fc00c16e31
There are two expressions in HCL2 that are used to iterate over collections: - Splat expressions, e.g. `foo.*.bar`, and - For expressions, e.g. `[for v in foo: v.bar]` In both of these cases, the parts of the expression that are not the collection being iterated behave like callbacks, and must be treated as such by the apply rewriter.
641 lines
20 KiB
Go
641 lines
20 KiB
Go
// Copyright 2016-2020, Pulumi Corporation.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package hcl2
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import (
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"fmt"
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"github.com/gedex/inflector"
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"github.com/hashicorp/hcl/v2"
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"github.com/pulumi/pulumi/pkg/v2/codegen"
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"github.com/pulumi/pulumi/pkg/v2/codegen/hcl2/model"
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"github.com/pulumi/pulumi/sdk/v2/go/common/util/contract"
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"github.com/zclconf/go-cty/cty"
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)
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type NameInfo interface {
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Format(name string) string
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}
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// The applyRewriter is responsible for driving the apply rewrite process. The rewriter uses a stack of contexts to
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// deal with the possibility of expressions that observe outputs nested inside expressions that do not.
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type applyRewriter struct {
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nameInfo NameInfo
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applyPromises bool
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activeContext applyRewriteContext
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exprStack []model.Expression
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}
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type applyRewriteContext interface {
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PreVisit(x model.Expression) (model.Expression, hcl.Diagnostics)
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PostVisit(x model.Expression) (model.Expression, hcl.Diagnostics)
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}
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// An inspectContext is used when we are inside an expression that does not observe eventual values. When it
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// encounters an expression that observes eventual values, it pushes a new observeContext onto the stack.
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type inspectContext struct {
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*applyRewriter
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parent *observeContext
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root model.Expression
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}
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// An observeContext is used when we are inside an expression that does observe eventual values. It is responsible for
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// finding the values that are observed, replacing them with references to apply parameters, and replacing the root
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// expression with a call to the __apply intrinsic.
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type observeContext struct {
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*applyRewriter
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parent applyRewriteContext
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root model.Expression
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applyArgs []model.Expression
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callbackParams []*model.Variable
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paramReferences []*model.ScopeTraversalExpression
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assignedNames codegen.StringSet
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nameCounts map[string]int
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}
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func (r *applyRewriter) hasEventualTypes(t model.Type) bool {
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resolved := model.ResolveOutputs(t)
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return resolved != t
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}
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func (r *applyRewriter) hasEventualValues(x model.Expression) bool {
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return r.hasEventualTypes(x.Type())
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}
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func (r *applyRewriter) isEventualType(t model.Type) (model.Type, bool) {
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switch t := t.(type) {
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case *model.OutputType:
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return t.ElementType, true
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case *model.PromiseType:
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if r.applyPromises {
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return t.ElementType, true
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}
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case *model.UnionType:
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types, isEventual := make([]model.Type, len(t.ElementTypes)), false
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for i, t := range t.ElementTypes {
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if element, elementIsEventual := r.isEventualType(t); elementIsEventual {
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t, isEventual = element, true
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}
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types[i] = t
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}
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if isEventual {
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return model.NewUnionType(types...), true
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}
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}
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return nil, false
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}
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func (r *applyRewriter) hasEventualElements(x model.Expression) bool {
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t := x.Type()
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if resolved, ok := r.isEventualType(t); ok {
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t = resolved
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}
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return r.hasEventualTypes(t)
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}
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func (r *applyRewriter) isPromptArg(paramType model.Type, arg model.Expression) bool {
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if !r.hasEventualValues(arg) {
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return true
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}
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if union, ok := paramType.(*model.UnionType); ok {
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for _, t := range union.ElementTypes {
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if t != model.DynamicType && t.ConversionFrom(arg.Type()) != model.NoConversion {
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return true
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}
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}
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return false
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}
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return paramType != model.DynamicType && paramType.ConversionFrom(arg.Type()) != model.NoConversion
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}
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func (r *applyRewriter) isIteratorExpr(x model.Expression) (bool, model.Type) {
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if len(r.exprStack) < 2 {
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return false, nil
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}
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parent := r.exprStack[len(r.exprStack)-2]
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switch parent := parent.(type) {
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case *model.ForExpression:
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return x != parent.Collection, parent.ValueVariable.Type()
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case *model.SplatExpression:
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return x != parent.Source, parent.Item.Type()
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default:
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return false, nil
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}
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}
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func (r *applyRewriter) inspectsEventualValues(x model.Expression) bool {
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switch x := x.(type) {
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case *model.ConditionalExpression:
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return r.hasEventualValues(x.TrueResult) || r.hasEventualValues(x.FalseResult)
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case *model.ForExpression:
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return r.hasEventualElements(x.Collection)
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case *model.FunctionCallExpression:
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for i, arg := range x.Args {
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if r.hasEventualValues(arg) && r.isPromptArg(x.Signature.Parameters[i].Type, arg) {
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return true
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}
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}
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return false
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case *model.IndexExpression:
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_, isCollectionEventual := r.isEventualType(x.Collection.Type())
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return !isCollectionEventual && r.hasEventualValues(x.Collection)
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case *model.SplatExpression:
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return r.hasEventualElements(x.Source)
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default:
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if isIteratorExpr, elementType := r.isIteratorExpr(x); isIteratorExpr {
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_, isElementEventual := r.isEventualType(elementType)
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return !isElementEventual && r.hasEventualTypes(elementType)
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}
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return false
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}
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}
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func (r *applyRewriter) observesEventualValues(x model.Expression) bool {
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_, isEventual := r.isEventualType(x.Type())
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if !isEventual {
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return false
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}
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switch x := x.(type) {
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case *model.AnonymousFunctionExpression:
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return false
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case *model.ConditionalExpression:
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return r.hasEventualValues(x.Condition)
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case *model.ForExpression:
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_, collectionIsEventual := r.isEventualType(x.Collection.Type())
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return collectionIsEventual
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case *model.FunctionCallExpression:
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for i, arg := range x.Args {
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if !r.isPromptArg(x.Signature.Parameters[i].Type, arg) {
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return true
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}
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}
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return false
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case *model.IndexExpression:
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if _, collectionIsEventual := r.isEventualType(x.Collection.Type()); collectionIsEventual {
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return true
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}
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return r.hasEventualValues(x.Key)
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case *model.RelativeTraversalExpression:
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// A traversal is eventual if at least one of its nonterminals is eventual.
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for _, p := range x.Parts[:len(x.Parts)-1] {
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if _, isEventual := r.isEventualType(model.GetTraversableType(p)); isEventual {
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return true
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}
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}
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return false
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case *model.ScopeTraversalExpression:
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// A traversal is eventual if at least one of its nonterminals is eventual.
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for _, p := range x.Parts[:len(x.Parts)-1] {
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if _, isEventual := r.isEventualType(model.GetTraversableType(p)); isEventual {
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return true
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}
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}
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return false
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case *model.SplatExpression:
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_, sourceIsEventual := r.isEventualType(x.Source.Type())
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return sourceIsEventual
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default:
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return true
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}
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}
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func (r *applyRewriter) preVisit(expr model.Expression) (model.Expression, hcl.Diagnostics) {
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r.exprStack = append(r.exprStack, expr)
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return r.activeContext.PreVisit(expr)
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}
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func (r *applyRewriter) postVisit(expr model.Expression) (model.Expression, hcl.Diagnostics) {
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x, diags := r.activeContext.PostVisit(expr)
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r.exprStack = r.exprStack[:len(r.exprStack)-1]
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return x, diags
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}
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// disambiguateName ensures that the given name is unambiguous by appending an integer starting with 1 if necessary.
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func (ctx *observeContext) disambiguateName(name string) string {
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if name == "" {
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name = "arg"
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}
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if !ctx.assignedNames.Has(name) {
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return name
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}
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root := name
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for i := 1; ctx.nameCounts[name] != 0; i++ {
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name = fmt.Sprintf("%s%d", root, i)
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}
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return name
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}
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func (ctx *observeContext) bestTraversalName(rootName string, traversal hcl.Traversal) string {
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for i := len(traversal) - 1; i >= 0; i-- {
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switch t := traversal[i].(type) {
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case hcl.TraverseAttr:
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return t.Name
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case hcl.TraverseIndex:
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if t.Key.Type().Equals(cty.String) {
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return t.Key.AsString()
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}
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return inflector.Singularize(ctx.bestTraversalName(rootName, traversal[:i]))
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}
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}
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return rootName
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}
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// bestArgName computes the "best" name for a given apply argument. If this name is unambiguous after all best names
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// have been calculated, it will be assigned to the argument. Otherwise, it will go through the disambiguation process
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// in disambiguateArgName.
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func (ctx *observeContext) bestArgName(x model.Expression) string {
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switch x := x.(type) {
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case *model.ForExpression:
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if x.Key == nil {
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return inflector.Pluralize(ctx.bestArgName(x.Value))
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}
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case *model.FunctionCallExpression:
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switch x.Name {
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case IntrinsicApply:
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_, then := ParseApplyCall(x)
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return ctx.bestArgName(then.Body)
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case "element":
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return ctx.bestArgName(x.Args[0])
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case "fileArchive", "fileAsset", "readDir", "readFile":
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return ctx.bestArgName(x.Args[0])
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case "lookup":
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return ctx.bestArgName(x.Args[1])
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}
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return x.Name
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case *model.IndexExpression:
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switch model.ResolveOutputs(x.Collection.Type()).(type) {
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case *model.ListType, *model.SetType, *model.TupleType:
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return inflector.Singularize(ctx.bestArgName(x.Collection))
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case *model.MapType, *model.ObjectType:
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return ctx.bestArgName(x.Key)
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}
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case *model.LiteralValueExpression:
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if x.Value.Type().Equals(cty.String) {
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return x.Value.AsString()
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}
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case *model.RelativeTraversalExpression:
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if n := ctx.bestTraversalName(ctx.bestArgName(x.Source), x.Traversal); n != "" {
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return n
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}
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case *model.ScopeTraversalExpression:
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if n := ctx.bestTraversalName(x.RootName, x.Traversal[1:]); n != "" {
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return n
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}
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case *model.SplatExpression:
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return inflector.Pluralize(ctx.bestArgName(x.Each))
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}
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switch t := model.ResolveOutputs(x.Type()).(type) {
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case *model.ListType, *model.SetType, *model.TupleType:
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return "values"
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case *model.MapType, *model.ObjectType:
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return "obj"
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case *model.UnionType:
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return "value"
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default:
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switch t {
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case model.BoolType:
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return "b"
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case model.IntType:
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return "i"
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case model.NumberType:
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return "n"
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case model.StringType:
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return "s"
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case model.DynamicType:
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return "obj"
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default:
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return "v"
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}
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}
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}
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// disambiguateArgName applies type-specific disambiguation to an argument name.
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func (ctx *observeContext) disambiguateArgName(x model.Expression, bestName string) string {
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if x, ok := x.(*model.ScopeTraversalExpression); ok {
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if n, ok := x.Parts[0].(*Resource); ok {
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// If dealing with a broken access, defer to the generic disambiguator. Otherwise, attempt to disambiguate
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// by prepending the resource's variable name.
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if len(x.Traversal) > 1 {
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return ctx.disambiguateName(n.Name() + titleCase(bestName))
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}
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}
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}
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// Hand off to the generic disambiguator.
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return ctx.disambiguateName(bestName)
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}
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// rewriteApplyArg replaces a single expression with an apply parameter.
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func (ctx *observeContext) rewriteApplyArg(applyArg model.Expression, paramType model.Type, traversal hcl.Traversal,
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parts []model.Traversable, isRoot bool) model.Expression {
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if len(traversal) == 0 && isRoot {
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return applyArg
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}
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callbackParam := &model.Variable{
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Name: fmt.Sprintf("<arg%d>", len(ctx.callbackParams)),
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VariableType: paramType,
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}
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ctx.applyArgs, ctx.callbackParams = append(ctx.applyArgs, applyArg), append(ctx.callbackParams, callbackParam)
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// TODO(pdg): this risks information loss for nested output-typed properties... The `Types` array on traversals
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// ought to store the original types.
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resolvedParts := make([]model.Traversable, len(parts)+1)
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resolvedParts[0] = callbackParam
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for i, p := range parts {
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resolvedParts[i+1] = model.ResolveOutputs(model.GetTraversableType(p))
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}
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result := &model.ScopeTraversalExpression{
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Parts: resolvedParts,
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RootName: callbackParam.Name,
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Traversal: hcl.TraversalJoin(hcl.Traversal{hcl.TraverseRoot{Name: callbackParam.Name}}, traversal),
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}
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ctx.paramReferences = append(ctx.paramReferences, result)
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return result
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}
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// rewriteRelativeTraversalExpression replaces a single access to an ouptut-typed RelativeTraversalExpression with an
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// apply parameter.
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func (ctx *observeContext) rewriteRelativeTraversalExpression(expr *model.RelativeTraversalExpression,
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isRoot bool) model.Expression {
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// Compute the type of the apply and callback arguments.
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paramType := model.ResolveOutputs(expr.Type())
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parts, traversal := expr.Parts, expr.Traversal
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for i := range expr.Traversal {
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partResolvedType, isEventual := paramType, true
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if i < len(expr.Traversal)-1 {
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partResolvedType, isEventual = ctx.isEventualType(model.GetTraversableType(expr.Parts[i+1]))
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}
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if isEventual {
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expr.Traversal, expr.Parts = expr.Traversal[:i+1], expr.Parts[:i+1]
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paramType, traversal, parts = partResolvedType, expr.Traversal[i+1:], expr.Parts[i+1:]
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break
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}
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}
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return ctx.rewriteApplyArg(expr, paramType, traversal, parts, isRoot)
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}
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// rewriteScopeTraversalExpression replaces a single access to an ouptut-typed ScopeTraversalExpression with an apply
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// parameter.
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func (ctx *observeContext) rewriteScopeTraversalExpression(expr *model.ScopeTraversalExpression,
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isRoot bool) model.Expression {
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// If the access is not an output() or a promise(), return the node as-is.
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resolvedType, isEventual := ctx.isEventualType(expr.Type())
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if !isEventual {
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// If this is a reference to a named variable, put the name in scope.
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if definition, ok := expr.Traversal[0].(Node); ok {
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ctx.assignedNames.Add(definition.Name())
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ctx.nameCounts[definition.Name()] = 1
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}
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return expr
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}
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// Otherwise, append the access to the list of apply arguments and return an appropriate call to __applyArg.
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//
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// TODO: deduplicate multiple accesses to the same variable and field.
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// Compute the type of the apply and callback arguments.
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var applyArg *model.ScopeTraversalExpression
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var paramType model.Type
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var parts []model.Traversable
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var traversal hcl.Traversal
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splitTraversal := expr.Traversal.SimpleSplit()
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rootResolvedType, rootIsEventual := resolvedType, true
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if len(splitTraversal.Rel) > 0 {
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rootResolvedType, rootIsEventual = ctx.isEventualType(model.GetTraversableType(expr.Parts[0]))
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}
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if rootIsEventual {
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applyArg = &model.ScopeTraversalExpression{
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Parts: expr.Parts[:1],
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RootName: splitTraversal.Abs.RootName(),
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Traversal: splitTraversal.Abs,
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}
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paramType, traversal, parts = rootResolvedType, expr.Traversal.SimpleSplit().Rel, expr.Parts[1:]
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} else {
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for i := range splitTraversal.Rel {
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partResolvedType, isEventual := resolvedType, true
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if i < len(splitTraversal.Rel)-1 {
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partResolvedType, isEventual = ctx.isEventualType(model.GetTraversableType(expr.Parts[i+1]))
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}
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if isEventual {
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absTraversal, relTraversal := expr.Traversal[:i+2], expr.Traversal[i+2:]
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applyArg = &model.ScopeTraversalExpression{
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Parts: expr.Parts[:i+2],
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RootName: absTraversal.RootName(),
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Traversal: absTraversal,
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}
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paramType, traversal, parts = partResolvedType, relTraversal, expr.Parts[i+2:]
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break
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}
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}
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}
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return ctx.rewriteApplyArg(applyArg, paramType, traversal, parts, isRoot)
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}
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// rewriteRoot replaces the root node in a bound expression with a call to the __apply intrinsic if necessary.
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func (ctx *observeContext) rewriteRoot(expr model.Expression) model.Expression {
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contract.Require(expr == ctx.root, "expr")
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if len(ctx.applyArgs) == 0 {
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return expr
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}
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// Assign argument names.
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for i, arg := range ctx.applyArgs {
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bestName := ctx.nameInfo.Format(ctx.bestArgName(arg))
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ctx.callbackParams[i].Name, ctx.nameCounts[bestName] = bestName, ctx.nameCounts[bestName]+1
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}
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for i, param := range ctx.callbackParams {
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if ctx.nameCounts[param.Name] > 1 {
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param.Name = ctx.disambiguateArgName(ctx.applyArgs[i], param.Name)
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if ctx.nameCounts[param.Name] == 0 {
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ctx.nameCounts[param.Name] = 1
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}
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ctx.assignedNames.Add(param.Name)
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}
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}
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// Update parameter references with the assigned names.
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for _, x := range ctx.paramReferences {
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|
v := x.Parts[0].(*model.Variable)
|
|
rootTraversal := x.Traversal[0].(hcl.TraverseRoot)
|
|
x.RootName, rootTraversal.Name = v.Name, v.Name
|
|
x.Traversal[0] = rootTraversal
|
|
}
|
|
|
|
// Create a new anonymous function definition.
|
|
callback := &model.AnonymousFunctionExpression{
|
|
Signature: model.StaticFunctionSignature{
|
|
Parameters: make([]model.Parameter, len(ctx.callbackParams)),
|
|
ReturnType: expr.Type(),
|
|
},
|
|
Parameters: ctx.callbackParams,
|
|
Body: expr,
|
|
}
|
|
for i, p := range ctx.callbackParams {
|
|
callback.Signature.Parameters[i] = model.Parameter{Name: p.Name, Type: p.VariableType}
|
|
}
|
|
|
|
return NewApplyCall(ctx.applyArgs, callback)
|
|
}
|
|
|
|
func (ctx *observeContext) PreVisit(expr model.Expression) (model.Expression, hcl.Diagnostics) {
|
|
if ctx.inspectsEventualValues(expr) {
|
|
if ctx.observesEventualValues(expr) {
|
|
ctx.activeContext = &observeContext{
|
|
applyRewriter: ctx.applyRewriter,
|
|
parent: ctx,
|
|
root: expr,
|
|
assignedNames: codegen.StringSet{},
|
|
nameCounts: map[string]int{},
|
|
}
|
|
} else {
|
|
ctx.activeContext = &inspectContext{
|
|
applyRewriter: ctx.applyRewriter,
|
|
parent: ctx,
|
|
root: expr,
|
|
}
|
|
}
|
|
}
|
|
return expr, nil
|
|
}
|
|
|
|
func (ctx *observeContext) PostVisit(expr model.Expression) (model.Expression, hcl.Diagnostics) {
|
|
isRoot := expr == ctx.root
|
|
|
|
// TODO(pdg): arrays of outputs, for expressions, etc.
|
|
diagnostics := expr.Typecheck(false)
|
|
contract.Assert(len(diagnostics) == 0)
|
|
|
|
if isIteratorExpr, _ := ctx.isIteratorExpr(expr); isIteratorExpr {
|
|
return expr, nil
|
|
}
|
|
|
|
switch x := expr.(type) {
|
|
case *model.RelativeTraversalExpression:
|
|
expr = ctx.rewriteRelativeTraversalExpression(x, isRoot)
|
|
case *model.ScopeTraversalExpression:
|
|
expr = ctx.rewriteScopeTraversalExpression(x, isRoot)
|
|
default:
|
|
_, isEventual := ctx.isEventualType(expr.Type())
|
|
if isEventual && ctx.inspectsEventualValues(x) {
|
|
expr = ctx.rewriteApplyArg(x, model.ResolveOutputs(x.Type()), nil, nil, isRoot)
|
|
}
|
|
}
|
|
if isRoot {
|
|
ctx.root = expr
|
|
expr = ctx.rewriteRoot(expr)
|
|
|
|
ctx.activeContext = ctx.parent
|
|
return ctx.activeContext.PostVisit(expr)
|
|
}
|
|
return expr, nil
|
|
}
|
|
|
|
func (ctx *inspectContext) PreVisit(expr model.Expression) (model.Expression, hcl.Diagnostics) {
|
|
if ctx.observesEventualValues(expr) {
|
|
observeCtx := &observeContext{
|
|
applyRewriter: ctx.applyRewriter,
|
|
parent: ctx,
|
|
root: expr,
|
|
assignedNames: codegen.StringSet{},
|
|
nameCounts: map[string]int{},
|
|
}
|
|
ctx.activeContext = observeCtx
|
|
}
|
|
return expr, nil
|
|
}
|
|
|
|
func (ctx *inspectContext) PostVisit(expr model.Expression) (model.Expression, hcl.Diagnostics) {
|
|
if expr == ctx.root {
|
|
ctx.activeContext = ctx.parent
|
|
if ctx.parent != nil {
|
|
return ctx.activeContext.PostVisit(expr)
|
|
}
|
|
}
|
|
return expr, nil
|
|
}
|
|
|
|
// RewriteApplies transforms all expressions that observe the resolved values of outputs and promises into calls to the
|
|
// __apply intrinsic. Expressions that generate or inspect outputs or promises are passed as arguments to these calls,
|
|
// and are replaced by references to the corresponding parameter.
|
|
//
|
|
// As an example, assuming that resource.id is an output, this transforms the following expression:
|
|
//
|
|
// toJSON({
|
|
// Version = "2012-10-17"
|
|
// Statement = [{
|
|
// Effect = "Allow"
|
|
// Principal = "*"
|
|
// Action = [ "s3:GetObject" ]
|
|
// Resource = [ "arn:aws:s3:::${resource.id}/*" ]
|
|
// }]
|
|
// })
|
|
//
|
|
// into this expression:
|
|
//
|
|
// __apply(resource.id, eval(id, toJSON({
|
|
// Version = "2012-10-17"
|
|
// Statement = [{
|
|
// Effect = "Allow"
|
|
// Principal = "*"
|
|
// Action = [ "s3:GetObject" ]
|
|
// Resource = [ "arn:aws:s3:::${id}/*" ]
|
|
// }]
|
|
// })))
|
|
//
|
|
// Here is a more advanced example, assuming that resource is an object whose properties are all outputs, this
|
|
// expression:
|
|
//
|
|
// "v: ${resource[resource.id]}"
|
|
//
|
|
// is transformed into this expression:
|
|
//
|
|
// __apply(__apply(resource.id,eval(id, resource[id])),eval(id, "v: ${id}"))
|
|
//
|
|
// This form is amenable to code generation for targets that require that outputs are resolved before their values are
|
|
// accessible (e.g. Pulumi's JS/TS libraries).
|
|
func RewriteApplies(expr model.Expression, nameInfo NameInfo, applyPromises bool) (model.Expression, hcl.Diagnostics) {
|
|
applyRewriter := &applyRewriter{
|
|
nameInfo: nameInfo,
|
|
applyPromises: applyPromises,
|
|
}
|
|
applyRewriter.activeContext = &inspectContext{
|
|
applyRewriter: applyRewriter,
|
|
root: expr,
|
|
}
|
|
return model.VisitExpression(expr, applyRewriter.preVisit, applyRewriter.postVisit)
|
|
}
|