109 lines
2.8 KiB
Go
109 lines
2.8 KiB
Go
package errors
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import (
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"errors"
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"reflect"
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_ "unsafe"
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"codeberg.org/gruf/go-bitutil"
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)
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// Is reports whether any error in err's chain matches any of targets
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// (up to a max of 64 targets).
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//
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// The chain consists of err itself followed by the sequence of errors obtained by
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// repeatedly calling Unwrap.
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//
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// An error is considered to match a target if it is equal to that target or if
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// it implements a method Is(error) bool such that Is(target) returns true.
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func Is(err error, targets ...error) bool {
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var flags bitutil.Flags64
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// Flags only has 64 bit-slots
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if len(targets) > 64 {
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panic("too many targets")
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}
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// Check if error is nil so we can catch
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// the fast-case where a target is nil
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isNil := (err == nil)
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for i := 0; i < len(targets); {
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// Drop nil targets
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if targets[i] == nil {
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if isNil /* match! */ {
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return true
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}
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targets = append(targets[:i], targets[i+1:]...)
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continue
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}
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// Check if this error is directly comparable
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if reflect.TypeOf(targets[i]).Comparable() {
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flags = flags.Set(uint8(i))
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}
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i++
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}
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for err != nil {
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// Check if this layer supports .Is interface
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is, ok := err.(interface{ Is(error) bool })
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if !ok {
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// Error does not support interface
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//
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// Only try perform direct compare
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for i := 0; i < len(targets); i++ {
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// Try directly compare errors
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if flags.Get(uint8(i)) &&
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err == targets[i] {
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return true
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}
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}
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} else {
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// Error supports the .Is interface
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//
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// Perform direct compare AND .Is()
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for i := 0; i < len(targets); i++ {
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if (flags.Get(uint8(i)) &&
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err == targets[i]) ||
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is.Is(targets[i]) {
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return true
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}
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}
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}
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// Unwrap to next layer
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err = errors.Unwrap(err)
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}
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return false
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}
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// As finds the first error in err's chain that matches target, and if one is found, sets
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// target to that error value and returns true. Otherwise, it returns false.
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//
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// The chain consists of err itself followed by the sequence of errors obtained by
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// repeatedly calling Unwrap.
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//
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// An error matches target if the error's concrete value is assignable to the value
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// pointed to by target, or if the error has a method As(interface{}) bool such that
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// As(target) returns true. In the latter case, the As method is responsible for
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// setting target.
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//
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// An error type might provide an As method so it can be treated as if it were a
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// different error type.
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//
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// As panics if target is not a non-nil pointer to either a type that implements
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// error, or to any interface type.
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//
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//go:linkname As errors.As
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func As(err error, target interface{}) bool
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// Unwrap returns the result of calling the Unwrap method on err, if err's
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// type contains an Unwrap method returning error. Otherwise, Unwrap returns nil.
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//
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//go:linkname Unwrap errors.Unwrap
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func Unwrap(err error) error
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