Vicare Scheme: syslib hashtables

12.22 Low level hashtable objects operations

The following bindings are exported by the library (vicare system $hashtables).

Unsafe Operation: $string-hash string

Unsafe Operation: $string-hash string max-len

Return an integer hash value for string, based on its current contents. This hash function is suitable for use with string=? as an equivalence function.

About the max-len argument:

When max-len is a non–negative fixnum: it is the maximum number of characters to use to compute the hash value, starting from the beginning of string. If the length of string is greater than max-len: only the first max-len characters are used. If the length of string is less than or equal to max-len: all the bytes in string are used.
When max-len is #f or not used: if the length of string is greater than 64 characters, only the first 64 bytes are used to compute the hash.
When max-len is #t: all the bytes in string are used.

NOTE When the hash value is computed using a number of characters N less than the string length: applications must not assume that two strings having the first N characters equal will have the same hash value.

Unsafe Operation: $string-ci-hash string

Unsafe Operation: $string-ci-hash string max-len

Return an integer hash value for string based on its current contents, ignoring case. This hash function is suitable for use with string-ci=? as an equivalence function.

The optional argument max-len is used as in $string-hash.

Unsafe Operation: $symbol-hash symbol: Return an integer hash value for symbol.

Unsafe Operation: $bytevector-hash bytevector

Unsafe Operation: $bytevector-hash bytevector max-len

Return an integer hash value for bytevector, based on its current contents. This hash function is suitable for use with bytevector=? as an equivalence function.

About the max-len argument:

When max-len is a non–negative fixnum: it is the maximum number of bytes to use to compute the hash value, starting from the beginning of bv. If the length of bv is greater than max-len: only the first max-len bytes are used. If the length of bv is less than or equal to max-len: all the bytes in bv are used.
When max-len is #f or not present: if the length of bv is greater than 256 bytes, only the first 256 bytes are used to compute the hash.
When max-len is #t: all the bytes in bv are used.

NOTE When the hash value is computed using a number of bytes N less than the bytevector length: applications must not assume that two bytevectors having the first N bytes equal will have the same hash value.

Unsafe Operation: $vector-hash vec

Unsafe Operation: $vector-hash vec max-len

Return a non–negative fixnum representing the hash value for vec, based on its current contents. When creating hash tables using vectors as keys: this hash function is suitable for use with vector=? as an equivalence function.

About the max-len argument:

When max-len is a non–negative fixnum: it is the maximum number of items to use to compute the hash value, starting from the beginning of vec. If the length of vec is greater than max-len: only the first max-len items are used. If the length of vec is less than or equal to max-len: all the items in vec are used.
When max-len is #f or not present: if the length of vec is greater than 3 items, only the first 3 items are used to compute the hash.
When max-len is #t: all the items in vec are used.

NOTE When the hash value is computed using a number of items N less than the vector length: applications must not assume that two vectors having the first N items equal will have the same hash value.

Unsafe Operation: $list-hash ell

Unsafe Operation: $list-hash ell max-len

Return a non–negative fixnum representing the hash value for ell, based on its current contents. When creating hash tables using lists as keys: this hash function is suitable for use with list=? as an equivalence function.

About the max-len argument:

When max-len is a non–negative fixnum: it is the maximum number of items to use to compute the hash value, starting from the beginning of ell. If the length of ell is greater than max-len: only the first max-len items are used. If the length of ell is less than or equal to max-len: all the items in ell are used.
When max-len is #f or not present: if the length of ell is greater than 3 items, only the first 3 items are used to compute the hash.
When max-len is #t: all the items in ell are used.

NOTE When the hash value is computed using a number of items N less than the list length: applications must not assume that two lists having the first N items equal will have the same hash value.

Unsafe Operation: $pair-hash pair
Unsafe Operation: $ipair-hash ipair: Hash function for pairs and immutable pairs.

Unsafe Operation: $char-hash ch
Unsafe Operation: $char-ci-hash ch: Compute and return the hash value.

Unsafe Operation: $fixnum-hash fx: Compute and return the hash value.

Unsafe Operation: $bignum-hash bn: Compute and return the hash value.

Unsafe Operation: $exact-integer-hash ei: Compute and return the hash value.

Unsafe Operation: $ratnum-hash rn: Compute and return the hash value.

Unsafe Operation: $flonum-hash fl: Compute and return the hash value.

Unsafe Operation: $cflonum-hash cfl: Compute and return the hash value.

Unsafe Operation: $compnum-hash cn: Compute and return the hash value.

Unsafe Operation: $transcoder-hash tran: Compute and return the hash value.

Unsafe Operation: $enum-set-hash es: Hash function for enumeration sets.

Unsafe Operation: $pointer-hash ptr: Return a fixnum representing the hash value of ptr.

Unsafe Operation: $promise-hash prom: Hash function for promise objects.

Unsafe Operation: $record-hash reco
Unsafe Operation: $struct-hash stru: Compute and return the hash value.

NOTE The result returned by these hash functions depends on the values in the fields, so: it will change if the fields are mutated.

Unsafe Operation: $hashtable-type-descriptor table
Unsafe Operation: $hashtable-type-descriptor-set! table des: Setter and getter for the hashtable run–time type descriptor. des must be an instance of <hashtable-type-descr>.