sigs.k8s.io/controller-tools@v0.15.1-0.20240515195456-85686cb69316/pkg/crd/schema_visitor.go (about) 1 /* 2 Copyright 2019 The Kubernetes Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package crd 18 19 import ( 20 apiext "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1" 21 ) 22 23 // SchemaVisitor walks the nodes of a schema. 24 type SchemaVisitor interface { 25 // Visit is called for each schema node. If it returns a visitor, 26 // the visitor will be called on each direct child node, and then 27 // this visitor will be called again with `nil` to indicate that 28 // all children have been visited. If a nil visitor is returned, 29 // children are not visited. 30 // 31 // It is *NOT* safe to save references to the given schema. 32 // Make deepcopies if you need to keep things around beyond 33 // the lifetime of the call. 34 Visit(schema *apiext.JSONSchemaProps) SchemaVisitor 35 } 36 37 // EditSchema walks the given schema using the given visitor. Actual 38 // pointers to each schema node are passed to the visitor, so any changes 39 // made by the visitor will be reflected to the passed-in schema. 40 func EditSchema(schema *apiext.JSONSchemaProps, visitor SchemaVisitor) { 41 walker := schemaWalker{visitor: visitor} 42 walker.walkSchema(schema) 43 } 44 45 // schemaWalker knows how to walk the schema, saving modifications 46 // made by the given visitor. 47 type schemaWalker struct { 48 visitor SchemaVisitor 49 } 50 51 // walkSchema walks the given schema, saving modifications made by the visitor 52 // (this is as simple as passing a pointer in most cases, but special care 53 // needs to be taken to persist with maps). It also visits referenced 54 // schemata, dealing with circular references appropriately. The returned 55 // visitor will be used to visit all "children" of the current schema, followed 56 // by a nil schema with the returned visitor to mark completion. If a nil visitor 57 // is returned, traversal will no continue into the children of the current schema. 58 func (w schemaWalker) walkSchema(schema *apiext.JSONSchemaProps) { 59 // Walk a potential chain of schema references, keeping track of seen 60 // references to avoid circular references 61 subVisitor := w.visitor 62 seenRefs := map[string]bool{} 63 if schema.Ref != nil { 64 seenRefs[*schema.Ref] = true 65 } 66 for { 67 subVisitor = subVisitor.Visit(schema) 68 if subVisitor == nil { 69 return 70 } 71 // mark completion of the visitor 72 defer subVisitor.Visit(nil) 73 74 // Break if schema is not a reference or a cycle is detected 75 if schema.Ref == nil || len(*schema.Ref) == 0 || seenRefs[*schema.Ref] { 76 break 77 } 78 seenRefs[*schema.Ref] = true 79 } 80 81 // walk sub-schemata 82 subWalker := schemaWalker{visitor: subVisitor} 83 if schema.Items != nil { 84 subWalker.walkPtr(schema.Items.Schema) 85 subWalker.walkSlice(schema.Items.JSONSchemas) 86 } 87 subWalker.walkSlice(schema.AllOf) 88 subWalker.walkSlice(schema.OneOf) 89 subWalker.walkSlice(schema.AnyOf) 90 subWalker.walkPtr(schema.Not) 91 subWalker.walkMap(schema.Properties) 92 if schema.AdditionalProperties != nil { 93 subWalker.walkPtr(schema.AdditionalProperties.Schema) 94 } 95 subWalker.walkMap(schema.PatternProperties) 96 for name, dep := range schema.Dependencies { 97 subWalker.walkPtr(dep.Schema) 98 schema.Dependencies[name] = dep 99 } 100 if schema.AdditionalItems != nil { 101 subWalker.walkPtr(schema.AdditionalItems.Schema) 102 } 103 subWalker.walkMap(schema.Definitions) 104 } 105 106 // walkMap walks over values of the given map, saving changes to them. 107 func (w schemaWalker) walkMap(defs map[string]apiext.JSONSchemaProps) { 108 for name, def := range defs { 109 // this is iter var reference is because we immediately preseve it below 110 //nolint:gosec 111 w.walkSchema(&def) 112 // make sure the edits actually go through since we can't 113 // take a reference to the value in the map 114 defs[name] = def 115 } 116 } 117 118 // walkSlice walks over items of the given slice. 119 func (w schemaWalker) walkSlice(defs []apiext.JSONSchemaProps) { 120 for i := range defs { 121 w.walkSchema(&defs[i]) 122 } 123 } 124 125 // walkPtr walks over the contents of the given pointer, if it's not nil. 126 func (w schemaWalker) walkPtr(def *apiext.JSONSchemaProps) { 127 if def == nil { 128 return 129 } 130 w.walkSchema(def) 131 }