08b131c5ee
Performance is comparable to sting.ToLower BenchmarkSnakeCase-4 200000 5922 ns/op 1216 B/op 97 allocs/op BenchmarkToLower-4 300000 5418 ns/op 704 B/op 74 allocs/op
41 lines
960 B
Go
41 lines
960 B
Go
package gocqlx
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import (
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"fmt"
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"unicode"
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"github.com/jmoiron/sqlx/reflectx"
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)
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// DefaultMapper uses `db` tag and automatically converts struct field names to
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// snake case. It can be set to whatever you want, but it is encouraged to be
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// set before gocqlx is used as name-to-field mappings are cached after first
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// use on a type.
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var DefaultMapper = reflectx.NewMapperFunc("db", snakeCase)
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// snakeCase converts camel case to snake case.
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func snakeCase(s string) string {
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buf := []byte(s)
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out := make([]byte, 0, len(buf)+3)
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l := len(buf)
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for i := 0; i < l; i++ {
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if !(allowedBindRune(buf[i]) || buf[i] == '_') {
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panic(fmt.Sprint("not allowed name ", s))
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}
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b := rune(buf[i])
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if unicode.IsUpper(b) {
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if i > 0 && buf[i-1] != '_' && (unicode.IsLower(rune(buf[i-1])) || (i+1 < l && unicode.IsLower(rune(buf[i+1])))) {
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out = append(out, '_')
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}
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b = unicode.ToLower(b)
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}
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out = append(out, byte(b))
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}
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return string(out)
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}
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