Add b plus tree page.

Cargo.toml

@@ -12,4 +12,5 @@ prettytable-rs = "0.10.0"
 signal-hook = "0.3.17"
 
 [dev-dependencies]
+itertools = "0.12.0"
 tempfile = "3.9.0"

src/page.rs

@@ -2,6 +2,8 @@ use crate::common::PageID;
 
 use self::table_page::{TablePage, TABLE_PAGE_PAGE_TYPE};
 
+pub mod b_plus_tree_internal_page;
+pub mod b_plus_tree_leaf_page;
 pub mod table_page;
 
 const PAGE_TYPE_OFFSET: usize = 0;

src/page/b_plus_tree_internal_page.rs

@@ -0,0 +1,67 @@
+use crate::common::{PageID, LSN, PAGE_SIZE};
+
+use super::{PageType, PAGE_ID_OFFSET, PAGE_ID_SIZE, PAGE_TYPE_OFFSET, PAGE_TYPE_SIZE};
+
+pub const B_PLUS_TREE_INTERNAL_PAGE_PAGE_TYPE: PageType = PageType(3);
+
+const LSN_OFFSET: usize = PAGE_ID_OFFSET + PAGE_ID_SIZE;
+const LSN_SIZE: usize = 8;
+const PARENT_PAGE_ID_OFFSET: usize = LSN_OFFSET + LSN_SIZE;
+const PARENT_PAGE_ID_SIZE: usize = 4;
+const LOWER_OFFSET_OFFSET: usize = PARENT_PAGE_ID_OFFSET + PARENT_PAGE_ID_SIZE;
+const LOWER_OFFSET_SIZE: usize = 4;
+const UPPER_OFFSET_OFFSET: usize = LOWER_OFFSET_OFFSET + LOWER_OFFSET_SIZE;
+const UPPER_OFFSET_SIZE: usize = 4;
+const HEADER_SIZE: usize = PAGE_TYPE_SIZE
+    + PAGE_ID_SIZE
+    + LSN_SIZE
+    + PARENT_PAGE_ID_SIZE
+    + LOWER_OFFSET_SIZE
+    + UPPER_OFFSET_SIZE;
+// const LINE_POINTER_OFFSET_SIZE: usize = 4;
+// const LINE_POINTER_SIZE_SIZE: usize = 4;
+// const LINE_POINTER_SIZE: usize = LINE_POINTER_OFFSET_SIZE + LINE_POINTER_SIZE_SIZE;
+
+pub struct BPlusTreeInternalPage {
+    pub data: Box<[u8]>,
+}
+
+impl BPlusTreeInternalPage {
+    pub fn new(page_id: PageID, parent_page_id: PageID) -> Self {
+        let mut data = vec![0u8; PAGE_SIZE];
+        data[PAGE_TYPE_OFFSET..(PAGE_TYPE_OFFSET + PAGE_TYPE_SIZE)]
+            .copy_from_slice(&B_PLUS_TREE_INTERNAL_PAGE_PAGE_TYPE.0.to_le_bytes());
+        data[PAGE_ID_OFFSET..(PAGE_ID_OFFSET + PAGE_ID_SIZE)]
+            .copy_from_slice(&page_id.0.to_le_bytes());
+        data[PARENT_PAGE_ID_OFFSET..(PARENT_PAGE_ID_OFFSET + PARENT_PAGE_ID_SIZE)]
+            .copy_from_slice(&parent_page_id.0.to_le_bytes());
+        data[LOWER_OFFSET_OFFSET..(LOWER_OFFSET_OFFSET + LOWER_OFFSET_SIZE)]
+            .copy_from_slice(&(HEADER_SIZE as u32).to_le_bytes());
+        data[UPPER_OFFSET_OFFSET..(UPPER_OFFSET_OFFSET + UPPER_OFFSET_SIZE)]
+            .copy_from_slice(&(PAGE_SIZE as u32).to_le_bytes());
+        BPlusTreeInternalPage { data: data.into() }
+    }
+    pub fn from_data(data: &[u8]) -> Self {
+        BPlusTreeInternalPage { data: data.into() }
+    }
+
+    pub fn lsn(&self) -> LSN {
+        let mut buf = [0u8; 8];
+        buf.copy_from_slice(&self.data[LSN_OFFSET..(LSN_OFFSET + LSN_SIZE)]);
+        LSN(u64::from_le_bytes(buf))
+    }
+    pub fn set_lsn(&mut self, lsn: LSN) {
+        self.data[LSN_OFFSET..(LSN_OFFSET + LSN_SIZE)].copy_from_slice(&lsn.0.to_le_bytes());
+    }
+    pub fn parent_page_id(&self) -> PageID {
+        let mut buf = [0u8; 4];
+        buf.copy_from_slice(
+            &self.data[PARENT_PAGE_ID_OFFSET..(PARENT_PAGE_ID_OFFSET + PARENT_PAGE_ID_SIZE)],
+        );
+        PageID(u32::from_le_bytes(buf))
+    }
+    pub fn set_parent_page_id(&mut self, parent_page_id: PageID) {
+        self.data[PARENT_PAGE_ID_OFFSET..(PARENT_PAGE_ID_OFFSET + PARENT_PAGE_ID_SIZE)]
+            .copy_from_slice(&parent_page_id.0.to_le_bytes());
+    }
+}