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ethdebug/format/pointer/collection/scope

$schema: "https://json-schema.org/draft/2020-12/schema"
$id: "schema:ethdebug/format/pointer/collection/scope"

title: ethdebug/format/pointer/collection/scope
description: |
  A pointer defined with the aid of additional variables with values specified
  as expressions.

  Variables are specified by the `define` field as an object mapping of
  expression by identifier. The members of one `define` can use each other
  in any order. Member order has no effect.

  - A name in a variable's expression that matches **another** member of
    the same `define` means that member.
  - A name that matches the variable **itself** means the variable with
    that name in the enclosing scope. So a variable can never depend on
    itself.
  - Any other name means a variable of the enclosing scope.

  A consumer evaluates each member after the members it uses. If members
  depend on each other in a cycle, the pointer is invalid.

  Each variable has the sort of the expression that defines it (see
  **ethdebug/format/pointer/expression**). A variable defined by an integer
  expression is an integer. A variable defined by a bytes expression is
  bytes and keeps its width, so it may be used where bytes are required,
  such as an operand of `~concat` or `~keccak256`.

  The variables are visible only within `in`. Pointers outside this scope
  do not see them: later members of an enclosing group, for example, see
  only the variables of their own enclosing scopes. A variable defined here
  with the same identifier as an outer variable shadows it within `in` and
  within the expressions of the other members.

type: object

properties:
  name:
    $ref: "schema:ethdebug/format/pointer/collection#/$defs/Name"

  define:
    title: Mapping of variables to expression value
    type: object
    propertyNames:
      $ref: "schema:ethdebug/format/pointer/identifier"
    additionalProperties:
      $ref: "schema:ethdebug/format/pointer/expression"
  in:
    $ref: "schema:ethdebug/format/pointer"

required:
  - define
  - in

additionalProperties: false

examples:
  - define:
      example-offset:
        ~sum: [1, 2]
      example-length:
        ~product: [2, ~wordsize]
    in:
      name: example
      location: memory
      offset: example-offset
      length: example-length

  - # example: `end` uses `offset`, a member that appears after it. in its
    # own expression, `offset` means the outer `offset` (64), so the inner
    # `offset` is 96 and `end` is 128: the region is 32 bytes at 96.
    define:
      offset: 64
    in:
      define:
        end:
          ~sum: [offset, ~wordsize]
        offset:
          ~sum: [offset, 32]
      in:
        location: memory
        offset: offset
        length:
          ~difference: [end, offset]

  - # example: a variable with a bytes value keeps its width, so it can be
    # hashed directly. this is the storage slot of `m["abc"]` for a Solidity
    # `mapping(string => uint256) m` at slot 0: the key's raw bytes followed
    # by the word-sized slot.
    define:
      key: "0x616263"
    in:
      name: entry
      location: storage
      slot:
        ~keccak256:
          - key
          - ~wordsized: 0

JSON

ethdebug/format/pointer/collection/scope

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "schema:ethdebug/format/pointer/collection/scope",
  "title": "ethdebug/format/pointer/collection/scope",
  "description": "A pointer defined with the aid of additional variables with values specified\nas expressions.\n\nVariables are specified by the `define` field as an object mapping of\nexpression by identifier. The members of one `define` can use each other\nin any order. Member order has no effect.\n\n- A name in a variable's expression that matches **another** member of\n  the same `define` means that member.\n- A name that matches the variable **itself** means the variable with\n  that name in the enclosing scope. So a variable can never depend on\n  itself.\n- Any other name means a variable of the enclosing scope.\n\nA consumer evaluates each member after the members it uses. If members\ndepend on each other in a cycle, the pointer is invalid.\n\nEach variable has the sort of the expression that defines it (see\n**ethdebug/format/pointer/expression**). A variable defined by an integer\nexpression is an integer. A variable defined by a bytes expression is\nbytes and keeps its width, so it may be used where bytes are required,\nsuch as an operand of `~concat` or `~keccak256`.\n\nThe variables are visible only within `in`. Pointers outside this scope\ndo not see them: later members of an enclosing group, for example, see\nonly the variables of their own enclosing scopes. A variable defined here\nwith the same identifier as an outer variable shadows it within `in` and\nwithin the expressions of the other members.\n",
  "type": "object",
  "properties": {
    "name": {
      "$ref": "schema:ethdebug/format/pointer/collection#/$defs/Name"
    },
    "define": {
      "title": "Mapping of variables to expression value",
      "type": "object",
      "propertyNames": {
        "$ref": "schema:ethdebug/format/pointer/identifier"
      },
      "additionalProperties": {
        "$ref": "schema:ethdebug/format/pointer/expression"
      }
    },
    "in": {
      "$ref": "schema:ethdebug/format/pointer"
    }
  },
  "required": [
    "define",
    "in"
  ],
  "additionalProperties": false,
  "examples": [
    {
      "define": {
        "example-offset": {
          "~sum": [
            1,
            2
          ]
        },
        "example-length": {
          "~product": [
            2,
            "~wordsize"
          ]
        }
      },
      "in": {
        "name": "example",
        "location": "memory",
        "offset": "example-offset",
        "length": "example-length"
      }
    },
    {
      "define": {
        "offset": 64
      },
      "in": {
        "define": {
          "end": {
            "~sum": [
              "offset",
              "~wordsize"
            ]
          },
          "offset": {
            "~sum": [
              "offset",
              32
            ]
          }
        },
        "in": {
          "location": "memory",
          "offset": "offset",
          "length": {
            "~difference": [
              "end",
              "offset"
            ]
          }
        }
      }
    },
    {
      "define": {
        "key": "0x616263"
      },
      "in": {
        "name": "entry",
        "location": "storage",
        "slot": {
          "~keccak256": [
            "key",
            {
              "~wordsized": 0
            }
          ]
        }
      }
    }
  ]
}

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