Generalized loops to iterate all combinations and permutations

CombinationsAndPermutations.js

//
// call initRowPerms( [], /* number of columns to permutate */, /* number from */, /*number to */ )
//
//----------------------------------------------------------------------------
//  generate combinations to a callback
//----------------------------------------------------------------------------

function getCombinations(cb, cols, from, to) {
	var indexes = [];
	for (var n = 0; n < cols; n++) indexes.push(from);
	var curIndex = cols - 1;
	var comb = new Array(cols);

	do {
		for (var n = 0; n < cols; n++) comb[n] = indexes[n];

		if (!cb(comb)) return;

		do {
			indexes[curIndex]++;
			if (indexes[curIndex] > to) {
				indexes[curIndex] = from;
				curIndex--;
				if (curIndex < 0) return;
				continue;
			}
			curIndex = indexes.length - 1;
			break;
		} while (1);
	} while (1);
}

// demonstrate usage of getCombinations
// call generator with a callback that saves output for test code below.

function runCombinationGenerator(output, cols, from, to) {
	function saveOutput(val) {
		output.push(val);
		return true; // allow continue.  ( similar to [].find() )
	}
	getCombinations(saveOutput, cols, from, to);
}

//----------------------------------------------------------------------------
//  generator method.
//----------------------------------------------------------------------------

function* genCombinations(cols, from, to) {
	var indexes = [];
	for (var n = 0; n < cols; n++) indexes.push(from);
	var curIndex = cols - 1;
	var comb = new Array(cols);

	do {
		for (var n = 0; n < cols; n++) comb[n] = indexes[n];

		yield comb;

		do {
			indexes[curIndex]++;
			if (indexes[curIndex] > to) {
				indexes[curIndex] = from;
				curIndex--;
				if (curIndex < 0) return;
				continue;
			}
			curIndex = indexes.length - 1;
			break;
		} while (1);
	} while (1);
}

// demonstrate usage of genCombinations (generator)
// call generator with a callback that saves output for test code below.

function runCombinations(output, cols, from, to) {
	var iter = genCombinations(cols, from, to);
	var next;
	while ((next = iter.next()).value) {
		output.push(next.value);
	}
}

//----------------------------------------------
// BEGIN Test code.....
//----------------------------------------------

var comb = [];

runCombinations(comb, 4, 1, 9);
console.log("combination length 4 of 1-9 elements %d total", comb.length);

console.log(JSON.stringify(comb));

//----------------------------------------------
// END Test code.....
//----------------------------------------------

//----------------------------------------------------------------------------
//  generator method.
//----------------------------------------------------------------------------

// utility function to test if duplicate is in array.
function findPair(array, a, b, cols) {
	//console.log( "find:", a, b, cols );
	if (a == b) return findPair(array, a, b + 1, cols);
	if (b >= cols) {
		if (a < cols - 1) return findPair(array, a + 1, 0, cols);
		return false;
	}
	if (array[a] == array[b]) return true;

	if (b + 1 != a) return findPair(array, a, b + 1, cols);
	else return findPair(array, a, b + 2, cols);
}

function* genPermutations(cols, range) {
	var indexes = [];
	for (var n = 0; n < cols; n++) indexes.push(0);
	var curIndex = cols - 1;
	var perm = new Array(cols);
	do {
		if (!findPair(indexes, 0, 1, cols, range)) {
			for (var p = 0; p < cols; p++) perm[p] = indexes[p];
			yield perm;
		}

		do {
			indexes[curIndex]++;
			if (indexes[curIndex] == range) {
				indexes[curIndex] = 0;
				curIndex--;
				if (curIndex < 0) return;
				continue;
			}
			curIndex = indexes.length - 1;
			break;
		} while (1);
	} while (1);
}

// demonstrate usage of getCombinations (generator)
// call generator with a callback that saves output for test code below.

function runPermutationGenerator(output, cols, range) {
	var iter = genPermutations(cols, range);
	var next;
	while ((next = iter.next()).value) {
		output.push(next.value);
	}
}

//----------------------------------------------------------------------------
//  generate combinations to a callback
//----------------------------------------------------------------------------

function getPermutations(cb, cols, range) {
	var indexes = [];
	for (var n = 0; n < cols; n++) indexes.push(0);
	var curIndex = cols - 1;

	var perm = new Array(cols);
	do {
		if (!findPair(indexes, 0, 1, cols, range)) {
			for (var p = 0; p < cols; p++) perm[p] = indexes[p];
			cb(perm);
		}

		do {
			indexes[curIndex]++;
			if (indexes[curIndex] == range) {
				indexes[curIndex] = 0;
				curIndex--;
				if (curIndex < 0) return;
				continue;
			}
			curIndex = indexes.length - 1;
			break;
		} while (1);
	} while (1);
}

// demonstrate usage of getPerms
// call generator with a callback that saves output for test code below.

function runPermutations(output, cols, range) {
	function saveOutput(val) {
		output.push(val);
		return true; // allow continue.  ( similar to [].find() )
	}
	getPermutations(saveOutput, cols, range);
}

//----------------------------------------------------------------------------
//  generator method.
//----------------------------------------------------------------------------

// call initPerms( [], 5 ) ; // permuatations of 0-4
function initPerms(output, cols, range) {
	var indexes = [];
	for (var n = 0; n < cols; n++) indexes.push(0);
	var curIndex = cols - 1;

	do {
		if (!findPair(indexes, 0, 1, cols, range)) {
			var perm = indexes.map(v => v);
			output.push(perm);
		}

		do {
			indexes[curIndex]++;
			if (indexes[curIndex] == range) {
				indexes[curIndex] = 0;
				curIndex--;
				if (curIndex < 0) return;
				continue;
			}
			curIndex = indexes.length - 1;
			break;
		} while (1);
	} while (1);
}

//-----------------------
// BEGIN TEST CODE
//-----------------------

var perms = [];
initPerms(perms, 4, 9);
console.log("permutation length 4 of 9 elements %d total", perms.length);

perms = [];
runPermutationGenerator(perms, 4, 9);
console.log("permutation length 4 of 9 elements %d total", perms.length);

perms = [];
runPermutations(perms, 4, 9);
console.log("permutation length 4 of 9 elements %d total", perms.length);

console.log(JSON.stringify(perms));

//-----------------------
// END TEST CODE
//-----------------------