/
fragment.scala
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/
fragment.scala
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// Copyright (c) 2013-2018 Rob Norris and Contributors
// This software is licensed under the MIT License (MIT).
// For more information see LICENSE or https://opensource.org/licenses/MIT
package doobie.util
import cats._
import cats.data.Chain
import cats.implicits._
import doobie._, doobie.implicits._
import doobie.util.pos.Pos
import doobie.util.param.Param.Elem
import doobie.enum.Nullability._
import java.sql.{ PreparedStatement, ResultSet }
import scala.Predef.augmentString
/** Module defining the `Fragment` data type. */
object fragment {
/**
* A statement fragment, which may include interpolated values. Fragments can be composed by
* concatenation, which maintains the correct offset and mappings for interpolated values. Once
* constructed a `Fragment` is opaque; it has no externally observable properties. Fragments are
* eventually used to construct a [[Query0]] or [[Update0]].
*/
final class Fragment(
protected val sql: String,
protected val elems: Chain[Elem],
protected val pos: Option[Pos]
) {
// Unfortunately we need to produce a Write for our list of elems, which is a bit of a grunt
// but straightforward nonetheless. And it's stacksafe!
private implicit lazy val write: Write[elems.type] = {
import Elem._
val puts: List[(Put[_], NullabilityKnown)] =
elems.map {
case Arg(_, p) => (p, NoNulls)
case Opt(_, p) => (p, Nullable)
} .toList
val toList: elems.type => List[Any] = elems =>
elems.map {
case Arg(a, _) => a
case Opt(a, _) => a
} .toList
@SuppressWarnings(Array("org.wartremover.warts.Var"))
val unsafeSet: (PreparedStatement, Int, elems.type) => Unit = { (ps, n, elems) =>
var index = n
elems.iterator.foreach { e =>
e match {
case Arg(a, p) => p.unsafeSetNonNullable(ps, index, a)
case Opt(a, p) => p.unsafeSetNullable(ps, index, a)
}
index += 1
}
}
@SuppressWarnings(Array("org.wartremover.warts.Var"))
val unsafeUpdate: (ResultSet, Int, elems.type) => Unit = { (ps, n, elems) =>
var index = n
elems.iterator.foreach { e =>
e match {
case Arg(a, p) => p.unsafeUpdateNonNullable(ps, index, a)
case Opt(a, p) => p.unsafeUpdateNullable(ps, index, a)
}
index += 1
}
}
new Write(puts, toList, unsafeSet, unsafeUpdate)
}
/**
* Construct a program in ConnectionIO that constructs and prepares a PreparedStatement, with
* further handling delegated to the provided program.
*/
def execWith[B](fa: PreparedStatementIO[B]): ConnectionIO[B] =
HC.prepareStatement(sql)(write.set(1, elems) *> fa)
/** Concatenate this fragment with another, yielding a larger fragment. */
def ++(fb: Fragment): Fragment =
new Fragment(sql + fb.sql, elems ++ fb.elems, pos orElse fb.pos)
@SuppressWarnings(Array("org.wartremover.warts.Overloading"))
def stripMargin(marginChar: Char): Fragment =
new Fragment(sql.stripMargin(marginChar), elems, pos)
@SuppressWarnings(Array("org.wartremover.warts.Overloading"))
def stripMargin: Fragment = stripMargin('|')
/** Construct a [[Query0]] from this fragment, with asserted row type `B`. */
@SuppressWarnings(Array("org.wartremover.warts.DefaultArguments"))
def query[B: Read](implicit h: LogHandler = LogHandler.nop): Query0[B] =
queryWithLogHandler(h)
/**
* Construct a [[Query0]] from this fragment, with asserted row type `B` and the given
* `LogHandler`.
*/
def queryWithLogHandler[B](h: LogHandler)(implicit cb: Read[B]): Query0[B] =
Query[elems.type, B](sql, pos, h).toQuery0(elems)
/** Construct an [[Update0]] from this fragment. */
@SuppressWarnings(Array("org.wartremover.warts.DefaultArguments"))
def update(implicit h: LogHandler = LogHandler.nop): Update0 =
updateWithLogHandler(h)
/** Construct an [[Update0]] from this fragment with the given `LogHandler`. */
def updateWithLogHandler(h: LogHandler): Update0 =
Update[elems.type](sql, pos, h).toUpdate0(elems)
override def toString =
s"""Fragment("$sql")"""
/** Used only for testing; this pulls out the arguments as an untyped list. */
private def args: List[Any] =
elems.toList.map {
case Elem.Arg(a, _) => a
case Elem.Opt(a, _) => a
}
/** Used only for testing; this uses universal equality on the captured arguments. */
@SuppressWarnings(Array("org.wartremover.warts.Equals"))
private[util] def unsafeEquals(fb: Fragment): Boolean =
sql == fb.sql && args == fb.args
}
object Fragment {
/**
* Construct a statement fragment with the given SQL string, which must contain sufficient `?`
* placeholders to accommodate the given list of interpolated elements. This is normally
* accomplished via the string interpolator rather than direct construction.
*/
@SuppressWarnings(Array("org.wartremover.warts.DefaultArguments"))
def apply(sql: String, elems: List[Elem], pos: Option[Pos] = None): Fragment =
new Fragment(sql, Chain.fromSeq(elems), pos)
/**
* Construct a statement fragment with no interpolated values and no trailing space; the
* passed SQL string must not contain `?` placeholders.
*/
@SuppressWarnings(Array("org.wartremover.warts.DefaultArguments"))
def const0(sql: String, pos: Option[Pos] = None): Fragment =
new Fragment(sql, Chain.empty, pos)
/**
* Construct a statement fragment with no interpolated values and a trailing space; the
* passed SQL string must not contain `?` placeholders.
*/
@SuppressWarnings(Array("org.wartremover.warts.DefaultArguments"))
def const(sql: String, pos: Option[Pos] = None): Fragment =
const0(sql + " ", pos)
/** The empty fragment. Adding this to another fragment has no effect. */
val empty: Fragment =
const0("")
/** Statement fragments form a monoid. */
implicit val FragmentMonoid: Monoid[Fragment] =
new Monoid[Fragment] {
val empty = Fragment.empty
def combine(a: Fragment, b: Fragment) = a ++ b
}
}
}