/// <summary>
/// Adds a string to the set if it does not already exist.
/// </summary>
/// <param name="chars">A pointer to the string you want to add.</param>
/// <param name="count">The length of the string (in chars).</param>
/// <param name="str">The string object representation of the characters. A new string is only allocated when it does not already exist in the set.</param>
/// <param name="knownHashValue">(optional) If the StringHash has already been calculated, you can provide it here to save re-calculation.</param>
/// <returns>True if the string was added. False if the string already existed in the set.</returns>
public unsafe bool Add(char *chars, int count, out string str, StringHash knownHashValue = default(StringHash))
{
if (knownHashValue == default(StringHash))
{
knownHashValue = StringHash.GetHash(chars, count);
}
str = GetExistingString(chars, count, knownHashValue);
if (str != null)
{
return(false); // didn't add anything
}
// an existing string wasn't found, we need to add it to the hash
lock (_writeLock)
{
// first, check one more time to see if it exists
str = GetExistingString(chars, count, knownHashValue);
if (str == null)
{
// it definitely doesn't exist. Let's add it
str = new string(chars, 0, count);
AddImpl(str, knownHashValue);
return(true);
}
return(false);
}
}
void AddImpl(string s, StringHash hash)
{
var data = _data;
if (data.NextAvailableSlotIndex == data.Slots.Length)
{
Grow();
data = _data;
}
var slots = data.Slots;
var buckets = data.Buckets;
var bucket = hash.Value % slots.Length;
var slotIndex = data.NextAvailableSlotIndex;
data.NextAvailableSlotIndex++;
slots[slotIndex].Value = s;
slots[slotIndex].HashCode = hash;
slots[slotIndex].Next = buckets[bucket] - 1;
// The hash set would no longer be thread-safe on reads if somehow the bucket got reassigned before the slot was setup
Thread.MemoryBarrier();
buckets[bucket] = slotIndex + 1;
}
/// <summary>
/// Adds a string to the set if it does not already exist.
/// </summary>
/// <param name="buffer">The character array which represents the string you want to add.</param>
/// <param name="start">The index in the character array where your string starts.</param>
/// <param name="count">The length of the string you want to add.</param>
/// <param name="str">The string object representation of the characters. A new string is only allocated when it does not already exist in the set.</param>
/// <param name="knownHashValue">(optional) If the StringHash has already been calculated, you can provide it here to save re-calculation.</param>
/// <returns>True if the string was added. False if the string already existed in the set.</returns>
public bool Add(char[] buffer, int start, int count, out string str, StringHash knownHashValue = default(StringHash))
{
if (knownHashValue == default(StringHash))
{
knownHashValue = StringHash.GetHash(buffer, start, count);
}
else
{
StringHash.AssertBufferArgumentsAreSane(buffer.Length, start, count);
}
str = GetExistingStringImpl(buffer, start, count, knownHashValue);
if (str != null)
{
return(false); // didn't add anything
}
// an existing string wasn't found, we need to add it to the hash
lock (_writeLock)
{
// first, check one more time to see if it exists
str = GetExistingStringImpl(buffer, start, count, knownHashValue);
if (str == null)
{
// it definitely doesn't exist. Let's add it
str = new string(buffer, start, count);
AddImpl(str, knownHashValue);
return(true);
}
return(false);
}
}
/// <summary>
/// Uses the characters from a buffer to check whether a string exists in the set, and retrieve it if so.
/// </summary>
/// <param name="buffer">The character array which represents the string you want to check for.</param>
/// <param name="start">The index in the character array where your string starts.</param>
/// <param name="count">The length of the string you want to check for.</param>
/// <param name="knownHashValue">(optional) If the StringHash has already been calculated, you can provide it here to save re-calculation.</param>
/// <returns>If found in the set, the existing string is returned. If not found, null is returned.</returns>
public string GetExistingString(char[] buffer, int start, int count, StringHash knownHashValue = default(StringHash))
{
if (knownHashValue == default(StringHash))
{
knownHashValue = StringHash.GetHash(buffer, start, count);
}
else
{
StringHash.AssertBufferArgumentsAreSane(buffer.Length, start, count);
}
return(GetExistingStringImpl(buffer, start, count, knownHashValue));
}
bool ContainsString(string str, StringHash hash)
{
var cursor = GetSearchCursor(hash);
while (cursor.MightHaveMore)
{
if (str == cursor.NextString())
{
return(true);
}
}
return(false);
}
string GetExistingStringImpl(char[] buffer, int start, int length, StringHash hash)
{
var cursor = GetSearchCursor(hash);
while (cursor.MightHaveMore)
{
var value = cursor.NextString();
if (value != null && UnsafeStringComparer.AreEqual(value, buffer, start, length))
{
return(value);
}
}
return(null);
}
/// <summary>
/// Returns a search cursor which allows you to iterate over every string in the set with the same StringHash.
/// </summary>
public StringSearchCursor GetSearchCursor(StringHash hash)
{
var data = _data;
var cursor = new StringSearchCursor();
cursor.Slots = data.Slots;
cursor.Hash = hash;
var buckets = data.Buckets;
var bucket = hash.Value % buckets.Length;
cursor.SlotIndex = buckets[bucket] - 1;
return(cursor);
}
/// <summary>
/// Uses the characters from a buffer to check whether a string exists in the set, and retrieve it if so.
/// </summary>
/// <param name="chars">A pointer to the string to search for.</param>
/// <param name="count">The length of the string (in chars).</param>
/// <param name="knownHashValue">(optional) If the StringHash has already been calculated, you can provide it here to save re-calculation.</param>
/// <returns>If found in the set, the existing string is returned. If not found, null is returned.</returns>
public unsafe string GetExistingString(char *chars, int count, StringHash knownHashValue = default(StringHash))
{
if (knownHashValue == default(StringHash))
{
knownHashValue = StringHash.GetHash(chars, count);
}
var cursor = GetSearchCursor(knownHashValue);
while (cursor.MightHaveMore)
{
var value = cursor.NextString();
if (value != null && UnsafeStringComparer.AreEqual(value, chars, count))
{
return(value);
}
}
return(null);
}
/// <summary>
/// Adds a string to the set if it does not already exist.
/// </summary>
/// <param name="str">The string to add to the set.</param>
/// <param name="knownHashValue">(optional) If the StringHash for str has already been calculated, you can provide it here to save re-calculation.</param>
/// <returns>True if the string was added. False if the string already existed in the set.</returns>
public bool Add(string str, StringHash knownHashValue = default(StringHash))
{
if (knownHashValue == default(StringHash))
{
knownHashValue = StringHash.GetHash(str);
}
if (!ContainsString(str, knownHashValue))
{
lock (_writeLock)
{
if (!ContainsString(str, knownHashValue))
{
AddImpl(str, knownHashValue);
return(true);
}
}
}
return(false);
}
