Created
July 2, 2016 03:05
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A Swift DSL for building SQLite table creation statements intended for GRDB
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struct _CreateTableBuilder {} | |
struct _PrimaryKeyBuilder {} | |
struct _ForeignKeyBuilder {} | |
struct _SQLExpressible {} | |
struct _SQLSelectable {} | |
struct _CreateTableSelectBuilder {} | |
struct SQLColumn { | |
var name: String | |
init(name: String) { | |
self.name = name | |
} | |
} | |
enum SQL { | |
static func create( | |
table: String, | |
temp: Bool = false, | |
ifNotExists: Bool = false, | |
withoutRowID: Bool = false) -> _CreateTableBuilder { | |
return _CreateTableBuilder() | |
} | |
static func primaryKey( | |
autoIncrement: Bool? = nil, | |
order: _Order? = nil, | |
onConflict: _ConflictResolution? = nil) -> _PrimaryKeyBuilder { | |
return _PrimaryKeyBuilder() | |
} | |
static func foreignKey( | |
table: String, | |
columns: SQLColumn..., | |
onDelete: _DeleteUpdateAction? = nil, | |
onUpdate: _DeleteUpdateAction? = nil, | |
deferrable: Bool? = nil) -> _ForeignKeyBuilder { | |
return _ForeignKeyBuilder() | |
} | |
} | |
extension _CreateTableBuilder { | |
func column( | |
name: SQLColumn, | |
primaryKey: _PrimaryKeyBuilder = false, | |
affinity: _Affinity = .numeric, | |
notNull: _ConflictClause = false, | |
unique: _ConflictClause = false, | |
check: _SQLExpressible? = nil, | |
default: _DefaultOption? = nil, | |
collate: String? = nil, | |
references: _ForeignKeyBuilder? = nil) -> _CreateTableBuilder { | |
return _CreateTableBuilder() | |
} | |
func foreignKey( | |
columns: SQLColumn..., | |
onConflict: _ConflictResolution = .abort, | |
references: _ForeignKeyBuilder) -> _CreateTableBuilder { | |
return _CreateTableBuilder() | |
} | |
func primaryKey( | |
columns: SQLColumn..., | |
onConflict: _ConflictResolution = .abort) -> _CreateTableBuilder { | |
return _CreateTableBuilder() | |
} | |
func unique( | |
columns: SQLColumn..., | |
onConflict: _ConflictResolution = .abort) -> _CreateTableBuilder { | |
return _CreateTableBuilder() | |
} | |
func check(_ expr: _SQLExpressible) -> _CreateTableBuilder { | |
return _CreateTableBuilder() | |
} | |
func select(_ expr: _SQLSelectable) -> _CreateTableSelectBuilder { | |
return _CreateTableSelectBuilder() | |
} | |
} | |
enum _DefaultOption { | |
case number(Int) | |
case literal(String) | |
case expression(_SQLExpressible) | |
} | |
enum _DeleteUpdateAction { | |
case none | |
case restrict | |
case setNull | |
case setDefault | |
case cascade | |
} | |
enum _ConflictResolution { | |
case rollback | |
case abort | |
case fail | |
case ignore | |
case replace | |
} | |
enum _Order { | |
case asc | |
case desc | |
} | |
enum _ConflictClause { | |
case onConflict(_ConflictResolution) | |
case none | |
} | |
enum _Affinity { | |
case integer | |
case text | |
case double | |
case blob | |
case numeric | |
} | |
protocol _ConflictResolvable { | |
var resolution: _ConflictClause { get } | |
} | |
extension _ConflictClause: BooleanLiteralConvertible { | |
init(booleanLiteral value: Bool) { | |
self = value | |
? .onConflict(.abort) | |
: .none | |
} | |
} | |
extension _ConflictClause: _ConflictResolvable { | |
var resolution: _ConflictClause { | |
return self | |
} | |
} | |
extension _PrimaryKeyBuilder: BooleanLiteralConvertible { | |
init(booleanLiteral value: Bool) { | |
self = value | |
? _PrimaryKeyBuilder() | |
: _PrimaryKeyBuilder() | |
} | |
} | |
extension _DefaultOption: IntegerLiteralConvertible { | |
init(integerLiteral value: Int) { | |
self = .number(value) | |
} | |
} | |
extension SQLColumn: StringLiteralConvertible { | |
init(unicodeScalarLiteral value: String) { | |
self = SQLColumn(name: value) | |
} | |
init(extendedGraphemeClusterLiteral value: String) { | |
self = SQLColumn(name: value) | |
} | |
init(stringLiteral value: String) { | |
self = SQLColumn(name: value) | |
} | |
} | |
extension _DefaultOption: StringLiteralConvertible { | |
init(unicodeScalarLiteral value: String) { | |
self = .literal(value) | |
} | |
init(extendedGraphemeClusterLiteral value: String) { | |
self = .literal(value) | |
} | |
init(stringLiteral value: String) { | |
self = .literal(value) | |
} | |
} | |
SQL.create(table: "foo", ifNotExists: true) | |
.column( | |
name: "id", | |
primaryKey: true, | |
affinity: .integer, | |
notNull: true) | |
SQL.create(table: "foo", ifNotExists: true) | |
.column( | |
name: "id", | |
primaryKey: SQL.primaryKey(autoIncrement: true), | |
affinity: .integer, | |
notNull: true) | |
SQL.create(table: "foo", ifNotExists: true) | |
.column( | |
name: "id", | |
primaryKey: SQL.primaryKey( | |
autoIncrement: true, | |
order: .desc, | |
onConflict: .abort), | |
affinity: .integer, | |
notNull: true) | |
SQL.create(table: "foo", ifNotExists: true) | |
.column( | |
name: "id", | |
primaryKey: SQL.primaryKey(onConflict: .abort), | |
affinity: .integer, | |
notNull: true) | |
SQL.create(table: "foo", ifNotExists: true) | |
.column( | |
name: "bar_id", | |
affinity: .integer, | |
references: SQL.foreignKey( | |
table: "bar", | |
columns: "id")) | |
SQL.create(table: "foo", ifNotExists: true) | |
.column( | |
name: "bar_id", | |
affinity: .integer, | |
references: SQL.foreignKey( | |
table: "bar", | |
columns: "id", | |
onDelete: .cascade, | |
onUpdate: .cascade, | |
deferrable: true)) | |
let fooId: SQLColumn = "foo_id" | |
let bazId: SQLColumn = "baz_id" | |
let a: SQLColumn = "a" | |
let b: SQLColumn = "b" | |
let c: SQLColumn = "c" | |
SQL.create(table: "bar", ifNotExists: true) | |
.column(name: fooId, affinity: .integer) | |
.column(name: bazId, affinity: .integer) | |
.column(name: a, affinity: .integer) | |
.column(name: b, affinity: .integer) | |
.column(name: c, affinity: .integer) | |
.unique(columns: fooId, bazId, onConflict: .rollback) | |
.primaryKey(columns: a, b, c, onConflict: .rollback) // runtime error if multiple `primaryKey()` used | |
.foreignKey( | |
columns: fooId, | |
onConflict: .rollback, | |
references: SQL.foreignKey( | |
table: "foo", | |
columns: "id")) | |
.foreignKey( | |
columns: bazId, | |
onConflict: .rollback, | |
references: SQL.foreignKey( | |
table: "baz", | |
columns: "id")) | |
SQL.create(table: "foo", ifNotExists: true) | |
.column(name: "id", affinity: .integer) | |
.column(name: "a", default: 1) |
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