118 lines
4.2 KiB
Go
118 lines
4.2 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 model
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import (
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"fmt"
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"github.com/hashicorp/hcl/v2"
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"github.com/hashicorp/hcl/v2/hclsyntax"
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"github.com/pulumi/pulumi/pkg/v2/codegen/hcl2/syntax"
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)
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// OutputType represents eventual values that carry additional application-specific information.
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type OutputType struct {
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// ElementType is the element type of the output.
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ElementType Type
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}
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// NewOutputType creates a new output type with the given element type after replacing any output or promise types
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// within the element type with their respective element types.
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func NewOutputType(elementType Type) *OutputType {
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return &OutputType{ElementType: ResolveOutputs(elementType)}
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}
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// SyntaxNode returns the syntax node for the type. This is always syntax.None.
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func (*OutputType) SyntaxNode() hclsyntax.Node {
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return syntax.None
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}
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// Traverse attempts to traverse the output type with the given traverser. The result type of traverse(output(T))
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// is output(traverse(T)).
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func (t *OutputType) Traverse(traverser hcl.Traverser) (Traversable, hcl.Diagnostics) {
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element, diagnostics := t.ElementType.Traverse(traverser)
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return NewOutputType(element.(Type)), diagnostics
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}
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// Equals returns true if this type has the same identity as the given type.
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func (t *OutputType) Equals(other Type) bool {
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return t.equals(other, nil)
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}
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func (t *OutputType) equals(other Type, seen map[Type]struct{}) bool {
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if t == other {
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return true
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}
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otherOutput, ok := other.(*OutputType)
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return ok && t.ElementType.equals(otherOutput.ElementType, seen)
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}
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// AssignableFrom returns true if this type is assignable from the indicated source type. An output(T) is assignable
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// from values of type output(U), promise(U), and U, where T is assignable from U.
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func (t *OutputType) AssignableFrom(src Type) bool {
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return assignableFrom(t, src, func() bool {
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switch src := src.(type) {
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case *OutputType:
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return t.ElementType.AssignableFrom(src.ElementType)
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case *PromiseType:
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return t.ElementType.AssignableFrom(src.ElementType)
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}
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return t.ElementType.AssignableFrom(src)
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})
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}
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// ConversionFrom returns the kind of conversion (if any) that is possible from the source type to this type. An
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// output(T) is convertible from a type U, output(U), or promise(U) if U is convertible to T. If the conversion from
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// U to T is unsafe, the entire conversion is unsafe. Otherwise, the conversion is safe.
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func (t *OutputType) ConversionFrom(src Type) ConversionKind {
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return t.conversionFrom(src, false)
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}
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func (t *OutputType) conversionFrom(src Type, unifying bool) ConversionKind {
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return conversionFrom(t, src, unifying, func() ConversionKind {
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switch src := src.(type) {
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case *OutputType:
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return t.ElementType.conversionFrom(src.ElementType, unifying)
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case *PromiseType:
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return t.ElementType.conversionFrom(src.ElementType, unifying)
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}
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return t.ElementType.conversionFrom(src, unifying)
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})
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}
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func (t *OutputType) String() string {
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return fmt.Sprintf("output(%v)", t.ElementType)
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}
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func (t *OutputType) unify(other Type) (Type, ConversionKind) {
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return unify(t, other, func() (Type, ConversionKind) {
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switch other := other.(type) {
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case *OutputType:
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// If the other type is an output type, unify based on the element type.
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elementType, conversionKind := t.ElementType.unify(other.ElementType)
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return NewOutputType(elementType), conversionKind
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case *PromiseType:
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// If the other type is a promise type, unify based on the element type.
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elementType, conversionKind := t.ElementType.unify(other.ElementType)
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return NewOutputType(elementType), conversionKind
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default:
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// Prefer the output type.
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return t, t.conversionFrom(other, true)
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}
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})
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}
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func (t *OutputType) isType() {}
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