Provided by: tdom_0.9.4-1_amd64 
NAME
tdom::schema - Creates a schema validation command
SYNOPSIS
package require tdom
tdom::schema ?create? cmdName
_________________________________________________________________
DESCRIPTION
Every call of this command creates a new validation command. A validation command has methods to define a
schema and is able to validate XML data or to post-validate a tDOM DOM tree (and to some degree other
kind of hierarchical data) against this schema.
Also, a validation command may be used as argument to the -validateCmd option of the dom parse and the
expat commands to enable validation additionally to what they do otherwise.
The methods of created commands are:
prefixns ?prefixUriList?
This method controls prefix (or abbreviation) to namespace URI mapping. Wherever a namespace
argument is expected in the schema command methods the "prefix" could be used instead of the
namespace URI. If the list maps the same prefix to different namespace URIs, the first one wins.
If there is no such prefix, the namespace argument is used literally as namespace URI. If the
method is called without argument, it returns the current prefixUriList. If the method is called
with the empty string, any namespace URI arguments are used literally. This is the default.
defelement name ?namespace? <definition script>
This method defines the element name (optional in the namespace namespace) in the schema. The
definition script is evaluated and defines the content model of the element. If the namespace
argument is given, any element or ref references in the definition script not wrapped inside a
namespace command are resolved in that namespace. If there is already a element definition for the
name/namespace combination, the command raises error.
defelementtype typename ?namespace? <definition script>
This method defines the element type typename (optional in the namespace namespace) in the schema.
If the element type is used in a definition script with the schema command element, the validation
engine expects an element content according to content model definition script. Defining (and
using) element types seems only sensible if you really have elements with the same name and
namespace but different content models. The definition script is evaluated and defines the content
model of the element it is assgned to. If the namespace argument is given, any element or ref
references in the definition script not wrapped inside a namespace command are resolved in that
namespace. If there is already an elementtype definition for the typename/namespace combination,
the command raises error. The document element of any XML to validate cannot be a defelementtype
defined element.
defpattern name ?namespace? <definition script>
This method defines a (maybe complex) content particle with the name (optional in the namespace
namespace) in the schema, to be used in other definition scripts with the definition command ref.
The definition script is evaluated and defines the content model of the content particle. If the
namespace argument is given, any element or ref references in the definition script not wrapped
inside a namespace command are resolved in that namespace. If there is already a pattern
definition for the name/namespace combination, the command raises error.
deftexttype name <constraint script>
This method defines a bundle of text constraints that can be referred to by name while defining
constraints on text element or attribute values. If there is already a text type definition with
this name, the command raises error. A text type may be referred before it is defined in the
schema. If a referred text type isn't defined anywhere in the schema then any text will match this
type during validation.
start documentElement ?namespace?
This method defines the name and namespace of the root element of a tree to validate. If this
method is used, the root element must match for validity. If start is not used, any element
defined by defelement may be the root of a valid document. The start method may be used several
times with varying arguments during the lifetime of a validation command. If the command is called
with just the empty string (and no namespace argument), the validation constraint for the root
element is removed and any defined element will be valid as root of a tree to validate.
define <definition script>
This method defines several elements or patterns or a whole schema with one call, by evaluating
the definition script>. All schema command methods so far (prefixns, defelement, defelementtype,
defpattern, deftexttype and start) are allowed top level in the definition script. The define
method itself isn't allowed recursively.
event (start|end|text) ?event specific data?
This method enables validation of hierarchical data against the content constraints of the
validation command.
start name ?attributes? ?namespace?
Checks if the current validation state allows the element name in the namespace to start
here. It raises error if not.
end Checks if the current innermost open element may end there in the current state without
violation of validation constraints. It raises error if not.
text text
Checks if the current validation state allows the given text content. It raises error if
not.
validate ?options? <XML string> ?objVar?
Returns true if the <XML string> is valid, or false, otherwise. If validation has failed and the
optional objVar argument is given, the variable with that name is set to a validation error
message. If the XML string is valid and the optional objVar argument is given, the variable will
be untouched.
The valid options are:
-baseurl <baseURI>
If -baseurl <baseURI> is specified, the baseURI is used as the base URI of the document.
External entities references in the document are resolved relative to this base URI. This
base URI is also stored within the DOM tree.
-externalentitycommand <script>
If -externalentitycommand <script> is specified, the specified Tcl script is called to
resolve any external entities of the document. The default is "::tdom::extRefHandler",
which is a simple file URL resolver defined by the script part of the package. Setting the
option value to the empty string disables resolving of external entities. The actual
evaluated command consists of this option followed by three arguments: the base uri, the
system identifier of the entity and the public identifier of the entity. The base uri and
the public identifier may be the empty list. The script has to return a Tcl list consisting
of three elements. The first element of this list signals how the external entity is
returned to the processor. Currently the two allowed types are "string" and "channel". The
second element of the list has to be the (absolute) base URI of the external entity to be
parsed. The third element of the list are data, either the already read data out of the
external entity as string in the case of type "string", or the name of a Tcl channel, in
the case of type "channel". Note that if the script returns a Tcl channel, it will not be
closed by the processor. It must be closed separately if it is no longer needed.
-paramentityparsing <always|never|notstandalone>
The -paramentityparsing option controls, if the parser tries to resolve the external
entities (including the external DTD subset) of the document while building the DOM tree.
-paramentityparsing requires an argument, which must be either "always", "never", or
"notstandalone". The value "always" means that the parser tries to resolves (recursively)
all external entities of the XML source. This is the default in case -paramentityparsing is
omitted. The value "never" means that only the given XML source is parsed and no external
entity (including the external subset) will be resolved and parsed. The value
"notstandalone" means, that all external entities will be resolved and parsed, with the
exception of documents, which explicitly states standalone="yes" in their XML declaration.
-useForeignDTD <boolean>
If <boolean> is true and the document does not have an external subset, the parser will
call the -externalentitycommand script with empty values for the systemId and publicID
arguments. Please note that if the document also doesn't have an internal subset, the
-startdoctypedeclcommand and -enddoctypedeclcommand scripts, if set, are not called.
validatefile ?options? filename ?objVar?
Returns true if the content of filename is valid, or false, otherwise. The given file is fed as
binary stream to expat, therefore, only US-ASCII, ISO-8859-1, UTF-8 or UTF-16 encoded data will
work with this method. If validation has failed and the optional objVar argument is given, the
variable with that name is set to a validation error message. If the XML data is valid and the
optional objVar argument is given, the variable will be untouched. The allowed options and their
meaning are the same as for the validate method; see there for a description.
validatechannel ?options? channel ?objVar?
Returns true if the content read from the Tcl channel channel is valid, or false, otherwise. Since
data read out of a Tcl channel is UTF-8 encoded, any misleading encoding declaration at the
beginning of the data will lead to errors. If the validation fails and the optional objVar
argument is given, the variable with that name is set to a validation error message. If the XML
data is valid and the optional objVar argument is given, the variable will be untouched. The
allowed options and their meaning are the same as for the validate method; see there for a
description.
domvalidate domNode ?objVar?
Returns true if the first argument is a valid tree, or false, otherwise. If validation has failed
and the optional objVar argument is given, the variable with that name is set to a validation
error message. If the dom tree is valid and the optional objVar argument is given, the variable
with that name is set to the empty string.
reportcmd ?cmd?
This method expects the name of a Tcl command to be called in case of validation error. The
command will be called with two arguments appended: the schema command which raises the validation
error, and a validation error code.
The possible error codes are:
MISSING_ELEMENT
MISSING_TEXT
UNEXPECTED_ELEMENT
UNEXPECTED_ROOT_ELEMENT
UNEXPECTED_TEXT
UNKNOWN_ROOT_ELEMENT
UNKNOWN_ATTRIBUTE
MISSING_ATTRIBUTE
INVALID_ATTRIBUTE_VALUE
DOM_KEYCONSTRAINT
DOM_XPATH_BOOLEAN
INVALID_KEYREF
INVALID_VALUE
UNKNOWN_GLOBAL_ID
UNKNOWN_ID
For more detailed information see section Recovering.
delete This method deletes the validation command.
info ?args?
This method bundles methods to query the state of and details about the schema command.
validationstate
This method returns the state of the validation command with respect to validation state.
The possible return values and their meanings are:
READY The validation command is ready to start validation
VALIDATING
The validation command is in the process of validating input.
FINISHED
The validation has finished, no further events are expected.
vstate This method is a shorter alias for validationstate; see there.
line If the schema command is currently validating, this method returns the line part of the
parsing position information, and the empty string in all other cases. If the schema
command is currently post-validating a DOM tree, there may be no position information
stored at some or all nodes. The empty string is returned in these cases.
column If the schema command is currently validating this method returns the column part of the
parsing position information, and the empty string in all other cases. If the schema
command is currently post-validating a DOM tree, there may be no position information
stored at some or all nodes. The empty string is returned in these cases.
byteIndex
If the schema command is currently validating this method returns the byte position of the
parsing position information, and the empty string in all other cases. If the schema
command is currently post-validating a DOM tree, there may be no position information
stored at some or all nodes. The empty string is returned in these cases.
domNode
If the schema command isn't currently post-validating a DOM tree this method returns the
empty string. Otherwise, if the schema command waits for the reportcmd script to finish
while recovering from a validation error it returns the node on which the validation engine
is currently looking at in case the node is an ELEMENT_NODE or, if not, its parent node. It
is recommended that you do not use this method. Or at least leave the DOM tree alone, use
it read-only.
nrForwardDefinitions
Returns how many elements, element types and ref patterns are referenced that aren't
defined so far (summed together).
definedElements
Returns in no particular order the defined elements in the grammar as list. If an element
is namespaced, its list entry will be itself a list with two elements, with the name as
first and the namespace as second element.
definedElementtypes
Returns in no particular order the defined element types in the grammar as list. If an
element type is namespaced, its list entry will be itself a list with two elements, with
the name as first and the namespace as second element.
definedPatterns
Returns in no particular order the defined named pattern in the grammar as list. If a named
pattern is namespaced, its list entry will be itself a list with two elements, with the
name as first and the namespace as second element.
expected
Returns in no particular order all possible next events (since the last successful event
match, if there was one) as a list. If an element is namespaced its list entry will be
itself a list with two elements, with the name as first and the namespace as second
element. If text is a possible next event, the list entry will be a two elements list, with
#text as first element and the empty string as second. If an any element constraint is
possible. the list entry will be a two elements list, with <any> as first element and the
empty string as second. If an any element in a certain namespace constraint is possible,
the list entry will be a two elements list, with <any> as first element and the namespace
as second. If element end is a possible event, the list entry will be a two elements list
with <elementend> as first element and the empty string as second element.
definition name ?namespace?
Returns the code that defines the given element. The command raises error if there is no
definition of that element.
typedefinition name ?namespace?
Returns the code that defines the given element type definition. The command raises error
if there is no definition of that element.
patterndefinition name ?namespace?
Returns the code that defines the given pattern definition. The command raises error if
there is no definition of a pattern with that name and, if given, namespace.
vaction ?name|namespace|text?
This method returns useful information only if the schema command waits for the reportcmd
script to finish while recovering from a validation error. Otherwise it returns NONE.
If the command is called without the optional argument the possible return values and their
meanings are:
NONE The schema command currently does not recover from a validation event.
MATCH_ELEMENT_START
Element start event, which includes looking for missing or unknown attributes.
MATCH_ELEMENT_END
Element end event.
MATCH_TEXT
Validating text between tags.
MATCH_ATTRIBUTE_TEXT
Attribute text value constraint check
MATCH_GLOBAL
Checking global IDs
MATCH_DOM_KEYCONSTRAINT
Checking domunique constraint
MATCH_DOM_XPATH_BOOLEAN
Checking domxpathboolean constant
If called with one of the possible optional arguments, the command returns detail
information depending on current action.
name Returns the name of the element that has to match in case of MATCH_ELEMENT_START.
Returns the name of the closed element in case of MATCH_ELEMENT_END. Returns the
name of the attribute in case of MATCH_ATTRIBUTE_TEXT. Returns the name of the
parent element in case of MATCH_TEXT.
namespace
Returns the namespace of the element that has to match in case of
MATCH_ELEMENT_START. Returns the namespace of the closed element in case of
MATCH_ELEMENT_END. Returns the namespace of the attribute in case of
MATCH_ATTRIBUTE_TEXT. Returns the namespace of the parent element in case of
MATCH_TEXT.
text Returns the text to match in case of MATCH_TEXT. Returns the value of the attribute
in case of MATCH_ATTRIBUTE_TEXT.
stack top|inside|associated
In Tcl scripts evaluated by validation this method provides information about the current
validation stack. Called outside this context the method returns the empty string.
top Returns the element whose content is currently checked (the open element tag at this
moment).
inside Returns all currently open elements as a list.
associated
Returns the data associated with the current top most stack content particle or the
empty string if there isn't any.
reset This method resets the validation command into state READY (while preserving the defined grammar).
Schema definition scripts
Schema definition scripts are ordinary Tcl scripts evaluated in the namespace tdom::schema. The schema
definition commands listed below in this Tcl namespace allow the definition of a wide variety of document
structures. Every schema definition command establishes a validation constraint on the content which has
to match or must be optional to qualify the content as valid. It is a validation error if there is
additional (not matched) content. White-space-only text (in the XML sense of white space) between any
different tags is ignored, with the exception of text only elements (for which even white-space-only text
will be considered as significant content).
The schema definition commands are:
element name ?quant? (?<definition script>|“type“ typename)?
If neither the optional argument definition script nor the string "type" and a typename is given
this command refers to the element defined with defelement with the name name in the current
context namespace.
If the string "type" and a typename is given then the content of the element is described by the
content model defined with defelementtype with the name typename in the current context namespace.
If the defelement script argument is given, the validation constraint expects an element with the
name name in the current namespace with content "locally" defined by the definition script.
Forward references to so far not defined elements or patterns or other local definitions of the
same name inside the definition script are allowed. If a forward referenced element is not defined
until validation, only an empty element with name name and namespace namespace and no attributes
matches.
ref name ?quant?
This command refers to the content particle defined with defpattern with the name name in the
current context namespace. Forward references to a so far not defined pattern and recursive
references are allowed. If a forward referenced pattern is not defined until validation no content
whatsoever is expected ("empty match").
group ?quant? <definition script>
This method group a sequence of content particles defined by the definition script>, which have to
match in this sequence order.
choice ?quant? <definition script>
This schema constraint matches if one of the top level content particles defined by the definition
script> matches. If one of this top level content particle is optional this constraint matches the
"empty match".
interleave ?quant? <definition script>
This schema constraint matches after every of the required top level content particles defined by
the definition script> have matched (and, optional, some or all other) in any arbitrary order.
mixed ?quant? <definition script>
This schema constraint matches for any text (including the empty one) and every top level content
particle defined by the definition script> with default quantifier *.
text ?<constraint script>|“type“ typename?
Without the optional constraint script this validation constraint matches every string (including
the empty one). With constraint script or with a given text type argument a text matching this
script or the text type is expected.
any ?options? ?<namespace list>? ?quant?
Without arguments the any command matches every element. If the <namespace list> argument is
given, this matches any element in a namespace out of that list. The empty string means elements
with no namespace. If additionally the option -not is given then this maches every element with a
namespace not in the list. The only other recognized option is -- which signals the end of any
options. Please note that in case of no namespace argument is given that means that the
quantifier * and + will eat up any elements until the enclosing element ends. If you really have a
namespace that looks like a valid tDOM schema quantifier you will have to spell out always both
arguments.
attribute name ?quant? (?<constraint script>|“type“ typename?)
The attribute command defines an attribute (in no namespace) to the enclosing element. The first
definition of name inside an element definition wins; later definitions of the same name are
silently ignored. After the name argument there may be one of the quantifiers ? or !. If there is,
it will be used. Otherwise the attribute will be required (must be present in the XML source). If
there is one argument more this argument is evaluated as constraint script, defining the value
constraints of the attribute. Otherwise, if there are two more arguments and the first of them is
the bare-word "type" the following argument is used as a text type name. This command is only
allowed at top level in the definition script of a defelement/element script.
nsattribute name namespace ?quant? (?<constraint script>|“type“ typename?)
This command does the same as the command attribute, for the attribute name in the namespace
namespace.
namespace URI <definition script>
Evaluates the definition script with context namespace URI. Every element, element type or ref
command name will be looked up in the namespace URI, and local defined elements will be in that
namespace. An empty string as URI means no namespace.
tcl tclcmd ?arg arg ...?
Evaluates the Tcl script tclcmd arg arg ... . This validation command is only allowed in strict
sequential context (not in choice, mixed and interleave). If the return code is something else
than TCL_OK, this is an error (which is not caught and reported by reportcmd).
self Returns the schema command.
associate data
This command is only allowed top-level inside definition scripts of the element, elementtype,
pattern or interleave content particles. Associates the data given as argument with the currently
defined content particle and may be requested in scripts evaluated while validating the content of
that particle with the schema command method call info stack associated.
domunique selector fieldlist ?name? ?“IGNORE_EMPTY_FIELD_SET“|(“EMPTY_FIELD_SET_VALUE“
emptyFieldSetValue)?
If not postvalidating a DOM tree with domvalidate this constraint always matches. If
postvalidating this constraint resembles the xsd key/keyref mechanism. The selector argument may
be any valid XPath expression (without the xsd limits). Several domunique commands within one
element definition are allowed. They are checked in definition order. The argument name is
available in the recovering script per info vaction name. If the fieldlist does not select
something for a node of the result set of the selector the key value will be the empty string by
default. If the arguments EMPTY_FIELD_SET_VALUE <value> are given an empty node set will have the
key value value. If instead the flag IGNORE_EMPTY_FIELD_SET flag is given an empty node set result
will not have any key value.
domxpathboolean XPath_expr ?name?
If not postvalidating a DOM tree with domvalidate this constraint always matches. If
postvalidating the XPath_expr argument is evaluated (with the node matching the schema parent of
the domxpathboolean command as context node). The constraint maches if the result of this XPath
expression, converted to boolean by XPath rules, is true. Several domxpathboolean commands within
one element definition are allowed. They are checked in definition order.
This enables checks depending on more than one element. Consider
tdom::schema s
s define {
defelement doc {
element a ! text
element b ! text
element c ! text
domxpathboolean "a * b * c >= 20000" volume
domxpathboolean "a > b and b > c" sequence
}
}
jsontype JSON structure type
If not postvalidating a DOM tree with domvalidate this constraint always matches. If
postvalidating the constraint matches if the enclosing element has the JSON type given as argument
to the structure constraint. The possible JSON structure types are NONE, OBJECT and ARRAY. This
constraint is only allowed as direct child of a defelement, defelementtype or local element
definition.
prefixns ?prefixUriList?
This defines a prefix to namespace URI mapping exactly as a schemacmd prefixns would. It is meant
as top-level command of a schemacmd define script. This command is not allowed nested in another
definition script command and will raise error, if you call it there.
defelement name ?namespace? <definition script>
This defines an element exactly as a schemacmd defelement call would. It is meant as top-level
command of a schemacmd define script. This command is not allowed nested in another definition
script command and will raise error, if you call it there.
defelementtype typename ?namespace? <definition script>
This defines an elementtype exactly as a schemacmd defelementtype call would. It is meant as top-
level command of a schemacmd define script. This command is not allowed nested in another
definition script command and will raise error, if you call it there.
defpattern name ?namespace? <definition script>
This defines a named pattern exactly as a schemacmd defpattern call would. It is meant as top-
level command of a schemacmd define script. This command is not allowed nested in another
definition script command and will raise error, if you call it there.
deftexttype name <constraint script>
This defines a named bundle of text constraints exactly as a schemacmd deftexttype call would. It
is meant as top-level command of a schemacmd define script. This command is not allowed nested in
another definition script command and will raise error, if you call it there.
start name ?namespace?
This command works exactly as a schemacmd start call would. It is meant as top-level command of a
schemacmd define script. This command is not allowed nested in another definition script command
and will raise error, if you call it there.
Quantity specifier
Several schema definition commands expect a quantifier as one of their arguments which determines how
often the content particle specified by the command is expected. The valid values for a quant argument
are:
! The content particle has to occur exactly once in valid documents.
? The content particle may not occur more than once in valid documents - the particle is optional.
* The content particle may occur zero or more times in a row in valid documents.
+ The content particle may occur one or more times in a row in valid documents.
n The content particle must occur n times in a row in valid documents. The quantifier must be an
integer greater zero.
{n m} The content particle must occur at least n and at most m times in a row in valid documents. The
quantifier must be a Tcl list with two elements. The first element of this list must be an integer
with n >= 0. If the second list element is the character *, then there is no upper limit.
Otherwise the second list element must be an integer with n < m.
If an optional quantifier is not given, it defaults to * in case of the mixed command and to ! for all
other commands.
Text constraint scripts
Text (parsed character data, as XML calls it) sometimes has to be of a certain kind or comply with
certain rules to be valid. The text constraint script arguments to text, attribute, nsattribute and
deftexttype commands are evaluated in the Tcl namespace tdom::schema::text namespace and allow the
ensuing text constraint commands to check text for certain properties. The commands are defined in the
Tcl namespace tdom::schema::text. They raise error in case they are called outside of a text constraint
script.
A few of the ensuing text type commands are exposed as general Tcl commands. They are defined in the
namespace tdom::type and are called as documented below with the text to check appended to the argument
list. They return a logical value. Please note that the commands may not accept starting or ending white
space. If a command is available in the tdom::type namespace is recorded in its documentation.
The tcl text constraint command
The tcl text constraint command dispatches the check to an arbitrary Tcl command, thus enable any
programmable decision rules.
tcl tclcmd ?arg arg ...?
Evaluates the Tcl script tclcmd arg arg ... and the text to validate appended to the argument
list. The return value of the Tcl command is interpreted as a boolean.
Basic XML types
name <URL: https://www.w3.org/TR/xml/#NT-Name> ⟨https://www.w3.org/TR/xml/#NT-Name⟩ This text
constraint matches if the text value matches the XML name production . This means that the text
value must start with a letter, underscore (_), or colon (:), and may contain only letters,
digits, underscores (_), colons (:), hyphens (-), and periods (.).
ncname <URL: https://www.w3.org/TR/xml-names/#NT-NCName> ⟨https://www.w3.org/TR/xml-names/#NT-NCName⟩
This text constraint matches if the text value matches the XML ncname production . This means
that the text value must start with a letter or underscore (_), and may contain only letters,
digits, underscores (_), hyphens (-), and periods (.) (The only difference to the name constraint
is that colons are not permitted.)
qname <URL: https://www.w3.org/TR/xml-names/#NT-QName> ⟨https://www.w3.org/TR/xml-names/#NT-QName⟩ This
text constraint matches if the text value matches the XML qname production . This means that the
text value is either a ncname or two ncnames joined by a colon (:).
nmtoken
<URL: https://www.w3.org/TR/xml/#NT-Nmtoken> ⟨https://www.w3.org/TR/xml/#NT-Nmtoken⟩ This text
constraint matches if the text value matches the XML nmtoken production
nmtokens
<URL: https://www.w3.org/TR/xml/#NT-Nmtokens> ⟨https://www.w3.org/TR/xml/#NT-Nmtokens⟩ This text
constraint matches if the text value matches the XML nmtokens production
Basic type tests
integer ?(xsd|tcl)?
This text constraint matches if the text value could be parsed as an integer. If the optional
argument to the command is tcl, everything that returns TCL_OK if fed into Tcl_GetInt() matches.
If the optional argument to the command is xsd, the constraint matches if the value is a valid
xsd:integer. Without argument xsd is the default.
negativeInteger ?(xsd|tcl)?
This text constraint matches the same text values as the integer text constraint (see there), with
the additional constraint, that the value must be < zero.
nonNegativeInteger ?(xsd|tcl)?
This text constraint matches the same text values as the integer text constraint (see there), with
the additional constraint, that the value must be >= zero.
nonPositiveInteger ?(xsd|tcl)?
This text constraint matches the same text values as the integer text constraint (see there), with
the additional constraint, that the value must be <= zero.
positiveInteger ?(xsd|tcl)?
This text constraint matches the same text values as the integer text constraint (see there), with
the additional constraint, that the value must be > zero.
number ?(xsd|tcl)?
This text constraint matches if the text value could be parsed as a number. If the optional
argument to the command is tcl, everything that returns TCL_OK if fed into Tcl_GetDouble()
matches. If the optional argument to the command is xsd, the constraint matches if the value is a
valid xsd:decimal. Without argument xsd is the default.
boolean ?(xsd|tcl)?
This text constraint matches if the text value could be parsed as a boolean. If the optional
argument to the command is tcl, everything that returns TCL_OK if fed into Tcl_GetBoolean()
matches. If the optional argument to the command is xsd, the constraint matches if the value is a
valid xsd:boolean. Without argument xsd is the default.
date This text constraint matches if the text value is a xsd:date, which is basically like an ISO 8601
date of the form YYYY-MM-DD, with optional time zone part (either the letter Z or plus (+) or
minus (-) followed by hh:mm and with maximum allowed positive or negative time zone 14:00). It
follows the date rules of the Gregorian calendar for all dates. A preceding minus sign for bce
dates is allowed. There is no year 0. The year may have more than 4 digits, but only if needed (no
extra leading zeros). This is available as common Tcl command tdom::type::date.
time This text constraint matches if the text value is a xsd:time, which is basically like an ISO 8601
time of the form hh:mm:ss with optional time zone part. The time zone part follow the rules of the
date command; see there. All three parts of the time value (hours, minutes, seconds) must be
spelled out with 2 digits. Additional fractional seconds (with a point ('.') as separator) are
allowed, but not just a dangling point. The time value 24:00:00 (without fractional part) is
allowed. This is available as common Tcl command tdom::type::time.
dateTime
This text constraint matches if the text value is a xsd:dateTime, which is basically like an ISO
8601 date time of the form YYYY-MM-DDThh:mm:ss with optional time zone part. The date and time
zone parts follows the rules of the date and time command; see there. The time part (including the
signaling 'T' character) is mandatory. This is available as common Tcl command
tdom::type::dateTime.
duration
This text constraint matches if the text value is a xsd:duration, which is basically like an ISO
8601 duration of the form PnYnMnDTnHnMnS. All parts other than the starting P and - if one of H, M
or S is given - T are optional. In case the following sign letter is S, n may be a decimal (with
at least one digit before and after the dot), otherwise it must be a (positive) integer. This is
available as common Tcl command tdom::type::duration.
base64 This text constraint matches if text is valid according to RFC 4648.
hexBinary
This text constraint matches if text is a sequence of binary octets in hexadecimal encoding, where
each binary octet is a two-character hexadecimal number. Lowercase and uppercase letters A through
F are permitted.
unsignedByte
This text constraint matches if the text value is a xsd:unsignedByte. This is an integer between 0
and 255, both included, optionally preceded by a + sign and leading zeros.
unsignedShort
This text constraint matches if the text value is a xsd:unsignedShort. This is an integer between
0 and 65535, both included, optionally preceded by a + sign and leading zeros.
unsignedInt
This text constraint matches if the text value is a xsd:unsignedInt. This is an integer between 0
and 4294967295, both included, optionally preceded by a + sign and leading zeros.
unsignedLong
This text constraint matches if the text value is a xsd:unsignedLong. This is an integer between 0
and 18446744073709551615, both included, optionally preceded by a + sign and leading zeros.
byte This text constraint matches if the text value is a xsd:byte. This is an integer between -128 and
127, both included, optionally preceded by a + or a - sign and leading zeros.
short This text constraint matches if the text value is a xsd:short. This is an integer between -32768
and 32767, both included, optionally preceded by a + or a - sign and leading zeros.
int This text constraint matches if the text value is a xsd:int. This is an integer between
-2147483648 and 2147483647, both included, optionally preceded by a + or a - sign and leading
zeros.
long This text constraint matches if the text value is a xsd:long. This is an integer between
-9223372036854775808 and 9223372036854775807, both included, optionally preceded by a + or a -
sign and leading zeros.
Logical constructs
oneOf <constraint script>
This text constraint matches if one of the text constraints defined in the argument constraint
script matches the text. It stops after the first matches and probes the text constraints in the
order of definition.
allOf <constraint script>
This text constraint matches if all of the text constraints defined in the argument constraint
script matches the text. It stops after the first match failure and probes the text constraints in
the order of definition. Since the schema definition command text also expects all text
constraints to match the text constraint, allOf is useful mostly in connection with the oneOf text
constraint command.
not <constraint script>
This text constraint matches if none of the text constraints defined in the argument constraint
script matches the text. It stops after the first matching constraint in the constraint script and
reports validation error. The text constraints in the constraint script are probed in the order of
definition.
type text type name
This text constraint matches if the text type given as argument matches.
Constraints on processed text value
whitespace (preserve|replace|collapse) <constraint script>
This text constraint command does white-space (#x20 (space, ' '), #x9 (tab, \t), #xA (linefeed,
\n), and #xD (carriage return, \r) normalization to the text value and checks the resulting text
with the text constraints of the constraint script argument. The normalization method preserve
keeps everything as it is; this is another way to say allOf. The replace normalization method
replaces any single white-space character (as above) to a space. The collapse normalization method
removes all leading and trailing white-space, and all the other sequences of contiguous white-
space are replaced by a single space.
split ?type ?args??<constraint script>
This text constraint command splits the text to test into a list of values and tests all elements
of that list for the text constraints in the evaluated constraint script>.
The available types are:
whitespace
The text to split is stripped of all white space at start and end and split into a list at
any successive white space.
tcl tclcmd ?arg ...?
The text to split is handed to the tclcmd, which is evaluated on global level, appended
with every given arg and the text to split as last argument. This call must return a valid
Tcl list whose elements are tested.
The default in case no split type argument is given is whitespace.
strip <constraint script>
This text constraint command tests all text constraints in the evaluated constraint script> with
the text to test stripped of all white space at start and end.
Various other string properties
fixed value
The text constraint only matches if the text value is string equal to the given value.
enumeration list
This text constraint matches if the text value is equal to one element (respecting case and any
white-space) of the argument list, which has to be a valid Tcl list.
match ?-nocase? glob_style_match_pattern>
<URL: https://www.tcl.tk/man/tcl8.6/TclCmd/string.htm#M35>
⟨https://www.tcl.tk/man/tcl8.6/TclCmd/string.htm#M35⟩ This text constraint matches if the text
value matches the glob style pattern given as argument. It follows the rules of the Tcl [string
match] command, see .
regexp expression
<URL: https://www.tcl.tk/man/tcl8.6/TclCmd/re_syntax.htm>
⟨https://www.tcl.tk/man/tcl8.6/TclCmd/re_syntax.htm⟩ This text constraint matches if the text
value matches the regular expression given as argument. describes the regular expression syntax
length length
This text constraint matches if the length of the text value (in characters, not bytes) is length.
The length argument must be a positive integer or zero.
maxLength length
This text constraint matches if the length of the text value (in characters, not bytes) is at most
length. The length argument must be an integer greater zero.
minLength length
This text constraint matches if the length of the text value (in characters, not bytes) is at
least length. The length argument must be an integer greater zero.
id ?keySpace?
This text constraint command marks the text as a document wide ID (to be referenced by an idref).
Every ID value within a document must be unique. It isn't an error if the ID isn't actually
referenced within the document. The optional argument keySpace does all this for a named key
space. The key space "" (the empty sting) is another key space then the id command without
keySpace argument.
idref ?keySpace?
This text constraint command expects the text to be a reference to an ID within the document. The
referenced ID may appear later in the document, that the reference. Several references within the
document to one ID are possible.
jsontype <JSON text type>
If not postvalidating a DOM tree with domvalidate this constraint always matches. If
postvalidating the current TEXT_NODE to check must have the JSON text type given as argument to
the text constraint command. The possible types are NULL, TRUE, FALSE, STRING and NUMBER.
Local key constraints
Document wide uniqueness and foreign key constraints are available with the text constraint commands id
and idref. Keyspaces allow for sub-tree local uniqueness and foreign key constraints.
keyspace <names list> <constraint script>
Any number of keyspaces are possible. A keyspace is either active or not. An inside a constraint
script called keyspace with the same name does nothing.
This text constraint commands work with keyspaces:
key <name>
If the keyspace with the name <name> is not active the constraint always matches. If the keyspace
is active, reports error if there is already a key with the value. Otherwise it stores the value
as key in this keyspace and matches.
keyref <name>
If the keyspace with the name <name> is not active always matches. If the keyspace is active then
reports error if there is still no key as the value at the end of the keyspace <name>. Otherwise,
it matches.
Recovering
By default the validation engine stops at the first detected validation violation and reports that
finding. It does so by return false (and sets, if given, the result variable with an error message) in
case the schema command itself is used to validate input. If the schema command is used by a SAX parser
or the DOM parser, it does so by throwing error.
If a reportcmd is set this command is called on global level appended with the schema command and an
error type as arguments in case a validation violation is detected. Then the validation recovers from the
error and continues. For some validation errors the recover strategy can be determined with the script
result of the reportcmd.
With a reportcmd (as long as the reportcmd does not throw error while called) the validation engine will
never report validation failure to its caller. The validation engine recovers, continues, and reports the
next error (if occurring) and so on until the end of the input. The schema command will return true and
the SAX parser and DOM builder will process normally until the end of the input, as if there had not been
a validation error.
Please note that this happens only for validation errors. It is not possible to recover from well-
formedness errors. If the input is not well-formed, the schema command returns false and sets (if given)
the result variable with an error message about the well-formedness error.
If the reportcmd throws error while called by the validation engine then validation stops and the schema
command throws error with the error message of the script.
While validating basically three events can happen: an element start tag has to match, a piece of text
has to match or an element end tag has to match. The method info vaction called in the recovering script
or any script code called from there returns, which event has triggered the error report
(MATCH_ELEMENT_START, MATCH_TEXT, MATCH_ELEMENT_END, respectively). While the command walks throu the
schema looking whether the event matches other, data driven events (as, for example checking, if any
keyref within a keyspace exists) may happen.
Several of the validation error codes, appended as second argument to the reportcmd calls, may happen at
more than one kind of validation event. The info vaction method and its subcommands provide information
about the current validation event, if called from the report command.
If a structural validation error happens, the default recovering strategy is to ignore any following (or
missing) content within the current subtree and to continue with the element end event of the subtree.
Returning "ignore" from the recovering script in case of error type MISSING_ELEMENT recovers by ignoring
the failed constraint and continues to match the event further against the schema.
Returning "vanish" from the recover script in case of the error types MISSING_ELEMENT and
UNEXPECTED_ELEMENT recovers by ignoring the event.
Examples
<URL: https://www.w3.org/TR/xmlschema-0/> ⟨https://www.w3.org/TR/xmlschema-0/⟩ The XML Schema Part 0:
Primer Second Edition () starts with this example schema:
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:annotation>
<xsd:documentation xml:lang="en">
Purchase order schema for Example.com.
Copyright 2000 Example.com. All rights reserved.
</xsd:documentation>
</xsd:annotation>
<xsd:element name="purchaseOrder" type="PurchaseOrderType"/>
<xsd:element name="comment" type="xsd:string"/>
<xsd:complexType name="PurchaseOrderType">
<xsd:sequence>
<xsd:element name="shipTo" type="USAddress"/>
<xsd:element name="billTo" type="USAddress"/>
<xsd:element ref="comment" minOccurs="0"/>
<xsd:element name="items" type="Items"/>
</xsd:sequence>
<xsd:attribute name="orderDate" type="xsd:date"/>
</xsd:complexType>
<xsd:complexType name="USAddress">
<xsd:sequence>
<xsd:element name="name" type="xsd:string"/>
<xsd:element name="street" type="xsd:string"/>
<xsd:element name="city" type="xsd:string"/>
<xsd:element name="state" type="xsd:string"/>
<xsd:element name="zip" type="xsd:decimal"/>
</xsd:sequence>
<xsd:attribute name="country" type="xsd:NMTOKEN"
fixed="US"/>
</xsd:complexType>
<xsd:complexType name="Items">
<xsd:sequence>
<xsd:element name="item" minOccurs="0" maxOccurs="unbounded">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="productName" type="xsd:string"/>
<xsd:element name="quantity">
<xsd:simpleType>
<xsd:restriction base="xsd:positiveInteger">
<xsd:maxExclusive value="100"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:element>
<xsd:element name="USPrice" type="xsd:decimal"/>
<xsd:element ref="comment" minOccurs="0"/>
<xsd:element name="shipDate" type="xsd:date" minOccurs="0"/>
</xsd:sequence>
<xsd:attribute name="partNum" type="SKU" use="required"/>
</xsd:complexType>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
<!-- Stock Keeping Unit, a code for identifying products -->
<xsd:simpleType name="SKU">
<xsd:restriction base="xsd:string">
<xsd:pattern value="\d{3}-[A-Z]{2}"/>
</xsd:restriction>
</xsd:simpleType>
</xsd:schema>
A simple one-to-one translation of that into a tDOM schema definition script would be:
tdom::schema schema
schema define {
# Purchase order schema for Example.com.
# Copyright 2000 Example.com. All rights reserved.
defelement purchaseOrder {ref PurchaseOrderType}
foreach elm {comment name street city state product} {
defelement $elm text
}
defpattern PurchaseOrderType {
element shipTo ! {ref USAddress}
element billTo ! {ref USAddress}
element comment ?
element items
attribute orderDate date
}
defpattern USAddress {
element name
element street
element city
element state
element zip ! {text number}
attribute country {fixed "US"}
}
defelement items {
element item * {
element product
element quantity ! {text positiveInteger}
element USPrice ! {text number}
element comment
element shipDate ? {text date}
attribute partNum {regexp "^\d{3}-[A-Z]{2}$"}
}
}
}
<URL: http://relaxng.org/tutorial-20011203.html> ⟨http://relaxng.org/tutorial-20011203.html⟩ The RELAX NG
Tutorial () starts with this example:
Consider a simple XML representation of an email address book:
<addressBook>
<card>
<name>John Smith</name>
<email>js@example.com</email>
</card>
<card>
<name>Fred Bloggs</name>
<email>fb@example.net</email>
</card>
</addressBook>
The DTD would be as follows:
<!DOCTYPE addressBook [
<!ELEMENT addressBook (card*)>
<!ELEMENT card (name, email)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT email (#PCDATA)>
]>
A RELAX NG pattern for this could be written as follows:
<element name="addressBook" xmlns="http://relaxng.org/ns/structure/1.0">
<zeroOrMore>
<element name="card">
<element name="name">
<text/>
</element>
<element name="email">
<text/>
</element>
</element>
</zeroOrMore>
</element>
This schema definition script will do the same:
tdom::schema schema
schema define {
defelement addressBook {
element card *
}
defelement card {
element name
element email
}
foreach e {name email} {
defelement $e text
}
}
KEYWORDS
Validation, Postvalidation, DOM, SAX