The library library(sgml_write) provides the inverse of
the parser, converting the parser's output back into a file. This
process is fairly simple for XML, but due to the power of the SGML DTD
it is much harder to achieve a reasonable generic result for SGML.
These predicates can write the output in two encoding schemas
depending on the encoding of the Stream. In UTF-8 mode, all
characters are encoded using UTF-8 sequences. In ISO Latin-1 mode,
characters outside the ISO Latin-1 range are represented using a named
character entity if provided by the DTD or a numeric character entity.
- xml_write(+Stream,
+Term, +Options)
- Write the XML header with encoding information and the content of the
document as represented by Term to Stream. This
predicate deals with XML with or without namespaces. If namespace
identifiers are not provided they are generated. This predicate defines
the following Options
- dtd(DTD)
- Specify the DTD. In SGML documents the DTD is required to distinguish
between elements that are declared empty in the DTD and elements that
just happen to have no content. Further optimisation (shortref, omitted
tags, etc.) could be considered in the future. The DTD is also used to
find the declared named character entities.
- doctype(Doctype)
- Document type to include in the header. When omitted it is taken from
the outer element.
- header(Bool)
- If Bool is
false, the XML header is suppressed.
Useful for embedding in other XML streams.
- layout(Bool)
- Do/do not emit layout characters to make the output readable, Default is
to emit layout. With layout enabled, elements only containing other
elements are written using increasing indentation. This introduces
(depending on the mode and defined whitespace handling) CDATA sequences
with only layout between elements when read back in. If
false,
no layout characters are added. As this mode does not need to analyse
the document it is faster and guarantees correct output when read back.
Unfortunately the output is hardly human readable and causes problems
with many editors.
- indent(Integer)
- Set the initial element indentation. It more than zero, the indent is
written before the document.
- nsmap(Map)
- Set the initial namespace map. Map is a list of
Name = URI. This option, together with
header
and
ident is added to use xml_write/3
to generate XML that is embedded in a larger XML document.
- net(Bool)
- Use/do not use Null End Tags. For XML, this applies only to
empty elements, so you get
<foo/> (default,
net(true)) or <foo></foo> (net(false)).
For SGML, this applies to empty elements, so you get <foo>
(if foo is declared to be EMPTY in the DTD),
<foo></foo> (default, net(false))
or
<foo// (net(true)). In SGML code, short
character content not containing /<b>xxx</b> (default, net(false)
or <b/xxx/ (net(true))
- sgml_write(+Stream,
+Term, +Options)
- Write the SGML
DOCTYPE header and the content of the
document as represented by Term to Stream. The Options
are described with xml_write/3.
- html_write(+Stream,
+Term, +Options)
- Same as sgml_write/3,
but passes the HTML DTD as obtained from dtd/2.
The Options are described with
xml_write/3.