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Table of Contents

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  1. Preface
  2. Introduction to Data Transformation
  3. Data Processor Transformation
  4. Wizard Input and Output Formats
  5. Relational Input and Output
  6. XMap
  7. Libraries
  8. Schema Object
  9. Command Line Interface
  10. Scripts
  11. Parsers
  12. Script Ports
  13. Document Processors
  14. Formats
  15. Data Holders
  16. Anchors
  17. Transformers
  18. Actions
  19. Serializers
  20. Mappers
  21. Locators, Keys, and Indexing
  22. Streamers
  23. Validators, Notifications, and Failure Handling
  24. Validation Rules
  25. Custom Script Components

Data Transformation User Guide

Data Transformation User Guide

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Using Alternatives to Select a Secondary Parser

Using Alternatives to Select a Secondary Parser

You can use an
Alternatives
 anchor to control which of several secondary parsers processes a document. The main Parser can use this feature to process source documents of multiple types.
For example, suppose that the home page of a newspaper web site has links to articles. Following each link, the article is labeled
News
,
Business
, or
Sports
. You want to parse the articles, using a different Parser for each type, like this: 
<a href="PrincessWeds.html">Norwegian Princess Weds</a> - News
<a href="BanksMerge.html">Local Banks to Merge</a> - Business
<a href="HomeTeamWins.html">Bears Trounce Antelopes</a> - Sports
You can support this situation in the following way:
  1. The main Parser retrieves the filename of an article and stores it in a variable.
  2. The main Parser contains an
    Alternatives
     anchor that is configured with the
    DocumentOrder
     option.
  3. The
    Alternatives
     anchor contains nested
    Group
     anchors.
  4. Each
    Group
     anchor is configured with a
    Marker
     anchor and a
    RunParser
     action, as follows:
    • The first
      Group
       contains a
      Marker
       that searches for the string
      News
      . The
      Group
       is configured with a
      RunParser
       action that runs a secondary Parser called
      NewsParser
      .
    • The second
      Group
       contains a
      Marker
       that searches for
      Business
       and runs
      BusinessParser
      .
    • The third
      Group
       contains a
      Marker
       that searches for the
      Sports
       and runs
      SportsParser
      .
The
Alternatives
 anchor tests all three
Group
 anchors. It accepts the
Group
 containing the first
Marker
 that occurs after the filename. The
Group
 runs the appropriate Parser on the file.