From 30a167398de3bac335f864f3c81feef2f5410196 Mon Sep 17 00:00:00 2001
From: jules Ivanic <jules.ivanic@gmail.com>
Date: Fri, 27 Oct 2023 12:43:33 +0400
Subject: [PATCH] Fix #172

---
 core/src/main/scala/zio/jdbc/SqlFragment.scala |  6 +++++-
 .../main/scala/zio/jdbc/SqlInterpolator.scala  |  6 ++----
 core/src/main/scala/zio/jdbc/package.scala     |  2 +-
 .../test/scala/zio/jdbc/SqlFragmentSpec.scala  | 18 ++++++++++++++++--
 4 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/core/src/main/scala/zio/jdbc/SqlFragment.scala b/core/src/main/scala/zio/jdbc/SqlFragment.scala
index 3a60d70f..39b618b4 100644
--- a/core/src/main/scala/zio/jdbc/SqlFragment.scala
+++ b/core/src/main/scala/zio/jdbc/SqlFragment.scala
@@ -272,6 +272,7 @@ sealed trait SqlFragment { self =>
 
   private[jdbc] def foreachSegment(addSyntax: Segment.Syntax => Any)(addParam: Segment.Param => Any): Unit =
     segments.foreach {
+      case Segment.Empty          => ()
       case syntax: Segment.Syntax => addSyntax(syntax)
       case param: Segment.Param   => addParam(param)
       case nested: Segment.Nested => nested.sql.foreachSegment(addSyntax)(addParam)
@@ -288,10 +289,13 @@ object SqlFragment {
 
   sealed trait Segment
   object Segment {
+    case object Empty                                       extends Segment
     final case class Syntax(value: String)                  extends Segment
     final case class Param(value: Any, setter: Setter[Any]) extends Segment
     final case class Nested(sql: SqlFragment)               extends Segment
 
+    @inline def empty: Segment = Empty
+
     implicit def paramSegment[A](a: A)(implicit setter: Setter[A]): Segment.Param =
       Segment.Param(a, setter.asInstanceOf[Setter[Any]])
 
@@ -385,7 +389,7 @@ object SqlFragment {
     implicit val instantSetter: Setter[java.time.Instant]             = sqlTimestampSetter.contramap(java.sql.Timestamp.from)
   }
 
-  def apply(sql: String): SqlFragment = sql
+  def apply(sql: String): SqlFragment = SqlFragment(Chunk.single(SqlFragment.Segment.Syntax(sql)))
 
   def apply(segments: Chunk[Segment]): SqlFragment =
     SqlFragment.Append(segments)
diff --git a/core/src/main/scala/zio/jdbc/SqlInterpolator.scala b/core/src/main/scala/zio/jdbc/SqlInterpolator.scala
index c3b0f5ad..bb5c90bb 100644
--- a/core/src/main/scala/zio/jdbc/SqlInterpolator.scala
+++ b/core/src/main/scala/zio/jdbc/SqlInterpolator.scala
@@ -29,10 +29,8 @@ final class SqlInterpolator(val context: StringContext) extends AnyVal {
 
     while (syntaxIterator.hasNext) {
       val syntax = syntaxIterator.next()
-      if (syntax.nonEmpty) {
-        chunkBuilder += SqlFragment.Segment.Syntax(syntax)
-        if (paramsIterator.hasNext) chunkBuilder += paramsIterator.next()
-      }
+      chunkBuilder += (if (syntax.isEmpty) SqlFragment.Segment.empty else SqlFragment.Segment.Syntax(syntax))
+      if (paramsIterator.hasNext) chunkBuilder += paramsIterator.next()
     }
     while (paramsIterator.hasNext)
       chunkBuilder += paramsIterator.next()
diff --git a/core/src/main/scala/zio/jdbc/package.scala b/core/src/main/scala/zio/jdbc/package.scala
index 3f8898d8..649c38ee 100644
--- a/core/src/main/scala/zio/jdbc/package.scala
+++ b/core/src/main/scala/zio/jdbc/package.scala
@@ -24,7 +24,7 @@ package object jdbc {
   /**
    * Converts a String into a pure SQL expression
    */
-  implicit def stringToSql(s: String): SqlFragment = SqlFragment(Chunk(SqlFragment.Segment.Syntax(s)))
+  implicit def stringToSql(s: String): SqlFragment = SqlFragment(s)
 
   /**
    * A new transaction, which may be applied to ZIO effects that require a
diff --git a/core/src/test/scala/zio/jdbc/SqlFragmentSpec.scala b/core/src/test/scala/zio/jdbc/SqlFragmentSpec.scala
index a5a0daa0..4785e625 100644
--- a/core/src/test/scala/zio/jdbc/SqlFragmentSpec.scala
+++ b/core/src/test/scala/zio/jdbc/SqlFragmentSpec.scala
@@ -29,10 +29,15 @@ object SqlFragmentSpec extends ZIOSpecDefault {
               s"Sql(select name, age from users where id = ?, $id)"
           )
         } +
-        test("ensure no empty Syntax instances") {
+        test("Empty Segment instances are insignificant") {
           val age  = 42
           val name = "sholmes"
-          assertTrue(sql"select name, age from users where age = $age and name = $name".segments.size == 4)
+          val sql = sql"select name, age from users where age = $age and name = $name"
+          assertTrue(
+            sql.segments.size == 5,
+            sql.segments.last == SqlFragment.Segment.Empty, // Empty Syntax instances are insignificant
+            sql.toString == "Sql(select name, age from users where age = ? and name = ?, 42, sholmes)"
+          )
         } +
         test("interpolate Sql values") {
           val tableName    = sql"table1"
@@ -247,6 +252,15 @@ object SqlFragmentSpec extends ZIOSpecDefault {
           assertTrue(
             result.toString == "Sql(UPDATE persons)"
           )
+        } +
+        test("'interpolation <=> ++ operator' equivalence") {
+          val s1 = sql"${"1"}::varchar"
+          val s2 = (sql"${"1"}" ++ sql"::varchar")
+
+          assertTrue(
+            s1.toString == "Sql(?::varchar, 1)",
+            s1.toString == s2.toString
+          )
         }
     } +
       suite("SqlFragment ResultSet tests") {