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JSON Schema Grammar

A JSG definition consists of three sections:

  1. Directives -- .TYPE and .IGNORE directives
  2. Definitions -- JSON Object and Arrary definitions
  3. Lexical Rules -- string and number matching rules

Directives

.TYPE directive

The .TYPE directive:

  1. Identifies a single property that names the JSG production type of a JSON object
  2. (Optionally) lists one or more production types that do not use the .TYPE discriminator

Syntax

.TYPE <type> [- <type> [<type> ...]] ;

JSG JSON result
doc { a:. } {"a":"hello"} pass
{"type": "doc", "a":"hello"} fail
.TYPE type; doc {a:.} {"type": "doc", "a":"hello"} pass
{"type": "doc", "a":{"a":0}} fail
{"a":"hello"} (depends on context)

.IGNORE directive

The .IGNORE directive identifies a list of properties to globally ignore.

Syntax

.IGNORE <type> [<type> ...] ;

Examples

JSG JSON result
doc {a:@string} {"a":"hello"} pass
{"id": "doc", "a":"hello"} fail
.IGNORE id, idx; doc {a:@string} {"id": "doc", "a":"hello", "idx":243} pass
{"id": "doc", "a":"hello", "foo":243} fail

Definitions

A JSG definition consists of the definition name followed by the definition enclosed in curly braces ({ ... })

JSG Description
<identifier> : <valueType> [<cardinality>] <identifier> is any valid JSON string, with the exception that the enclosing quotes can be double ("), single (') or omitted completely if the string consists solely of a-z, A-Z, 0-9 and @ characters.

Value Type

Type Description Example
<quoted string> Fixed value doc {a:"hello"}
<builtin type> Builtin JSON type (w/ extensions). Possible values are:

@string : JSON string
@number : JSON number
@int : JSON number without ., e or E characters
@bool: true or false
@null : null
@array : a JSON array ([ ... ])
@object : a JSON object ( { ... })		 doc {a:@number}
<any> Any JSON type. Represented by a single dot (.) doc {a: .}
<pattern reference> The name of a lexical pattern defined in the Lexical Rules doc {a: HEX4 }

@terminals
HEX4: HEX HEX HEX HEX
HEX : [0-9]
<identifier reference> A reference to a JSG definition. person {legal: name, alt: alias }
name {first: @string, last: @string}
alias [name]
(empty) An empty object. doc {}
<sequence>