test/hashmap.go: delete

It's in an odd style and it's unclear what true purpose it serves as
a test other than to be another Go program.

R=gri
CC=golang-dev
https://golang.org/cl/5674111

test/hashmap.go

-// run
-
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package main
-
-// ----------------------------------------------------------------------------
-// Helper functions
-
-func ASSERT(p bool) {
-	if !p {
-		// panic 0
-	}
-}
-
-
-// ----------------------------------------------------------------------------
-// Implementation of the HashMap
-
-type KeyType interface {
-	Hash() uint32
-	Match(other KeyType) bool
-}
-
-
-type ValueType interface {
-	// empty interface
-}
-
-
-type Entry struct {
-	key KeyType
-	value ValueType
-}
-
-
-type Array [1024]Entry
-
-type HashMap struct {
-	map_ *Array
-	log2_capacity_ uint32
-	occupancy_ uint32
-}
-
-
-func (m *HashMap) capacity() uint32 {
-	return 1 << m.log2_capacity_
-}
-
-
-func (m *HashMap) Clear() {
-	// Mark all entries as empty.
-	var i uint32 = m.capacity() - 1
-	for i > 0 {
-		m.map_[i].key = nil
-		i = i - 1
-	}
-	m.occupancy_ = 0
-}
-
-
-func (m *HashMap) Initialize (initial_log2_capacity uint32) {
-	m.log2_capacity_ = initial_log2_capacity
-	m.map_ = new(Array)
-	m.Clear()
-}
-
-
-func (m *HashMap) Probe (key KeyType) *Entry {
-	ASSERT(key != nil)
-
-	var i uint32 = key.Hash() % m.capacity()
-	ASSERT(0 <= i && i < m.capacity())
-
-	ASSERT(m.occupancy_ < m.capacity())	// guarantees loop termination
-	for m.map_[i].key != nil && !m.map_[i].key.Match(key) {
-		i++
-		if i >= m.capacity() {
-			i = 0
-		}
-	}
-
-	return &m.map_[i]
-}
-
-
-func (m *HashMap) Lookup (key KeyType, insert bool) *Entry {
-	// Find a matching entry.
-	var p *Entry = m.Probe(key)
-		if p.key != nil {
-		return p
-	}
-
-	// No entry found; insert one if necessary.
-	if insert {
-		p.key = key
-		p.value = nil
-		m.occupancy_++
-
-		// Grow the map if we reached >= 80% occupancy.
-		if m.occupancy_ + m.occupancy_/4 >= m.capacity() {
-			m.Resize()
-			p = m.Probe(key)
-		}
-
-		return p
-	}
-
-	// No entry found and none inserted.
-	return nil
-}
-
-
-func (m *HashMap) Resize() {
-	var hmap *Array = m.map_
-	var n uint32 = m.occupancy_
-
-	// Allocate a new map of twice the current size.
-	m.Initialize(m.log2_capacity_ << 1)
-
-	// Rehash all current entries.
-	var i uint32 = 0
-	for n > 0 {
-		if hmap[i].key != nil {
-			m.Lookup(hmap[i].key, true).value = hmap[i].value
-			n = n - 1
-		}
-		i++
-	}
-}
-
-
-// ----------------------------------------------------------------------------
-// Test code
-
-type Number struct {
-	x uint32
-}
-
-
-func (n *Number) Hash() uint32 {
-	return n.x * 23
-}
-
-
-func (n *Number) Match(other KeyType) bool {
-	// var y *Number = other
-	// return n.x == y.x
-	return false
-}
-
-
-func MakeNumber (x uint32) *Number {
-	var n *Number = new(Number)
-	n.x = x
-	return n
-}
-
-
-func main() {
-	// func (n int) int { return n + 1; }(1)
-
-	//print "HashMap - gri 2/8/2008\n"
-
-	var hmap *HashMap = new(HashMap)
-	hmap.Initialize(0)
-
-	var x1 *Number = MakeNumber(1001)
-	var x2 *Number = MakeNumber(2002)
-	var x3 *Number = MakeNumber(3003)
-	_, _, _ = x1, x2, x3
-
-	// this doesn't work I think...
-	//hmap.Lookup(x1, true)
-	//hmap.Lookup(x2, true)
-	//hmap.Lookup(x3, true)
-
-	//print "done\n"
-}