PHPLIB-1273: Improve $switch syntax (#62)

* PHPLIB-1273: Improve $switch syntax

* Restore previously deleted encoding type in schema

* Introduce dedicated interface for branches in $switch

* Remove optional parameter in encodeAsObject

* Use case operator throughout tests

Author: alcaeus

generator/config/expression/case.yaml

@@ -0,0 +1,21 @@
+# $schema: ../schema.json
+name: $case
+link: 'https://www.mongodb.com/docs/manual/reference/operator/aggregation/switch/'
+type:
+    - switchBranch
+encode: flat_object
+description: |
+    Represents a single case in a $switch expression
+arguments:
+    -
+        name: case
+        type:
+            - resolvesToBool
+        description: |
+            Can be any valid expression that resolves to a boolean. If the result is not a boolean, it is coerced to a boolean value. More information about how MongoDB evaluates expressions as either true or false can be found here.
+    -
+        name: then
+        type:
+            - expression
+        description: |
+            Can be any valid expression.

generator/config/expression/switch.yaml

@@ -10,7 +10,7 @@ arguments:
     -
         name: branches
         type:
-            - array # of object{case:resolvesToBool, then:expression}
+            - array # of CaseOperator
         description: |
             An array of control branch documents. Each branch is a document with the following fields:
             - case Can be any valid expression that resolves to a boolean. If the result is not a boolean, it is coerced to a boolean value. More information about how MongoDB evaluates expressions as either true or false can be found here.

generator/config/expressions.php

@@ -113,6 +113,10 @@
         'returnType' => Type\GeometryInterface::class,
         'acceptedTypes' => [Type\GeometryInterface::class, ...$bsonTypes['object']],
     ],
+    'switchBranch' => [
+        'returnType' => Type\SwitchBranchInterface::class,
+        'acceptedTypes' => [Type\SwitchBranchInterface::class, ...$bsonTypes['object']],
+    ],
 
     // @todo add enum values
     'Granularity' => [

generator/config/schema.json

@@ -29,6 +29,7 @@
                             "filter",
                             "window",
                             "geometry",
+                            "switchBranch",
                             "resolvesToAny",
                             "resolvesToNumber",
                             "resolvesToDouble",
@@ -59,6 +60,7 @@
                     "enum": [
                         "array",
                         "object",
+                        "flat_object",
                         "dollar_object",
                         "single",
                         "group"

generator/src/Definition/OperatorDefinition.php

@@ -39,6 +39,7 @@ public function __construct(
             'single' => Encode::Single,
             'array' => Encode::Array,
             'object' => Encode::Object,
+            'flat_object' => Encode::FlatObject,
             'dollar_object' => Encode::DollarObject,
             'group' => Encode::Group,
             default => throw new UnexpectedValueException(sprintf('Unexpected "encode" value for operator "%s". Got "%s"', $name, $encode)),

src/Builder/Encoder/OperatorEncoder.php

@@ -46,6 +46,7 @@ public function encode(mixed $value): stdClass
                 return $this->encodeAsArray($value);
 
             case Encode::Object:
+            case Encode::FlatObject:
                 return $this->encodeAsObject($value);
 
             case Encode::DollarObject:
@@ -107,7 +108,9 @@ private function encodeAsObject(OperatorInterface $value): stdClass
             $result->{$key} = $this->recursiveEncode($val);
         }
 
-        return $this->wrap($value, $result);
+        return $value::ENCODE === Encode::FlatObject
+            ? $result
+            : $this->wrap($value, $result);
     }
 
     private function encodeAsDollarObject(OperatorInterface $value): stdClass

src/Builder/Expression/CaseOperator.php

@@ -23,6 +23,11 @@ enum Encode
      */
     case Object;
 
+    /**
+     * Same as Object, but only parameters are returned. The operator name will not be used.
+     */
+    case FlatObject;
+
     /**
      * Parameters are encoded as an object with keys matching the parameter names prefixed with a dollar sign ($)
      */

src/Builder/Expression/FactoryTrait.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MongoDB\Builder\Type;
+
+/**
+ * Interface for branches in $switch operators
+ *
+ * @see https://www.mongodb.com/docs/manual/reference/operator/aggregation/switch/
+ */
+interface SwitchBranchInterface
+{
+}