124 lines
3.7 KiB
Go
124 lines
3.7 KiB
Go
package addrs
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import (
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"fmt"
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"github.com/zclconf/go-cty/cty"
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"github.com/zclconf/go-cty/cty/gocty"
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)
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// InstanceKey represents the key of an instance within an object that
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// contains multiple instances due to using "count" or "for_each" arguments
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// in configuration.
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//
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// IntKey and StringKey are the two implementations of this type. No other
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// implementations are allowed. The single instance of an object that _isn't_
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// using "count" or "for_each" is represented by NoKey, which is a nil
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// InstanceKey.
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type InstanceKey interface {
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instanceKeySigil()
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String() string
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}
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// ParseInstanceKey returns the instance key corresponding to the given value,
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// which must be known and non-null.
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//
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// If an unknown or null value is provided then this function will panic. This
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// function is intended to deal with the values that would naturally be found
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// in a hcl.TraverseIndex, which (when parsed from source, at least) can never
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// contain unknown or null values.
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func ParseInstanceKey(key cty.Value) (InstanceKey, error) {
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switch key.Type() {
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case cty.String:
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return StringKey(key.AsString()), nil
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case cty.Number:
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var idx int
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err := gocty.FromCtyValue(key, &idx)
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return IntKey(idx), err
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default:
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return NoKey, fmt.Errorf("either a string or an integer is required")
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}
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}
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// NoKey represents the absense of an InstanceKey, for the single instance
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// of a configuration object that does not use "count" or "for_each" at all.
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var NoKey InstanceKey
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// IntKey is the InstanceKey representation representing integer indices, as
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// used when the "count" argument is specified or if for_each is used with
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// a sequence type.
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type IntKey int
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func (k IntKey) instanceKeySigil() {
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}
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func (k IntKey) String() string {
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return fmt.Sprintf("[%d]", int(k))
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}
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// StringKey is the InstanceKey representation representing string indices, as
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// used when the "for_each" argument is specified with a map or object type.
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type StringKey string
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func (k StringKey) instanceKeySigil() {
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}
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func (k StringKey) String() string {
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// FIXME: This isn't _quite_ right because Go's quoted string syntax is
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// slightly different than HCL's, but we'll accept it for now.
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return fmt.Sprintf("[%q]", string(k))
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}
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// InstanceKeyLess returns true if the first given instance key i should sort
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// before the second key j, and false otherwise.
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func InstanceKeyLess(i, j InstanceKey) bool {
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iTy := instanceKeyType(i)
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jTy := instanceKeyType(j)
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switch {
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case i == j:
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return false
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case i == NoKey:
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return true
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case j == NoKey:
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return false
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case iTy != jTy:
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// The ordering here is arbitrary except that we want NoKeyType
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// to sort before the others, so we'll just use the enum values
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// of InstanceKeyType here (where NoKey is zero, sorting before
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// any other).
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return uint32(iTy) < uint32(jTy)
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case iTy == IntKeyType:
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return int(i.(IntKey)) < int(j.(IntKey))
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case iTy == StringKeyType:
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return string(i.(StringKey)) < string(j.(StringKey))
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default:
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// Shouldn't be possible to get down here in practice, since the
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// above is exhaustive.
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return false
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}
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}
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func instanceKeyType(k InstanceKey) InstanceKeyType {
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if _, ok := k.(StringKey); ok {
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return StringKeyType
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}
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if _, ok := k.(IntKey); ok {
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return IntKeyType
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}
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return NoKeyType
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}
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// InstanceKeyType represents the different types of instance key that are
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// supported. Usually it is sufficient to simply type-assert an InstanceKey
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// value to either IntKey or StringKey, but this type and its values can be
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// used to represent the types themselves, rather than specific values
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// of those types.
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type InstanceKeyType rune
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const (
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NoKeyType InstanceKeyType = 0
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IntKeyType InstanceKeyType = 'I'
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StringKeyType InstanceKeyType = 'S'
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)
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