mirror of
https://gitea.com/Lydanne/buildx.git
synced 2025-07-09 21:17:09 +08:00
Patrick Van Stee
314
vendor/github.com/zclconf/go-cty/cty/convert/unify.go
generated
vendored
Normal file
314
vendor/github.com/zclconf/go-cty/cty/convert/unify.go
generated
vendored
Normal file
@ -0,0 +1,314 @@
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package convert
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import (
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"github.com/zclconf/go-cty/cty"
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)
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// The current unify implementation is somewhat inefficient, but we accept this
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// under the assumption that it will generally be used with small numbers of
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// types and with types of reasonable complexity. However, it does have a
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// "happy path" where all of the given types are equal.
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//
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// This function is likely to have poor performance in cases where any given
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// types are very complex (lots of deeply-nested structures) or if the list
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// of types itself is very large. In particular, it will walk the nested type
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// structure under the given types several times, especially when given a
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// list of types for which unification is not possible, since each permutation
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// will be tried to determine that result.
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func unify(types []cty.Type, unsafe bool) (cty.Type, []Conversion) {
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if len(types) == 0 {
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// Degenerate case
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return cty.NilType, nil
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}
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// If all of the given types are of the same structural kind, we may be
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// able to construct a new type that they can all be unified to, even if
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// that is not one of the given types. We must try this before the general
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// behavior below because in unsafe mode we can convert an object type to
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// a subset of that type, which would be a much less useful conversion for
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// unification purposes.
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{
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objectCt := 0
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tupleCt := 0
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dynamicCt := 0
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for _, ty := range types {
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switch {
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case ty.IsObjectType():
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objectCt++
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case ty.IsTupleType():
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tupleCt++
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case ty == cty.DynamicPseudoType:
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dynamicCt++
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default:
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break
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}
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}
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switch {
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case objectCt > 0 && (objectCt+dynamicCt) == len(types):
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return unifyObjectTypes(types, unsafe, dynamicCt > 0)
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case tupleCt > 0 && (tupleCt+dynamicCt) == len(types):
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return unifyTupleTypes(types, unsafe, dynamicCt > 0)
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case objectCt > 0 && tupleCt > 0:
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// Can never unify object and tuple types since they have incompatible kinds
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return cty.NilType, nil
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}
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}
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prefOrder := sortTypes(types)
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// sortTypes gives us an order where earlier items are preferable as
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// our result type. We'll now walk through these and choose the first
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// one we encounter for which conversions exist for all source types.
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conversions := make([]Conversion, len(types))
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Preferences:
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for _, wantTypeIdx := range prefOrder {
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wantType := types[wantTypeIdx]
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for i, tryType := range types {
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if i == wantTypeIdx {
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// Don't need to convert our wanted type to itself
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conversions[i] = nil
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continue
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}
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if tryType.Equals(wantType) {
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conversions[i] = nil
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continue
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}
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if unsafe {
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conversions[i] = GetConversionUnsafe(tryType, wantType)
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} else {
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conversions[i] = GetConversion(tryType, wantType)
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}
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if conversions[i] == nil {
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// wantType is not a suitable unification type, so we'll
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// try the next one in our preference order.
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continue Preferences
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}
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}
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return wantType, conversions
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}
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// If we fall out here, no unification is possible
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return cty.NilType, nil
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}
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func unifyObjectTypes(types []cty.Type, unsafe bool, hasDynamic bool) (cty.Type, []Conversion) {
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// If we had any dynamic types in the input here then we can't predict
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// what path we'll take through here once these become known types, so
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// we'll conservatively produce DynamicVal for these.
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if hasDynamic {
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return unifyAllAsDynamic(types)
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}
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// There are two different ways we can succeed here:
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// - If all of the given object types have the same set of attribute names
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// and the corresponding types are all unifyable, then we construct that
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// type.
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// - If the given object types have different attribute names or their
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// corresponding types are not unifyable, we'll instead try to unify
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// all of the attribute types together to produce a map type.
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//
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// Our unification behavior is intentionally stricter than our conversion
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// behavior for subset object types because user intent is different with
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// unification use-cases: it makes sense to allow {"foo":true} to convert
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// to emptyobjectval, but unifying an object with an attribute with the
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// empty object type should be an error because unifying to the empty
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// object type would be suprising and useless.
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firstAttrs := types[0].AttributeTypes()
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for _, ty := range types[1:] {
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thisAttrs := ty.AttributeTypes()
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if len(thisAttrs) != len(firstAttrs) {
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// If number of attributes is different then there can be no
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// object type in common.
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return unifyObjectTypesToMap(types, unsafe)
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}
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for name := range thisAttrs {
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if _, ok := firstAttrs[name]; !ok {
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// If attribute names don't exactly match then there can be
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// no object type in common.
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return unifyObjectTypesToMap(types, unsafe)
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}
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}
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}
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// If we get here then we've proven that all of the given object types
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// have exactly the same set of attribute names, though the types may
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// differ.
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retAtys := make(map[string]cty.Type)
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atysAcross := make([]cty.Type, len(types))
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for name := range firstAttrs {
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for i, ty := range types {
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atysAcross[i] = ty.AttributeType(name)
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}
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retAtys[name], _ = unify(atysAcross, unsafe)
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if retAtys[name] == cty.NilType {
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// Cannot unify this attribute alone, which means that unification
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// of everything down to a map type can't be possible either.
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return cty.NilType, nil
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}
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}
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retTy := cty.Object(retAtys)
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conversions := make([]Conversion, len(types))
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for i, ty := range types {
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if ty.Equals(retTy) {
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continue
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}
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if unsafe {
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conversions[i] = GetConversionUnsafe(ty, retTy)
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} else {
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conversions[i] = GetConversion(ty, retTy)
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}
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if conversions[i] == nil {
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// Shouldn't be reachable, since we were able to unify
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return unifyObjectTypesToMap(types, unsafe)
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}
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}
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return retTy, conversions
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}
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func unifyObjectTypesToMap(types []cty.Type, unsafe bool) (cty.Type, []Conversion) {
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// This is our fallback case for unifyObjectTypes, where we see if we can
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// construct a map type that can accept all of the attribute types.
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var atys []cty.Type
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for _, ty := range types {
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for _, aty := range ty.AttributeTypes() {
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atys = append(atys, aty)
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}
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}
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ety, _ := unify(atys, unsafe)
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if ety == cty.NilType {
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return cty.NilType, nil
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}
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retTy := cty.Map(ety)
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conversions := make([]Conversion, len(types))
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for i, ty := range types {
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if ty.Equals(retTy) {
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continue
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}
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if unsafe {
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conversions[i] = GetConversionUnsafe(ty, retTy)
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} else {
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conversions[i] = GetConversion(ty, retTy)
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}
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if conversions[i] == nil {
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return cty.NilType, nil
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}
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}
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return retTy, conversions
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}
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func unifyTupleTypes(types []cty.Type, unsafe bool, hasDynamic bool) (cty.Type, []Conversion) {
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// If we had any dynamic types in the input here then we can't predict
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// what path we'll take through here once these become known types, so
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// we'll conservatively produce DynamicVal for these.
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if hasDynamic {
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return unifyAllAsDynamic(types)
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}
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// There are two different ways we can succeed here:
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// - If all of the given tuple types have the same sequence of element types
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// and the corresponding types are all unifyable, then we construct that
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// type.
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// - If the given tuple types have different element types or their
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// corresponding types are not unifyable, we'll instead try to unify
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// all of the elements types together to produce a list type.
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firstEtys := types[0].TupleElementTypes()
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for _, ty := range types[1:] {
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thisEtys := ty.TupleElementTypes()
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if len(thisEtys) != len(firstEtys) {
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// If number of elements is different then there can be no
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// tuple type in common.
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return unifyTupleTypesToList(types, unsafe)
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}
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}
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// If we get here then we've proven that all of the given tuple types
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// have the same number of elements, though the types may differ.
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retEtys := make([]cty.Type, len(firstEtys))
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atysAcross := make([]cty.Type, len(types))
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for idx := range firstEtys {
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for tyI, ty := range types {
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atysAcross[tyI] = ty.TupleElementTypes()[idx]
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}
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retEtys[idx], _ = unify(atysAcross, unsafe)
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if retEtys[idx] == cty.NilType {
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// Cannot unify this element alone, which means that unification
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// of everything down to a map type can't be possible either.
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return cty.NilType, nil
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}
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}
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retTy := cty.Tuple(retEtys)
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conversions := make([]Conversion, len(types))
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for i, ty := range types {
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if ty.Equals(retTy) {
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continue
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}
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if unsafe {
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conversions[i] = GetConversionUnsafe(ty, retTy)
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} else {
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conversions[i] = GetConversion(ty, retTy)
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}
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if conversions[i] == nil {
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// Shouldn't be reachable, since we were able to unify
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return unifyTupleTypesToList(types, unsafe)
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}
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}
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return retTy, conversions
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}
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func unifyTupleTypesToList(types []cty.Type, unsafe bool) (cty.Type, []Conversion) {
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// This is our fallback case for unifyTupleTypes, where we see if we can
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// construct a list type that can accept all of the element types.
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var etys []cty.Type
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for _, ty := range types {
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for _, ety := range ty.TupleElementTypes() {
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etys = append(etys, ety)
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}
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}
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ety, _ := unify(etys, unsafe)
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if ety == cty.NilType {
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return cty.NilType, nil
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}
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retTy := cty.List(ety)
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conversions := make([]Conversion, len(types))
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for i, ty := range types {
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if ty.Equals(retTy) {
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continue
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}
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if unsafe {
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conversions[i] = GetConversionUnsafe(ty, retTy)
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} else {
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conversions[i] = GetConversion(ty, retTy)
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}
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if conversions[i] == nil {
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// Shouldn't be reachable, since we were able to unify
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return unifyObjectTypesToMap(types, unsafe)
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}
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}
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return retTy, conversions
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}
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func unifyAllAsDynamic(types []cty.Type) (cty.Type, []Conversion) {
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conversions := make([]Conversion, len(types))
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for i := range conversions {
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conversions[i] = func(cty.Value) (cty.Value, error) {
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return cty.DynamicVal, nil
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}
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}
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return cty.DynamicPseudoType, conversions
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}
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Reference in New Issue
Block a user