Document.movePositionBytes

import std.regex;

auto intRegex = regex(`\bint\b`);

Document d;
d.setContent("int foo(int x, uint y)\n{\n    return cast(int)(x + y);\n}\n");

// either use size_t.max or 0, both work as starting points for different reasons:
// - 0 always matches Position.init, so the offset can be calculated
// - size_t.max is larger than the checked index match, so position is recomputed
size_t lastIndex = size_t.max;
Position lastPosition;

Position[] matches;

foreach (match; d.rawText.matchAll(intRegex))
{
	size_t index = match.pre.length;
	// to reduce boilerplate, use d.nextPositionBytes instead!
	auto pos = d.movePositionBytes(lastPosition, lastIndex, index);
	lastIndex = index;
	lastPosition = pos;
	matches ~= pos;
}

assert(matches == [
	Position(0, 0),
	Position(0, 8),
	Position(2, 16)
]);