_StringTable Class Reference

#include <stringTable.h>

Public Member Functions
StringTableEntry	insert (const char *string, bool caseSens=false)
StringTableEntry	insertn (const char *string, S32 len, bool caseSens=false)
StringTableEntry	lookup (const char *string, bool caseSens=false)
StringTableEntry	lookupn (const char *string, S32 len, bool caseSens=false)
void	resize (const U32 newSize)

Static Public Member Functions
static void	create ()
static void	destroy ()
static U32	hashString (const char *in_pString)
	Hash a string into a U32.
static U32	hashStringn (const char *in_pString, S32 len)
	Hash a string of given length into a U32.

Static Public Attributes
static StringTableEntry	EmptyString
	Empty string.

Implementation details
static const U32	csm_stInitSize = 29
	_StringTable ()
	~_StringTable ()

Detailed Description

A global table for the hashing and tracking of strings.

Only one _StringTable is ever instantiated in Torque. It is accessible via the global variable StringTable.

StringTable is used to manage strings in Torque. It performs the following tasks:

• Ensures that only one pointer is ever used for a given string (through insert()).
• Allows the lookup of a string in the table.

// Adding a string to the StringTable.
StringTableEntry mRoot;
mRoot = StringTable->insert(root);
 
// Looking up a string in the StringTable.
StringTableEntry stName = StringTable->lookupn(name, len);
 
// Comparing two strings in the StringTable (see below).
if(mRoot == stName) Con::printf("These strings are equal!");

But why is this useful, you ask? Because every string that's run through the StringTable is stored once and only once, every string has one and only one pointer mapped to it. As a pointer is an integer value (usually an unsigned int), so we can do several neat things:

• StringTableEntrys can be compared directly for equality, instead of using the time-consuming dStrcmp() or dStricmp() function.
• For things like object names, we can avoid storing multiple copies of the string containing the name. The StringTable ensures that we only ever store one copy.
• When we're doing lookups by name (for instances, of resources), we can determine if the object is even registered in the system by looking up its name in the StringTable. Then, we can use the pointer as a hash key.

The scripting engine and the resource manager are the primary users of the StringTable.

Note

Be aware that the StringTable NEVER DEALLOCATES memory, so be careful when you add strings to it. If you carelessly add many strings, you will end up wasting space.

Constructor & Destructor Documentation

_StringTable()

_StringTable ( )

protected

~_StringTable()

~_StringTable ( )

protected

Member Function Documentation

create()

void create ( )

static

Initialize StringTable.

This is called at program start to initialize the StringTable global.

destroy()

void destroy ( )

static

Destroy the StringTable

This is called at program end to destroy the StringTable global.

hashString()

U32 hashString ( const char * in_pString )

static

Hash a string into a U32.

hashStringn()

U32 hashStringn ( const char * in_pString, S32 len )

static

Hash a string of given length into a U32.

insert()

StringTableEntry insert	(	const char *	string,
		bool	caseSens = false )

Get a pointer from the string table, adding the string to the table if it was not already present.

Parameters

string	String to check in the table (and add).
caseSens	Determines whether case matters.

insertn()

StringTableEntry insertn	(	const char *	string,
		S32	len,
		bool	caseSens = false )

Get a pointer from the string table, adding the string to the table if it was not already present.

Parameters

string	String to check in the table (and add).
len	Length of the string in bytes.
caseSens	Determines whether case matters.

lookup()

StringTableEntry lookup	(	const char *	string,
		bool	caseSens = false )

Get a pointer from the string table, NOT adding the string to the table if it was not already present.

Parameters

string	String to check in the table (but not add).
caseSens	Determines whether case matters.

lookupn()

StringTableEntry lookupn	(	const char *	string,
		S32	len,
		bool	caseSens = false )

Get a pointer from the string table, NOT adding the string to the table if it was not already present.

Parameters

string	String to check in the table (but not add).
len	Length of string in bytes.
caseSens	Determines whether case matters.

resize()

void resize

(

const U32

newSize

)

Resize the StringTable to be able to hold newSize items. This is called automatically by the StringTable when the table is full past a certain threshhold.

Parameters

newSize

Number of new items to allocate space for.

Member Data Documentation

csm_stInitSize

const U32 csm_stInitSize = 29

staticprotected

EmptyString

StringTableEntry EmptyString

static

Empty string.

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The documentation for this class was generated from the following files:

• string/stringTable.h
• string/stringTable.cc