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<!doctype html>
<title>An+B Serialization</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
foo { color: blue; }
</style>
<meta name="author" title="Tab Atkins-Bittner">
<link rel=help href="https://drafts.csswg.org/css-syntax/#serializing-anb">
<script>
function roundtripANB(str) {
const rule = document.styleSheets[0].cssRules[0];
rule.selectorText = "foo";
rule.selectorText = `:nth-child(${str})`;
// Check for parse error.
if(rule.selectorText == "foo") return "parse error";
return rule.selectorText.slice(11, -1);
}
function testANB(input, expected) {
test(()=>{
assert_equals(roundtripANB(input), expected);
}, `"${input}" becomes "${expected}"`);
}
/* A is 0, or omitted */
testANB("1", "1");
testANB("+1", "1");
testANB("-1", "-1");
testANB("0n + 0", "0");
testANB("0n + 1", "1");
testANB("0n - 1", "-1");
/* A is 1 */
testANB("1n", "n");
testANB("1n - 0", "n");
testANB("1n + 1", "n+1");
testANB("1n - 1", "n-1");
/* A is -1 */
testANB("-1n", "-n");
testANB("-1n - 0", "-n");
testANB("-1n + 1", "-n+1");
testANB("-1n - 1", "-n-1");
/* A is implied via + or - */
testANB("+n+1", "n+1");
testANB("-n-1", "-n-1");
/* B is 0 */
testANB("n + 0", "n");
testANB("n - 0", "n");
/* A & B both nonzero */
testANB("2n + 2", "2n+2");
testANB("-2n - 2", "-2n-2");
</script>
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