mirror of
https://github.com/MontFerret/ferret.git
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1af8b37a0f
* New type system * Fixed dot notation for HTML elements
57 lines
1.6 KiB
Go
57 lines
1.6 KiB
Go
package strings
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import (
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"context"
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"math/rand"
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"time"
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"github.com/MontFerret/ferret/pkg/runtime/core"
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"github.com/MontFerret/ferret/pkg/runtime/values"
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"github.com/MontFerret/ferret/pkg/runtime/values/types"
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)
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const (
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letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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letterIdxBits = 6 // 6 bits to represent a letter index
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letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
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letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
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)
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// RandomToken generates a pseudo-random token string with the specified length. The algorithm for token generation should be treated as opaque.
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// @param length (Int) - The desired string length for the token. It must be greater than 0 and at most 65536.
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// @return (String) - A generated token consisting of lowercase letters, uppercase letters and numbers.
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func RandomToken(_ context.Context, args ...core.Value) (core.Value, error) {
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err := core.ValidateArgs(args, 1, 1)
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if err != nil {
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return values.EmptyString, err
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}
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err = core.ValidateType(args[0], types.Int)
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if err != nil {
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return values.EmptyString, err
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}
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size := args[0].(values.Int)
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randSrc := rand.NewSource(time.Now().UnixNano())
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b := make([]byte, size)
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for i, cache, remain := size-1, randSrc.Int63(), letterIdxMax; i >= 0; {
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if remain == 0 {
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cache, remain = randSrc.Int63(), letterIdxMax
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}
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if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
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b[i] = letterBytes[idx]
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i--
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}
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cache >>= letterIdxBits
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remain--
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}
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return values.NewString(string(b)), nil
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}
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