6257ddba78
The big change is that the GeoJSON package has been completely rewritten to fix a few of geometry calculation bugs, increase performance, and to better follow the GeoJSON spec RFC 7946. GeoJSON updates - A LineString now requires at least two points. - All json members, even foreign, now persist with the object. - The bbox member persists too but is no longer used for geometry calculations. This is change in behavior. Previously Tile38 would treat the bbox as the object's physical rectangle. - Corrections to geometry intersects and within calculations. Faster spatial queries - The performance of Point-in-polygon and object intersect operations are greatly improved for complex polygons and line strings. It went from O(n) to roughly O(log n). - The same for all collection types with many children, including FeatureCollection, GeometryCollection, MultiPoint, MultiLineString, and MultiPolygon. Codebase changes - The pkg directory has been renamed to internal - The GeoJSON internal package has been moved to a seperate repo at https://github.com/tidwall/geojson. It's now vendored. Please look out for higher memory usage for datasets using complex shapes. A complex shape is one that has 64 or more points. For these shapes it's expected that there will be increase of least 54 bytes per point.
45 lines
1.0 KiB
Go
45 lines
1.0 KiB
Go
package geohash
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// encoding encapsulates an encoding defined by a given base32 alphabet.
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type encoding struct {
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encode string
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decode [256]byte
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}
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// newEncoding constructs a new encoding defined by the given alphabet,
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// which must be a 32-byte string.
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func newEncoding(encoder string) *encoding {
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e := new(encoding)
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e.encode = encoder
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for i := 0; i < len(e.decode); i++ {
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e.decode[i] = 0xff
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}
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for i := 0; i < len(encoder); i++ {
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e.decode[encoder[i]] = byte(i)
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}
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return e
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}
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// Decode string into bits of a 64-bit word. The string s may be at most 12
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// characters.
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func (e *encoding) Decode(s string) uint64 {
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x := uint64(0)
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for i := 0; i < len(s); i++ {
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x = (x << 5) | uint64(e.decode[s[i]])
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}
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return x
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}
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// Encode bits of 64-bit word into a string.
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func (e *encoding) Encode(x uint64) string {
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b := [12]byte{}
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for i := 0; i < 12; i++ {
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b[11-i] = e.encode[x&0x1f]
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x >>= 5
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}
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return string(b[:])
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}
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// Base32Encoding with the Geohash alphabet.
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var base32encoding = newEncoding("0123456789bcdefghjkmnpqrstuvwxyz")
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