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hydrogen-web/prototypes/idb-cmp.html

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<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style type="text/css">
pre {
font-family: "courier";
display: block;
white-space: pre;
}
</style>
</head>
<body>
<script type="text/javascript">
function encodeNumber(n) {
const a = (n & 0xFFFF);
const b = (n & 0xFFFF0000) >> 16;
const c = (n & 0xFFFF00000000) >> 32;
const d = (n & 0xFFFF000000000000) >> 48;
return String.fromCharCode(a, b, c, d);
}
function formatArg(a) {
if (typeof a === "string") {
return `"${a}"`;
}
if (Array.isArray(a)) {
return `[${a.map(formatArg)}]`;
}
return a+"";
}
function cmp(a, b) {
let value;
try {
const result = indexedDB.cmp(encodeNumber(a), encodeNumber(b));
if (result < 0) {
value = "a < b";
} else if (result === 0) {
value = "a = b";
} else if (result > 0) {
value = "a > b";
}
} catch(err) {
value = err.message;
}
return `cmp(${formatArg(a)},\n ${formatArg(b)}): ${value}`;
}
try {
const tests = [
(cmp) => cmp(Number.MIN_SAFE_INTEGER, Number.MAX_SAFE_INTEGER),
(cmp) => cmp([Number.MIN_SAFE_INTEGER], [Number.MAX_SAFE_INTEGER]),
// see https://stackoverflow.com/questions/28413947/space-efficient-way-to-encode-numbers-as-sortable-strings
// need to encode numbers with base 256 and zero padded at start
// should still fit in 8 bytes then?
(cmp) => cmp("foo-9", "foo-10000"),
(cmp) => cmp("foo-\u0000", "foo-\uFFFF"),
(cmp) => cmp("foo-\u0000", "foo-0"),
(cmp) => cmp("foo-" + Number.MAX_SAFE_INTEGER, "foo-\uFFFF"),
(cmp) => cmp("!abc:host.tld,"+Number.MIN_SAFE_INTEGER, "!abc:host.tld,"+(Number.MIN_SAFE_INTEGER + 1)),
(cmp) => cmp("!abc:host.tld,"+0, "!abc:host.tld,"+(Number.MAX_SAFE_INTEGER)),
(cmp) => cmp("!abc:host.tld,"+Math.floor(Number.MAX_SAFE_INTEGER / 2), "!abc:host.tld,"+(Number.MAX_SAFE_INTEGER)),
];
for (const fn of tests) {
const txt = document.createTextNode(fn(cmp));
const p = document.createElement("pre");
p.appendChild(txt);
document.body.appendChild(p);
}
} catch(err) {
alert(err.message);
}
</script>
</body>
</html>