optmize null checking of nullable columns

.travis.yml

@@ -11,7 +11,7 @@ services:
 addons:
   postgresql: "9.6"
 script:
-  - ./build/build.sh
+  -        ./build/build.sh
 branches:
   except:
     - release
@@ -31,5 +31,5 @@ jobs:
   include:
       stage: release
       if: type != pull_request
-      script: 
+      script:
         - travis_retry ./build/release.sh

quill-cassandra/src/main/scala/io/getquill/context/cassandra/CqlNormalize.scala

@@ -1,6 +1,7 @@
 package io.getquill.context.cassandra
 
 import io.getquill.ast._
+import io.getquill.norm.ConcatBehavior.AnsiConcat
 import io.getquill.norm.{ FlattenOptionOperation, Normalize, RenameProperties, SimplifyNullChecks }
 
 object CqlNormalize {
@@ -10,7 +11,7 @@ object CqlNormalize {
 
   private[this] val normalize =
     (identity[Ast] _)
-      .andThen(FlattenOptionOperation.apply _)
+      .andThen(new FlattenOptionOperation(AnsiConcat).apply _)
       .andThen(SimplifyNullChecks.apply _)
       .andThen(Normalize.apply _)
       .andThen(RenameProperties.apply _)

quill-core/src/main/scala/io/getquill/norm/ConcatBehavior.scala

@@ -0,0 +1,7 @@
+package io.getquill.norm
+
+trait ConcatBehavior
+object ConcatBehavior {
+  case object AnsiConcat extends ConcatBehavior
+  case object NonAnsiConcat extends ConcatBehavior
+}

quill-core/src/main/scala/io/getquill/norm/FlattenOptionOperation.scala

@@ -2,29 +2,42 @@ package io.getquill.norm
 
 import io.getquill.ast._
 import io.getquill.ast.Implicits._
+import io.getquill.norm.ConcatBehavior.NonAnsiConcat
 
-object FlattenOptionOperation extends StatelessTransformer {
+class FlattenOptionOperation(concatBehavior: ConcatBehavior) extends StatelessTransformer {
 
   private def emptyOrNot(b: Boolean, ast: Ast) =
     if (b) OptionIsEmpty(ast) else OptionNonEmpty(ast)
 
+  def uncheckedReduction(ast: Ast, alias: Ident, body: Ast) =
+    apply(BetaReduction(body, alias -> ast))
+
+  def uncheckedForall(ast: Ast, alias: Ident, body: Ast) = {
+    val reduced = BetaReduction(body, alias -> ast)
+    apply((IsNullCheck(ast) +||+ reduced): Ast)
+  }
+
+  def containsNonFallthroughElement(ast: Ast) =
+    CollectAst(ast) {
+      case If(_, _, _) => true
+      case Infix(_, _) => true
+      case BinaryOperation(_, StringOperator.`+`, _) if (concatBehavior == NonAnsiConcat) => true
+    }.nonEmpty
+
   override def apply(ast: Ast): Ast =
     ast match {
 
-      // TODO Check if there is an optional in here, if there is, warn the user about changing behavior
-
       case OptionTableFlatMap(ast, alias, body) =>
-        apply(BetaReduction(body, alias -> ast))
+        uncheckedReduction(ast, alias, body)
 
       case OptionTableMap(ast, alias, body) =>
-        apply(BetaReduction(body, alias -> ast))
+        uncheckedReduction(ast, alias, body)
 
       case OptionTableExists(ast, alias, body) =>
-        apply(BetaReduction(body, alias -> ast))
+        uncheckedReduction(ast, alias, body)
 
       case OptionTableForall(ast, alias, body) =>
-        val reduced = BetaReduction(body, alias -> ast)
-        apply((IsNullCheck(ast) +||+ reduced): Ast)
+        uncheckedForall(ast, alias, body)
 
       case OptionFlatten(ast) =>
         apply(ast)
@@ -50,20 +63,36 @@ object FlattenOptionOperation extends StatelessTransformer {
         apply(If(IsNotNullCheck(ast), ast, body))
 
       case OptionFlatMap(ast, alias, body) =>
-        val reduced = BetaReduction(body, alias -> ast)
-        apply(IfExistElseNull(ast, reduced))
+        if (containsNonFallthroughElement(body)) {
+          val reduced = BetaReduction(body, alias -> ast)
+          apply(IfExistElseNull(ast, reduced))
+        } else {
+          uncheckedReduction(ast, alias, body)
+        }
 
       case OptionMap(ast, alias, body) =>
-        val reduced = BetaReduction(body, alias -> ast)
-        apply(IfExistElseNull(ast, reduced))
+        if (containsNonFallthroughElement(body)) {
+          val reduced = BetaReduction(body, alias -> ast)
+          apply(IfExistElseNull(ast, reduced))
+        } else {
+          uncheckedReduction(ast, alias, body)
+        }
 
       case OptionForall(ast, alias, body) =>
-        val reduction = BetaReduction(body, alias -> ast)
-        apply((IsNullCheck(ast) +||+ (IsNotNullCheck(ast) +&&+ reduction)): Ast)
+        if (containsNonFallthroughElement(body)) {
+          val reduction = BetaReduction(body, alias -> ast)
+          apply((IsNullCheck(ast) +||+ (IsNotNullCheck(ast) +&&+ reduction)): Ast)
+        } else {
+          uncheckedForall(ast, alias, body)
+        }
 
       case OptionExists(ast, alias, body) =>
-        val reduction = BetaReduction(body, alias -> ast)
-        apply((IsNotNullCheck(ast) +&&+ reduction): Ast)
+        if (containsNonFallthroughElement(body)) {
+          val reduction = BetaReduction(body, alias -> ast)
+          apply((IsNotNullCheck(ast) +&&+ reduction): Ast)
+        } else {
+          uncheckedReduction(ast, alias, body)
+        }
 
       case OptionContains(ast, body) =>
         apply((ast +==+ body): Ast)