XQuery Extensions - Revision history

CG: Text replacement - "syntaxhighlight" to "pre"

2023-12-01T16:39:03Z

Text replacement - "syntaxhighlight" to "pre"

CG: Text replacement - "" to ""

2023-12-01T16:33:43Z

Text replacement - "</syntaxhighlight>" to "</pre>"

CG: Text replacement - "" to "

2023-12-01T16:33:05Z

Text replacement - "<syntaxhighlight lang="xquery">" to "<pre lang='xquery'>"

CG at 13:20, 31 October 2023

2023-10-31T13:20:00Z

CG at 13:18, 31 October 2023

2023-10-31T13:18:42Z

CG at 13:13, 31 October 2023

2023-10-31T13:13:00Z

CG: /* Nondeterminism */

2023-10-31T13:07:12Z

Nondeterminism

CG at 12:56, 31 October 2023

2023-10-31T12:56:33Z

CG: /* Expressions */

2022-08-07T14:22:03Z

Expressions

CG: Text replacement - "db:pre(" to "db:get("

2022-07-20T11:34:02Z

Text replacement - "db:pre(" to "db:get("

@@ Line 173: / Line 173: @@
 '''Result:'''
-<syntaxhighlight lang="xml">
+<pre lang="xml">
 Stopped at query.xq, 1/53:
 [FOER0000] Halted on error().

@@ Line 14: / Line 14: @@
 (: ternary if :)
 $ok ?? 1 !! 0
-</syntaxhighlight>
+</pre>
 The expression returns <code>ok</code> if the effective boolean value of <code>$test</code> is true, and it returns <code>fails</code> otherwise.
@@ Line 26: / Line 26: @@
 if (file:exists($file)) then file:delete($file),
 if (permissions:valid($user)) then <html>Welcome!</html>
-</syntaxhighlight>
+</pre>
 If conditions are nested, a trailing else branch will be associated with the innermost <code>if</code>:
@@ Line 32: / Line 32: @@
 <pre lang='xquery'>
 if ($a) then if($b) then '$a and $b is true' else 'only $a is true'
-</syntaxhighlight>
+</pre>
 In general, if you have multiple or nested if expressions, additional parentheses can improve the readibility of your code:
@@ Line 40: / Line 40: @@
    if($b) then '$a and $b is true' else 'only $a is true'
+)
-</syntaxhighlight>
+</pre>
 =Functions=
@@ Line 52: / Line 52: @@
 (: yields "!Hi! !there!" :)
 replace('Hi there', '\b', '!', 'j')
-</syntaxhighlight>
+</pre>
 =Serialization=
@@ Line 71: / Line 71: @@
 declare option db:catalog 'etc/w3-catalog.xml';
 doc('doc.xml')
-</syntaxhighlight>
+</pre>
 ==XQuery Locks==
@@ Line 89: / Line 89: @@
 to 100000000
 })
-</syntaxhighlight>
+</pre>
 This pragma can be helpful when debugging your code.
@@ Line 99: / Line 99: @@
    file:write('config.xml', <config/>)
+}
-</syntaxhighlight>
+</pre>
 ==Database Pragmas==
@@ Line 112: / Line 112: @@
    return db:get($db)//name[text() = 'John']
+}
-</syntaxhighlight>
+</pre>
 * Node copying in node constructors can be disabled (see {{Option|COPYNODE}} for more details). The following query will consume much less memory than without pragma as the database nodes will not be fully duplicated, but only attached to the {{Code|xml}} parent element:
@@ Line 123: / Line 123: @@
+   }
+)
-</syntaxhighlight>
+</pre>
 * An XML catalog can be specified for URI rewritings. See the [[Catalog Resolver]] section for an example.
@@ Line 141: / Line 141: @@
 for $i in 1 to 3
 return local:square($i)
-</syntaxhighlight>
+</pre>
 '''Query after function inlining:'''
@@ Line 150: / Line 150: @@
    let $a := $i
    return $a * $a
-</syntaxhighlight>
+</pre>
 '''Query after further optimizations:'''
@@ Line 157: / Line 157: @@
 for $i in 1 to 3
 return $i * $i
-</syntaxhighlight>
+</pre>
 By default, XQuery functions will be ''inlined'' if the query body is not too large and does not exceed a fixed number of expressions, which can be adjusted via the {{Option|INLINELIMIT}} option.
@@ Line 169: / Line 169: @@
 declare %basex:inline(0) function local:e() { error() };
 local:e()
-</syntaxhighlight>
+</pre>
 '''Result:'''
@@ Line 179: / Line 179: @@
 Stack Trace:
 - query.xq, 2/9
-</syntaxhighlight>
+</pre>
 ==Lazy Evaluation==
@@ Line 189: / Line 189: @@
 declare %basex:lazy variable $january := doc('does-not-exist.xml');
 if(month-from-date(current-date()) = 1) then $january else ()
-</syntaxhighlight>
+</pre>
 The annotation ensures that an error is only raised if the condition yields true. Without the annotation, the error is always raised if the referenced document is not found.
@@ Line 204: / Line 204: @@
 <xml:abc xmlns:prefix='uri' local:fn='x'/>,
 fn:exists(1)
-</syntaxhighlight>
+</pre>
 In BaseX, various other namespaces are predefined. Apart from the namespaces that are listed on the [[Module Library]] page, the following namespaces are statically bound:
@@ Line 243: / Line 243: @@
 <pre lang='xquery'>
 'Hello World!'
-</syntaxhighlight>
+</pre>
 * Library modules start with a module namespace declaration and have no query body:
@@ Line 253: / Line 253: @@
    'Hello World!'
 };
-</syntaxhighlight>
+</pre>
 We recommend {{Code|.xq}} as suffix for for main modules, and {{Code|.xqm}} for library modules. However, the actual module type will dynamically be detected when a file is opened and parsed.

@@ Line 9: / Line 9: @@
 The [https://en.wikipedia.org/wiki/%3F: ternary if] operator provides a short syntax for conditions. It is also called '''conditional operator''' or '''ternary operator'''. In most languages, the syntax is <code>a ? b : c</code>. As <code>?</code> and <code>:</code> have already been taken in XQuery, the syntax of Perl 6 is used:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 (: if/then/else :)
 if ($ok) then 1 else 0,
@@ Line 22: / Line 22: @@
 In XQuery 3.1, both branches of the <code>if</code> expression need to be specified. In many cases, only one branch is required, so the <code>else</code> branch was made optional in BaseX. If the second branch is omitted, an empty sequence will be returned if the effective boolean value of the test expression is false. Some examples:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 if (doc-available($doc)) then doc($doc),
 if (file:exists($file)) then file:delete($file),
@@ Line 30: / Line 30: @@
 If conditions are nested, a trailing else branch will be associated with the innermost <code>if</code>:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 if ($a) then if($b) then '$a and $b is true' else 'only $a is true'
 </syntaxhighlight>
@@ Line 36: / Line 36: @@
 In general, if you have multiple or nested if expressions, additional parentheses can improve the readibility of your code:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 if ($a) then (
    if($b) then '$a and $b is true' else 'only $a is true'
@@ Line 49: / Line 49: @@
 '''Example:'''
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 (: yields "!Hi! !there!" :)
 replace('Hi there', '\b', '!', 'j')
@@ Line 68: / Line 68: @@
 [[Options|Local database options]] can be set in the prolog of an XQuery main module. In the option declaration, options need to be bound to the [[Database Module]] namespace. All values will be reset after the evaluation of a query:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 declare option db:catalog 'etc/w3-catalog.xml';
 doc('doc.xml')
@@ Line 85: / Line 85: @@
 Many optimizations in BaseX will only be performed if an expression is ''deterministic'' (i. e., if it always yields the same output and does not have side effects). By flagging an expression as nondeterministic, optimizations and query rewritings can be suppressed:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 sum( (# basex:nondeterministic #) {
 to 100000000
@@ Line 95: / Line 95: @@
 In analogy with option declarations and function annotations, XQuery locks can also set via pragmas. See [[Transaction Management#Options|Transaction Management]] for details and examples.
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 (# basex:write-lock CONFIGLOCK #) {
    file:write('config.xml', <config/>)
@@ Line 107: / Line 107: @@
 * [[Indexes|Index access rewritings]] can be enforced. This is helpful if the name of a database is not static (see [[Indexes#Enforce Rewritings|Enforce Rewritings]] for more details):
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 (# db:enforceindex #) {
    for $db in ('persons1', 'persons2', 'persons3')
@@ Line 116: / Line 116: @@
 * Node copying in node constructors can be disabled (see {{Option|COPYNODE}} for more details). The following query will consume much less memory than without pragma as the database nodes will not be fully duplicated, but only attached to the {{Code|xml}} parent element:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 file:write(
    'wrapped-db-nodes.xml',
@@ Line 137: / Line 137: @@
 '''Query:'''
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 declare function local:square($a) { $a * $a };
 for $i in 1 to 3
@@ Line 145: / Line 145: @@
 '''Query after function inlining:'''
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 for $i in 1 to 3
 return
@@ Line 154: / Line 154: @@
 '''Query after further optimizations:'''
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 for $i in 1 to 3
 return $i * $i
@@ Line 165: / Line 165: @@
 '''Example:'''
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 (: disable function inlining; the full stack trace will be shown... :)
 declare %basex:inline(0) function local:e() { error() };
@@ Line 186: / Line 186: @@
 '''Example:'''
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 declare %basex:lazy variable $january := doc('does-not-exist.xml');
 if(month-from-date(current-date()) = 1) then $january else ()
@@ Line 201: / Line 201: @@
 In XQuery, some namespaces are statically bound to prefixes. The following query requires no additional namespaces declarations in the query prolog:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 <xml:abc xmlns:prefix='uri' local:fn='x'/>,
 fn:exists(1)
@@ Line 241: / Line 241: @@
 * Main modules have an expression as query body. Here is a minimum example:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 'Hello World!'
 </syntaxhighlight>
@@ Line 247: / Line 247: @@
 * Library modules start with a module namespace declaration and have no query body:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 module namespace hello = 'http://basex.org/examples/hello';

@@ Line 3: / Line 3: @@
 =Expressions=
-Some of the extensions that have been added to BaseX may also be made available in other XQuery processors in the near future.
+{{Announce|Removed with Version 11}}: Elvis operator <code>?:</code>, in favor of the new <code>[https://qt4cg.org/specifications/xquery-40/xquery-40.html#id-otherwise otherwise]</code> expression.
 ==Ternary If==

@@ Line 17: / Line 17: @@
 The expression returns <code>ok</code> if the effective boolean value of <code>$test</code> is true, and it returns <code>fails</code> otherwise.
 ==If Without Else==
@@ Line 54: / Line 41: @@
+)
 </syntaxhighlight>
 =Functions=
@@ Line 280: / Line 265: @@
 ;Version 11:
 * Updated: Renamed from {{Code|non-deterministic}} to {{Code|nondeterministic}}.

← Older revision		Revision as of 13:13, 31 October 2023
Line 211:		Line 211:

	In analogy with option declarations and pragmas, locks can also set via annotations. See [[Transaction Management#Annotations\|Transaction Management]] for details and examples.		In analogy with option declarations and pragmas, locks can also set via annotations. See [[Transaction Management#Annotations\|Transaction Management]] for details and examples.
−
−	~~=Nondeterminism=~~
−
−	~~{{Announce\|Updated with Version 11}}: Renamed from {{Code\|non-deterministic}} to {{Code\|nondeterministic}}.~~
−
−	In [https://www.w3.org/TR/xpath-functions-31/#dt-deterministic XQuery], deterministic functions are “guaranteed to produce ·identical· results from repeated calls within a single ·execution scope· if the explicit and implicit arguments are identical”. In BaseX, many extension functions are nondeterministic or side-effecting. If an expression is internally flagged as nondeterministic, various optimizations that might change their execution order will not be applied.
−
−	~~<syntaxhighlight lang="xquery">~~
−	~~(: QUERY A... :)~~
−	~~let $n := 456~~
−	~~for $i in 1 to 2~~
−	~~return $n~~
−
−	~~(: ...will be optimized to :)~~
−	~~for $i in 1 to 2~~
−	~~return 456~~
−
−	~~(: QUERY B will not be rewritten :)~~
−	~~let $n := random:integer()~~
−	~~for $i in 1 to 2~~
−	~~return $n~~
−	~~</syntaxhighlight>~~
−
−	~~In some cases, functions may contain nondeterministic code, but the query compiler may not be able to detect this statically. See the following example:~~
−
−	~~<syntaxhighlight lang="xquery">~~
−	~~for $read in (file:read-text#1, file:read-binary#1)~~
−	~~let $ignored := nondeterministic $read('input.file')~~
−	~~return ()~~
−	~~</syntaxhighlight>~~
−
−	Two nondeterministic functions will be bound to <code>$read</code>, and the result of the function call will be bound to <code>$ignored</code>. As the variable is not referenced in the subsequent code, the let clause would usually be discarded by the compiler. In the given query, however, execution will be enforced because of the BaseX-specific {{Code\|nondeterministic}} keyword.

	=Namespaces=		=Namespaces=

@@ Line 216: / Line 216: @@
 {{Announce|Updated with Version 11}}: Renamed from {{Code|non-deterministic}} to {{Code|nondeterministic}}.
-In [https://www.w3.org/TR/xpath-functions-31/#dt-deterministic XQuery], ''deterministic'' functions are “guaranteed to produce ·identical· results from repeated calls within a single ·execution scope· if the explicit and implicit arguments are identical”. In BaseX, many extension functions are nondeterministic or side-effecting. If an expression is internally flagged as nondeterministic, various optimizations that might change their execution order will not be applied.
+In [https://www.w3.org/TR/xpath-functions-31/#dt-deterministic XQuery], deterministic functions are “guaranteed to produce ·identical· results from repeated calls within a single ·execution scope· if the explicit and implicit arguments are identical”. In BaseX, many extension functions are nondeterministic or side-effecting. If an expression is internally flagged as nondeterministic, various optimizations that might change their execution order will not be applied.
 <syntaxhighlight lang="xquery">

@@ Line 96: / Line 96: @@
 ==BaseX Pragmas==
-Many optimizations in BaseX will only be performed if an expression is ''deterministic'' (i. e., if it always yields the same output and does not have side effects). By flagging an expression as non-deterministic, optimizations and query rewritings can be suppressed:
+{{Announce|Updated with Version 11}}: Renamed from {{Code|non-deterministic}} to {{Code|nondeterministic}}.
 <syntaxhighlight lang="xquery">
-sum( (# basex:non-deterministic #) {
+sum( (# basex:nondeterministic #) {
 to 100000000
 })
@@ Line 210: / Line 212: @@
 In analogy with option declarations and pragmas, locks can also set via annotations. See [[Transaction Management#Annotations|Transaction Management]] for details and examples.
-=Non-Determinism=
+=Nondeterminism=
-In [https://www.w3.org/TR/xpath-functions-31/#dt-deterministic XQuery], ''deterministic'' functions are “guaranteed to produce ·identical· results from repeated calls within a single ·execution scope· if the explicit and implicit arguments are identical”. In BaseX, many extension functions are non-deterministic or side-effecting. If an expression is internally flagged as non-deterministic, various optimizations that might change their execution order will not be applied.
+In [https://www.w3.org/TR/xpath-functions-31/#dt-deterministic XQuery], ''deterministic'' functions are “guaranteed to produce ·identical· results from repeated calls within a single ·execution scope· if the explicit and implicit arguments are identical”. In BaseX, many extension functions are nondeterministic or side-effecting. If an expression is internally flagged as nondeterministic, various optimizations that might change their execution order will not be applied.
 <syntaxhighlight lang="xquery">
@@ Line 230: / Line 234: @@
 </syntaxhighlight>
-In some cases, functions may contain non-deterministic code, but the query compiler may not be able to detect this statically. See the following example:
+In some cases, functions may contain nondeterministic code, but the query compiler may not be able to detect this statically. See the following example:
 <syntaxhighlight lang="xquery">
 for $read in (file:read-text#1, file:read-binary#1)
-let $ignored := non-deterministic $read('input.file')
+let $ignored := nondeterministic $read('input.file')
 return ()
 </syntaxhighlight>
-Two non-deterministic functions will be bound to <code>$read</code>, and the result of the function call will be bound to <code>$ignored</code>. As the variable is not referenced in the subsequent code, the let clause would usually be discarded by the compiler. In the given query, however, execution will be enforced because of the BaseX-specific {{Code|non-deterministic}} keyword.
+Two nondeterministic functions will be bound to <code>$read</code>, and the result of the function call will be bound to <code>$ignored</code>. As the variable is not referenced in the subsequent code, the let clause would usually be discarded by the compiler. In the given query, however, execution will be enforced because of the BaseX-specific {{Code|nondeterministic}} keyword.
 =Namespaces=
@@ Line 305: / Line 309: @@
 =Changelog=
 ;Version 9.1: