395 lines
11 KiB
Go
395 lines
11 KiB
Go
package funcs
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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/convert"
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"github.com/zclconf/go-cty/cty/function"
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"github.com/zclconf/go-cty/cty/function/stdlib"
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"github.com/zclconf/go-cty/cty/gocty"
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)
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var ElementFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "list",
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Type: cty.DynamicPseudoType,
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},
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{
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Name: "index",
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Type: cty.Number,
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},
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},
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Type: func(args []cty.Value) (cty.Type, error) {
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list := args[0]
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listTy := list.Type()
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switch {
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case listTy.IsListType():
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return listTy.ElementType(), nil
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case listTy.IsTupleType():
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etys := listTy.TupleElementTypes()
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var index int
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err := gocty.FromCtyValue(args[1], &index)
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if err != nil {
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// e.g. fractional number where whole number is required
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return cty.DynamicPseudoType, fmt.Errorf("invalid index: %s", err)
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}
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if len(etys) == 0 {
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return cty.DynamicPseudoType, fmt.Errorf("cannot use element function with an empty list")
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}
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index = index % len(etys)
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return etys[index], nil
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default:
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return cty.DynamicPseudoType, fmt.Errorf("cannot read elements from %s", listTy.FriendlyName())
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}
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},
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Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
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var index int
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err := gocty.FromCtyValue(args[1], &index)
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if err != nil {
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// can't happen because we checked this in the Type function above
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return cty.DynamicVal, fmt.Errorf("invalid index: %s", err)
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}
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l := args[0].LengthInt()
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if l == 0 {
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return cty.DynamicVal, fmt.Errorf("cannot use element function with an empty list")
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}
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index = index % l
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// We did all the necessary type checks in the type function above,
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// so this is guaranteed not to fail.
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return args[0].Index(cty.NumberIntVal(int64(index))), nil
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},
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})
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var LengthFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "value",
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Type: cty.DynamicPseudoType,
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AllowDynamicType: true,
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AllowUnknown: true,
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},
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},
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Type: func(args []cty.Value) (cty.Type, error) {
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collTy := args[0].Type()
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switch {
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case collTy == cty.String || collTy.IsTupleType() || collTy.IsListType() || collTy.IsMapType() || collTy.IsSetType() || collTy == cty.DynamicPseudoType:
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return cty.Number, nil
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default:
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return cty.Number, fmt.Errorf("argument must be a string, a collection type, or a structural type")
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}
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},
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Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
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coll := args[0]
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collTy := args[0].Type()
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switch {
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case collTy == cty.DynamicPseudoType:
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return cty.UnknownVal(cty.Number), nil
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case collTy.IsTupleType():
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l := len(collTy.TupleElementTypes())
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return cty.NumberIntVal(int64(l)), nil
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case collTy.IsObjectType():
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l := len(collTy.AttributeTypes())
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return cty.NumberIntVal(int64(l)), nil
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case collTy == cty.String:
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// We'll delegate to the cty stdlib strlen function here, because
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// it deals with all of the complexities of tokenizing unicode
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// grapheme clusters.
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return stdlib.Strlen(coll)
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case collTy.IsListType() || collTy.IsSetType() || collTy.IsMapType():
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return coll.Length(), nil
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default:
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// Should never happen, because of the checks in our Type func above
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return cty.UnknownVal(cty.Number), fmt.Errorf("impossible value type for length(...)")
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}
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},
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})
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// CoalesceListFunc contructs a function that takes any number of list arguments
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// and returns the first one that isn't empty.
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var CoalesceListFunc = function.New(&function.Spec{
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Params: []function.Parameter{},
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VarParam: &function.Parameter{
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Name: "vals",
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Type: cty.List(cty.DynamicPseudoType),
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AllowUnknown: true,
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AllowDynamicType: true,
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AllowNull: true,
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},
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Type: func(args []cty.Value) (ret cty.Type, err error) {
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if len(args) == 0 {
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return cty.NilType, fmt.Errorf("at least one argument is required")
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}
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argTypes := make([]cty.Type, len(args))
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for i, arg := range args {
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argTypes[i] = arg.Type()
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}
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retType, _ := convert.UnifyUnsafe(argTypes)
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if retType == cty.NilType {
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return cty.NilType, fmt.Errorf("all arguments must have the same type")
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}
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return retType, nil
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},
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Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
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vals := make([]cty.Value, 0, len(args))
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for _, arg := range args {
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// We already know this will succeed because of the checks in our Type func above
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arg, _ = convert.Convert(arg, retType)
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it := arg.ElementIterator()
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for it.Next() {
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_, v := it.Element()
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vals = append(vals, v)
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}
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if len(vals) > 0 {
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return cty.ListVal(vals), nil
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}
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}
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return cty.NilVal, fmt.Errorf("no non-null arguments")
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},
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})
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// CompactFunc contructs a function that takes a list of strings and returns a new list
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// with any empty string elements removed.
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var CompactFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "list",
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Type: cty.List(cty.String),
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},
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},
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Type: function.StaticReturnType(cty.List(cty.String)),
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Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
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var outputList []cty.Value
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for it := args[0].ElementIterator(); it.Next(); {
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_, v := it.Element()
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if v.AsString() == "" {
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continue
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}
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outputList = append(outputList, v)
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}
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if len(outputList) == 0 {
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return cty.ListValEmpty(cty.String), nil
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}
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return cty.ListVal(outputList), nil
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},
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})
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// ContainsFunc contructs a function that determines whether a given list contains
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// a given single value as one of its elements.
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var ContainsFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "list",
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Type: cty.List(cty.DynamicPseudoType),
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},
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{
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Name: "value",
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Type: cty.DynamicPseudoType,
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},
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},
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Type: function.StaticReturnType(cty.Bool),
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Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
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_, err = Index(args[0], args[1])
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if err != nil {
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return cty.False, nil
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}
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return cty.True, nil
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},
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})
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// IndexFunc contructs a function that finds the element index for a given value in a list.
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var IndexFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "list",
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Type: cty.DynamicPseudoType,
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},
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{
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Name: "value",
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Type: cty.DynamicPseudoType,
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},
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},
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Type: function.StaticReturnType(cty.Number),
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Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
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if !(args[0].Type().IsListType() || args[0].Type().IsTupleType()) {
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return cty.NilVal, fmt.Errorf("argument must be a list or tuple")
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}
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if args[0].LengthInt() == 0 { // Easy path
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return cty.NilVal, fmt.Errorf("Cannot search an empty list")
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}
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for it := args[0].ElementIterator(); it.Next(); {
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i, v := it.Element()
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eq, err := stdlib.Equal(v, args[1])
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if err != nil {
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return cty.NilVal, err
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}
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if !eq.IsKnown() {
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return cty.UnknownVal(cty.Number), nil
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}
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if eq.True() {
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return i, nil
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}
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}
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return cty.NilVal, fmt.Errorf("item not found")
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},
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})
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// DistinctFunc contructs a function that takes a list and returns a new list
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// with any duplicate elements removed.
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var DistinctFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "list",
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Type: cty.List(cty.DynamicPseudoType),
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},
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},
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Type: function.StaticReturnType(cty.List(cty.DynamicPseudoType)),
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Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
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var list []cty.Value
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for it := args[0].ElementIterator(); it.Next(); {
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_, v := it.Element()
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list, err = appendIfMissing(list, v)
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if err != nil {
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return cty.NilVal, err
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}
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}
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return cty.ListVal(list), nil
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},
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})
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// ChunklistFunc contructs a function that splits a single list into fixed-size chunks,
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// returning a list of lists.
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var ChunklistFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "list",
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Type: cty.List(cty.DynamicPseudoType),
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},
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{
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Name: "size",
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Type: cty.Number,
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},
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},
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Type: func(args []cty.Value) (cty.Type, error) {
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return cty.List(args[0].Type()), nil
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},
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Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
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var size int
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err = gocty.FromCtyValue(args[1], &size)
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if err != nil {
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return cty.NilVal, fmt.Errorf("invalid index: %s", err)
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}
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if size < 0 {
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return cty.NilVal, fmt.Errorf("The size argument must be positive")
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}
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output := make([]cty.Value, 0)
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// if size is 0, returns a list made of the initial list
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if size == 0 {
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output = append(output, args[0])
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return cty.ListVal(output), nil
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}
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chunk := make([]cty.Value, 0)
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l := args[0].LengthInt()
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i := 0
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for it := args[0].ElementIterator(); it.Next(); {
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_, v := it.Element()
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chunk = append(chunk, v)
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// Chunk when index isn't 0, or when reaching the values's length
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if (i+1)%size == 0 || (i+1) == l {
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output = append(output, cty.ListVal(chunk))
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chunk = make([]cty.Value, 0)
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}
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i++
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}
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return cty.ListVal(output), nil
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},
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})
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// helper function to add an element to a list, if it does not already exsit
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func appendIfMissing(slice []cty.Value, element cty.Value) ([]cty.Value, error) {
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for _, ele := range slice {
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eq, err := stdlib.Equal(ele, element)
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if err != nil {
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return slice, err
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}
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if eq.True() {
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return slice, nil
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}
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}
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return append(slice, element), nil
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}
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// Element returns a single element from a given list at the given index. If
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// index is greater than the length of the list then it is wrapped modulo
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// the list length.
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func Element(list, index cty.Value) (cty.Value, error) {
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return ElementFunc.Call([]cty.Value{list, index})
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}
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// Length returns the number of elements in the given collection or number of
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// Unicode characters in the given string.
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func Length(collection cty.Value) (cty.Value, error) {
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return LengthFunc.Call([]cty.Value{collection})
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}
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// CoalesceList takes any number of list arguments and returns the first one that isn't empty.
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func CoalesceList(args ...cty.Value) (cty.Value, error) {
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return CoalesceListFunc.Call(args)
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}
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// Compact takes a list of strings and returns a new list
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// with any empty string elements removed.
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func Compact(list cty.Value) (cty.Value, error) {
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return CompactFunc.Call([]cty.Value{list})
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}
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// Contains determines whether a given list contains a given single value
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// as one of its elements.
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func Contains(list, value cty.Value) (cty.Value, error) {
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return ContainsFunc.Call([]cty.Value{list, value})
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}
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// Index finds the element index for a given value in a list.
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func Index(list, value cty.Value) (cty.Value, error) {
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return IndexFunc.Call([]cty.Value{list, value})
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}
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// Distinct takes a list and returns a new list with any duplicate elements removed.
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func Distinct(list cty.Value) (cty.Value, error) {
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return DistinctFunc.Call([]cty.Value{list})
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}
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// Chunklist splits a single list into fixed-size chunks, returning a list of lists.
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func Chunklist(list, size cty.Value) (cty.Value, error) {
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return ChunklistFunc.Call([]cty.Value{list, size})
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}
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