148 lines
3.6 KiB
Go
148 lines
3.6 KiB
Go
package hcl
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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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)
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// Index is a helper function that performs the same operation as the index
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// operator in the zcl expression language. That is, the result is the
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// same as it would be for collection[key] in a configuration expression.
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//
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// This is exported so that applications can perform indexing in a manner
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// consistent with how the language does it, including handling of null and
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// unknown values, etc.
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//
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// Diagnostics are produced if the given combination of values is not valid.
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// Therefore a pointer to a source range must be provided to use in diagnostics,
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// though nil can be provided if the calling application is going to
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// ignore the subject of the returned diagnostics anyway.
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func Index(collection, key cty.Value, srcRange *Range) (cty.Value, Diagnostics) {
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if collection.IsNull() {
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Attempt to index null value",
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Detail: "This value is null, so it does not have any indices.",
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Subject: srcRange,
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},
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}
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}
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if key.IsNull() {
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Invalid index",
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Detail: "Can't use a null value as an indexing key.",
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Subject: srcRange,
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},
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}
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}
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ty := collection.Type()
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kty := key.Type()
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if kty == cty.DynamicPseudoType || ty == cty.DynamicPseudoType {
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return cty.DynamicVal, nil
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}
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switch {
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case ty.IsListType() || ty.IsTupleType() || ty.IsMapType():
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var wantType cty.Type
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switch {
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case ty.IsListType() || ty.IsTupleType():
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wantType = cty.Number
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case ty.IsMapType():
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wantType = cty.String
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default:
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// should never happen
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panic("don't know what key type we want")
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}
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key, keyErr := convert.Convert(key, wantType)
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if keyErr != nil {
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Invalid index",
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Detail: fmt.Sprintf(
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"The given key does not identify an element in this collection value: %s.",
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keyErr.Error(),
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),
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Subject: srcRange,
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},
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}
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}
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has := collection.HasIndex(key)
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if !has.IsKnown() {
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if ty.IsTupleType() {
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return cty.DynamicVal, nil
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} else {
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return cty.UnknownVal(ty.ElementType()), nil
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}
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}
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if has.False() {
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Invalid index",
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Detail: "The given key does not identify an element in this collection value.",
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Subject: srcRange,
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},
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}
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}
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return collection.Index(key), nil
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case ty.IsObjectType():
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key, keyErr := convert.Convert(key, cty.String)
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if keyErr != nil {
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Invalid index",
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Detail: fmt.Sprintf(
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"The given key does not identify an element in this collection value: %s.",
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keyErr.Error(),
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),
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Subject: srcRange,
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},
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}
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}
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if !collection.IsKnown() {
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return cty.DynamicVal, nil
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}
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if !key.IsKnown() {
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return cty.DynamicVal, nil
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}
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attrName := key.AsString()
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if !ty.HasAttribute(attrName) {
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Invalid index",
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Detail: "The given key does not identify an element in this collection value.",
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Subject: srcRange,
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},
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}
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}
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return collection.GetAttr(attrName), nil
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default:
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return cty.DynamicVal, Diagnostics{
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{
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Severity: DiagError,
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Summary: "Invalid index",
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Detail: "This value does not have any indices.",
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Subject: srcRange,
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},
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}
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}
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}
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