Tcl_HashEntry * Tcl_CreateHashEntry(tablePtr, key, newPtr)
Tcl_HashEntry * Tcl_FindHashEntry(tablePtr, key)
char * Tcl_GetHashKey(tablePtr, entryPtr)
Tcl_HashEntry * Tcl_FirstHashEntry(tablePtr, searchPtr)
Tcl_HashEntry * Tcl_NextHashEntry(searchPtr)
char * Tcl_HashStats(tablePtr)
- Tcl_HashTable *tablePtr (in)
Address of hash table structure (for all procedures but
Tcl_InitHashTable(), this must have been initialized by previous call to Tcl_InitHashTable()).
- int keyType (in)
Kind of keys to use for new hash table. Must be either TCL_STRING_KEYS, TCL_ONE_WORD_KEYS, or an integer value greater than 1.
- char *key (in)
Key to use for probe into table. Exact form depends on keyType used to create table.
- int *newPtr (out)
The word at *newPtr is set to 1 if a new entry was created and 0 if there was already an entry for key.
- Tcl_HashEntry *entryPtr (in)
Pointer to hash table entry.
- ClientData value (in)
New value to assign to hash table entry. Need not have type ClientData, but must fit in same space as ClientData.
- Tcl_HashSearch *searchPtr (in)
Pointer to record to use to keep track of progress in enumerating all the entries in a hash table.
A hash table consists of zero or more entries, each consisting of a key and a value. Given the key for an entry, the hashing routines can very quickly locate the entry, and hence its value. There may be at most one entry in a hash table with a particular key, but many entries may have the same value. Keys can take one of three forms: strings, one-word values, or integer arrays. All of the keys in a given table have the same form, which is specified when the table is initialized.
The value of a hash table entry can be anything that fits in the same space as a char * pointer. Values for hash table entries are managed entirely by clients, not by the hash module itself. Typically each entry's value is a pointer to a data structure managed by client code.
Hash tables grow gracefully as the number of entries increases, so that there are always less than three entries per hash bucket, on average. This allows for fast lookups regardless of the number of entries in a table.
Keys are null-terminated ASCII strings. They are passed to hashing routines using the address of the first character of the string.
Keys are single-word values; they are passed to hashing routines and stored in hash table entries as char * values. The pointer value is the key; it need not (and usually doesn't) actually point to a string.
If keyType is not TCL_STRING_KEYS or TCL_ONE_WORD_KEYS, then it must be an integer value greater than 1. In this case the keys will be arrays of int values, where keyType gives the number of ints in each key. This allows structures to be used as keys. All keys must have the same size. Array keys are passed into hashing functions using the address of the first int in the array.
The header file tcl.h defines the actual data structures used to implement hash tables. This is necessary so that clients can allocate Tcl_HashTable structures and so that macros can be used to read and write the values of entries. However, users of the hashing routines should never refer directly to any of the fields of any of the hash-related data structures; use the procedures and macros defined here.
Windows Server 2012. Windows 8.1. Windows Server 2012 R2. Windows 10. Windows Server 2016. Windows Server 2019.
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