XSLT Lab: variables/parameters, strings, and math

Your assignment is to transform people.xml into an HTML page that resembles people_output.html. As part of this transformation, you must calculate the person’s age at his or her death. Calculating the age at death is more complicated than simply subtracting the birth year from the death year. You must also take into account whether or not the person has had a birthday in the year of his or her death.

people.xml

<?xml version="1.0" encoding="UTF-8"?>  
<!DOCTYPE people [  
<!ELEMENT people (person+)>  
<!ELEMENT person (#PCDATA)>  
<!ATTLIST person  
  birth  CDATA #REQUIRED  
  death  CDATA #IMPLIED  
  source CDATA #IMPLIED>  
]>  
<people>  
  <person birth="1837-04-05"  
    death="1909-04-10"  
    source="https://en.wikipedia.org/wiki/Algernon_Charles_Swinburne">  
    Algernon Charles Swinburne  
  </person>  
  <person birth="1802-02-26"  
    death="1885-05-22"  
    source="https://en.wikipedia.org/wiki/Victor_Hugo">  
    Victor Hugo  
  </person>  
  <person birth="1788-01-22"  
    death="1824-04-19"  
    source="https://en.wikipedia.org/wiki/Lord_Byron">  
    George Gordon, Lord Byron  
  </person>  
  <person birth="1795-10-31"  
    death="1821-02-23"  
    source="https://en.wikipedia.org/wiki/John_Keats">  
    John Keats  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Percy_Bysshe_Shelley"  
    birth="1792-08-04"  
    death="1822-07-08">  
    Percy Bysshe Shelley  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Christina_Rossetti"  
    birth="1830-12-05"  
    death="1894-12-29">  
    Christina Rossetti  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Dante_Gabriel_Rossetti"  
    birth="1828-05-12"  
    death="1882-04-09">  
    Dante Gabriel Rossetti  
  </person>  
  <person source="https://en.wikipedia.org/wiki/William_Blake"  
    birth="1757-11-28"  
    death="1827-08-12">  
    William Blake  
  </person>  
  <person birth="1774-08-12"  
    death="1843-03-21"  
    source="https://en.wikipedia.org/wiki/Robert_Southey">  
    Robert Southey  
  </person>  
  <person birth="1775-01-30"  
    death="1864-09-17"  
    source="https://en.wikipedia.org/wiki/Walter_Savage_Landor">  
    Walter Savage Landor  
  </person>  
  <person birth="1770-04-07"  
    death="1850-04-23"  
    source="https://en.wikipedia.org/wiki/William_Wordsworth">  
    William Wordsworth  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Samuel_Taylor_Coleridge"  
    birth="1772-10-21"  
    death="1834-07-25">  
    Samuel Taylor Coleridge  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Matthew_Arnold"  
    birth="1822-12-24"  
    death="1888-04-15">  
    Matthew Arnold  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Alfred,_Lord_Tennyson"  
    birth="1809-08-06"  
    death="1892-10-06">  
    Alfred, Lord Tennyson  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Robert_Browning"  
    birth="1812-05-07"  
    death="1889-12-12">  
    Robert Browning  
  </person>  
  <person source="https://en.wikipedia.org/wiki/Elizabeth_Barrett_Browning"  
    birth="1806-03-06"  
    death="1861-06-29">  
    Elizabeth Barrett Browning  
  </person>  
</people>

Some tips

• In a template that matches person element, you may want to create variables for things like $birth-year, $birth-month, $birth-day, $death-year, etc. The substring() function can help you extract the correct values from @birth and @death.
• You will use XSLT/XPath math functions to compare years months and days and to calculate the correct age at death. In my solution I used =, >=, and -, but there are many other workable solutions that might use different functions.

Bonus

• Use <xsl:sort> to sort people by birth date.
• Make each name a link that goes to the wikipedia page in @source.
• Add birth year and death year in parentheses after the name. E.g., Algernon Charles Swinburne (1837–1909).
• Example bonus output: people_bonus.html.