Implemented find/find closest for B+ tree.

Added test suite.
Fixed some b+ tree bugs.

CMakeLists.txt

@@ -1,7 +1,41 @@
 cmake_minimum_required(VERSION 3.10)
-project(SDB C)
+set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 
+project(SDB C)
 set(CMAKE_C_STANDARD 11)
 
-include_directories(${CMAKE_SOURCE_DIR}/lib)
-add_executable(SDB src/main.c src/InputBuffer.c src/InputBuffer.h src/SQL.c src/SQL.h src/scanner.c src/scanner.h src/parser.c src/parser.h src/bplus_tree.c src/bplus_tree.h)
+#Check options
+include(CheckCSourceCompiles)
+include(CheckCSourceRuns)
+include(CheckFunctionExists)
+include(CheckIncludeFile)
+include(CheckIncludeFiles)
+include(CheckLibraryExists)
+include(CheckSymbolExists)
+include(CheckTypeSize)
+set(INCLUDES "")
+macro(ck_check_include_file header var)
+    check_include_files("${INCLUDES};${header}" ${var})
+    if(${var})
+        set(INCLUDES ${INCLUDES} ${header})
+    endif(${var})
+endmacro(ck_check_include_file)
+
+ck_check_include_file("stdlib.h" HAVE_STDLIB_H)
+check_type_size(intmax_t INTMAX_T)
+check_type_size(uintmax_t UINTMAX_T)
+
+check_type_size(pid_t PID_T)
+if(NOT HAVE_PID_T)
+    if(WIN32)
+        set(pid_t "int")
+    else(WIN32)
+        MESSAGE(FATAL_ERROR "pid_t doesn't exist on this platform?")
+    endif(WIN32)
+endif(NOT HAVE_PID_T)
+
+add_subdirectory(src)
+add_subdirectory(tests)
+
+enable_testing()
+add_test(NAME check_SDB COMMAND check_SDB)