decode.js
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(function (root, factory){
if (typeof define === 'function' && define.amd){ // AMD
define(factory);
} else if (typeof module !== 'undefined' && module.exports) { // Node.js
module.exports = factory();
} else { // Browser
root.decode = factory();
}
})(this, function () {
var keys, values, lengths, dim, e;
var geometryTypes = ['Point', 'MultiPoint', 'LineString', 'MultiLineString',
'Polygon', 'MultiPolygon', 'GeometryCollection'];
function decode(pbf) {
dim = 2;
e = Math.pow(10, 6);
lengths = null;
keys = [];
values = [];
var obj = pbf.readFields(readDataField, {});
keys = null;
return obj;
}
function readDataField(tag, obj, pbf) {
if (tag === 1) keys.push(pbf.readString());
else if (tag === 2) dim = pbf.readVarint();
else if (tag === 3) e = Math.pow(10, pbf.readVarint());
else if (tag === 4) readFeatureCollection(pbf, obj);
else if (tag === 5) readFeature(pbf, obj);
else if (tag === 6) readGeometry(pbf, obj);
}
function readFeatureCollection(pbf, obj) {
obj.type = 'FeatureCollection';
obj.features = [];
return pbf.readMessage(readFeatureCollectionField, obj);
}
function readFeature(pbf, feature) {
feature.type = 'Feature';
return pbf.readMessage(readFeatureField, feature);
}
function readGeometry(pbf, geom) {
return pbf.readMessage(readGeometryField, geom);
}
function readFeatureCollectionField(tag, obj, pbf) {
if (tag === 1) obj.features.push(readFeature(pbf, {}));
else if (tag === 13) values.push(readValue(pbf));
else if (tag === 15) readProps(pbf, obj);
}
function readFeatureField(tag, feature, pbf) {
if (tag === 1) feature.geometry = readGeometry(pbf, {});
else if (tag === 11) feature.id = pbf.readString();
else if (tag === 12) feature.id = pbf.readSVarint();
else if (tag === 13) values.push(readValue(pbf));
else if (tag === 14) feature.properties = readProps(pbf, {});
else if (tag === 15) readProps(pbf, feature);
}
function readGeometryField(tag, geom, pbf) {
if (tag === 1) geom.type = geometryTypes[pbf.readVarint()];
else if (tag === 2) lengths = pbf.readPackedVarint();
else if (tag === 3) readCoords(geom, pbf, geom.type);
else if (tag === 4) {
geom.geometries = geom.geometries || [];
geom.geometries.push(readGeometry(pbf, {}));
}
else if (tag === 13) values.push(readValue(pbf));
else if (tag === 15) readProps(pbf, geom);
}
function readCoords(geom, pbf, type) {
if (type === 'Point') geom.coordinates = readPoint(pbf);
else if (type === 'MultiPoint') geom.coordinates = readLine(pbf, true);
else if (type === 'LineString') geom.coordinates = readLine(pbf);
else if (type === 'MultiLineString') geom.coordinates = readMultiLine(pbf);
else if (type === 'Polygon') geom.coordinates = readMultiLine(pbf, true);
else if (type === 'MultiPolygon') geom.coordinates = readMultiPolygon(pbf);
}
function readValue(pbf) {
var end = pbf.readVarint() + pbf.pos,
value = null;
while (pbf.pos < end) {
var val = pbf.readVarint(),
tag = val >> 3;
if (tag === 1) value = pbf.readString();
else if (tag === 2) value = pbf.readDouble();
else if (tag === 3) value = pbf.readVarint();
else if (tag === 4) value = -pbf.readVarint();
else if (tag === 5) value = pbf.readBoolean();
else if (tag === 6) value = JSON.parse(pbf.readString());
}
return value;
}
function readProps(pbf, props) {
var end = pbf.readVarint() + pbf.pos;
while (pbf.pos < end) props[keys[pbf.readVarint()]] = values[pbf.readVarint()];
values = [];
return props;
}
function readPoint(pbf) {
var end = pbf.readVarint() + pbf.pos,
coords = [];
while (pbf.pos < end) coords.push(pbf.readSVarint() / e);
return coords;
}
function readLinePart(pbf, end, len, closed) {
var i = 0,
coords = [],
p, d;
var prevP = [];
for (d = 0; d < dim; d++) prevP[d] = 0;
while (len ? i < len : pbf.pos < end) {
p = [];
for (d = 0; d < dim; d++) {
prevP[d] += pbf.readSVarint();
p[d] = prevP[d] / e;
}
coords.push(p);
i++;
}
if (closed) coords.push(coords[0]);
return coords;
}
function readLine(pbf) {
return readLinePart(pbf, pbf.readVarint() + pbf.pos);
}
function readMultiLine(pbf, closed) {
var end = pbf.readVarint() + pbf.pos;
if (!lengths) return [readLinePart(pbf, end, null, closed)];
var coords = [];
for (var i = 0; i < lengths.length; i++) coords.push(readLinePart(pbf, end, lengths[i], closed));
lengths = null;
return coords;
}
function readMultiPolygon(pbf) {
var end = pbf.readVarint() + pbf.pos;
if (!lengths) return [[readLinePart(pbf, end, null, true)]];
var coords = [];
var j = 1;
for (var i = 0; i < lengths[0]; i++) {
var rings = [];
for (var k = 0; k < lengths[j]; k++) rings.push(readLinePart(pbf, end, lengths[j + 1 + k], true));
j += lengths[j] + 1;
coords.push(rings);
}
lengths = null;
return coords;
}
return decode;
});