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Bilawal SidhuandKuraPiee
cca6442997
Supersedes #388 by @KuraPiee, ported onto the current component layout with fixes from review. Verified before merge: format, package boundaries, unit suite, build, and the browser tracking suite; a browser harness for the change where one applies; adversarial review applied. Co-authored-by: KuraPiee <[email protected]>
101 lines
3.8 KiB
JavaScript
101 lines
3.8 KiB
JavaScript
/**
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* Strict decimal-degree coordinate parsing for the search box.
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*
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* A search that guesses is worse than one that declines: reading `12junk, 34oops`
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* as 12, 34 flies the operator somewhere they did not ask for and looks like a
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* successful search. So every rule here is exact — a component is a decimal
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* number, optionally signed, optionally marked with one hemisphere letter, and
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* nothing else. Degrees/minutes/seconds and grid references are not handled;
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* they fall through to the geocoders, which is what happens today.
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*/
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/** One decimal-degree component: an optional hemisphere letter on either side. */
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const COMPONENT =
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/^([NSEW])?\s*([+-]?(?:\d+(?:\.\d+)?|\.\d+))\s*°?\s*([NSEW])?$/i;
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/** Hemisphere letters, by the axis each one can name. */
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const LATITUDE_LETTERS = new Set(['N', 'S']);
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/**
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* Read one component into a signed value plus the axis its letter names.
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*
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* @param {string} text
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* @returns {{ value: number, axis: 'lat'|'lon'|null } | null}
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*/
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function readComponent(text) {
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const match = COMPONENT.exec(String(text).trim());
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if (!match) return null;
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const [, before, digits, after] = match;
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// Two letters on one component is a contradiction, not a coordinate.
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if (before && after) return null;
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const letter = (before || after || '').toUpperCase();
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const value = Number(digits);
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if (!Number.isFinite(value)) return null;
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// A sign and a hemisphere letter both claim the direction; "-40N" means
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// neither one thing nor the other, so it is refused rather than guessed.
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if (letter && /^[+-]/.test(digits)) return null;
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if (!letter) return { value, axis: null };
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const magnitude = Math.abs(value);
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return {
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value: letter === 'S' || letter === 'W' ? -magnitude : magnitude,
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axis: LATITUDE_LETTERS.has(letter) ? 'lat' : 'lon',
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};
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}
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/** Split on a comma, a semicolon, or whitespace — never on anything else. */
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function splitComponents(query) {
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const text = String(query).trim();
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if (!text) return null;
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const parts = /[,;]/.test(text)
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? text.split(/[,;]/)
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: text.split(/\s+(?=[+-]?[.\d]|[NSEW]\s*[+-]?[.\d])/i);
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const trimmed = parts.map((part) => part.trim()).filter(Boolean);
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return trimmed.length === 2 ? trimmed : null;
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}
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/** Present a parsed pair the way a coordinate is normally written. */
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export function formatCoordinateLabel(lat, lon) {
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const latLetter = lat >= 0 ? 'N' : 'S';
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const lonLetter = lon >= 0 ? 'E' : 'W';
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return `${Math.abs(lat).toFixed(4)}° ${latLetter}, ${Math.abs(lon).toFixed(4)}° ${lonLetter}`;
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}
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/**
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* Parse a decimal-degree query, or return null.
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*
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* Both orders are accepted when the hemisphere letters say which is which
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* (`W 40, N 74` is longitude then latitude); with no letters the conventional
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* latitude-then-longitude order applies. Two letters naming the same axis, a
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* letter that fixes nothing, an out-of-range latitude or longitude, and any
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* trailing text all decline.
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*
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* @param {string} query
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* @returns {{ lat: number, lon: number, label: string } | null}
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*/
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export function parseCoordinateQuery(query) {
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if (typeof query !== 'string') return null;
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const parts = splitComponents(query);
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if (!parts) return null;
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const first = readComponent(parts[0]);
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const second = readComponent(parts[1]);
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if (!first || !second) return null;
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// Both components naming the same axis leaves the other one unstated.
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if (first.axis && first.axis === second.axis) return null;
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let lat;
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let lon;
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if (first.axis === 'lon' || second.axis === 'lat') {
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lat = second.value;
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lon = first.value;
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} else {
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lat = first.value;
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lon = second.value;
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}
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if (!Number.isFinite(lat) || !Number.isFinite(lon)) return null;
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if (lat < -90 || lat > 90) return null;
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if (lon < -180 || lon > 180) return null;
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return { lat, lon, label: formatCoordinateLabel(lat, lon) };
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}
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