Changes

A <em>''map</em> '' can also be viewed as a function from keys to associated values. To achieve this, a map is also a function item. The function corresponding to the map has the signature <code>function($key as xs:anyAtomicType) as item()*</code>. Calling the function has the same effect as calling the <code>get</code> function: the expression <code>$map($key)</code> returns the same result as <code>map:get($map, $key)</code>. For example, if <code>$books-by-isbn</code> is a map whose keys are ISBNs and whose assocated values are <code>book</code> elements, then the expression <code>$books-by-isbn("0470192747")</code> returns the <code>book</code> element with the given ISBN. The fact that a map is a function item allows it to be passed as an argument to higher-order functions that expect a function item as one of their arguments. As an example, the following query uses the higher-order function <code>fn:map($f, $seq)</code> to extract all bound values from a <em>''map</em>'':

Like all other values, <em>''maps</em> '' are immutable. For example, the <code>map:remove</code> function creates a new map by removing an entry from an existing map, but the existing map is not changed by the operation.

Like sequences, <em>''maps</em> '' have no identity. It is meaningful to compare the contents of two maps, but there is no way of asking whether they are "the same map": two maps with the same content are indistinguishable.

| * <code><strong>map:collation</strong>($map as map(*)) as xs:string</code><br/>

| Returns the collation URI of the <em>''map</em> '' supplied as <code>$map</code>.

| * <code><strong>map:contains</strong>($map as map(*), $key as item()) as xs:boolean</code><br/>

| Returns true if the <em>''map</em> '' supplied as <code>$map</code> contains an entry with a key equal to the supplied value of <code>$key</code>; otherwise it returns false. The equality comparison uses the map's collation; no error occurs if the map contains keys that are not comparable with the supplied <code>$key</code>.

|– * <code>map:contains($week, 2)</code> returns <code>true()</code>.<br/>– * <code>map:contains($week, 9)</code> returns <code>false()</code>.<br/>– * <code>map:contains(map{}, "xyz")</code> returns <code>false()</code>.<br/>– * <code>map:contains(map{ "xyz":=23 }, "xyz")</code> returns <code>true()</code>.<br/>

| * <code><strong>map:entry</strong>($key as item(), $value as item()*) as map(*)</code><br/>

| Creates a new <em>''map</em> '' containing a single entry. The collation of the new map is the default collation from the static context. The key of the entry in the new map is <code>$key</code>, and its associated value is <code>$value</code>. If the supplied key is <code>xs:untypedAtomic</code>, it is converted to <code>xs:string</code>. If the supplied key is the <code>xs:float</code> or <code>xs:double</code> value <code>NaN</code>, the supplied <code>$map</code> is returned unchanged.

|– * <code>map:entry("M", "Monday")</code> creates a map with the values <code>{ "M":="Monday" }</code>.

| * <code><strong>map:get</strong>($map as map(*), $key as item()) as item()*</code><br/>

|Returns the value associated with a supplied key in a given map. This function attempts to find an entry within the <em>''map</em> '' supplied as <code>$map</code> that has a key equal to the supplied value of <code>$key</code>. If there is such an entry, it returns the associated value; otherwise it returns an empty sequence. The equality comparison uses the map's collation; no error occurs if the map contains keys that are not comparable with the supplied <code>$key</code>. If the supplied key is <code>xs:untypedAtomic</code>, it is converted to <code>xs:string</code>. If the supplied key is the <code>xs:float</code> or <code>xs:double</code> value <code>NaN</code>, the function returns an empty sequence.

Invoking the <em>''map</em> '' as a function item has the same effect as calling <code>get</code>: that is, when <code>$map</code> is a map, the expression <code>$map($K)</code> is equivalent to <code>get($map, $K)</code>. Similarly, the expression <code>get(get(get($map, 'employee'), 'name'), 'first')</code> can be written as <code>$map('employee')('name')('first')</code>.

|– * <code>map:get($week, 4)</code> returns <code>"Donnerstag"</code>.<br/>– * <code>map:get($week, 9)</code> returns <code>()</code>. <em>''(When the key is not present, the function returns an empty sequence.).</em><br/>– ''* <code>map:get(map:entry(7,())), 7)</code> returns <code>()</code>. <em>''(An empty sequence as the result can also signify that the key is present and the associated value is an empty sequence.).</em><br/>''

| * <code><strong>map:keys</strong>($map as map(*)) as xs:anyAtomicType*</code><br/>

|Returns a sequence containing all the key values present in a map. The function takes any <em>''map</em> '' as its <code>$map</code> argument and returns the keys that are present in the map as a sequence of atomic values, in implementation-dependent order.

|– * <code>map:keys(map{ 1:="yes", 2:="no" })</code> returns some permutation of <code>(1,2)</code> <em>''(the result is in implementation-dependent order).</em><br/>''

| * <code><strong>map:new</strong>() as map(*)</code><br/>* <code><strong>map:new</strong>($maps as map(*)*) as map(*)</code><br/>* <code><strong>map:new</strong>($maps as map(*)*, $coll as xs:string) as map(*)</code><br/>

| Constructs and returns a new map. The zero-argument form of the function returns an empty <em>''map</em> '' whose collation is the default collation in the static context. It is equivalent to calling the one-argument form of the function with an empty sequence as the value of the first argument.The one-argument form of the function returns a <em>''map</em> '' that is formed by combining the contents of the maps supplied in the <code>$maps</code> argument. It is equivalent to calling the two-argument form of the function with the default collation from the static context as the second argument.The two-argument form of the function returns a <em>''map</em> '' that is formed by combining the contents of the maps supplied in the <code>$maps</code> argument. The collation of the new map is the value of the <code>$collation</code> argument. The supplied maps are combined as follows:<ol> <li> <p> # There is one entry in the new map for each distinct key value present in the union of the input maps, where keys are considered distinct according to the rules of the <code>distinct-values</code> function with <code>$collation</code> as the collation. </p> </li> <li> <p> # The associated value for each such key is taken from the last map in the input sequence <code>$maps</code> that contains an entry with this key. If this map contains more than one entry with this key (which can happen if its collation is different from that of the new map) then it is <em>''implementation-dependent</em> '' which of them is selected. </p> </li></ol>

|– * <code>map:new()</code> creates an empty map.<br/>– * <code>map:new(())</code> creates an empty map.<br/>– * <code>map:new(map:entry(0, "no"), map:entry(1, "yes"))</code> creates a map with the values <code>{ 0:="no", 1:="yes" }</code>.<br/>– * <code>map:new(map:entry(0, "no"), map:entry(1, "yes"))</code> creates a map with the values <code>{ 0:="no", 1:="yes" }</code>.<br/>– * <code>map:new(($week, map{ 7:="Unbekannt" }))</code> creates a map with the values <code>{ 0:="Sonntag", 1:="Montag", 2:="Dienstag", 3:="Mittwoch", 4:="Donnerstag", 5:="Freitag", 6:="Samstag", 7:="Unbekannt" }</code>.<br/>– * <code>map:new(($week, map{ 6:="Sonnabend" }))</code> creates a map with the values <code>{ 0:="Sonntag", 1:="Montag", 2:="Dienstag", 3:="Mittwoch", 4:="Donnerstag", 5:="Freitag", 6:="Sonnabend" }</code>.<br/>

| * <code><strong>map:remove</strong>($map as map(*), $key as item()) as map(*)</code><br/>

|– * <code>map:remove($week, 4)</code> creates a map with the values <code>{ 0:="Sonntag", 1:="Montag", 2:="Dienstag", 3:="Mittwoch", 5:="Freitag", 6:="Samstag" }</code>.<br/>– * <code>map:remove($week, 23)</code> creates a map with the values <code>{ 0:="Sonntag", 1:="Montag", 2:="Dienstag", 3:="Mittwoch", 4:="Donnerstag", 5:="Freitag", 6:="Samstag" }</code>.<br/>

| * <code><strong>map:size</strong>($map as map(*)) as xs:integer</code><br/>

| Returns a the number of entries in the supplied map. The function takes any <em>''map</em> '' as its <code>$map</code> argument and returns the number of entries that are present in the map.

|– * <code>map:size(map:new())</code> returns <code>0</code>.<br/>– * <code>map:size(map{ "true":=1, "false":=0 })</code> returns <code>2</code>.<br/>