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Self::new(
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original,
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cook_operations(elongate_operations(diff), side).collect(),
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updated.cursors(),
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)
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}
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/// Create a new `EditedText` with the given operations.
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/// The operations must be in the order in which they are meant to be
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/// applied. The operations must not overlap.
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fn new(text: &'a str, operations: Vec<Operation<T>>, mut cursors: Vec<CursorPosition>) -> Self {
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cursors.sort_by_key(|cursor| cursor.char_index);
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Self {
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text,
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operations,
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cursors,
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}
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}
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#[must_use]
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#[allow(clippy::too_many_lines)]
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pub fn merge(self, other: Self) -> Self {
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debug_assert_eq!(
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self.text, other.text,
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"`EditedText`-s must be derived from the same text to be mergable"
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);
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let mut merged_cursors = Vec::with_capacity(self.cursors.len() + other.cursors.len());
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let mut left_cursors = self.cursors.into_iter().peekable();
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let mut right_cursors = other.cursors.into_iter().peekable();
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let mut merged_operations: Vec<Operation<T>> =
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Vec::with_capacity(self.operations.len() + other.operations.len());
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let mut left_iter = self.operations.into_iter();
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let mut right_iter = other.operations.into_iter();
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let mut maybe_left_op = left_iter.next();
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let mut maybe_right_op = right_iter.next();
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let mut seen_left_length: usize = 0;
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let mut seen_right_length: usize = 0;
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let mut merged_length: usize = 0;
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let mut last_left_op = None;
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let mut last_right_op = None;
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loop {
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let (side, operation, mut last_other_op) =
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match (maybe_left_op.clone(), maybe_right_op.clone()) {
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(Some(left_op), Some(right_op)) => {
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if left_op
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.get_sort_key(seen_left_length)
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.partial_cmp(&right_op.get_sort_key(seen_right_length))
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== Some(std::cmp::Ordering::Less)
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{
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(Side::Left, left_op, last_right_op.clone())
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} else {
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(Side::Right, right_op, last_left_op.clone())
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}
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}
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(Some(left_op), None) => (Side::Left, left_op, last_right_op.clone()),
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(None, Some(right_op)) => (Side::Right, right_op, last_left_op.clone()),
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(None, None) => break,
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};
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let is_advancing_operation = matches!(
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operation,
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Operation::Insert { .. } | Operation::Equal { .. }
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);
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let original_length = operation.len();
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let result = match side {
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Side::Left => {
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let result = operation.merge_operations(&mut last_other_op);
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if let ref op @ (Operation::Insert { .. } | Operation::Equal { .. }) = result {
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let merged_length_signed =
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isize::try_from(merged_length).unwrap_or(isize::MAX);
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let seen_left_length_signed =
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isize::try_from(seen_left_length).unwrap_or(isize::MAX);
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let op_len_signed = isize::try_from(op.len()).unwrap_or(isize::MAX);
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let original_length_signed =
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isize::try_from(original_length).unwrap_or(isize::MAX);
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let shift = merged_length_signed - seen_left_length_signed + op_len_signed
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- original_length_signed;
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while let Some(cursor) = left_cursors.next_if(|cursor| {
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cursor.char_index <= seen_left_length + original_length
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}) {
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merged_cursors.push(
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cursor.with_index(cursor.char_index.saturating_add_signed(shift)),
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);
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}
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}
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if is_advancing_operation {
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seen_left_length += original_length;
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}
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maybe_left_op = left_iter.next();
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last_left_op = Some(result.clone());
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result
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}
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Side::Right => {
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let result = operation.merge_operations(&mut last_other_op);
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if let ref op @ (Operation::Insert { .. } | Operation::Equal { .. }) = result {
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let merged_length_signed =
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isize::try_from(merged_length).unwrap_or(isize::MAX);
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let seen_right_length_signed =
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isize::try_from(seen_right_length).unwrap_or(isize::MAX);
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let op_len_signed = isize::try_from(op.len()).unwrap_or(isize::MAX);
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let original_length_signed =
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isize::try_from(original_length).unwrap_or(isize::MAX);
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let shift = merged_length_signed - seen_right_length_signed + op_len_signed
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- original_length_signed;
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while let Some(cursor) = right_cursors.next_if(|cursor| {
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cursor.char_index <= seen_right_length + original_length
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}) {
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merged_cursors.push(
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cursor.with_index(cursor.char_index.saturating_add_signed(shift)),
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);
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}
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}
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if is_advancing_operation {
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seen_right_length += original_length;
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}
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maybe_right_op = right_iter.next();
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last_right_op = Some(result.clone());
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result
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}
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};
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if result.len() == 0 {
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continue;
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}
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if is_advancing_operation {
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merged_length += result.len();
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}
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merged_operations.push(result);
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}
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for cursor in left_cursors.chain(right_cursors) {
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merged_cursors.push(cursor.with_index(merged_length));
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}
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Self::new(self.text, merged_operations, merged_cursors)
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}
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/// Apply the operations to the text and return the resulting text.
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#[must_use]
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pub fn apply(&self) -> TextWithCursors {
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let mut builder: StringBuilder<'_> = StringBuilder::new(self.text);
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for operation in &self.operations {
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builder = operation.apply(builder);
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}
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TextWithCursors::new(builder.take(), self.cursors.clone())
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}
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#[must_use]
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pub fn apply_with_history(&self) -> Vec<SpanWithHistory> {
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let mut builder: StringBuilder<'_> = StringBuilder::new(self.text);
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let mut history = Vec::with_capacity(self.operations.len());
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for operation in &self.operations {
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builder = operation.apply(builder);
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match operation {
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Operation::Equal { .. } => {
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history.push(SpanWithHistory::new(builder.take(), History::Unchanged));
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}
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Operation::Insert { side, .. } => match side {
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Side::Left => {
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history.push(SpanWithHistory::new(builder.take(), History::AddedFromLeft));
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}
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Side::Right => history.push(SpanWithHistory::new(
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builder.take(),
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History::AddedFromRight,
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)),
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},
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Operation::Delete {
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deleted_character_count,
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order,
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side,
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..
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} => {
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let deleted = self.text[*order..*order + *deleted_character_count].to_string();
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match side {
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Side::Left => {
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history.push(SpanWithHistory::new(deleted, History::RemovedFromLeft));
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}
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Side::Right => {
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history.push(SpanWithHistory::new(deleted, History::RemovedFromRight));
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}
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}
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}
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}
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}
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history
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}
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}
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#[cfg(test)]
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mod tests {
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use insta::assert_debug_snapshot;
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use pretty_assertions::assert_eq;
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use super::*;
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#[test]
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fn test_calculate_operations() {
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let left = "hello world! How are you? Adam";
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let right = "Hello, my friend! How are you doing? Albert";
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let operations = EditedText::from_strings(left, &right.into(), Side::Right);
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insta::assert_debug_snapshot!(operations);
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let new_right = operations.apply();
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assert_eq!(new_right.text(), right);
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}
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#[test]
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fn test_calculate_operations_with_no_diff() {
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let text = "hello world!";
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let operations = EditedText::from_strings(text, &text.into(), Side::Right);
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assert_debug_snapshot!(operations);
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let new_right = operations.apply();
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assert_eq!(new_right.text(), text);
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}
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#[test]
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fn test_calculate_operations_with_insert() {
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let original = "hello world! ...";
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let left = "Hello world! I'm Andras.";
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let right = "Hello world! How are you?";
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let expected = "Hello world! How are you? I'm Andras.";
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let operations_1 = EditedText::from_strings(original, &left.into(), Side::Left);
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let operations_2 = EditedText::from_strings(original, &right.into(), Side::Right);
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let operations = operations_1.merge(operations_2);
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assert_eq!(operations.apply().text(), expected);
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}
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}
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