LibSQL: Database layer

This patch implements the beginnings of a database API allowing for the
creation of tables, inserting rows in those tables, and retrieving those
rows.

Tests/LibSQL/TestSqlDatabase.cpp

@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <unistd.h>
+
+#include <AK/ScopeGuard.h>
+#include <LibSQL/BTree.h>
+#include <LibSQL/Database.h>
+#include <LibSQL/Heap.h>
+#include <LibSQL/Meta.h>
+#include <LibSQL/Row.h>
+#include <LibSQL/Value.h>
+#include <LibTest/TestCase.h>
+
+NonnullRefPtr<SQL::SchemaDef> setup_schema(SQL::Database&);
+NonnullRefPtr<SQL::SchemaDef> setup_table(SQL::Database&);
+void insert_into_table(SQL::Database&, int);
+void verify_table_contents(SQL::Database&, int);
+void insert_and_verify(int);
+
+NonnullRefPtr<SQL::SchemaDef> setup_schema(SQL::Database& db)
+{
+    auto schema = SQL::SchemaDef::construct("TestSchema");
+    EXPECT(schema != nullptr);
+    db.add_schema(schema);
+    return schema;
+}
+
+NonnullRefPtr<SQL::SchemaDef> setup_table(SQL::Database& db)
+{
+    auto schema = setup_schema(db);
+    auto table = SQL::TableDef::construct(schema, "TestTable");
+    EXPECT(table != nullptr);
+    db.add_table(table);
+    table->append_column("TextColumn", SQL::SQLType::Text);
+    table->append_column("IntColumn", SQL::SQLType::Integer);
+    EXPECT_EQ(table->num_columns(), 2u);
+    db.add_table(table);
+    return table;
+}
+
+void insert_into_table(SQL::Database& db, int count)
+{
+    auto table = db.get_table("TestSchema", "TestTable");
+    EXPECT(table);
+
+    for (int ix = 0; ix < count; ix++) {
+        SQL::Row row(*table);
+        StringBuilder builder;
+        builder.appendff("Test{}", ix);
+
+        row["TextColumn"] = builder.build();
+        row["IntColumn"] = ix;
+        EXPECT(db.insert(row));
+    }
+}
+
+void verify_table_contents(SQL::Database& db, int expected_count)
+{
+    auto table = db.get_table("TestSchema", "TestTable");
+    EXPECT(table);
+
+    int sum = 0;
+    int count = 0;
+    for (auto& row : db.select_all(*table)) {
+        StringBuilder builder;
+        builder.appendff("Test{}", row["IntColumn"].to_int().value());
+        EXPECT_EQ(row["TextColumn"].to_string().value(), builder.build());
+        count++;
+        sum += row["IntColumn"].to_int().value();
+    }
+    EXPECT_EQ(count, expected_count);
+    EXPECT_EQ(sum, (expected_count * (expected_count - 1)) / 2);
+}
+
+void insert_and_verify(int count)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    {
+        auto db = SQL::Database::construct("test.db");
+        setup_table(db);
+        db->commit();
+    }
+    {
+        auto db = SQL::Database::construct("test.db");
+        insert_into_table(db, count);
+        db->commit();
+    }
+    {
+        auto db = SQL::Database::construct("test.db");
+        verify_table_contents(db, count);
+    }
+}
+
+TEST_CASE(create_heap)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    auto heap = SQL::Heap::construct("test.db");
+    EXPECT_EQ(heap->version(), 0x00000001u);
+}
+
+TEST_CASE(create_database)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    auto db = SQL::Database::construct("test.db");
+    db->commit();
+}
+
+TEST_CASE(add_schema_to_database)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    auto db = SQL::Database::construct("test.db");
+    setup_schema(db);
+    db->commit();
+}
+
+TEST_CASE(get_schema_from_database)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    {
+        auto db = SQL::Database::construct("test.db");
+        setup_schema(db);
+        db->commit();
+    }
+    {
+        auto db = SQL::Database::construct("test.db");
+        auto schema = db->get_schema("TestSchema");
+        EXPECT(schema);
+    }
+}
+
+TEST_CASE(add_table_to_database)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    auto db = SQL::Database::construct("test.db");
+    setup_table(db);
+    db->commit();
+}
+
+TEST_CASE(get_table_from_database)
+{
+    ScopeGuard guard([]() { unlink("test.db"); });
+    {
+        auto db = SQL::Database::construct("test.db");
+        setup_table(db);
+        db->commit();
+    }
+    {
+        auto db = SQL::Database::construct("test.db");
+        auto table = db->get_table("TestSchema", "TestTable");
+        EXPECT(table);
+        EXPECT_EQ(table->name(), "TestTable");
+        EXPECT_EQ(table->num_columns(), 2u);
+    }
+}
+
+TEST_CASE(insert_one_into_and_select_from_table)
+{
+    insert_and_verify(1);
+}
+
+TEST_CASE(insert_two_into_table)
+{
+    insert_and_verify(2);
+}
+
+TEST_CASE(insert_10_into_table)
+{
+    insert_and_verify(10);
+}
+
+TEST_CASE(insert_100_into_table)
+{
+    insert_and_verify(100);
+}
+
+TEST_CASE(insert_1000_into_table)
+{
+    insert_and_verify(1000);
+}
+
+TEST_CASE(insert_10000_into_table)
+{
+    insert_and_verify(10000);
+}