hclext: Add schema mode to BodySchema

hclext/schema.go

@@ -7,9 +7,23 @@ import (
 	"strings"
 )
 
+// SchemaMode controls how the body's schema is declared.
+//
+//go:generate stringer -type=SchemaMode
+type SchemaMode int32
+
+const (
+	// SchemaDefaultMode is a mode for explicitly declaring the structure of attributes and blocks.
+	SchemaDefaultMode SchemaMode = iota
+	// SchemaJustAttributesMode is the mode to extract body as attributes.
+	// In this mode you don't need to declare schema for attributes or blocks.
+	SchemaJustAttributesMode
+)
+
 // BodySchema represents the desired body.
 // This structure is designed to have attributes similar to hcl.BodySchema.
 type BodySchema struct {
+	Mode       SchemaMode
 	Attributes []AttributeSchema
 	Blocks     []BlockSchema
 }

hclext/structure.go

@@ -1,6 +1,7 @@
 package hclext
 
 import (
+	"fmt"
 	"reflect"
 
 	"github.com/hashicorp/hcl/v2"
@@ -71,7 +72,16 @@ func Content(body hcl.Body, schema *BodySchema) (*BodyContent, hcl.Diagnostics)
 		childS[blockS.Type] = blockS.Body
 	}
 
-	content, diags := body.Content(hclS)
+	content := &hcl.BodyContent{}
+	var diags hcl.Diagnostics
+	switch schema.Mode {
+	case SchemaDefaultMode:
+		content, diags = body.Content(hclS)
+	case SchemaJustAttributesMode:
+		content.Attributes, diags = body.JustAttributes()
+	default:
+		panic(fmt.Sprintf("invalid SchemaMode: %s", schema.Mode))
+	}
 
 	ret := &BodyContent{
 		Attributes: Attributes{},
@@ -127,7 +137,16 @@ func PartialContent(body hcl.Body, schema *BodySchema) (*BodyContent, hcl.Diagno
 		childS[blockS.Type] = blockS.Body
 	}
 
-	content, _, diags := body.PartialContent(hclS)
+	content := &hcl.BodyContent{}
+	var diags hcl.Diagnostics
+	switch schema.Mode {
+	case SchemaDefaultMode:
+		content, _, diags = body.PartialContent(hclS)
+	case SchemaJustAttributesMode:
+		content.Attributes, diags = body.JustAttributes()
+	default:
+		panic(fmt.Sprintf("invalid SchemaMode: %s", schema.Mode))
+	}
 
 	ret := &BodyContent{
 		Attributes: Attributes{},

hclext/structure_test.go

@@ -696,6 +696,127 @@ func TestContent_PartialContent(t *testing.T) {
 	}
 }
 
+func TestContent_JustAttributes(t *testing.T) {
+	tests := []struct {
+		Name      string
+		Body      *hclsyntax.Body
+		Schema    *BodySchema
+		Partial   bool
+		Want      *BodyContent
+		DiagCount int
+	}{
+		{
+			Name: "just attributes in the top level",
+			Body: &hclsyntax.Body{
+				Attributes: hclsyntax.Attributes{
+					"foo": &hclsyntax.Attribute{Name: "foo"},
+					"bar": &hclsyntax.Attribute{Name: "bar"},
+					"baz": &hclsyntax.Attribute{Name: "baz"},
+				},
+			},
+			Schema: &BodySchema{Mode: SchemaJustAttributesMode},
+			Want: &BodyContent{
+				Attributes: Attributes{
+					"foo": &Attribute{Name: "foo"},
+					"bar": &Attribute{Name: "bar"},
+					"baz": &Attribute{Name: "baz"},
+				},
+				Blocks: Blocks{},
+			},
+		},
+		{
+			Name: "just attributes in nested blocks",
+			Body: &hclsyntax.Body{
+				Blocks: hclsyntax.Blocks{
+					&hclsyntax.Block{
+						Type: "bar",
+						Body: &hclsyntax.Body{
+							Attributes: hclsyntax.Attributes{
+								"foo": &hclsyntax.Attribute{Name: "foo"},
+								"bar": &hclsyntax.Attribute{Name: "bar"},
+								"baz": &hclsyntax.Attribute{Name: "baz"},
+							},
+						},
+					},
+				},
+			},
+			Schema: &BodySchema{
+				Blocks: []BlockSchema{
+					{
+						Type: "bar",
+						Body: &BodySchema{Mode: SchemaJustAttributesMode},
+					},
+				},
+			},
+			Want: &BodyContent{
+				Attributes: Attributes{},
+				Blocks: Blocks{
+					{
+						Type: "bar",
+						Body: &BodyContent{
+							Attributes: Attributes{
+								"foo": &Attribute{Name: "foo"},
+								"bar": &Attribute{Name: "bar"},
+								"baz": &Attribute{Name: "baz"},
+							},
+							Blocks: Blocks{},
+						},
+					},
+				},
+			},
+		},
+		{
+			Name: "just attributes in body with blocks",
+			Body: &hclsyntax.Body{
+				Attributes: hclsyntax.Attributes{
+					"foo": &hclsyntax.Attribute{Name: "foo"},
+					"bar": &hclsyntax.Attribute{Name: "bar"},
+					"baz": &hclsyntax.Attribute{Name: "baz"},
+				},
+				Blocks: hclsyntax.Blocks{
+					&hclsyntax.Block{
+						Type: "bar",
+						Body: &hclsyntax.Body{},
+					},
+				},
+			},
+			Schema: &BodySchema{Mode: SchemaJustAttributesMode},
+			Want: &BodyContent{
+				Attributes: Attributes{
+					"foo": &Attribute{Name: "foo"},
+					"bar": &Attribute{Name: "bar"},
+					"baz": &Attribute{Name: "baz"},
+				},
+				Blocks: Blocks{},
+			},
+			DiagCount: 1, // Unexpected "bar" block; Blocks are not allowed here.
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			var got *BodyContent
+			var diags hcl.Diagnostics
+			if test.Partial {
+				got, diags = PartialContent(test.Body, test.Schema)
+			} else {
+				got, diags = Content(test.Body, test.Schema)
+			}
+
+			if len(diags) != test.DiagCount {
+				t.Errorf("wrong number of diagnostics %d; want %d", len(diags), test.DiagCount)
+				for _, diag := range diags {
+					t.Logf(" - %s", diag.Error())
+				}
+			}
+
+			if diff := cmp.Diff(test.Want, got); diff != "" {
+				t.Errorf("wrong result\ndiff: %s", diff)
+			}
+		})
+	}
+}
+
 func Test_IsEmpty(t *testing.T) {
 	tests := []struct {
 		name string

plugin/fromproto/fromproto.go

@@ -32,11 +32,26 @@ func BodySchema(body *proto.BodySchema) *hclext.BodySchema {
 	}
 
 	return &hclext.BodySchema{
+		Mode:       SchemaMode(body.Mode),
 		Attributes: attributes,
 		Blocks:     blocks,
 	}
 }
 
+// SchemaMode converts proto.SchemaMode to hclext.SchemaMode
+func SchemaMode(mode proto.SchemaMode) hclext.SchemaMode {
+	switch mode {
+	case proto.SchemaMode_SCHEMA_MODE_UNSPECIFIED:
+		return hclext.SchemaDefaultMode
+	case proto.SchemaMode_SCHEMA_MODE_DEFAULT:
+		return hclext.SchemaDefaultMode
+	case proto.SchemaMode_SCHEMA_MODE_JUST_ATTRIBUTES:
+		return hclext.SchemaJustAttributesMode
+	default:
+		panic(fmt.Sprintf("invalid SchemaMode: %s", mode))
+	}
+}
+
 // BodyContent converts proto.BodyContent to hclext.BodyContent
 func BodyContent(body *proto.BodyContent) (*hclext.BodyContent, hcl.Diagnostics) {
 	if body == nil {

plugin/plugin2host/plugin2host_test.go

@@ -527,6 +527,25 @@ resource "aws_instance" "foo" {
 			},
 			ErrCheck: neverHappend,
 		},
+		{
+			Name: "get content as just attributes",
+			Args: func() (*hclext.BodySchema, *tflint.GetModuleContentOption) {
+				return &hclext.BodySchema{Mode: hclext.SchemaJustAttributesMode}, nil
+			},
+			ServerImpl: func(schema *hclext.BodySchema, opts tflint.GetModuleContentOption) (*hclext.BodyContent, hcl.Diagnostics) {
+				file := hclFile("test.tf", `
+instance_type = "t2.micro"
+volume_size = 10`)
+				return hclext.Content(file.Body, schema)
+			},
+			Want: func(schema *hclext.BodySchema, opts *tflint.GetModuleContentOption) (*hclext.BodyContent, hcl.Diagnostics) {
+				file := hclFile("test.tf", `
+instance_type = "t2.micro"
+volume_size = 10`)
+				return hclext.Content(file.Body, schema)
+			},
+			ErrCheck: neverHappend,
+		},
 		{
 			Name: "get content with options",
 			Args: func() (*hclext.BodySchema, *tflint.GetModuleContentOption) {