140 lines
2.4 KiB
Go
140 lines
2.4 KiB
Go
package jsn
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import (
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"github.com/cespare/xxhash/v2"
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)
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const (
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expectKey int = iota
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expectKeyClose
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expectColon
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expectValue
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expectString
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expectNull
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expectListClose
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expectObjClose
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expectBoolClose
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expectNumClose
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)
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type Field struct {
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Key []byte
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Value []byte
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}
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func Value(b []byte) []byte {
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e := (len(b) - 1)
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switch {
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case b[0] == '"' && b[e] == '"':
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return b[1:(len(b) - 1)]
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case b[0] == '[' && b[e] == ']':
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return nil
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case b[0] == '{' && b[e] == '}':
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return nil
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default:
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return b
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}
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}
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func Get(b []byte, keys [][]byte) []Field {
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kmap := make(map[uint64]struct{}, len(keys))
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for i := range keys {
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kmap[xxhash.Sum64(keys[i])] = struct{}{}
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}
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res := make([]Field, 0, 20)
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s, e, d := 0, 0, 0
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var k []byte
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state := expectKey
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n := 0
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for i := 0; i < len(b); i++ {
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if state == expectObjClose || state == expectListClose {
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switch b[i] {
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case '{', '[':
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d++
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case '}', ']':
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d--
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}
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}
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switch {
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case state == expectKey && b[i] == '"':
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state = expectKeyClose
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s = i
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case state == expectKeyClose && b[i] == '"':
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state = expectColon
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k = b[(s + 1):i]
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case state == expectColon && b[i] == ':':
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state = expectValue
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case state == expectValue && b[i] == '"':
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state = expectString
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s = i
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case state == expectString && b[i] == '"':
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e = i
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case state == expectValue && b[i] == '[':
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state = expectListClose
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s = i
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d++
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case state == expectListClose && d == 0 && b[i] == ']':
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e = i
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i = s
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case state == expectValue && b[i] == '{':
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state = expectObjClose
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s = i
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d++
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case state == expectObjClose && d == 0 && b[i] == '}':
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e = i
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i = s
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case state == expectValue && (b[i] >= '0' && b[i] <= '9'):
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state = expectNumClose
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s = i
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case state == expectNumClose &&
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((b[i] < '0' || b[i] > '9') &&
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(b[i] != '.' && b[i] != 'e' && b[i] != 'E' && b[i] != '+' && b[i] != '-')):
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e = i - 1
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case state == expectValue &&
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(b[i] == 'f' || b[i] == 'F' || b[i] == 't' || b[i] == 'T'):
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state = expectBoolClose
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s = i
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case state == expectBoolClose && (b[i] == 'e' || b[i] == 'E'):
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e = i
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case state == expectValue && b[i] == 'n':
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state = expectNull
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case state == expectNull && b[i] == 'l':
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e = i
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}
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if e != 0 {
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_, ok := kmap[xxhash.Sum64(k)]
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if ok {
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res = append(res, Field{k, b[s:(e + 1)]})
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n++
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}
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state = expectKey
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e = 0
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}
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}
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return res[:n]
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}
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