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NAME

XML::Axk::Core::L1 - awk-like XML processor, language 1

EXAMPLE

#!axk -L1
on { xpath(q<//item>) } run {say "$NOW: " . $E->getTagName}, CIAO
    # "CIAO" can also be "HI" or "BYE" (default BYE).
    # "leaving" is a synonym for "on" with no HI/BYE/CIAO.
whenever { xpath(q<//item>) } run {say "$NOW: " . $E->getTagName};
    # the same as the "on ... CIAO" line
entering { xpath(q<//item>) } run {say "$NOW: " . $E->getTagName};

PATTERNS AND ACTIONS

  • on {<matcher>} run {<action>} [, <when>]

    Whenever <matcher> says that a node matches, run <action>. The optional <when> parameter says when in the course of processing to run <action>:

    • HI

      When the node is first reached, before any of its children are processed

    • BYE

      After all of the node's children have been processed. This is the default so that you have the text content of the node available for inspection.

    • CIAO

      Both HI and BYE. Suggestions for alternative terminology are welcome.

  • entering, whenever leaving

      entering {<matcher>} run {<action>}
  whenever {<matcher>} run {<action>}
  leaving {<matcher>} run {<action>}

    The same as on {} run {}, with when set to HI, CIAO, or BYE respectively.

  • perform { <action> } <matcher> [, <when>]

    If you prefer RPN, or you want to save some characters, you can put the <matcher> after the <action> using perform. For example, the following two lines have exactly the same effect:

      on { xpath(q<//item>) } run {say "$NOW: " . $E->getTagName}, CIAO
  perform {say "$NOW: " . $E->getTagName} xpath(q<//item>), CIAO

VARIABLES

When an <action> is running, it has access to predefined variables that hold the state of the element being matched. This is similar to $0, $1, ... in awk.

At present, L1 uses XML::DOM.

  • $D

    The current XML document (XML::DOM::Document)

  • $E

    The XML element that was matched (XML::DOM::Element)

  • $NOW

    The current phase, as a human-readable string: entering for HI, leaving for BYE, and both for CIAO.

MATCHERS

  • xpath('xpath expression')

    Match nodes that match the given XPath expression. Remember that Perl will interpolate @name in double-quotes, so single-quote or q{} your XPath expressions.

  • sel('selector')

    Match nodes that match the given selector.

  • always, never

    Always or never match, respectively.

SPECIAL ACTIONS

  • pre_all {<block>}

    Run <block> before any file is processed.

  • pre_file {<block>}

    Run <block>($filename) before each file is processed.

  • post_file {<block>}

    Run <block>($filename) after each file is processed.

  • post_all {<block>}

    Run <block> after all files have been processed.

AUTHOR

Christopher White, cxwembedded at gmail.com

CONTACT

For any bug reports, feature requests, or questions, please see the information in XML::Axk.

LICENSE AND COPYRIGHT

Copyright (c) 2018 Christopher White. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). Details are in the LICENSE file accompanying this distribution.