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#include <vector>
#include "properties/Coordinate.hh"
#include "algorithms/expand_dummies.hh"
#include "Cleanup.hh"
#include "Compare.hh"
#include "IndexClassifier.hh"
#include "IndexIterator.hh"
#include "Functional.hh"
#include "substitute.hh"
using namespace cadabra;
expand_dummies::expand_dummies(const Kernel& kernel, Ex& ex, const Ex* components, bool zero_missing_components)
: Algorithm(kernel, ex)
, comp(kernel.properties)
, components(components)
, zero_missing_components(zero_missing_components)
{
enumerate_patterns();
}
void expand_dummies::enumerate_patterns()
{
// If components is provided create a list of patterns which are inside
// the components
if (components != nullptr) {
do_list(*components, components->begin(), [this] (Ex::iterator c) {
char idx_placeholder = 'A';
Ex pattern(c.begin());
auto beg = index_iterator::begin(kernel.properties, pattern.begin());
auto end = index_iterator::end(kernel.properties, pattern.begin());
while (beg != end) {
auto pr = beg->fl.parent_rel;
auto repl = pattern.replace(beg, str_node(std::string(1, idx_placeholder++) + "?"));
repl->fl.parent_rel = pr;
beg.walk = repl;
beg.node = repl.node;
++beg;
}
bool found = false;
for (const auto& other : component_patterns) {
comp.clear();
if (comp.equal_subtree(pattern.begin(), other.begin()) == Ex_comparator::match_t::subtree_match) {
found = true;
break;
}
}
if (!found)
component_patterns.push_back(pattern);
return true;
});
}
}
bool expand_dummies::can_apply(iterator it)
{
if (*it->name == "\\sum" || *it->name == "\\equals")
return false;
// Require a node which has dummy indices with values attached
std::vector<Ex::iterator> candidates;
auto beg = index_iterator::begin(kernel.properties, it);
auto end = index_iterator::end(kernel.properties, it);
while (beg != end) {
auto prop = kernel.properties.get<Indices>(beg);
if (prop && !prop->values.empty()) {
for (const auto& candidate : candidates) {
comp.clear();
auto res = comp.equal_subtree(candidate, beg, Ex_comparator::useprops_t::always, true);
if (res == Ex_comparator::match_t::subtree_match)
return true;
}
candidates.push_back(beg);
}
++beg;
}
return false;
}
Algorithm::result_t expand_dummies::apply(iterator& it)
{
// Create a new expression which we will modify and a sum node which will
// replace it
Ex pat(it), sum("\\sum");
std::vector<std::vector<iterator>> dummies;
std::vector<const std::vector<Ex>*> values;
index_map_t full_ind_free, full_ind_dummy;
classify_indices(pat.begin(), full_ind_free, full_ind_dummy);
for (const auto& kv : full_ind_dummy) {
auto pos = std::find_if(dummies.begin(), dummies.end(),
[this, kv](const std::vector<iterator>& lhs) {
comp.clear();
auto res = comp.equal_subtree(lhs[0], kv.second, Ex_comparator::useprops_t::always, true);
return res == Ex_comparator::match_t::subtree_match;
});
if (pos == dummies.end()) {
auto prop = kernel.properties.get<Indices>(kv.first.begin(), true);
if (prop && !prop->values.empty()) {
dummies.emplace_back(1, kv.second);
values.push_back(&(prop->values));
}
}
else {
pos->push_back(kv.second);
}
}
// Set up 'positions' to hold iterators into the corresponding elements of the
// 'values' vector, we will loop through all possible combinations
std::vector<std::vector<Ex>::const_iterator> positions;
for (const auto& vec : values)
positions.push_back(vec->begin());
do {
// Rewrite each dummy pair with the coordinate pointed to by the
// positions vector and append to the sum
for (size_t i = 0; i < dummies.size(); ++i) {
for (iterator& dummy : dummies[i])
dummy = pat.replace_index(dummy, positions[i]->begin(), true);
}
auto term = sum.append_child(sum.begin(), pat.begin());
fill_components(term);
// Increment the positions vector
for (size_t i = 0; i < positions.size(); ++i) {
++positions[i];
if (positions[i] != values[i]->end())
break;
else if (i != positions.size() - 1)
positions[i] = values[i]->begin();
}
} while (positions.back() != values.back()->end());
// Replace the node with the new sum
it = tr.replace(it, sum.begin());
return result_t::l_applied;
}
void expand_dummies::fill_components(Ex::iterator it)
{
if (components == nullptr)
return;
Ex::post_order_iterator walk = it, last = it;
walk.descend_all();
++last;
do {
auto next = walk;
++next;
// Try to match a pattern against the current node
for (const auto& pattern : component_patterns) {
comp.clear();
auto res = comp.equal_subtree(pattern.begin(), walk);
if ((res != Ex_comparator::match_t::subtree_match) &&
(res != Ex_comparator::match_t::match_index_greater) &&
(res != Ex_comparator::match_t::match_index_less))
continue;
// Ensure all indices are coordinates
auto ibeg = index_iterator::begin(kernel.properties, walk);
auto iend = index_iterator::end(kernel.properties, walk);
while (ibeg != iend) {
if (kernel.properties.get<Coordinate>(ibeg, true) == nullptr)
break;
++ibeg;
}
if (ibeg != iend)
continue;
// Find the matching term in components
bool replaced = false;
auto head = components->begin();
if (*head->name == "\\comma") {
for (Ex::sibling_iterator cbeg = head.begin(), cend = head.end(); cbeg != cend; ++cbeg) {
Ex::sibling_iterator term = cbeg.begin();
comp.clear();
if (comp.equal_subtree(term, walk) == Ex_comparator::match_t::subtree_match) {
++term;
if (walk == it)
it = tr.replace(walk, term);
else
tr.replace(walk, term);
replaced = true;
break;
}
}
}
else {
auto term = head.begin();
comp.clear();
if (comp.equal_subtree(walk, term) == Ex_comparator::match_t::subtree_match) {
++term;
if (walk == it)
it = tr.replace(walk, term);
else
tr.replace(walk, term);
replaced = true;
}
}
if (!replaced && zero_missing_components) {
// No rule found, term is 0
tr.erase(it);
return;
}
break;
}
walk = next;
} while (walk != last);
cleanup_dispatch(kernel, tr, it);
}
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