Start defining the Schema type.

attribute.go

@@ -0,0 +1,86 @@
+package tfsdk
+
+import (
+	"context"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov6"
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+// AttributeType defines an interface for describing a kind of attribute.
+// AttributeTypes are collections of constraints and behaviors such that they
+// can be reused on multiple attributes easily.
+type AttributeType interface {
+	// TerraformType returns the tftypes.Type that should be used to
+	// represent this type. This constrains what user input will be
+	// accepted and what kind of data can be set in state. The framework
+	// will use this to translate the AttributeType to something Terraform
+	// can understand.
+	TerraformType(context.Context) tftypes.Type
+
+	// ValueFromTerraform returns an AttributeValue given a tftypes.Value.
+	// This is meant to convert the tftypes.Value into a more convenient Go
+	// type for the provider to consume the data with.
+	ValueFromTerraform(context.Context, tftypes.Value) (AttributeValue, error)
+
+	// Equal must return true if the AttributeType is considered
+	// semantically equal to the AttributeType passed as an argument.
+	Equal(AttributeType) bool
+}
+
+// AttributeTypeWithValidate extends the AttributeType interface to include a
+// Validate method, used to bundle consistent validation logic with the
+// AttributeType.
+type AttributeTypeWithValidate interface {
+	AttributeType
+
+	// Validate returns any warnings or errors about the value that is
+	// being used to populate the AttributeType. It is generally used to
+	// check the data format and ensure that it complies with the
+	// requirements of the AttributeType.
+	//
+	// TODO: don't use tfprotov6.Diagnostic, use our type
+	Validate(context.Context, tftypes.Value) []*tfprotov6.Diagnostic
+}
+
+// AttributeTypeWithPlaintextDescription extends the AttributeType interface to
+// include a Description method, used to bundle extra information to include in
+// attribute descriptions with the AttributeType. It expects the description to
+// be written as plain text, with no special formatting.
+type AttributeTypeWithPlaintextDescription interface {
+	AttributeType
+
+	// Description returns a practitioner-friendly explanation of the type
+	// and the constraints of the data it accepts and returns. It will be
+	// combined with the Description associated with the Attribute.
+	Description(context.Context) string
+}
+
+// AttributeTypeWithMarkdownDescription extends the AttributeType interface to
+// include a MarkdownDescription method, used to bundle extra information to
+// include in attribute descriptions with the AttributeType. It expects the
+// description to be formatted for display with Markdown.
+type AttributeTypeWithMarkdownDescription interface {
+	// MarkdownDescription returns a practitioner-friendly explanation of
+	// the type and the constraints of the data it accepts and returns. It
+	// will be combined with the MarkdownDescription associated with the
+	// Attribute.
+	MarkdownDescription(context.Context) string
+}
+
+// AttributeValue defines an interface for describing data associated with an attribute.
+// AttributeValues allow provider developers to specify data in a convenient format, and
+// have it transparently be converted to formats Terraform understands.
+type AttributeValue interface {
+	// ToTerraformValue returns the data contained in the AttributeValue as
+	// a Go type that tftypes.NewAttributeValue will accept.
+	ToTerraformValue(context.Context) (interface{}, error)
+
+	// SetTerraformValue updates the data in AttributeValue to match the
+	// passed tftypes.Value
+	SetTerraformValue(context.Context, tftypes.Value) error
+
+	// Equal must return true if the AttributeValue is considered
+	// semantically equal to the AttributeValue passed as an argument.
+	Equal(AttributeValue) bool
+}

go.mod

@@ -2,4 +2,7 @@ module github.com/hashicorp/terraform-plugin-framework
 
 go 1.16
 
-require github.com/hashicorp/terraform-plugin-go v0.2.1
+require (
+	github.com/google/go-cmp v0.5.2
+	github.com/hashicorp/terraform-plugin-go v0.3.0
+)

go.sum

@@ -30,8 +30,8 @@ github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/hashicorp/go-hclog v0.0.0-20180709165350-ff2cf002a8dd/go.mod h1:9bjs9uLqI8l75knNv3lV1kA55veR+WUPSiKIWcQHudI=
 github.com/hashicorp/go-plugin v1.3.0/go.mod h1:F9eH4LrE/ZsRdbwhfjs9k9HoDUwAHnYtXdgmf1AVNs0=
-github.com/hashicorp/terraform-plugin-go v0.2.1 h1:EW/R8bB2Zbkjmugzsy1d27yS8/0454b3MtYHkzOknqA=
-github.com/hashicorp/terraform-plugin-go v0.2.1/go.mod h1:10V6F3taeDWVAoLlkmArKttR3IULlRWFAGtQIQTIDr4=
+github.com/hashicorp/terraform-plugin-go v0.3.0 h1:AJqYzP52JFYl9NABRI7smXI1pNjgR5Q/y2WyVJ/BOZA=
+github.com/hashicorp/terraform-plugin-go v0.3.0/go.mod h1:dFHsQMaTLpON2gWhVWT96fvtlc/MF1vSy3OdMhWBzdM=
 github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
 github.com/jhump/protoreflect v1.6.0/go.mod h1:eaTn3RZAmMBcV0fifFvlm6VHNz3wSkYyXYWUh7ymB74=
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=

internal/reflect/helpers.go

@@ -0,0 +1,96 @@
+package reflect
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"regexp"
+	"strings"
+
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+// trueReflectValue returns the reflect.Value for `in` after derefencing all
+// the pointers and unwrapping all the interfaces. It's the concrete value
+// beneath it all.
+func trueReflectValue(val reflect.Value) reflect.Value {
+	kind := val.Type().Kind()
+	for kind == reflect.Interface || kind == reflect.Ptr {
+		innerVal := val.Elem()
+		if !innerVal.IsValid() {
+			break
+		}
+		val = innerVal
+		kind = val.Type().Kind()
+	}
+	return val
+}
+
+// commaSeparatedString returns an English joining of the strings in `in`,
+// using "and" and commas as appropriate.
+func commaSeparatedString(in []string) string {
+	switch len(in) {
+	case 0:
+		return ""
+	case 1:
+		return in[0]
+	case 2:
+		return strings.Join(in, " and ")
+	default:
+		in[len(in)-1] = "and " + in[len(in)-1]
+		return strings.Join(in, ", ")
+	}
+}
+
+// getStructTags returns a map of Terraform field names to their position in
+// the tags of the struct `in`. `in` must be a struct.
+func getStructTags(ctx context.Context, in reflect.Value, path *tftypes.AttributePath) (map[string]int, error) {
+	tags := map[string]int{}
+	typ := trueReflectValue(in).Type()
+	if typ.Kind() != reflect.Struct {
+		return nil, path.NewErrorf("can't get struct tags of %s, is not a struct", in.Type())
+	}
+	for i := 0; i < typ.NumField(); i++ {
+		field := typ.Field(i)
+		if field.PkgPath != "" {
+			// skip unexported fields
+			continue
+		}
+		tag := field.Tag.Get(`tfsdk`)
+		if tag == "-" {
+			// skip explicitly excluded fields
+			continue
+		}
+		if tag == "" {
+			return nil, path.NewErrorf(`need a struct tag for "tfsdk" on %s`, field.Name)
+		}
+		path := path.WithAttributeName(tag)
+		if !isValidFieldName(tag) {
+			return nil, path.NewError(errors.New("invalid field name, must only use lowercase letters, underscores, and numbers, and must start with a letter"))
+		}
+		if other, ok := tags[tag]; ok {
+			return nil, path.NewErrorf("can't use field name for both %s and %s", typ.Field(other).Name, field.Name)
+		}
+		tags[tag] = i
+	}
+	return tags, nil
+}
+
+// isValidFieldName returns true if `name` can be used as a field name in a
+// Terraform resource or data source.
+func isValidFieldName(name string) bool {
+	re := regexp.MustCompile("^[a-z][a-z0-9_]*$")
+	return re.MatchString(name)
+}
+
+// canBeNil returns true if `target`'s type can hold a nil value
+func canBeNil(target reflect.Value) bool {
+	switch target.Kind() {
+	case reflect.Ptr, reflect.Slice, reflect.Map, reflect.Interface:
+		// these types can all hold nils
+		return true
+	default:
+		// nothing else can be set to nil
+		return false
+	}
+}