151 lines
5 KiB
Go
151 lines
5 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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// ListType represents lists of particular element types.
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type ListType struct {
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// ElementType is the element type of the list.
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ElementType Type
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}
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// NewListType creates a new list type with the given element type.
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func NewListType(elementType Type) *ListType {
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return &ListType{ElementType: 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 (*ListType) SyntaxNode() hclsyntax.Node {
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return syntax.None
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}
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// Traverse attempts to traverse the optional type with the given traverser. The result type of traverse(list(T))
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// is T; the traversal fails if the traverser is not a number.
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func (t *ListType) Traverse(traverser hcl.Traverser) (Traversable, hcl.Diagnostics) {
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_, indexType := GetTraverserKey(traverser)
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var diagnostics hcl.Diagnostics
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if !InputType(NumberType).ConversionFrom(indexType).Exists() {
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diagnostics = hcl.Diagnostics{unsupportedListIndex(traverser.SourceRange())}
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}
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return t.ElementType, 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 *ListType) Equals(other Type) bool {
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return t.equals(other, nil)
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}
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func (t *ListType) 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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otherList, ok := other.(*ListType)
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return ok && t.ElementType.equals(otherList.ElementType, seen)
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}
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// AssignableFrom returns true if this type is assignable from the indicated source type. A list(T) is assignable
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// from values of type list(U) where T is assignable from U.
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func (t *ListType) 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 *ListType:
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return t.ElementType.AssignableFrom(src.ElementType)
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case *TupleType:
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for _, src := range src.ElementTypes {
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if !t.ElementType.AssignableFrom(src) {
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return false
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}
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}
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return true
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}
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return false
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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. A list(T)
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// is safely convertible from list(U), set(U), or tuple(U_0 ... U_N) if the element type(s) U is/are safely convertible
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// to T. If any element type is unsafely convertible to T and no element type is safely convertible to T, the
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// conversion is unsafe. Otherwise, no conversion exists.
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func (t *ListType) ConversionFrom(src Type) ConversionKind {
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return t.conversionFrom(src, false, nil)
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}
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func (t *ListType) conversionFrom(src Type, unifying bool, seen map[Type]struct{}) ConversionKind {
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return conversionFrom(t, src, unifying, seen, func() ConversionKind {
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switch src := src.(type) {
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case *ListType:
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return t.ElementType.conversionFrom(src.ElementType, unifying, seen)
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case *SetType:
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return t.ElementType.conversionFrom(src.ElementType, unifying, seen)
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case *TupleType:
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conversionKind := SafeConversion
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for _, src := range src.ElementTypes {
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if ck := t.ElementType.conversionFrom(src, unifying, seen); ck < conversionKind {
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conversionKind = ck
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}
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}
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return conversionKind
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}
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return NoConversion
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})
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}
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func (t *ListType) String() string {
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return t.string(nil)
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}
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func (t *ListType) string(seen map[Type]struct{}) string {
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return fmt.Sprintf("list(%s)", t.ElementType.string(seen))
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}
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func (t *ListType) 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 *TupleType:
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// If the other element is a list type, prefer the list type, but unify the element type.
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elementType, conversionKind := t.ElementType, SafeConversion
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for _, other := range other.ElementTypes {
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element, ck := elementType.unify(other)
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if ck < conversionKind {
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conversionKind = ck
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}
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elementType = element
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}
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return NewListType(elementType), conversionKind
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case *SetType:
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// If the other element is a set type, prefer the list type, but unify the element types.
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elementType, conversionKind := t.ElementType.unify(other.ElementType)
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return NewListType(elementType), conversionKind
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case *ListType:
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// If the other type is a list type, unify based on the element type.
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elementType, conversionKind := t.ElementType.unify(other.ElementType)
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return NewListType(elementType), conversionKind
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default:
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// Prefer the list type.
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return t, t.conversionFrom(other, true, nil)
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}
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})
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}
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func (*ListType) isType() {}
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