f44382c4fa
Rather than writing a nil hcl.Expression, as a special case we'll deal with this within the cty type system, which we assume is what the caller wants if they are decoding into a hcl.Expression rather than a native Go type.
305 lines
8.5 KiB
Go
305 lines
8.5 KiB
Go
package gohcl
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import (
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"fmt"
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"reflect"
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"github.com/zclconf/go-cty/cty"
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"github.com/hashicorp/hcl2/hcl"
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"github.com/zclconf/go-cty/cty/convert"
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"github.com/zclconf/go-cty/cty/gocty"
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)
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// DecodeBody extracts the configuration within the given body into the given
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// value. This value must be a non-nil pointer to either a struct or
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// a map, where in the former case the configuration will be decoded using
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// struct tags and in the latter case only attributes are allowed and their
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// values are decoded into the map.
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//
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// The given EvalContext is used to resolve any variables or functions in
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// expressions encountered while decoding. This may be nil to require only
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// constant values, for simple applications that do not support variables or
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// functions.
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//
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// The returned diagnostics should be inspected with its HasErrors method to
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// determine if the populated value is valid and complete. If error diagnostics
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// are returned then the given value may have been partially-populated but
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// may still be accessed by a careful caller for static analysis and editor
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// integration use-cases.
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func DecodeBody(body hcl.Body, ctx *hcl.EvalContext, val interface{}) hcl.Diagnostics {
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rv := reflect.ValueOf(val)
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if rv.Kind() != reflect.Ptr {
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panic(fmt.Sprintf("target value must be a pointer, not %s", rv.Type().String()))
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}
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return decodeBodyToValue(body, ctx, rv.Elem())
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}
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func decodeBodyToValue(body hcl.Body, ctx *hcl.EvalContext, val reflect.Value) hcl.Diagnostics {
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et := val.Type()
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switch et.Kind() {
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case reflect.Struct:
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return decodeBodyToStruct(body, ctx, val)
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case reflect.Map:
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return decodeBodyToMap(body, ctx, val)
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default:
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panic(fmt.Sprintf("target value must be pointer to struct or map, not %s", et.String()))
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}
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}
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func decodeBodyToStruct(body hcl.Body, ctx *hcl.EvalContext, val reflect.Value) hcl.Diagnostics {
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schema, partial := ImpliedBodySchema(val.Interface())
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var content *hcl.BodyContent
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var leftovers hcl.Body
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var diags hcl.Diagnostics
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if partial {
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content, leftovers, diags = body.PartialContent(schema)
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} else {
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content, diags = body.Content(schema)
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}
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if content == nil {
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return diags
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}
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tags := getFieldTags(val.Type())
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if tags.Remain != nil {
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fieldIdx := *tags.Remain
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field := val.Type().Field(fieldIdx)
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fieldV := val.Field(fieldIdx)
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switch {
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case bodyType.AssignableTo(field.Type):
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fieldV.Set(reflect.ValueOf(leftovers))
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case attrsType.AssignableTo(field.Type):
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attrs, attrsDiags := leftovers.JustAttributes()
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if len(attrsDiags) > 0 {
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diags = append(diags, attrsDiags...)
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}
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fieldV.Set(reflect.ValueOf(attrs))
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default:
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diags = append(diags, decodeBodyToValue(leftovers, ctx, fieldV)...)
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}
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}
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for name, fieldIdx := range tags.Attributes {
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attr := content.Attributes[name]
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field := val.Type().Field(fieldIdx)
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fieldV := val.Field(fieldIdx)
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if attr == nil {
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if !exprType.AssignableTo(field.Type) {
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continue
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}
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// As a special case, if the target is of type hcl.Expression then
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// we'll assign an actual expression that evalues to a cty null,
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// so the caller can deal with it within the cty realm rather
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// than within the Go realm.
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synthExpr := hcl.StaticExpr(cty.NullVal(cty.DynamicPseudoType), body.MissingItemRange())
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fieldV.Set(reflect.ValueOf(synthExpr))
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continue
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}
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switch {
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case attrType.AssignableTo(field.Type):
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fieldV.Set(reflect.ValueOf(attr))
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case exprType.AssignableTo(field.Type):
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fieldV.Set(reflect.ValueOf(attr.Expr))
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default:
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diags = append(diags, DecodeExpression(
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attr.Expr, ctx, fieldV.Addr().Interface(),
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)...)
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}
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}
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blocksByType := content.Blocks.ByType()
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for typeName, fieldIdx := range tags.Blocks {
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blocks := blocksByType[typeName]
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field := val.Type().Field(fieldIdx)
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ty := field.Type
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isSlice := false
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isPtr := false
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if ty.Kind() == reflect.Slice {
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isSlice = true
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ty = ty.Elem()
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}
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if ty.Kind() == reflect.Ptr {
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isPtr = true
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ty = ty.Elem()
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}
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if len(blocks) > 1 && !isSlice {
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diags = append(diags, &hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: fmt.Sprintf("Duplicate %s block", typeName),
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Detail: fmt.Sprintf(
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"Only one %s block is allowed. Another was defined at %s.",
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typeName, blocks[0].DefRange.String(),
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),
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Subject: &blocks[1].DefRange,
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})
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continue
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}
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if len(blocks) == 0 {
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if isSlice || isPtr {
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val.Field(fieldIdx).Set(reflect.Zero(field.Type))
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} else {
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diags = append(diags, &hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: fmt.Sprintf("Missing %s block", typeName),
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Detail: fmt.Sprintf("A %s block is required.", typeName),
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Subject: body.MissingItemRange().Ptr(),
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})
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}
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continue
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}
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switch {
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case isSlice:
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elemType := ty
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if isPtr {
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elemType = reflect.PtrTo(ty)
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}
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sli := reflect.MakeSlice(reflect.SliceOf(elemType), len(blocks), len(blocks))
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for i, block := range blocks {
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if isPtr {
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v := reflect.New(ty)
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diags = append(diags, decodeBlockToValue(block, ctx, v.Elem())...)
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sli.Index(i).Set(v)
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} else {
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diags = append(diags, decodeBlockToValue(block, ctx, sli.Index(i))...)
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}
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}
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val.Field(fieldIdx).Set(sli)
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default:
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block := blocks[0]
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if isPtr {
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v := reflect.New(ty)
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diags = append(diags, decodeBlockToValue(block, ctx, v.Elem())...)
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val.Field(fieldIdx).Set(v)
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} else {
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diags = append(diags, decodeBlockToValue(block, ctx, val.Field(fieldIdx))...)
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}
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}
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}
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return diags
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}
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func decodeBodyToMap(body hcl.Body, ctx *hcl.EvalContext, v reflect.Value) hcl.Diagnostics {
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attrs, diags := body.JustAttributes()
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if attrs == nil {
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return diags
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}
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mv := reflect.MakeMap(v.Type())
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for k, attr := range attrs {
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switch {
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case attrType.AssignableTo(v.Type().Elem()):
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mv.SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(attr))
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case exprType.AssignableTo(v.Type().Elem()):
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mv.SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(attr.Expr))
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default:
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ev := reflect.New(v.Type().Elem())
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diags = append(diags, DecodeExpression(attr.Expr, ctx, ev.Interface())...)
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mv.SetMapIndex(reflect.ValueOf(k), ev.Elem())
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}
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}
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v.Set(mv)
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return diags
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}
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func decodeBlockToValue(block *hcl.Block, ctx *hcl.EvalContext, v reflect.Value) hcl.Diagnostics {
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var diags hcl.Diagnostics
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ty := v.Type()
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switch {
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case blockType.AssignableTo(ty):
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v.Elem().Set(reflect.ValueOf(block))
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case bodyType.AssignableTo(ty):
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v.Elem().Set(reflect.ValueOf(block.Body))
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case attrsType.AssignableTo(ty):
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attrs, attrsDiags := block.Body.JustAttributes()
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if len(attrsDiags) > 0 {
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diags = append(diags, attrsDiags...)
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}
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v.Elem().Set(reflect.ValueOf(attrs))
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default:
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diags = append(diags, decodeBodyToValue(block.Body, ctx, v)...)
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if len(block.Labels) > 0 {
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blockTags := getFieldTags(ty)
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for li, lv := range block.Labels {
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lfieldIdx := blockTags.Labels[li].FieldIndex
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v.Field(lfieldIdx).Set(reflect.ValueOf(lv))
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}
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}
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}
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return diags
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}
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// DecodeExpression extracts the value of the given expression into the given
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// value. This value must be something that gocty is able to decode into,
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// since the final decoding is delegated to that package.
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//
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// The given EvalContext is used to resolve any variables or functions in
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// expressions encountered while decoding. This may be nil to require only
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// constant values, for simple applications that do not support variables or
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// functions.
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//
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// The returned diagnostics should be inspected with its HasErrors method to
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// determine if the populated value is valid and complete. If error diagnostics
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// are returned then the given value may have been partially-populated but
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// may still be accessed by a careful caller for static analysis and editor
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// integration use-cases.
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func DecodeExpression(expr hcl.Expression, ctx *hcl.EvalContext, val interface{}) hcl.Diagnostics {
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srcVal, diags := expr.Value(ctx)
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convTy, err := gocty.ImpliedType(val)
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if err != nil {
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panic(fmt.Sprintf("unsuitable DecodeExpression target: %s", err))
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}
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srcVal, err = convert.Convert(srcVal, convTy)
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if err != nil {
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diags = append(diags, &hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Unsuitable value type",
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Detail: fmt.Sprintf("Unsuitable value: %s", err.Error()),
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Subject: expr.StartRange().Ptr(),
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Context: expr.Range().Ptr(),
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})
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return diags
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}
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err = gocty.FromCtyValue(srcVal, val)
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if err != nil {
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diags = append(diags, &hcl.Diagnostic{
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Severity: hcl.DiagError,
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Summary: "Unsuitable value type",
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Detail: fmt.Sprintf("Unsuitable value: %s", err.Error()),
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Subject: expr.StartRange().Ptr(),
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Context: expr.Range().Ptr(),
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})
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}
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return diags
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}
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