terraform: start eval stuff, untested

terraform/eval.go

@@ -0,0 +1,33 @@
+package terraform
+
+// EvalContext is the interface that is given to eval nodes to execute.
+type EvalContext interface {
+	// InitProvider initializes the provider with the given name and
+	// returns the implementation of the resource provider or an error.
+	InitProvider(string) (ResourceProvider, error)
+
+	// Provider gets the provider instance with the given name (already
+	// initialized) or returns nil if the provider isn't initialized.
+	Provider(string) ResourceProvider
+}
+
+// EvalNode is the interface that must be implemented by graph nodes to
+// evaluate/execute.
+type EvalNode interface {
+	// Args returns the arguments for this node as well as the list of
+	// expected types. The expected types are only used for type checking
+	// and not used at runtime.
+	Args() ([]EvalNode, []EvalType)
+
+	// Eval evaluates this node with the given context.
+	Eval(EvalContext) (interface{}, error)
+
+	// Type returns the type that will be returned by this node.
+	Type() EvalType
+}
+
+// GraphNodeEvalable is the interface that graph nodes must implement
+// to enable valuation.
+type GraphNodeEvalable interface {
+	EvalTree() EvalNode
+}

terraform/eval_interpolate.go

@@ -0,0 +1,23 @@
+package terraform
+
+import (
+	"github.com/hashicorp/terraform/config"
+)
+
+// EvalInterpolate is an EvalNode implementation that takes a raw
+// configuration and interpolates it.
+type EvalInterpolate struct {
+	Config *config.RawConfig
+}
+
+func (n *EvalInterpolate) Args() ([]EvalNode, []EvalType) {
+	return nil, nil
+}
+
+func (n *EvalInterpolate) Eval(ctx EvalContext) (interface{}, error) {
+	return nil, nil
+}
+
+func (n *EvalInterpolate) Type() EvalType {
+	return EvalTypeConfig
+}

terraform/eval_provider.go

@@ -0,0 +1,67 @@
+package terraform
+
+import (
+	"fmt"
+)
+
+// EvalConfigProvider is an EvalNode implementation that configures
+// a provider that is already initialized and retrieved.
+type EvalConfigProvider struct {
+	Provider EvalNode
+	Config   EvalNode
+}
+
+func (n *EvalConfigProvider) Args() ([]EvalNode, []EvalType) {
+	return []EvalNode{n.Provider, n.Config},
+		[]EvalType{EvalTypeResourceProvider, EvalTypeConfig}
+}
+
+func (n *EvalConfigProvider) Eval(ctx EvalContext) (interface{}, error) {
+	return nil, nil
+}
+
+func (n *EvalConfigProvider) Type() EvalType {
+	return EvalTypeNull
+}
+
+// EvalInitProvider is an EvalNode implementation that initializes a provider
+// and returns nothing. The provider can be retrieved again with the
+// EvalGetProvider node.
+type EvalInitProvider struct {
+	Name string
+}
+
+func (n *EvalInitProvider) Args() ([]EvalNode, []EvalType) {
+	return nil, nil
+}
+
+func (n *EvalInitProvider) Eval(ctx EvalContext) (interface{}, error) {
+	return ctx.InitProvider(n.Name)
+}
+
+func (n *EvalInitProvider) Type() EvalType {
+	return EvalTypeNull
+}
+
+// EvalGetProvider is an EvalNode implementation that retrieves an already
+// initialized provider instance for the given name.
+type EvalGetProvider struct {
+	Name string
+}
+
+func (n *EvalGetProvider) Args() ([]EvalNode, []EvalType) {
+	return nil, nil
+}
+
+func (n *EvalGetProvider) Eval(ctx EvalContext) (interface{}, error) {
+	result := ctx.Provider(n.Name)
+	if result == nil {
+		return nil, fmt.Errorf("provider %s not initialized", n.Name)
+	}
+
+	return result, nil
+}
+
+func (n *EvalGetProvider) Type() EvalType {
+	return EvalTypeResourceProvider
+}

terraform/eval_type.go

@@ -0,0 +1,19 @@
+package terraform
+
+// This separate file for EvalType exists so that stringer below
+// can work without error. See this thread for more details:
+//
+// http://comments.gmane.org/gmane.comp.lang.go.general/148740
+
+//go:generate stringer -type=EvalType eval_type.go
+
+// EvalType is the type of any value returned by an EvalNode. This is
+// used for type checking.
+type EvalType uint32
+
+const (
+	EvalTypeInvalid EvalType = 0
+	EvalTypeNull    EvalType = 1 << iota
+	EvalTypeConfig
+	EvalTypeResourceProvider
+)

terraform/evaltype_string.go

@@ -0,0 +1,34 @@
+// generated by stringer -type=EvalType eval_type.go; DO NOT EDIT
+
+package terraform
+
+import "fmt"
+
+const (
+	_EvalType_name_0 = "EvalTypeInvalid"
+	_EvalType_name_1 = "EvalTypeNull"
+	_EvalType_name_2 = "EvalTypeConfig"
+	_EvalType_name_3 = "EvalTypeResourceProvider"
+)
+
+var (
+	_EvalType_index_0 = [...]uint8{0, 15}
+	_EvalType_index_1 = [...]uint8{0, 12}
+	_EvalType_index_2 = [...]uint8{0, 14}
+	_EvalType_index_3 = [...]uint8{0, 24}
+)
+
+func (i EvalType) String() string {
+	switch {
+	case i == 0:
+		return _EvalType_name_0
+	case i == 2:
+		return _EvalType_name_1
+	case i == 4:
+		return _EvalType_name_2
+	case i == 8:
+		return _EvalType_name_3
+	default:
+		return fmt.Sprintf("EvalType(%d)", i)
+	}
+}

terraform/graph_config_node.go

@@ -73,6 +73,14 @@ func (n *GraphNodeConfigProvider) DependentOn() []string {
 	return result
 }
 
+// GraphNodeEvalable impl.
+func (n *GraphNodeConfigProvider) EvalTree() EvalNode {
+	return &EvalConfigProvider{
+		Provider: &EvalGetProvider{Name: n.Provider.Name},
+		Config:   &EvalInterpolate{Config: n.Provider.RawConfig},
+	}
+}
+
 // GraphNodeProvider implementation
 func (n *GraphNodeConfigProvider) ProviderName() string {
 	return n.Provider.Name

terraform/transform_provider.go

@@ -100,6 +100,11 @@ func (n *graphNodeMissingProvider) Name() string {
 	return fmt.Sprintf("provider.%s", n.ProviderNameValue)
 }
 
+// GraphNodeEvalable impl.
+func (n *graphNodeMissingProvider) EvalTree() EvalNode {
+	return &EvalInitProvider{Name: n.ProviderNameValue}
+}
+
 func (n *graphNodeMissingProvider) ProviderName() string {
 	return n.ProviderNameValue
 }