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//!
//! The context flipping algorithm.
//!
use std::{
cmp,
collections::VecDeque,
};
use log::*;
use crate::{
context::{Context, ContextHeader},
line::Line,
};
enum FlipState {
StartContext,
Context,
Buffering,
}
impl Context {
pub fn flip(&self, mut context_radius: usize) -> VecDeque<Self> {
context_radius = cmp::max(1, context_radius);
context_radius = cmp::min(context_radius, self.opening_context_size());
let mut results = VecDeque::new();
let mut output = Self::default();
output.header.file1_l = self.header.file2_l;
output.header.file2_l = self.header.file1_l;
let mut state = FlipState::StartContext;
let mut deletes = Vec::new();
let mut inserts = Vec::new();
trace!("START");
for line in self.data.iter() {
match line {
Line::Context(_) => {
match state {
FlipState::StartContext => {
trace!("Context StartContext");
while output.opening_context_size() >= context_radius {
output.data.pop();
output.header.file1_l += 1;
output.header.file2_l += 1;
trace!("POP START");
}
output.data.push(line.clone());
},
FlipState::Context => {
trace!("Context Context");
output.data.push(line.clone());
let lines = output.closing_context_size();
if lines > 2 * context_radius {
let mut data = Vec::new();
data.push(output.data.pop().unwrap());
for _ in context_radius*2..lines {
output.data.pop();
trace!("POP END");
}
output.update();
trace!("PUSH OUTPUT");
let output_next = Context {
header: ContextHeader {
file1_l: output.header.file2_l + output.header.file2_s + lines - 2,
file1_s: Default::default(),
file2_l: output.header.file1_l + output.header.file1_s + lines - 2,
file2_s: Default::default(),
},
data,
};
if output.has_changes() {
results.push_back(output);
}
output = output_next;
state = FlipState::Context;
}
},
FlipState::Buffering => {
trace!("Context Buffering");
output.data.append(&mut deletes);
output.data.append(&mut inserts);
state = FlipState::Context;
output.data.push(line.clone());
},
}
},
Line::Delete(_) => {
if let FlipState::StartContext = state {
trace!("Delete StartContext");
state = FlipState::Buffering;
}
if let FlipState::Context = state {
trace!("Delete Context");
state = FlipState::Buffering;
}
if let FlipState::Buffering = state {
trace!("Delete Buffering");
inserts.push(line.flip());
}
},
Line::Insert(_) => {
trace!("INSERT");
if let FlipState::StartContext = state {
trace!("Insert StartContext");
state = FlipState::Buffering;
}
if let FlipState::Context = state {
trace!("Insert Context");
state = FlipState::Buffering;
}
if let FlipState::Buffering = state {
trace!("Insert Buffering");
deletes.push(line.flip());
}
},
}
}
let lines = output.closing_context_size();
if lines > context_radius {
for _ in context_radius..lines {
output.data.pop();
trace!("POP END");
}
}
output.update();
if output.has_changes() {
results.push_back(output);
}
trace!("END");
results
}
}