xmlsimple.3am - Man Page

Provides facilities for writing simple one-line scripts with the gawk-xml extension. Also provides higher-level functions that simplify writing more complex scripts.

Synopsis

@include "xmlsimple"

parentpath = XmlParent(path)
test = XmlMatch(path)
scopepath = XmlMatchScope(path)
ancestorpath = XmlMatchAttr(path, name, value, mode)

XmlGrep()

The xmlsimple library facilitates writing scripts based on the gawk-xml extension. It is an alternative to the xmllib library. A key difference is that $0 is not changed, so xmlsimple is compatible with awk code that relies on the gawk-xml core interface.

Short token variable names

To shorten simple scripts, xmlsimple provides two-letter named variables that duplicate predefined token-related core variables:

XD: Equivalent to XMLDECLARATION.
SD: Equivalent to XMLSTARTDOCT.
ED: Equivalent to XMLENDDOCT.
PI: Equivalent to XMLPROCINST.
SE: Equivalent to XMLSTARTELEM.
EE: Equivalent to XMLENDELEM.
TX: Equivalent to XMLCHARDATA.
SC: Equivalent to XMLSTARTCDATA.
EC: Equivalent to XMLENDCDATA.
CM: Equivalent to XMLCOMMENT.
UP: Equivalent to XMLUNPARSED.
EOI: Equivalent to XMLENDDOCUMENT.

Collecting character data

Character data items between element tags are automatically collected in a single CHARDATA variable. This feature simplifies processing text data interspersed with comments, processing instructions or CDATA markup.

CHARDATA: Available at every XMLSTARTELEMENT or XMLENDELEMENT token. Contains all the character data since the previous start- or end-element tag.

Whitespace handling

The XMLTRIM mode variable controls whether whitespace in the CHARDATA variable is automatically trimmed or not. Possible values are:

XMLTRIM = 0: Keep all whitespace
XMLTRIM = 1 (default): Discard leading and trailing whitespace, and collapse contiguous whitespace characters into a single space char.
XMLTRIM = -1: Just collapse contiguous whitespace characters into a single space char. Keeps the collapsed leading or trailing whitespace.

Record ancestors information

The ATTR array variable automatically keeps the attributes of every ancestor of the current element, and of the element itself.

ATTR[path@attribute]: Contains the value of the specified attribute of the ancestor element at the given path.

Example

While processing a /books/book/title element, ATTR["/books/book@on-loan"] contains the name of the book loaner.

Path related functions

A fixed path is a slash delimited list of direct child elements (/name/name/...). A path expression accepts also an asterisk (*) to match any name, and a double slash (//) to represent a descendant at any level. An absolute path starts with a slash (path from the root element). A relative path without a leading slash can start at any level (path from some ancestor).

XmlParent(path): Returns the path of the parent element. I.e., the path argument without the last /name part. The path argument is optional. If not given the XMLPATH is used.
XmlMatch(path): Tests whether the current XMLPATH matches the path expression argument, anchored at the end.
XmlMatchScope(path): Returns the XMLPATH prefix not matched by the matching path expression argument. Returns a null value if there is no match.
XmlMatchAttr(path, name, value, mode): Returns the path of the innermost ancestor that matches the path argument and also has a name attribute with the given value. The mode argument is optional. If non-null then the value is handled as a regular expression instead of a fixed value.

Grep-like facilities

XmlGrep(): If invoked at the XMLSTARTELEM event, causes the whole element subtree to be copied to the output.

Notes

The xmlsimple library includes both the xmlbase and xmlcopy libraries. Their functionality is implicitly available.

Bugs

The path related functions only operate on elements. Comments, processing instructions or CDATA sections are not taken into account.

XmlGrep() cannot be used to copy tokens outside the root element (XML prologue or epilogue).

Author

Manuel Collado, m-collado@users.sourceforge.net.

Copying Permissions

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Info

January 2017 GAWK Extension Library (gawkextlib) GNU Awk Extension Modules