writes the database file, needs bugfixing

README.md

@@ -1,4 +1,24 @@
 # Sqlighte.Rs
 
 * rust version of https://gitlab.com/sander-hautvast/sqlighter
-* still very much work in progress
+* still work in progress
+
+Creating a database will be as simple as: 
+```rust
+fn test_build() -> Result<(), Error> {
+        let mut builder = Builder::new();
+        builder.schema(
+            "foo",
+            "create table foo(bar varchar(10))",
+        );
+        let mut record = Record::new(1);
+        record.add_value(values::string("helloworld"));
+        builder.add_record(record);
+
+        let database: Database = builder.into();
+        let file = File::create("foo.db")?;
+        let writer = BufWriter::new(file);
+        write(database, writer)?;
+        Ok(())
+    }
+```

src/builder.rs

@@ -10,11 +10,16 @@ pub struct Builder {
     schema: Option<SchemaRecord>,
 }
 
+fn new_page() -> Page {
+    let mut page = Page::new_leaf();
+    page.fw_position = 8;
+    page
+}
 
 impl Builder {
     pub fn new() -> Self {
         Self {
-            current_page: Page::new_leaf(),
+            current_page: new_page(),
             n_records_on_current_page: 0,
             leaf_pages: Vec::new(),
             schema: None,
@@ -24,7 +29,7 @@ impl Builder {
     pub fn add_record(&mut self, record: Record) {
         if self.current_page_is_full(&record) {
             self.finish_current_page();
-            self.leaf_pages.push(mem::replace(&mut self.current_page, Page::new_leaf()));
+            self.leaf_pages.push(mem::replace(&mut self.current_page, new_page()));
             self.n_records_on_current_page = 0;
         }
 
@@ -61,6 +66,7 @@ impl Into<Database> for Builder {
             self.current_page.put_u16(self.current_page.bw_position - 1);
         }
 
+        self.leaf_pages.push(self.current_page);
         Database::new(self.schema.unwrap(), self.leaf_pages) //panics is schema is not set
     }
 }
@@ -74,7 +80,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test_build() -> Result<(), Error>{
+    fn test_build() -> Result<(), Error> {
         let mut builder = Builder::new();
         builder.schema(
             "foo",
@@ -85,7 +91,7 @@ mod tests {
         builder.add_record(record);
 
         let database: Database = builder.into();
-        let file = File::create("foo.txt")?;
+        let file = File::create("foo.db")?;
         let writer = BufWriter::new(file);
         write(database, writer)?;
         Ok(())

src/database.rs

@@ -2,7 +2,7 @@ use std::io::{BufWriter, Error, Write};
 use std::mem;
 use crate::varint;
 use crate::page;
-use crate::page::Page;
+use crate::page::{Page, PageType};
 use crate::record::Record;
 use crate::values;
 
@@ -53,17 +53,60 @@ impl Into<Record> for SchemaRecord {
 pub fn write<W: Write>(database: Database, mut writer: BufWriter<W>) -> Result<(), Error> {
     let mut current_top_layer = database.leaf_pages;
     let mut n_pages = current_top_layer.len();
-    while current_top_layer.len() > 1 { // interior page needed?
+    while current_top_layer.len() > 1 { // db needs interior pages?
         current_top_layer = create_interior_pages(current_top_layer);
         n_pages += current_top_layer.len();
     }
 
-    let table_root_page = current_top_layer.get(0); //
+    let table_root_page = current_top_layer.get_mut(0).unwrap();
     writer.write_all(&create_header_page(n_pages + 1, database.schema).data)?; // 1 for header page
-    //
+
-    // recursiveAssignPagenumbers(table_root_page); // 3 extra passes... :(
+    assign_pagenumbers(table_root_page, 2);
-    // recursiveSetPageReferences(table_root_page); // don't think combining is possible
+    set_page_references(table_root_page);
-    // recursiveWritePages(channel, table_root_page);
+    write_pages(&mut writer, table_root_page)?;
+
+    Ok(())
+}
+
+fn assign_pagenumbers(page: &mut Page, page_counter: u32) {
+    page.number = page_counter;
+    let mut counter = page_counter;
+    for child in page.children.iter_mut() {
+        counter += 1;
+        assign_pagenumbers(child, counter);
+    }
+}
+
+fn set_page_references(page: &mut Page) {
+    if let PageType::Interior = page.page_type {
+        page.fw_position = page::POSITION_CELL_COUNT;
+        page.put_u16((page.children.len() - 1) as u16);
+
+        page.fw_position = page::POSITION_RIGHTMOST_POINTER_LEAFPAGES;
+        page.put_u32(page.get_page_nr_last_child());
+
+        let index = 0;
+        let before_last = page.children.len() - 1;
+        let child_numbers: Vec<u32> = page.children.iter().map(|child| child.number).collect();
+
+        for child_page_number in child_numbers {
+            if index < before_last {
+                page.fw_position = page::START_OF_INTERIOR_PAGE + (index as u16) * 2;
+                page.fw_position = page.get_u16();
+                page.put_u32(child_page_number);
+            }
+        }
+    }
+    for child in page.children.iter_mut() {
+        set_page_references(child);
+    }
+}
+
+fn write_pages<W: Write>(writer: &mut BufWriter<W>, page: &Page) -> Result<(), Error> {
+    writer.write(&page.data)?;
+    for child in page.children.iter() {
+        write_pages(writer, child)?;
+    }
     Ok(())
 }
 

src/page.rs

@@ -4,12 +4,13 @@ use crate::database;
 pub const POSITION_CELL_COUNT: u16 = 3;
 pub const START_OF_CONTENT_AREA: u16 = 5;
 pub const START_OF_INTERIOR_PAGE: u16 = 12;
+pub const POSITION_RIGHTMOST_POINTER_LEAFPAGES: u16 = 8;
 
 pub enum PageType {
     Leaf,
     Interior,
     Root,
-    Other
+    Other,
 }
 
 /// Represents an SQLite page
@@ -18,9 +19,9 @@ pub struct Page {
     pub fw_position: u16,
     pub bw_position: u16,
     pub key: u64,
-    children: Vec<Page>,
+    pub children: Vec<Page>,
-    number: u32,
+    pub number: u32,
-    page_type: PageType,
+    pub page_type: PageType,
 }
 
 impl Page {
@@ -36,7 +37,7 @@ impl Page {
         }
     }
 
-    fn default(size: usize) -> Self{
+    fn default(size: usize) -> Self {
         Self {
             data: vec![0; size],
             fw_position: 0,
@@ -81,6 +82,7 @@ impl Page {
             self.data[self.bw_position as usize] = *v;
             self.bw_position += 1;
         }
+        self.bw_position -= bytes.len() as u16;
     }
 
     pub fn put_u8(&mut self, value: u8) {
@@ -108,9 +110,15 @@ impl Page {
     }
 
     // may panic
-    pub fn get_page_nr_last_child(self) -> u32 {
+    pub fn get_page_nr_last_child(&self) -> u32 {
         self.children[self.children.len() - 1].number
     }
+
+    pub fn get_u16(&self) -> u16 {
+        let position = self.fw_position as usize;
+        (self.data[position] as u16) << 8 + self.data[position + 1]
+        // does not increase the fw pointerr
+    }
 }
 
 fn u16_to_bytes(value: u16) -> [u8; 2] {