mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-12-30 23:42:30 +03:00
87 lines
2.2 KiB
C++
87 lines
2.2 KiB
C++
/*
|
|
* ReorderingStack.cpp
|
|
** Author: Ankit K. Srivastava
|
|
** Date: Jan 26, 2010
|
|
*/
|
|
|
|
#include "ReorderingStack.h"
|
|
#include <vector>
|
|
|
|
namespace Moses
|
|
{
|
|
int ReorderingStack::Compare(const ReorderingStack& o) const
|
|
{
|
|
const ReorderingStack& other = static_cast<const ReorderingStack&>(o);
|
|
if (other.m_stack > m_stack) {
|
|
return 1;
|
|
} else if (other.m_stack < m_stack) {
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
// Method to push (shift element into the stack and reduce if reqd)
|
|
int ReorderingStack::ShiftReduce(WordsRange input_span)
|
|
{
|
|
int distance; // value to return: the initial distance between this and previous span
|
|
|
|
// stack is empty
|
|
if(m_stack.empty()) {
|
|
m_stack.push_back(input_span);
|
|
return input_span.GetStartPos() + 1; // - (-1)
|
|
}
|
|
|
|
// stack is non-empty
|
|
WordsRange prev_span = m_stack.back(); //access last element added
|
|
|
|
//calculate the distance we are returning
|
|
if(input_span.GetStartPos() > prev_span.GetStartPos()) {
|
|
distance = input_span.GetStartPos() - prev_span.GetEndPos();
|
|
} else {
|
|
distance = input_span.GetEndPos() - prev_span.GetStartPos();
|
|
}
|
|
|
|
if(distance == 1) { //monotone
|
|
m_stack.pop_back();
|
|
WordsRange new_span(prev_span.GetStartPos(), input_span.GetEndPos());
|
|
Reduce(new_span);
|
|
} else if(distance == -1) { //swap
|
|
m_stack.pop_back();
|
|
WordsRange new_span(input_span.GetStartPos(), prev_span.GetEndPos());
|
|
Reduce(new_span);
|
|
} else { // discontinuous
|
|
m_stack.push_back(input_span);
|
|
}
|
|
|
|
return distance;
|
|
}
|
|
|
|
// Method to reduce, if possible the spans
|
|
void ReorderingStack::Reduce(WordsRange current)
|
|
{
|
|
bool cont_loop = true;
|
|
|
|
while (cont_loop && m_stack.size() > 0) {
|
|
|
|
WordsRange previous = m_stack.back();
|
|
|
|
if(current.GetStartPos() - previous.GetEndPos() == 1) { //mono&merge
|
|
m_stack.pop_back();
|
|
WordsRange t(previous.GetStartPos(), current.GetEndPos());
|
|
current = t;
|
|
} else if(previous.GetStartPos() - current.GetEndPos() == 1) { //swap&merge
|
|
m_stack.pop_back();
|
|
WordsRange t(current.GetStartPos(), previous.GetEndPos());
|
|
current = t;
|
|
} else { // discontinuous, no more merging
|
|
cont_loop=false;
|
|
}
|
|
} // finished reducing, exit
|
|
|
|
// add to stack
|
|
m_stack.push_back(current);
|
|
}
|
|
|
|
}
|
|
|