XML Query Use Cases with xml.pl - Revision history

John: /* XMP link updated to https */

2022-08-01T19:11:09Z

XMP link updated to https

← Older revision		Revision as of 19:11, 1 August 2022
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	====test( +QueryId )====		====test( +QueryId )====
	The <code>test/1</code> predicate is the entry-point of the program and		The <code>test/1</code> predicate is the entry-point of the program and
	executes a Prolog implementation of a Query from [~~http~~://www.w3.org/TR/xquery-use-cases/#xmp Use Case “XMP”: Experiences and Exemplars], in the W3C's XML Query Use Cases, which “contains several example queries that illustrate requirements gathered from the database and document communities”.		executes a Prolog implementation of a Query from [https://www.w3.org/TR/xquery-use-cases/#xmp Use Case “XMP”: Experiences and Exemplars], in the W3C's XML Query Use Cases, which “contains several example queries that illustrate requirements gathered from the database and document communities”.

	<var>QueryId</var> is one of <code>q1</code>...<code>q12</code> selecting which of the 12 use cases is executed.		<var>QueryId</var> is one of <code>q1</code>...<code>q12</code> selecting which of the 12 use cases is executed.

John: /* input_document( +File, ?XML ) */

2018-01-13T20:31:09Z

input_document( +File, ?XML )

← Older revision	Revision as of 20:31, 13 January 2018
(No difference)

John: Remove broken syntax highlighting

2017-01-05T23:01:06Z

Remove broken syntax highlighting

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John at 16:01, 14 June 2015

2015-06-14T16:01:07Z

← Older revision		Revision as of 16:01, 14 June 2015
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	The following is a complete example to illustrate how the xml.pl module can be used.		The following is a complete example to illustrate how the xml.pl module can be used.
	It exercises both the input and output parsing modes of <code>xml_parse/[2,3]</code>, and illustrates		It exercises both the input and output parsing modes of <code>xml_parse/[2,3]</code>, and illustrates
	the use of <code>xml_subterm/2</code> to access the nodes of a "document value model".		the use of <code>xml_subterm/2</code> to access the nodes of a “document value model”.
	It's written for Quintus Prolog, but should port to other Prologs easily.		It's written for Quintus Prolog, but should port to other Prologs easily.

	====test( +QueryId )====		====test( +QueryId )====
	The <code>test/1</code> predicate is the entry-point of the program and		The <code>test/1</code> predicate is the entry-point of the program and
	executes a Prolog implementation of a Query from [http://www.w3.org/TR/xquery-use-cases/#xmp Use Case "XMP": Experiences and Exemplars], in the W3C's XML Query Use Cases, which "contains several example queries that illustrate requirements gathered from the database and document communities".		executes a Prolog implementation of a Query from [http://www.w3.org/TR/xquery-use-cases/#xmp Use Case “XMP”: Experiences and Exemplars], in the W3C's XML Query Use Cases, which “contains several example queries that illustrate requirements gathered from the database and document communities”.

	<var>QueryId</var> is one of <code>q1</code>...<code>q12</code> selecting which of the 12 use cases is executed.		<var>QueryId</var> is one of <code>q1</code>...<code>q12</code> selecting which of the 12 use cases is executed.

	The XML output is written to the file [QueryId].xml in the current directory.		The XML output is written to the file [QueryId].xml in the current directory.
	<code>xml_pp/1</code> is used to display the resulting "document value model" data-structures on the user output (stdout) stream.		<code>xml_pp/1</code> is used to display the resulting “document value model” data-structures on the user output (stdout) stream.
	<syntaxhighlight lang="prolog">test( Query ) :-		<syntaxhighlight lang="prolog">test( Query ) :-
	xml_query( Query, ResultElement ),		xml_query( Query, ResultElement ),
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	====xml_query( +QueryNo, ?OutputXML )====		====xml_query( +QueryNo, ?OutputXML )====
	when <var>OutputXML</var> is an XML Document Value Model produced by running an example, identified by <var>QueryNo</var>, taken from the XML Query "XMP" use case.		when <var>OutputXML</var> is an XML Document Value Model produced by running an example, identified by <var>QueryNo</var>, taken from the XML Query “XMP” use case.

	===Q1===		===Q1===
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	===Q2===		===Q2===

	Create a flat list of all the title-author pairs, with each pair enclosed in a "result" element.		Create a flat list of all the title-author pairs, with each pair enclosed in a “result” element.
	<syntaxhighlight lang="prolog">xml_query( q2, element(results, [], Results) ) :-		<syntaxhighlight lang="prolog">xml_query( q2, element(results, [], Results) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	===Q3===		===Q3===

	For each book in the bibliography, list the title and authors, grouped inside a "result" element.		For each book in the bibliography, list the title and authors, grouped inside a “result” element.
	<syntaxhighlight lang="prolog">xml_query( q3, element(results, [], Results) ) :-		<syntaxhighlight lang="prolog">xml_query( q3, element(results, [], Results) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	===Q4===		===Q4===

	For each author in the bibliography, list the author's name and the titles of all books by that author, grouped inside a "result" element.		For each author in the bibliography, list the author's name and the titles of all books by that author, grouped inside a “result” element.
	<syntaxhighlight lang="prolog">xml_query( q4, element(results, [], Results) ) :-		<syntaxhighlight lang="prolog">xml_query( q4, element(results, [], Results) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	===Q6===		===Q6===

	For each book that has at least one author, list the title and first two authors, and an empty "et-al" element if the book has additional authors.		For each book that has at least one author, list the title and first two authors, and an empty “et-al” element if the book has additional authors.
	<syntaxhighlight lang="prolog">xml_query( q6, element(bib, [], Results) ) :-		<syntaxhighlight lang="prolog">xml_query( q6, element(bib, [], Results) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	===Q8===		===Q8===

	Find books in which the name of some element ends with the string "or" and the same element contains the string "Suciu" somewhere in its content. For each such book, return the title and the qualifying element.		Find books in which the name of some element ends with the string “or” and the same element contains the string “Suciu” somewhere in its content. For each such book, return the title and the qualifying element.
	<syntaxhighlight lang="prolog">xml_query( q8, element(bib, [], Books) ) :-		<syntaxhighlight lang="prolog">xml_query( q8, element(bib, [], Books) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	===Q9===		===Q9===

	In the document "books.xml", find all section or chapter titles that contain the word "XML", regardless of the level of nesting.		In the document “books.xml”, find all section or chapter titles that contain the word “XML”, regardless of the level of nesting.
	<syntaxhighlight lang="prolog">xml_query( q9, element(results, [], Titles) ) :-		<syntaxhighlight lang="prolog">xml_query( q9, element(results, [], Titles) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	===Q10===		===Q10===

	In the document "prices.xml", find the minimum price for each book, in the form of a "minprice" element with the book title as its title attribute.		In the document “prices.xml”, find the minimum price for each book, in the form of a “minprice” element with the book title as its title attribute.
	<syntaxhighlight lang="prolog">xml_query( q10, element(results, [], MinPrices) ) :-		<syntaxhighlight lang="prolog">xml_query( q10, element(results, [], MinPrices) ) :-
	element_name( Title, title ),		element_name( Title, title ),
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	minimum1( T, Min1, Min ).</syntaxhighlight>		minimum1( T, Min1, Min ).</syntaxhighlight>
	====input_document( +File, ?XML )====		====input_document( +File, ?XML )====
	reads <var>File</var> and parses the input into the "Document Value Model" <var>XML</var>.		reads <var>File</var> and parses the input into the “Document Value Model” <var>XML</var>.
	<syntaxhighlight lang="prolog">input_document( File, XML ) :-		<syntaxhighlight lang="prolog">input_document( File, XML ) :-
	% Read InputFile as a list of chars		% Read InputFile as a list of chars

John at 18:32, 8 November 2014

2014-11-08T18:32:04Z

← Older revision		Revision as of 18:32, 8 November 2014
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	the use of <code>xml_subterm/2</code> to access the nodes of a "document value model".		the use of <code>xml_subterm/2</code> to access the nodes of a "document value model".
	It's written for Quintus Prolog, but should port to other Prologs easily.		It's written for Quintus Prolog, but should port to other Prologs easily.
	~~the <code>test/1</code> predicate is the entry-point of the program.~~
	====test( +QueryId )====		====test( +QueryId )====
			The <code>test/1</code> predicate is the entry-point of the program and
	executes a Prolog implementation of a Query from [http://www.w3.org/TR/xquery-use-cases/#xmp Use Case "XMP": Experiences and Exemplars], in the W3C's XML Query Use Cases, which "contains several example queries that illustrate requirements gathered from the database and document communities".		executes a Prolog implementation of a Query from [http://www.w3.org/TR/xquery-use-cases/#xmp Use Case "XMP": Experiences and Exemplars], in the W3C's XML Query Use Cases, which "contains several example queries that illustrate requirements gathered from the database and document communities".

John: Created page with "NOTOC The following is a complete example to illustrate how the xml.pl module can be used. It exercises both the input and output parsing modes of xml_parse/[2,3] 2014-05-04T23:32:09Z Created page with "NOTOC The following is a complete example to illustrate how the xml.pl module can be used. It exercises both the input and output parsing modes of <code>xml_parse/[2,3]</c..." New page NOTOC The following is a complete example to illustrate how the xml.pl module can be used. It exercises both the input and output parsing modes of <code>xml_parse/[2,3]</code>, and illustrates the use of <code>xml_subterm/2</code> to access the nodes of a "document value model". It's written for Quintus Prolog, but should port to other Prologs easily. the <code>test/1</code> predicate is the entry-point of the program. ====test( +QueryId )==== executes a Prolog implementation of a Query from [http://www.w3.org/TR/xquery-use-cases/#xmp Use Case "XMP": Experiences and Exemplars], in the W3C's XML Query Use Cases, which "contains several example queries that illustrate requirements gathered from the database and document communities". <var>QueryId</var> is one of <code>q1</code>...<code>q12</code> selecting which of the 12 use cases is executed. The XML output is written to the file [QueryId].xml in the current directory. <code>xml_pp/1</code> is used to display the resulting "document value model" data-structures on the user output (stdout) stream. <syntaxhighlight lang="prolog">test( Query ) :- xml_query( Query, ResultElement ), % Parse output XML into the Output chars xml_parse( Output, xml([], [ResultElement]) ), absolute_file_name( Query, [extensions(xml)], OutputFile ), % Write OutputFile from the Output list of chars tell( OutputFile ), put_chars( Output ), told, % Pretty print OutputXML write( 'Output XML' ), nl, xml_pp( xml([], [ResultElement]) ).</syntaxhighlight> ====xml_query( +QueryNo, ?OutputXML )==== when <var>OutputXML</var> is an XML Document Value Model produced by running an example, identified by <var>QueryNo</var>, taken from the XML Query "XMP" use case. ===Q1=== List books published by Addison-Wesley after 1991, including their year and title. <syntaxhighlight lang="prolog">xml_query( q1, element(bib, [], Books) ) :- element_name( Title, title ), element_name( Publisher, publisher ), input_document( 'bib.xml', Bibliography ), findall( element(book, [year=Year], [Title]), ( xml_subterm( Bibliography, element(book, Attributes, Content) ), xml_subterm( Content, Publisher ), xml_subterm( Publisher, Text ), text_value( Text, "Addison-Wesley" ), member( year=Year, Attributes ), number_codes( YearNo, Year ), YearNo > 1991, xml_subterm( Content, Title ) ), Books ).</syntaxhighlight> ===Q2=== Create a flat list of all the title-author pairs, with each pair enclosed in a "result" element. <syntaxhighlight lang="prolog">xml_query( q2, element(results, [], Results) ) :- element_name( Title, title ), element_name( Author, author ), element_name( Book, book ), input_document( 'bib.xml', Bibliography ), findall( element(result, [], [Title,Author]), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Title ), xml_subterm( Book, Author ) ), Results ).</syntaxhighlight> ===Q3=== For each book in the bibliography, list the title and authors, grouped inside a "result" element. <syntaxhighlight lang="prolog">xml_query( q3, element(results, [], Results) ) :- element_name( Title, title ), element_name( Author, author ), element_name( Book, book ), input_document( 'bib.xml', Bibliography ), findall( element(result, [], [Title|Authors]), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Title ), findall( Author, xml_subterm(Book, Author), Authors ) ), Results ).</syntaxhighlight> ===Q4=== For each author in the bibliography, list the author's name and the titles of all books by that author, grouped inside a "result" element. <syntaxhighlight lang="prolog">xml_query( q4, element(results, [], Results) ) :- element_name( Title, title ), element_name( Author, author ), element_name( Book, book ), input_document( 'bib.xml', Bibliography ), findall( Author, xml_subterm(Bibliography, Author), AuthorBag ), sort( AuthorBag, Authors ), findall( element(result, [], [Author|Titles]), ( member( Author, Authors ), findall( Title, ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Author ), xml_subterm( Book, Title ) ), Titles ) ), Results ).</syntaxhighlight> ===Q5=== For each book found at both bn.com and amazon.com, list the title of the book and its price from each source. <syntaxhighlight lang="prolog">xml_query( q5, element('books-with-prices', [], BooksWithPrices) ) :- element_name( Title, title ), element_name( Book, book ), element_name( Review, entry ), input_document( 'bib.xml', Bibliography ), input_document( 'reviews.xml', Reviews ), findall( element('book-with-prices', [], [ Title, element('price-bn',[], BNPrice ), element('price-amazon',[], AmazonPrice ) ] ), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Title ), xml_subterm( Reviews, Review ), xml_subterm( Review, Title ), xml_subterm( Book, element(price,_, BNPrice) ), xml_subterm( Review, element(price,_, AmazonPrice) ) ), BooksWithPrices ).</syntaxhighlight> ===Q6=== For each book that has at least one author, list the title and first two authors, and an empty "et-al" element if the book has additional authors. <syntaxhighlight lang="prolog">xml_query( q6, element(bib, [], Results) ) :- element_name( Title, title ), element_name( Author, author ), element_name( Book, book ), input_document( 'bib.xml', Bibliography ), findall( element(book, [], [Title,FirstAuthor|Authors]), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Title ), findall( Author, xml_subterm(Book, Author), [FirstAuthor|Others] ), other_authors( Others, Authors ) ), Results ).</syntaxhighlight> ===Q7=== List the titles and years of all books published by Addison-Wesley after 1991, in alphabetic order. <syntaxhighlight lang="prolog">xml_query( q7, element(bib, [], Books) ) :- element_name( Title, title ), element_name( Publisher, publisher ), input_document( 'bib.xml', Bibliography ), findall( Title-element(book, [year=Year], [Title]), ( xml_subterm( Bibliography, element(book, Attributes, Book) ), xml_subterm( Book, Publisher ), xml_subterm( Publisher, Text ), text_value( Text, "Addison-Wesley" ), member( year=Year, Attributes ), number_codes( YearNo, Year ), YearNo > 1991, xml_subterm( Book, Title ) ), TitleBooks ), keysort( TitleBooks, TitleBookSet ), range( TitleBookSet, Books ).</syntaxhighlight> ===Q8=== Find books in which the name of some element ends with the string "or" and the same element contains the string "Suciu" somewhere in its content. For each such book, return the title and the qualifying element. <syntaxhighlight lang="prolog">xml_query( q8, element(bib, [], Books) ) :- element_name( Title, title ), element_name( Book, book ), element_name( QualifyingElement, QualifyingName ), append( "Suciu", _Back, Suffix ), input_document( 'bib.xml', Bibliography ), findall( element(book, [], [Title,QualifyingElement]), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, QualifyingElement ), atom_codes( QualifyingName, QNChars ), append( _QNPrefix, "or", QNChars ), xml_subterm( QualifyingElement, TextItem ), text_value( TextItem, TextValue ), append( _Prefix, Suffix, TextValue ), xml_subterm( Book, Title ) ), Books ).</syntaxhighlight> ===Q9=== In the document "books.xml", find all section or chapter titles that contain the word "XML", regardless of the level of nesting. <syntaxhighlight lang="prolog">xml_query( q9, element(results, [], Titles) ) :- element_name( Title, title ), append( "XML", _Back, Suffix ), input_document( 'books.xml', Books ), findall( Title, ( xml_subterm( Books, Title ), xml_subterm( Title, TextItem ), text_value( TextItem, TextValue ), append( _Prefix, Suffix, TextValue ) ), Titles ).</syntaxhighlight> ===Q10=== In the document "prices.xml", find the minimum price for each book, in the form of a "minprice" element with the book title as its title attribute. <syntaxhighlight lang="prolog">xml_query( q10, element(results, [], MinPrices) ) :- element_name( Title, title ), element_name( Price, price ), input_document( 'prices.xml', Prices ), findall( Title, xml_subterm(Prices, Title), TitleBag ), sort( TitleBag, TitleSet ), element_name( Book, book ), findall( element(minprice, [title=TitleString], [MinPrice]), ( member( Title, TitleSet ), xml_subterm( Title, TitleText ), text_value( TitleText, TitleString ), findall( PriceValue-Price, ( xml_subterm( Prices, Book ), xml_subterm( Book, Title ), xml_subterm( Book, Price ), xml_subterm( Price, Text ), text_value( Text, PriceChars ), number_codes( PriceValue, PriceChars ) ), PriceValues ), minimum( PriceValues, PriceValue-MinPrice ) ), MinPrices ).</syntaxhighlight> ===Q11=== For each book with an author, return the book with its title and authors. For each book with an editor, return a reference with the book title and the editor's affiliation. <syntaxhighlight lang="prolog">xml_query( q11, element(bib, [], Results) ) :- element_name( Title, title ), element_name( Author, author ), element_name( Book, book ), element_name( Editor, editor ), element_name( Affiliation, affiliation ), input_document( 'bib.xml', Bibliography ), findall( element(book, [], [Title,FirstAuthor|Authors]), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Title ), findall( Author, xml_subterm(Book, Author), [FirstAuthor|Authors] ) ), Books ), findall( element(reference, [], [Title,Affiliation]), ( xml_subterm( Bibliography, Book ), xml_subterm( Book, Title ), xml_subterm( Book, Editor ), xml_subterm( Editor, Affiliation ) ), References ), append( Books, References, Results ).</syntaxhighlight> ===Q12=== Find pairs of books that have different titles but the same set of authors (possibly in a different order). <syntaxhighlight lang="prolog">xml_query( q12, element(bib, [], Pairs) ) :- element_name( Author, author ), element_name( Book1, book ), element_name( Book2, book ), element_name( Title1, title ), element_name( Title2, title ), input_document( 'bib.xml', Bibliography ), findall( element('book-pair', [], [Title1,Title2]), ( xml_subterm( Bibliography, Book1 ), findall( Author, xml_subterm(Book1, Author), AuthorBag1 ), sort( AuthorBag1, AuthorSet ), xml_subterm( Bibliography, Book2 ), Book2 @< Book1, findall( Author, xml_subterm(Book2, Author), AuthorBag2 ), sort( AuthorBag2, AuthorSet ), xml_subterm( Book1, Title1 ), xml_subterm( Book2, Title2 ) ), Pairs ).</syntaxhighlight> == Auxiliary Predicates == <syntaxhighlight lang="prolog">other_authors( [], [] ). other_authors( [Author|Authors], [Author|EtAl] ) :- et_al( Authors, EtAl ). et_al( [], [] ). et_al( [_|_], [element('et-al',[],[])] ). text_value( [pcdata(Text)], Text ). text_value( [cdata(Text)], Text ). element_name( element(Name, _Attributes, _Content), Name ).</syntaxhighlight> ====range( +Pairs, ?Range )==== when <var>Pairs</var> is a list of key-datum pairs and <var>Range</var> is the list of data. <syntaxhighlight lang="prolog">range( [], [] ). range( [_Key-Datum|Pairs], [Datum|Data] ) :- range( Pairs, Data ).</syntaxhighlight> ====minimum( +List, ?Min )==== is true if <var>Min</var> is the least member of <var>List</var> in the standard order. <syntaxhighlight lang="prolog">minimum( [H|T], Min ):- minimum1( T, H, Min ). minimum1( [], Min, Min ). minimum1( [H|T], Min0, Min ) :- compare( Relation, H, Min0 ), minimum2( Relation, H, Min0, T, Min ). minimum2( '=', Min0, Min0, T, Min ) :- minimum1( T, Min0, Min ). minimum2( '<', Min0, _Min1, T, Min ) :- minimum1( T, Min0, Min ). minimum2( '>', _Min0, Min1, T, Min ) :- minimum1( T, Min1, Min ).</syntaxhighlight> ====input_document( +File, ?XML )==== reads <var>File</var> and parses the input into the "Document Value Model" <var>XML</var>. <syntaxhighlight lang="prolog">input_document( File, XML ) :- % Read InputFile as a list of chars see( File ), get_chars( Input ), seen, % Parse the Input chars into the term XML xml_parse( Input, XML ).</syntaxhighlight> Load the [[XML Module]]. <syntaxhighlight lang="prolog">:- use_module( xml ).</syntaxhighlight> Load a small library of [[Puzzle Utilities]]. <syntaxhighlight lang="prolog"> :- ensure_loaded( misc ). </syntaxhighlight> Download a 5Kb tar.gz format [https://binding-time.co.uk/download/xml_example.tar.gz file containing this program with input and output data].