#ifndef SASS_SASS_UTIL_H
#define SASS_SASS_UTIL_H
#include "ast.hpp"
#include "node.hpp"
#include "debug.hpp"
namespace Sass {
/*
This is for ports of functions in the Sass:Util module.
*/
/*
# Return a Node collection of all possible paths through the given Node collection of Node collections.
#
# @param arrs [NodeCollection<NodeCollection<Node>>]
# @return [NodeCollection<NodeCollection<Node>>]
#
# @example
# paths([[1, 2], [3, 4], [5]]) #=>
# # [[1, 3, 5],
# # [2, 3, 5],
# # [1, 4, 5],
# # [2, 4, 5]]
*/
Node paths(const Node& arrs);
/*
This class is a default implementation of a Node comparator that can be passed to the lcs function below.
It uses operator== for equality comparision. It then returns one if the Nodes are equal.
*/
class DefaultLcsComparator {
public:
bool operator()(const Node& one, const Node& two, Node& out) const {
// TODO: Is this the correct C++ interpretation?
// block ||= proc {|a, b| a == b && a}
if (one == two) {
out = one;
return true;
}
return false;
}
};
typedef std::vector<std::vector<int> > LCSTable;
/*
This is the equivalent of ruby's Sass::Util.lcs_backtrace.
# Computes a single longest common subsequence for arrays x and y.
# Algorithm from http://en.wikipedia.org/wiki/Longest_common_subsequence_problem#Reading_out_an_LCS
*/
template<typename ComparatorType>
Node lcs_backtrace(const LCSTable& c, const Node& x, const Node& y, int i, int j, const ComparatorType& comparator) {
DEBUG_PRINTLN(LCS, "LCSBACK: X=" << x << " Y=" << y << " I=" << i << " J=" << j)
if (i == 0 || j == 0) {
DEBUG_PRINTLN(LCS, "RETURNING EMPTY")
return Node::createCollection();
}
NodeDeque& xChildren = *(x.collection());
NodeDeque& yChildren = *(y.collection());
Node compareOut = Node::createNil();
if (comparator(xChildren[i], yChildren[j], compareOut)) {
DEBUG_PRINTLN(LCS, "RETURNING AFTER ELEM COMPARE")
Node result = lcs_backtrace(c, x, y, i - 1, j - 1, comparator);
result.collection()->push_back(compareOut);
return result;
}
if (c[i][j - 1] > c[i - 1][j]) {
DEBUG_PRINTLN(LCS, "RETURNING AFTER TABLE COMPARE")
return lcs_backtrace(c, x, y, i, j - 1, comparator);
}
DEBUG_PRINTLN(LCS, "FINAL RETURN")
return lcs_backtrace(c, x, y, i - 1, j, comparator);
}
/*
This is the equivalent of ruby's Sass::Util.lcs_table.
# Calculates the memoization table for the Least Common Subsequence algorithm.
# Algorithm from http://en.wikipedia.org/wiki/Longest_common_subsequence_problem#Computing_the_length_of_the_LCS
*/
template<typename ComparatorType>
void lcs_table(const Node& x, const Node& y, const ComparatorType& comparator, LCSTable& out) {
DEBUG_PRINTLN(LCS, "LCSTABLE: X=" << x << " Y=" << y)
NodeDeque& xChildren = *(x.collection());
NodeDeque& yChildren = *(y.collection());
LCSTable c(xChildren.size(), std::vector<int>(yChildren.size()));
// These shouldn't be necessary since the vector will be initialized to 0 already.
// x.size.times {|i| c[i][0] = 0}
// y.size.times {|j| c[0][j] = 0}
for (size_t i = 1; i < xChildren.size(); i++) {
for (size_t j = 1; j < yChildren.size(); j++) {
Node compareOut = Node::createNil();
if (comparator(xChildren[i], yChildren[j], compareOut)) {
c[i][j] = c[i - 1][j - 1] + 1;
} else {
c[i][j] = std::max(c[i][j - 1], c[i - 1][j]);
}
}
}
out = c;
}
/*
This is the equivalent of ruby's Sass::Util.lcs.
# Computes a single longest common subsequence for `x` and `y`.
# If there are more than one longest common subsequences,
# the one returned is that which starts first in `x`.
# @param x [NodeCollection]
# @param y [NodeCollection]
# @comparator An equality check between elements of `x` and `y`.
# @return [NodeCollection] The LCS
http://en.wikipedia.org/wiki/Longest_common_subsequence_problem
*/
template<typename ComparatorType>
Node lcs(Node& x, Node& y, const ComparatorType& comparator) {
DEBUG_PRINTLN(LCS, "LCS: X=" << x << " Y=" << y)
Node newX = Node::createCollection();
newX.collection()->push_back(Node::createNil());
newX.plus(x);
Node newY = Node::createCollection();
newY.collection()->push_back(Node::createNil());
newY.plus(y);
LCSTable table;
lcs_table(newX, newY, comparator, table);
return lcs_backtrace(table, newX, newY, static_cast<int>(newX.collection()->size()) - 1, static_cast<int>(newY.collection()->size()) - 1, comparator);
}
/*
This is the equivalent of ruby sass' Sass::Util.flatten and [].flatten.
Sass::Util.flatten requires the number of levels to flatten, while
[].flatten doesn't and will flatten the entire array. This function
supports both.
# Flattens the first `n` nested arrays. If n == -1, all arrays will be flattened
#
# @param arr [NodeCollection] The array to flatten
# @param n [int] The number of levels to flatten
# @return [NodeCollection] The flattened array
*/
Node flatten(Node& arr, int n = -1);
/*
This is the equivalent of ruby's Sass::Util.group_by_to_a.
# Performs the equivalent of `enum.group_by.to_a`, but with a guaranteed
# order. Unlike [#hash_to_a], the resulting order isn't sorted key order;
# instead, it's the same order as `#group_by` has under Ruby 1.9 (key
# appearance order).
#
# @param enum [Enumerable]
# @return [Array<[Object, Array]>] An array of pairs.
TODO: update @param and @return once I know what those are.
The following is the modified version of the ruby code that was more portable to C++. You
should be able to drop it into ruby 3.2.19 and get the same results from ruby sass.
def group_by_to_a(enum, &block)
order = {}
arr = []
grouped = {}
for e in enum do
key = block[e]
unless order.include?(key)
order[key] = order.size
end
if not grouped.has_key?(key) then
grouped[key] = [e]
else
grouped[key].push(e)
end
end
grouped.each do |key, vals|
arr[order[key]] = [key, vals]
end
arr
end
*/
template<typename EnumType, typename KeyType, typename KeyFunctorType>
void group_by_to_a(std::vector<EnumType>& enumeration, KeyFunctorType& keyFunc, std::vector<std::pair<KeyType, std::vector<EnumType> > >& arr /*out*/) {
std::map<unsigned int, KeyType> order;
std::map<size_t, std::vector<EnumType> > grouped;
for (typename std::vector<EnumType>::iterator enumIter = enumeration.begin(), enumIterEnd = enumeration.end(); enumIter != enumIterEnd; enumIter++) {
EnumType& e = *enumIter;
KeyType key = keyFunc(e);
if (grouped.find(key->hash()) == grouped.end()) {
order.insert(std::make_pair((unsigned int)order.size(), key));
std::vector<EnumType> newCollection;
newCollection.push_back(e);
grouped.insert(std::make_pair(key->hash(), newCollection));
} else {
std::vector<EnumType>& collection = grouped.at(key->hash());
collection.push_back(e);
}
}
for (unsigned int index = 0; index < order.size(); index++) {
KeyType& key = order.at(index);
std::vector<EnumType>& values = grouped.at(key->hash());
std::pair<KeyType, std::vector<EnumType> > grouping = std::make_pair(key, values);
arr.push_back(grouping);
}
}
}
#endif