Adds a built-in PartiQL System catalog, support for SQL-Path, and SPI cleanup

partiql-spi/api/partiql-spi.api

@@ -241,6 +241,7 @@ public final class org/partiql/spi/catalog/Path$Companion {
 
 public abstract interface class org/partiql/spi/catalog/Session {
 	public static final field Companion Lorg/partiql/spi/catalog/Session$Companion;
+	public static fun bare (Ljava/lang/String;)Lorg/partiql/spi/catalog/Session;
 	public static fun builder ()Lorg/partiql/spi/catalog/Session$Builder;
 	public static fun empty ()Lorg/partiql/spi/catalog/Session;
 	public abstract fun getCatalog ()Ljava/lang/String;
@@ -261,9 +262,11 @@ public final class org/partiql/spi/catalog/Session$Builder {
 	public final fun namespace (Lorg/partiql/spi/catalog/Namespace;)Lorg/partiql/spi/catalog/Session$Builder;
 	public final fun namespace ([Ljava/lang/String;)Lorg/partiql/spi/catalog/Session$Builder;
 	public final fun property (Ljava/lang/String;Ljava/lang/String;)Lorg/partiql/spi/catalog/Session$Builder;
+	public final fun systemCatalog (Lorg/partiql/spi/catalog/Catalog;)Lorg/partiql/spi/catalog/Session$Builder;
 }
 
 public final class org/partiql/spi/catalog/Session$Companion {
+	public final fun bare (Ljava/lang/String;)Lorg/partiql/spi/catalog/Session;
 	public final fun builder ()Lorg/partiql/spi/catalog/Session$Builder;
 	public final fun empty ()Lorg/partiql/spi/catalog/Session;
 }

partiql-spi/src/main/java/org/partiql/spi/catalog/PartiQLSystemCatalog.java

@@ -0,0 +1,66 @@
+package org.partiql.spi.catalog;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.partiql.spi.function.Aggregation;
+import org.partiql.spi.function.Builtins;
+import org.partiql.spi.function.Function;
+
+import java.util.Collection;
+
+/**
+ * <p>
+ * This implements the PartiQL System Catalog.
+ * </p>
+ * <p>
+ * It provides the implementation for the PartiQL System Catalog, which is a built-in catalog
+ * that provides access to the PartiQL language and its built-in functions and aggregations.
+ * </p>
+ * @see Session.Builder
+ */
+final class PartiQLSystemCatalog implements Catalog {
+
+    /**
+     * TODO
+     */
+    @NotNull
+    private final String name;
+
+    /**
+     * Creates a new PartiQL System Catalog with the given name.
+     * @param name the name of the PartiQL System Catalog
+     */
+    PartiQLSystemCatalog(@NotNull String name) {
+        this.name = name;
+    }
+
+    @NotNull
+    @Override
+    public String getName() {
+        return this.name;
+    }
+
+    @Nullable
+    @Override
+    public Table getTable(@NotNull Session session, @NotNull Name name) {
+        return null;
+    }
+
+    @Nullable
+    @Override
+    public Table getTable(@NotNull Session session, @NotNull Identifier identifier) {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Collection<Function> getFunctions(@NotNull Session session, @NotNull String name) {
+        return Builtins.INSTANCE.getFunctions(name);
+    }
+
+    @NotNull
+    @Override
+    public Collection<Aggregation> getAggregations(@NotNull Session session, @NotNull String name) {
+        return Builtins.INSTANCE.getAggregations(name);
+    }
+}

partiql-spi/src/main/kotlin/org/partiql/spi/catalog/Session.kt

@@ -43,7 +43,8 @@ public interface Session {
     public companion object {
 
         /**
-         * Returns a [Session] with only the "empty" catalog implementation.
+         * Returns a [Session] with only the "empty" catalog implementation. Note that this does NOT add the
+         * PartiQL System Catalog.
          */
         @JvmStatic
         public fun empty(): Session = object : Session {
@@ -53,6 +54,19 @@ public interface Session {
             override fun getNamespace(): Namespace = Namespace.empty()
         }
 
+        /**
+         * Returns a [Session] with only the PartiQL System Catalog. Therefore, this provides PartiQL's built-in functions
+         * and aggregations.
+         * @param systemCatalogName the name to assign the system catalog
+         */
+        @JvmStatic
+        public fun bare(systemCatalogName: String): Session = object : Session {
+            override fun getIdentity(): String = "unknown"
+            override fun getCatalog(): String = systemCatalogName
+            override fun getCatalogs(): Catalogs = Catalogs.builder().add(PartiQLSystemCatalog(systemCatalogName)).build()
+            override fun getNamespace(): Namespace = Namespace.empty()
+        }
+
         @JvmStatic
         public fun builder(): Builder = Builder()
     }
@@ -64,6 +78,8 @@ public interface Session {
 
         private var identity: String = "unknown"
         private var catalog: String? = null
+        private var systemCatalogName: String = "\$pql_system"
+        private var systemCatalog: Catalog = PartiQLSystemCatalog(systemCatalogName)
         private var catalogs: Catalogs.Builder = Catalogs.builder()
         private var namespace: Namespace = Namespace.empty()
         private var properties: MutableMap<String, String> = mutableMapOf()
@@ -98,6 +114,16 @@ public interface Session {
             return this
         }
 
+        /**
+         * Adds and designates a catalog to always be on the SQL-Path. This [catalog] provides all built-in functions
+         * to the system at hand.
+         * If this is never invoked, a default system catalog is provided.
+         */
+        public fun systemCatalog(catalog: Catalog): Builder {
+            this.systemCatalogName = catalog.getName()
+            return this
+        }
+
         /**
          * Adds catalogs to this session.
          */
@@ -110,16 +136,24 @@ public interface Session {
 
         public fun build(): Session = object : Session {
 
-            private val _catalogs = catalogs.build()
+            private val _catalogs: Catalogs
+            private val systemCatalogNamespace: Namespace = Namespace.of(systemCatalogName)
 
             init {
                 require(catalog != null) { "Session catalog must be set" }
+                catalogs.add(systemCatalog)
+                _catalogs = catalogs.build()
             }
 
             override fun getIdentity(): String = identity
             override fun getCatalog(): String = catalog!!
             override fun getCatalogs(): Catalogs = _catalogs
             override fun getNamespace(): Namespace = namespace
+
+            override fun getPath(): Path {
+                val currentNamespace = getNamespace()
+                return Path.of(currentNamespace, systemCatalogNamespace)
+            }
         }
     }
 }