diff options
Diffstat (limited to 'cursor.go')
| -rw-r--r-- | cursor.go | 49 |
1 files changed, 31 insertions, 18 deletions
@@ -8,13 +8,7 @@ import ( type Cursor struct { transaction *Transaction root pgid - stack []elem -} - -// elem represents a node on a page that's on the cursor's stack. -type elem struct { - page *page - index uint16 + stack []pageElementRef } // First moves the cursor to the first item in the bucket and returns its key and data. @@ -41,18 +35,18 @@ func (c *Cursor) Get(key []byte) []byte { } // If our target node isn't the same key as what's passed in then return nil. - if !bytes.Equal(key, c.node().key()) { + if !bytes.Equal(key, c.element().key()) { return nil } - return c.node().value() + return c.element().value() } func (c *Cursor) search(key []byte, p *page) { if (p.flags & (p_branch | p_leaf)) == 0 { panic("invalid page type: " + p.typ()) } - e := elem{page: p} + e := pageElementRef{page: p} c.stack = append(c.stack, e) // If we're on a leaf page then find the specific node. @@ -77,10 +71,10 @@ func (c *Cursor) search(key []byte, p *page) { if !exact && index > 0 { index-- } - e.index = uint16(index) + c.stack[len(c.stack)-1].index = uint16(index) // Recursively search to the next page. - c.search(key, c.transaction.page(inodes[e.index].pgid)) + c.search(key, c.transaction.page(inodes[index].pgid)) } // nsearch searches a leaf node for the index of the node that matches key. @@ -97,8 +91,8 @@ func (c *Cursor) nsearch(key []byte, p *page) { // top returns the page and leaf node that the cursor is currently pointing at. func (c *Cursor) top() (*page, uint16) { - elem := c.stack[len(c.stack)-1] - return elem.page, elem.index + ptr := c.stack[len(c.stack)-1] + return ptr.page, ptr.index } // page returns the page that the cursor is currently pointing at. @@ -106,8 +100,27 @@ func (c *Cursor) page() *page { return c.stack[len(c.stack)-1].page } -// node returns the leaf node that the cursor is currently positioned on. -func (c *Cursor) node() *leafPageElement { - elem := c.stack[len(c.stack)-1] - return elem.page.leafPageElement(elem.index) +// element returns the leaf element that the cursor is currently positioned on. +func (c *Cursor) element() *leafPageElement { + ref := c.stack[len(c.stack)-1] + return ref.page.leafPageElement(ref.index) +} + +// node returns the node that the cursor is currently positioned on. +func (c *Cursor) node(t *RWTransaction) *node { + if len(c.stack) == 0 { + return nil + } + + // Start from root and traverse down the hierarchy. + n := t.node(c.stack[0].page.id, nil) + for _, ref := range c.stack[:len(c.stack)-1] { + __assert__(!n.isLeaf, "expected branch node") + __assert__(ref.page.id == n.pgid, "node/page mismatch a: %d != %d", ref.page.id, n.childAt(ref.index).pgid) + n = n.childAt(ref.index) + } + __assert__(n.isLeaf, "expected leaf node") + __assert__(n.pgid == c.stack[len(c.stack)-1].page.id, "node/page mismatch b: %d != %d", n.pgid, c.stack[len(c.stack)-1].page.id) + return n } + |