Pike: mapping

NAME: mapping - an associative array
SYNTAX EXAMPLE: ([ index1:data1, index2:data2 ])
DESCRIPTION: A mapping is basically an array that can be indexed on any type, not not just integers. It can also be seen as a way of linking data (usaully strings) together. It consists of a lot of index-data pairs which are linked togeter in such a way that map[index1] returns data1. It is also possible to set that data by writing map[index1]=new_data1. If you try to set an index in a mapping that isn't already present in the mapping then it will be added.
Here follows a list of operators that applies to mappings: In this list a and b is used to represent a mapping expression:

a + b summation ( ([1:1]) + ([2:2,2:2]) returns ([1:1,2:2,2:2]) )

a - b subtraction, returns a copy of a with all pairs whos index is present in b removed.

a & b intersection, return a mapping with all indices that are resent in both a and b, if an index is present in both a & b the data for that index will be taken from b.

a | b union, return a mapping with all values that are present in a or b, differs from summation in that values that are present in both a and b are only returned once, as with intersection, data will be taken from b when possible.

a ^ b xor, return a mapping with all indices that are present in a or b but not in both.

a == b returns 1 if a is the same mapping as b, same size, indices and values is not enough, 0 otherwise.

a != b returns 0 if a is the same mapping as b, same size, indices and values is not enough, 1 otherwise.

! a boolean not, returns 0

a[c] indexing, returns the value associated with the value c in the mapping a. If there is no index c in the mapping zero will be returned. (With zero_type = 1)

a[c]=d setting, this associates d with c in the mapping, the index c will be added to the mapping automatically if it isn't already there.
KEYWORDS: types
SEE ALSO: array, multiset, sizeof, indices, values and zero_type
RELATED PAGES

aggregate_mapping - construct a mapping
indices - return an array of all index possible for a value
m_delete - remove an index from a mapping
m_indices - return all indices from a mapping
m_sizeof - Return the size of a mapping
m_values - return all values from a mapping
mappingp - is the argument an mapping?
mkmapping - make a mapping
replace - generic replace function
search - search for a value in a string or array
sizeof - return the size of an array, string, multiset or mapping
sum - add values together
values - return an array of all possible values from indexing
zero_type - return the type of zero

a + b	summation ( ([1:1]) + ([2:2,2:2]) returns ([1:1,2:2,2:2]) )
a - b	subtraction, returns a copy of a with all pairs whos index is present in b removed.
a & b	intersection, return a mapping with all indices that are resent in both a and b, if an index is present in both a & b the data for that index will be taken from b.
a \| b	union, return a mapping with all values that are present in a or b, differs from summation in that values that are present in both a and b are only returned once, as with intersection, data will be taken from b when possible.
a ^ b	xor, return a mapping with all indices that are present in a or b but not in both.
a == b	returns 1 if a is the same mapping as b, same size, indices and values is not enough, 0 otherwise.
a != b	returns 0 if a is the same mapping as b, same size, indices and values is not enough, 1 otherwise.
! a	boolean not, returns 0
a[c]	indexing, returns the value associated with the value c in the mapping a. If there is no index c in the mapping zero will be returned. (With zero_type = 1)
a[c]=d	setting, this associates d with c in the mapping, the index c will be added to the mapping automatically if it isn't already there.