dtdtree
outputs the content hierarchy tree
(in ASCII) of SGML elements defined in a DTD.
dtdtree
is invoked from the command-line as follows:
% dtdtree [options] elementname elementname ...
Any strings after, and not part of, command-line options are treated as the elements (elementname) to output trees for. If no elements are specified, than the tree(s) for the top-most element(s) defined in the DTD are printed.
The following are the list of options available:
-catalog
filenameUse filename as the file for mapping public
identifiers and external entities to system files. If
-catalog
is not specified, "catalog
" is
used as the default filename.
See
Resolving External Entities for more
information.
-dtd
filenameUse filename as the SGML DTD to parse. Otherwise, read from standard in.
-help
Print a brief usage description. No other action is performed.
-level
#Set the prune level of the content hierachy tree to # Defaults to 15.
-treefile
filenameOutput element content tree(s) to filename.
Otherwise, dtdtree
prints to standard out.
-verbose
Ouput to standard error messages of what dtdtree
is doing.
This option
is mainly for debugging purposes.
The tree shows the overall content hierarchy for an element.
Content hierarchies of descendents will also be shown. Elements that
exist at a higher (or equal) level, or if the maximum depth has been
reached, are pruned. The string "...
" is appended to an
element if it has been pruned due to pre-existance at a higher (or
equal) level. The content of the pruned element can be determined
by searching for the complete tree of the element (ie. elements w/o
"...
"). Elements pruned because maximum depth has been
reached will not have "...
" appended.
Example:
|__section+) |_(effect?, ... |__title, ... |__toc?, ... |__epc-fig*, | |_(effect?, ... | |__figure, | | |_(effect?, ... | | |__title, ... | | |__graphic+, ... | | |__assoc-text?)
Pruning must be done to avoid a combinatorical explosion. It is common for DTD's to define content hierarchies of infinite depth. Even with a predefined maximum depth, the generated tree can become very large.
Since the tree outputed is static, the inclusion and exclusion sets
of elements are treated specially. Inclusion and exclusion elements
inherited from ancestors are not propagated down to determine
what elements are printed, but special markup is presented at a
given element if there exists inclusion and exclusion elements from
ancestors. The reason inclusions and exclusions are not propagated down
is because of the pruning done. Since an element may occur in multiple
contexts -- and have different ancestoral inclusions and exclusions in
effect -- an element without "...
" may be the only place
of reference to see the content hierarchy of the element.
Example:
D1 | {+} idx needbegin needend newline | |_(head, | | {A+} idx needbegin needend newline | | {-} needbegin needend | | | |_(((#PCDATA | | |____((acro | | | | {A+} idx needbegin needend newline | | | {A-} needbegin needend | | | | | |_(((#PCDATA | | | |____((super | ... | | |______sub)))*)) ...
Ignoring the lines starting with {}'s, one gets the content
hierachy of an element as defined by the DTD without concern of where
it may occur in the overall structure. The {} lines give additional
information regarding the element with respect to its existance
within a specific context. For example, when an ACRO
element occurs within D1,HEAD
-- along with its normal
content -- it can contain IDX
and NEWLINE
elements due to inclusions from ancestors. However, it cannot contain
NEEDBEGIN
and NEEDEND
regardless of its
defined content since an ancestor(s) excludes them.
NEEDBEGIN
,
NEEDEND
are excluded from ACRO
.Explanation of {}'s keys:
{+}
{+}
appended
to the subelement entry.
{A+}
{-}
{-}
appended to the subelement
listing.
{A-}
Defining the mapping between external entities to system files
may be done via the -catalog
command-line option. The catalog provides you with the
capability of mapping public identifiers to system identifiers
(files) or to map entity names to system identifiers.
Catalog Syntax
The syntax of a catalog is a subset of SGML catalogs (as defined in SGML Open Draft Technical Resolution 9401:1994).
A catalog contains a sequence of the following types of entries:
PUBLIC
public_id system_idThis maps public_id to system_id.
ENTITY
name system_idThis maps a general entity whose name is name to system_id.
ENTITY %
name system_idThis maps a parameter entity whose name is name to system_id.
Syntax Notes
A system_id string cannot contain any spaces. The system_id is treated as pathname of file.
Any line in a catalog file that does not follow the previously mentioned entries is ignored.
In case of duplicate entries, the first entry defined is used.
Example catalog file:
-- ISO public identifiers -- PUBLIC "ISO 8879-1986//ENTITIES General Technical//EN" iso-tech.ent PUBLIC "ISO 8879-1986//ENTITIES Publishing//EN" iso-pub.ent PUBLIC "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN" iso-num.ent PUBLIC "ISO 8879-1986//ENTITIES Greek Letters//EN" iso-grk1.ent PUBLIC "ISO 8879-1986//ENTITIES Diacritical Marks//EN" iso-dia.ent PUBLIC "ISO 8879-1986//ENTITIES Added Latin 1//EN" iso-lat1.ent PUBLIC "ISO 8879-1986//ENTITIES Greek Symbols//EN" iso-grk3.ent PUBLIC "ISO 8879-1986//ENTITIES Added Latin 2//EN" ISOlat2 PUBLIC "ISO 8879-1986//ENTITIES Added Math Symbols: Ordinary//EN" ISOamso -- HTML public identifiers and entities -- PUBLIC "-//IETF//DTD HTML//EN" html.dtd PUBLIC "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML" ISOlat1.ent ENTITY "%html-0" html-0.dtd ENTITY "%html-1" html-1.dtd
Environment Variables
The following envariables (ie. environment variables) are supported:
This is a colon (semi-colon for MSDOS users) separated list of paths for finding catalog files or system identifiers. For example, if a system identifier is not an absolute pathname, then the paths listed in P_SGML_PATH are used to find the file.
This envariable is a colon (semi-colon for MSDOS users) separated list of catalog files to read. If a file in the list is not an absolute path, then file is searched in the paths listed in the P_SGML_PATH and SGML_SEARCH_PATH.
This is a colon (semi-colon for MSDOS users) separated list of paths for finding catalog files or system identifiers. This envariable serves the same function as P_SGML_PATH. If both are defined, paths listed in P_SGML_PATH are searched first before any paths in SGML_SEARCH_PATH.
The use of P_SGML_PATH is for compatibility with earlier versions.
SGML_CATALOG_FILES and SGML_SEARCH_PATH
are supported for compatibility with James Clark's nsgmls(1)
.
The file specified by
-catalog
is read first before any files specified by SGML_CATALOG_FILES.
This program is part of the perlSGML package; see <URL:http://www.oac.uci.edu/indiv/ehood/perlSGML.html>