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XPath

XPath. A flexible notation for pointing into and navigating around XML documents. Content. What is XPath? General Expressions Location Steps and Paths Abbreviations. What is XPath?. General Expressions. Atomic Values. Numbers: integers, decimals, floats, doubles Booleans

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XPath

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  1. XPath A flexible notation for pointing into and navigating around XML documents

  2. Content • What is XPath? • General Expressions • Location Steps and Paths • Abbreviations

  3. What is XPath?

  4. General Expressions

  5. Atomic Values • Numbers: integers, decimals, floats, doubles • Booleans • Strings (Unicode)

  6. Literal Expressions

  7. Comments • (: this is a comment :) • /descendant::(: this is also a comment :)text()[18] • /descendant::text((: this too :))[18] • /descendant::text()[18(: and this :)] • (: btw, (: nesting is allowed :) :) • WRONG: /descendant::text()[1(: not a comment :)8] • WRONG: /descendant::te(: not a comment :)xt()[18]

  8. Arithmetic Expressions

  9. Sequence Expressions • exp1, exp2, …, expn • (1, (2, 3, 4), ((5)), (), (((6, 7), 8), 9)) • 1, 2, 3, 4, 5, 6, 7, 8, 9 • exp1to exp2 (e.g. 1 to 9)

  10. Location Steps and Paths

  11. Location paths location step 1/location step 2/… Input: context node or node sequence

  12. Location steps axis :: nodetest [ exp1] [ exp1] …

  13. Axes

  14. child

  15. descendant

  16. parent

  17. ancestor

  18. following

  19. preceding

  20. self

  21. descendant-or-self

  22. ancestor-or-self

  23. following-sibling

  24. preceding-sibling

  25. attribute

  26. Abbreviations

  27. child:: • Abbreviation: (nothing) • Example:/wikimedia/projects/projectfor/child::wikimedia/child::projects/child::project

  28. attribute:: • Abbreviation: @ • Example:/wikimedia/projects/project/@namefor/wikimedia/projects/project/attribute::name

  29. position()=x • Abbreviation: x • Example:/descendant::project[2] for/descendant::project[position()=2]

  30. /descendant-or-self::node()/ • Abbreviation: // • Example://projectfor/descendant-or-self::node()/project

  31. self::node() • Abbreviation: . • Example://edition[. = "de.wikipedia.org"]for//edition[self::node() = "de.wikipedia.org“]

  32. parent::node() • Abbreviation: .. • Example://edition[@language="German"]/../../@namefor//edition[@language="German"]/parent::node()/parent::node()/@name

  33. Node Tests

  34. name

  35. *

  36. node()

  37. text()

  38. comment()

  39. Predicates

  40. Values  Boolean

  41. Example

  42. Order and Conjunction • /descendant[3][1] • /descendant[1][3] • /descendant[position()=1 and position()=3]

  43. Tricky Expressions … are they?!

  44. Tricky Abbreviations • /descendant::edition[1] • //edition[1] • // ≠ /descendant:: • // = /descendant-or-self::node()/

  45. Tricky Predicates • //recipe/ingredient[//ingredient] • //recipe/ingredient[.//ingredient]

  46. Summarizing Examples

  47. Example 1

  48. Example 2

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