91 lines
2.6 KiB
Rust
91 lines
2.6 KiB
Rust
use core::fmt::Debug;
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use crate::operation_transformation::Operation;
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#[derive(Clone)]
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pub struct MergeContext<T>
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where
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T: PartialEq + Clone,
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{
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last_operation: Option<Operation<T>>,
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pub shift: i64,
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}
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impl<T> Default for MergeContext<T>
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where
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T: PartialEq + Clone,
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{
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fn default() -> Self {
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MergeContext {
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last_operation: None,
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shift: 0,
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}
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}
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}
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impl<T> Debug for MergeContext<T>
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where
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T: PartialEq + Clone,
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{
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fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
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f.debug_struct("MergeContext")
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.field("last_operation", &self.last_operation)
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.field("shift", &self.shift)
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.finish()
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}
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}
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impl<T> MergeContext<T>
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where
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T: PartialEq + Clone,
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{
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pub fn last_operation(&self) -> Option<&Operation<T>> { self.last_operation.as_ref() }
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/// Replace the last delete operation (if there was one) with a new one
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/// while applying it to the shift.
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pub fn consume_and_replace_last_operation(&mut self, operation: Option<Operation<T>>) {
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if let Some(Operation::Delete {
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deleted_character_count,
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..
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}) = self.last_operation.take()
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{
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self.shift -= deleted_character_count as i64;
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}
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self.last_operation = operation;
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}
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pub fn replace_last_operation(&mut self, operation: Option<Operation<T>>) {
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self.last_operation = operation;
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}
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/// Remove the last operation (if there was one) in case it is behind the
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/// threshold operation. This changes the shift in case the last operation
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/// was a delete.
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pub fn consume_last_operation_if_it_is_too_behind(
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&mut self,
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threshold_operation: &Operation<T>,
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) {
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if let Some(last_operation) = self.last_operation.as_ref() {
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if let Operation::Delete {
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deleted_character_count,
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..
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} = last_operation
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{
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if threshold_operation.start_index() as i64 + self.shift
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> last_operation.end_index() as i64
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{
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self.shift -= *deleted_character_count as i64;
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self.last_operation = None;
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}
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} else if let Operation::Insert { .. } = last_operation {
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if threshold_operation.start_index() as i64 + self.shift
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- last_operation.len() as i64
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> last_operation.end_index() as i64
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{
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self.last_operation = None;
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}
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}
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}
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}
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}
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