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gohcl: Struct Embedding #667

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9 changes: 9 additions & 0 deletions gohcl/decode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,11 @@ func decodeBodyToStruct(body hcl.Body, ctx *hcl.EvalContext, val reflect.Value)
return diags
}

return append(diags, decodeBodyToStructInner(body, content, leftovers, ctx, val)...)
}
func decodeBodyToStructInner(body hcl.Body, content *hcl.BodyContent, leftovers hcl.Body, ctx *hcl.EvalContext, val reflect.Value) hcl.Diagnostics {
var diags hcl.Diagnostics

tags := getFieldTags(val.Type())

if tags.Body != nil {
Expand Down Expand Up @@ -98,6 +103,10 @@ func decodeBodyToStruct(body hcl.Body, ctx *hcl.EvalContext, val reflect.Value)
diags = append(diags, decodeBodyToValue(leftovers, ctx, fieldV)...)
}
}
for _, embedded := range tags.Embedded {
fieldV := val.Field(embedded.FieldIndex)
diags = append(diags, decodeBodyToStructInner(body, content, leftovers, ctx, fieldV)...)
}

for name, fieldIdx := range tags.Attributes {
attr := content.Attributes[name]
Expand Down
49 changes: 38 additions & 11 deletions gohcl/schema.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,10 @@
package gohcl

import (
"cmp"
"fmt"
"reflect"
"sort"
"slices"
"strings"

"github.com/hashicorp/hcl/v2"
Expand All @@ -24,6 +25,10 @@ import (
// mapping is attempted, this function will panic.
func ImpliedBodySchema(val interface{}) (schema *hcl.BodySchema, partial bool) {
ty := reflect.TypeOf(val)
if nty, ok := val.(reflect.Value); ok {
// Recursion through embedded structs
ty = nty.Type()
}

if ty.Kind() == reflect.Ptr {
ty = ty.Elem()
Expand All @@ -38,12 +43,7 @@ func ImpliedBodySchema(val interface{}) (schema *hcl.BodySchema, partial bool) {

tags := getFieldTags(ty)

attrNames := make([]string, 0, len(tags.Attributes))
for n := range tags.Attributes {
attrNames = append(attrNames, n)
}
sort.Strings(attrNames)
for _, n := range attrNames {
idx := tags.Attributes[n]
optional := tags.Optional[n]
field := ty.Field(idx)
Expand All @@ -68,12 +68,7 @@ func ImpliedBodySchema(val interface{}) (schema *hcl.BodySchema, partial bool) {
})
}

blockNames := make([]string, 0, len(tags.Blocks))
for n := range tags.Blocks {
blockNames = append(blockNames, n)
}
sort.Strings(blockNames)
for _, n := range blockNames {
idx := tags.Blocks[n]
field := ty.Field(idx)
fty := field.Type
Expand Down Expand Up @@ -104,6 +99,25 @@ func ImpliedBodySchema(val interface{}) (schema *hcl.BodySchema, partial bool) {
}

partial = tags.Remain != nil

for _, embedded := range tags.Embedded {
nested, npartial := ImpliedBodySchema(reflect.New(embedded.Type))
if npartial && partial {
panic("only one 'remain' tag is permitted (nested)")
}

attrSchemas = append(attrSchemas, nested.Attributes...)
blockSchemas = append(blockSchemas, nested.Blocks...)
println(fmt.Sprintf("%v: %#v\n", embedded.Type, nested))
}

slices.SortStableFunc(attrSchemas, func(a, b hcl.AttributeSchema) int {
return cmp.Compare(a.Name, b.Name)
})
slices.SortStableFunc(blockSchemas, func(a, b hcl.BlockHeaderSchema) int {
return cmp.Compare(a.Type, b.Type)
})

schema = &hcl.BodySchema{
Attributes: attrSchemas,
Blocks: blockSchemas,
Expand All @@ -118,6 +132,12 @@ type fieldTags struct {
Remain *int
Body *int
Optional map[string]bool
Embedded []embeddedField
}

type embeddedField struct {
FieldIndex int
Type reflect.Type
}

type labelField struct {
Expand All @@ -135,8 +155,15 @@ func getFieldTags(ty reflect.Type) *fieldTags {
ct := ty.NumField()
for i := 0; i < ct; i++ {
field := ty.Field(i)

tag := field.Tag.Get("hcl")
if tag == "" {
if field.Type.Kind() == reflect.Struct && field.Anonymous {
ret.Embedded = append(ret.Embedded, embeddedField{
FieldIndex: i,
Type: field.Type,
})
}
continue
}

Expand Down