diff --git a/Sources/SQLite/Core/Statement.swift b/Sources/SQLite/Core/Statement.swift
index a9232bba..b763e40e 100644
--- a/Sources/SQLite/Core/Statement.swift
+++ b/Sources/SQLite/Core/Statement.swift
@@ -191,6 +191,14 @@ public final class Statement {
}
+extension Statement {
+
+ func rowCursorNext() throws -> [Binding?]? {
+ return try step() ? Array(row) : nil
+ }
+
+}
+
extension Statement : Sequence {
public func makeIterator() -> Statement {
diff --git a/Sources/SQLite/Typed/Query.swift b/Sources/SQLite/Typed/Query.swift
index c9d2ea9c..f3584f46 100644
--- a/Sources/SQLite/Typed/Query.swift
+++ b/Sources/SQLite/Typed/Query.swift
@@ -890,58 +890,88 @@ public struct Delete : ExpressionType {
}
+public struct RowCursor {
+ let statement: Statement
+ let columnNames: [String: Int]
+
+ public func next() throws -> Row? {
+ return try statement.rowCursorNext().flatMap { Row(columnNames, $0) }
+ }
+
+ public func map<T>(_ transform: (Row) throws -> T) throws -> [T] {
+ var elements = [T]()
+ while true {
+ if let row = try next() {
+ elements.append(try transform(row))
+ } else {
+ break
+ }
+ }
+
+ return elements
+ }
+}
+
extension Connection {
+
+ public func prepareCursor(_ query: QueryType) throws -> RowCursor {
+ let expression = query.expression
+ let statement = try prepare(expression.template, expression.bindings)
+ return RowCursor(statement: statement, columnNames: try columnNamesForQuery(query))
+ }
public func prepare(_ query: QueryType) throws -> AnySequence<Row> {
let expression = query.expression
let statement = try prepare(expression.template, expression.bindings)
- let columnNames: [String: Int] = try {
- var (columnNames, idx) = ([String: Int](), 0)
- column: for each in query.clauses.select.columns {
- var names = each.expression.template.characters.split { $0 == "." }.map(String.init)
- let column = names.removeLast()
- let namespace = names.joined(separator: ".")
-
- func expandGlob(_ namespace: Bool) -> ((QueryType) throws -> Void) {
- return { (query: QueryType) throws -> (Void) in
- var q = type(of: query).init(query.clauses.from.name, database: query.clauses.from.database)
- q.clauses.select = query.clauses.select
- let e = q.expression
- var names = try self.prepare(e.template, e.bindings).columnNames.map { $0.quote() }
- if namespace { names = names.map { "\(query.tableName().expression.template).\($0)" } }
- for name in names { columnNames[name] = idx; idx += 1 }
- }
- }
+ let columnNames = try columnNamesForQuery(query)
- if column == "*" {
- var select = query
- select.clauses.select = (false, [Expression<Void>(literal: "*") as Expressible])
- let queries = [select] + query.clauses.join.map { $0.query }
- if !namespace.isEmpty {
- for q in queries {
- if q.tableName().expression.template == namespace {
- try expandGlob(true)(q)
- continue column
- }
- }
- fatalError("no such table: \(namespace)")
- }
+ return AnySequence {
+ AnyIterator { statement.next().map { Row(columnNames, $0) } }
+ }
+ }
+
+ private func columnNamesForQuery(_ query: QueryType) throws -> [String: Int] {
+ var (columnNames, idx) = ([String: Int](), 0)
+ column: for each in query.clauses.select.columns {
+ var names = each.expression.template.characters.split { $0 == "." }.map(String.init)
+ let column = names.removeLast()
+ let namespace = names.joined(separator: ".")
+
+ func expandGlob(_ namespace: Bool) -> ((QueryType) throws -> Void) {
+ return { (query: QueryType) throws -> (Void) in
+ var q = type(of: query).init(query.clauses.from.name, database: query.clauses.from.database)
+ q.clauses.select = query.clauses.select
+ let e = q.expression
+ var names = try self.prepare(e.template, e.bindings).columnNames.map { $0.quote() }
+ if namespace { names = names.map { "\(query.tableName().expression.template).\($0)" } }
+ for name in names { columnNames[name] = idx; idx += 1 }
+ }
+ }
+
+ if column == "*" {
+ var select = query
+ select.clauses.select = (false, [Expression<Void>(literal: "*") as Expressible])
+ let queries = [select] + query.clauses.join.map { $0.query }
+ if !namespace.isEmpty {
for q in queries {
- try expandGlob(query.clauses.join.count > 0)(q)
+ if q.tableName().expression.template == namespace {
+ try expandGlob(true)(q)
+ continue column
+ }
}
- continue
+ fatalError("no such table: \(namespace)")
}
-
- columnNames[each.expression.template] = idx
- idx += 1
+ for q in queries {
+ try expandGlob(query.clauses.join.count > 0)(q)
+ }
+ continue
}
- return columnNames
- }()
-
- return AnySequence {
- AnyIterator { statement.next().map { Row(columnNames, $0) } }
+
+ columnNames[each.expression.template] = idx
+ idx += 1
}
+ return columnNames
}
public func scalar<V : Value>(_ query: ScalarQuery<V>) throws -> V {
@@ -967,7 +997,7 @@ extension Connection {
}
public func pluck(_ query: QueryType) throws -> Row? {
- return try prepare(query.limit(1, query.clauses.limit?.offset)).makeIterator().next()
+ return try prepareCursor(query.limit(1, query.clauses.limit?.offset)).next()
}
/// Runs an `Insert` query.
diff --git a/Tests/SQLiteTests/QueryTests.swift b/Tests/SQLiteTests/QueryTests.swift
index 2cf164c6..bbf1ee42 100644
--- a/Tests/SQLiteTests/QueryTests.swift
+++ b/Tests/SQLiteTests/QueryTests.swift
@@ -333,6 +333,16 @@ class QueryIntegrationTests : SQLiteTestCase {
_ = user[users[managerId]]
}
}
+
+ func test_prepareCursor() {
+ let names = ["a", "b", "c"]
+ try! InsertUsers(names)
+
+ let emailColumn = Expression<String>("email")
+ let emails = try! db.prepareCursor(users).map { $0[emailColumn] }
+
+ XCTAssertEqual(names.map({ "\($0)@example.com" }), emails.sorted())
+ }
func test_scalar() {
XCTAssertEqual(0, try! db.scalar(users.count))