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// Simple caching for constant-radius points.
let cacheDigits, cacheAppend, cacheRadius, cacheCircle;
export default class PathString {
constructor(digits) {
this._append = digits == null ? append : appendRound(digits);
this._radius = 4.5;
this._ = "";
}
pointRadius(_) {
this._radius = +_;
return this;
}
polygonStart() {
this._line = 0;
}
polygonEnd() {
this._line = NaN;
}
lineStart() {
this._point = 0;
}
lineEnd() {
if (this._line === 0) this._ += "Z";
this._point = NaN;
}
point(x, y) {
switch (this._point) {
case 0: {
this._append`M${x},${y}`;
this._point = 1;
break;
}
case 1: {
this._append`L${x},${y}`;
break;
}
default: {
this._append`M${x},${y}`;
if (this._radius !== cacheRadius || this._append !== cacheAppend) {
const r = this._radius;
const s = this._;
this._ = ""; // stash the old string so we can cache the circle path fragment
this._append`m0,${r}a${r},${r} 0 1,1 0,${-2 * r}a${r},${r} 0 1,1 0,${2 * r}z`;
cacheRadius = r;
cacheAppend = this._append;
cacheCircle = this._;
this._ = s;
}
this._ += cacheCircle;
break;
}
}
}
result() {
const result = this._;
this._ = "";
return result.length ? result : null;
}
}
function append(strings) {
let i = 1;
this._ += strings[0];
for (const j = strings.length; i < j; ++i) {
this._ += arguments[i] + strings[i];
}
}
function appendRound(digits) {
const d = Math.floor(digits);
if (!(d >= 0)) throw new RangeError(`invalid digits: ${digits}`);
if (d > 15) return append;
if (d !== cacheDigits) {
const k = 10 ** d;
cacheDigits = d;
cacheAppend = function append(strings) {
let i = 1;
this._ += strings[0];
for (const j = strings.length; i < j; ++i) {
this._ += Math.round(arguments[i] * k) / k + strings[i];
}
};
}
return cacheAppend;
}
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