prequel - v0.1.0

prequel/ast

Types

Attribute

</>

An attribute that can be found inside the body of an entity or a relationship.

pub type Attribute {
  Attribute(
    span: Span,
    name: String,
    cardinality: Cardinality,
    type_: Type,
  )
}

Constructors 

  • Attribute(
  span: Span,
  name: String,
  cardinality: Cardinality,
  type_: Type,
)

Cardinality

</>

The cardinality of an attribute or of an entity in a relationship.

pub type Cardinality {
  Unbounded(span: Span, lower_bound: Int)
  Bounded(span: Span, lower_bound: Int, upper_bound: Int)
}

Constructors 

  • Unbounded(span: Span, lower_bound: Int)

    A cardinality where the upper bound is the letter N, for example (1-N), (0-N) are both unbounded.

  • Bounded(span: Span, lower_bound: Int, upper_bound: Int)

    A cardinality where both upper and lower bound are numbers, for example (0-1), (1-1) are both bounded.

Entity

</>

An entity as described by the ER model. It has a name, it can have zero or more attributes that can also act as keys. The first key is always considered to be the primary key. An entity can also be the root of a hierarchy of sub-entities.

pub type Entity {
  Entity(
    span: Span,
    name: String,
    keys: List(Key),
    attributes: List(Attribute),
    inner_relationships: List(Relationship),
    children: Option(Hierarchy),
  )
}

Constructors 

  • Entity(
  span: Span,
  name: String,
  keys: List(Key),
  attributes: List(Attribute),
  inner_relationships: List(Relationship),
  children: Option(Hierarchy),
)

Hierarchy

</>

A hierarchy of entities, it specifies wether it is overlapping or disjoint and wether it is total or partial.

pub type Hierarchy {
  Hierarchy(
    span: Span,
    overlapping: Overlapping,
    totality: Totality,
    children: NonEmptyList(Entity),
  )
}

Constructors 

  • Hierarchy(
  span: Span,
  overlapping: Overlapping,
  totality: Totality,
  children: NonEmptyList(Entity),
)

Key

</>

The key of an entity, its composed of at least the name of one of the attributes (or one of the relationships that can be used as external keys).

pub type Key {
  SingleKey(span: Span, key: String, type_: Option(Type))
  ComposedKey(span: Span, keys: NonEmptyList(String))
}

Constructors 

  • SingleKey(span: Span, key: String, type_: Option(Type))
  • ComposedKey(span: Span, keys: NonEmptyList(String))

Module

</>

A module is the result obtained by parsing a file, it contains a list of entities and relationships.

pub type Module {
  Module(
    entities: List(Entity),
    relationships: List(Relationship),
  )
}

Constructors 

  • Module(entities: List(Entity), relationships: List(Relationship))

Overlapping

</>

The overlapping of a hierarchy: it can either be Overlapped or Disjoint.

pub type Overlapping {
  Overlapped
  Disjoint
}

Constructors 

  • Overlapped
  • Disjoint

Relationship

</>

A relationship as described by the ER model. It always involves at least two entities and can also have attributes.

pub type Relationship {
  Relationship(
    span: Span,
    name: String,
    entity: RelationshipEntity,
    entities: NonEmptyList(RelationshipEntity),
    attributes: List(Attribute),
  )
}

Constructors 

  • Relationship(
  span: Span,
  name: String,
  entity: RelationshipEntity,
  entities: NonEmptyList(RelationshipEntity),
  attributes: List(Attribute),
)

RelationshipEntity

</>

An entity that takes part in a relationship with a given cardinality.

pub type RelationshipEntity {
  RelationshipEntity(
    span: Span,
    name: String,
    cardinality: Cardinality,
  )
}

Constructors 

  • RelationshipEntity(
  span: Span,
  name: String,
  cardinality: Cardinality,
)

Totality

</>

The totality of a hierarchy: it can either be Total or Partial.

pub type Totality {
  Total
  Partial
}

Constructors 

  • Total
  • Partial

Type

</>

The type of an attribute.

pub type Type {
  NoType
  ComposedAttribute(span: Span, attributes: List(Attribute))
}

Constructors 

  • NoType
  • ComposedAttribute(span: Span, attributes: List(Attribute))
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