{
  "walker": "jsonschema-2019-09",
  "rules": [
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/core",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/upgrade-official-metaschema",
        "type": "object",
        "required": [ "$schema" ],
        "properties": {
          "$schema": {
            "const": "https://json-schema.org/draft/2019-09/schema"
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "schema" },
          { "$$schema": "https://json-schema.org/draft/2020-12/schema" }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/open-tuple",
        "$comment": "https://json-schema.org/draft/2020-12/release-notes.html",
        "type": "object",
        "required": [ "items" ],
        "properties": {
          "items": {
            "type": "array"
          },
          "additionalItems": false
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, 'items')" },
          {
            "prefixItems": {
              "$eval": "schema.items"
            }
          }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/open-tuple-in-ref",
        "$comment": "https://json-schema.org/draft/2020-12/release-notes.html",
        "type": "object",
        "required": [ "$ref" ],
        "properties": {
          "$ref": {
            "type": "string",
            "pattern": "/items/\\d+"
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, '$ref')" },
          {
            "$$ref": {
              "$eval": "replace(schema['$ref'], '/items/(\\d+)', '/prefixItems/$1')"
            }
          }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/additional-items-in-ref",
        "$comment": "https://json-schema.org/draft/2020-12/release-notes.html",
        "type": "object",
        "required": [ "$ref" ],
        "properties": {
          "$ref": {
            "type": "string",
            "pattern": "/additionalItems"
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, '$ref')" },
          {
            "$$ref": {
              "$eval": "replace(schema['$ref'], '/additionalItems', '/items')"
            }
          }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/closed-tuple",
        "$comment": "https://json-schema.org/draft/2020-12/release-notes.html",
        "type": "object",
        "required": [ "items", "additionalItems" ],
        "properties": {
          "additionalItems": true,
          "items": {
            "type": "array"
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, 'additionalItems')" },
          {
            "items": {
              "$eval": "schema.additionalItems"
            },
            "prefixItems": {
              "$eval": "schema.items"
            }
          }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/core",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/empty-object",
        "const": {}
      },
      "transform": {
        "$eval": "true"
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/core",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/negated-empty-object",
        "const": { "not": true }
      },
      "transform": {
        "$eval": "false"
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/enum-to-const",
        "type": "object",
        "required": [ "enum" ],
        "properties": {
          "enum": {
            "type": "array",
            "minItems": 1,
            "maxItems": 1
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, 'enum')" },
          {
            "const": {
              "$eval": "schema.enum[0]"
            }
          }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/recursive-anchor-false",
        "type": "object",
        "required": [ "$recursiveAnchor" ],
        "properties": {
          "$recursiveAnchor": {
            "const": false
          }
        }
      },
      "transform": {
        "$eval": "omit(schema, '$recursiveAnchor')"
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/recursive-anchor-true",
        "type": "object",
        "required": [ "$recursiveAnchor" ],
        "properties": {
          "$recursiveAnchor": {
            "const": true
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, '$recursiveAnchor')" },
          {
            "$$dynamicAnchor": {
              "$eval": "'anchor-' + jsonHash(original)"
            }
          }
        ]
      }
    },
    {
      "vocabulary": "https://json-schema.org/draft/2019-09/vocab/validation",
      "condition": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "$id": "https://github.com/sourcemeta/alterschema/rules/jsonschema-2019-09-to-2020-12/recursive-ref-empty-fragment",
        "type": "object",
        "required": [ "$recursiveRef" ],
        "properties": {
          "$recursiveRef": {
            "const": "#"
          }
        }
      },
      "transform": {
        "$merge": [
          { "$eval": "omit(schema, '$recursiveRef')" },
          {
            "$$dynamicRef": {
              "$if": "hasContext('$recursiveAnchor', true)",
              "then": {
                "$eval": "'#anchor-' + jsonHash(original)"
              },
              "else": {
                "$eval": "schema['$recursiveRef']"
              }
            }
          }
        ]
      }
    }
  ]
}