This is CORBA::IDLtree, a module that builds abstract syntax trees
from CORBA IDL.
The main export is sub Parse_File which takes an IDL input file name
as the parameter, and returns a reference to an array of references
to the root nodes constructed (or 0 if there were syntax errors.)
Parse_File uses two auxiliary data structures:
@include_path - Paths where to look for included IDL files
%defines - Symbol definitions for the preprocessor
(cf. the -D switch on many C compilers)
where -DSYM=VAL is represented as
$defines{SYM} = VAL. -DSYM is represented as
$defines{SYM} = 1.
A further export is the sub Dump_Symbols which takes the return value
of Parse_File as the parameter, and prints the trees constructed to
stdout in IDL syntax.
-----------------------------------------------------------------------------
SYMBOL TREE STRUCTURE
The following description of the structure of the symbol tree
applies to CORBA::IDLtree versions >= 1.0. The structure
has been changed w.r.t. previous releases, for example the
INTERFACE node now has an "abstract" flag. Also, all the
scalars used as constants, e.g. $INTERFACE, have been changed to
subroutines, e.g. &INTERFACE, to better express the constness
of these values. However, it is intended to keep further
changes to the user interface to a minimum, i.e. the IDLtree
programming interface is now considered stable.
A "thing" in the symbol tree can be either a reference to a node, or a
reference to an array of references to nodes.
A node is a five-element array with the elements
[0] => TYPE (MODULE|INTERFACE|STRUCT|UNION|ENUM|TYPEDEF...)
[1] => NAME
[2] => SUBORDINATES
[3] => COMMENT (introduced in IDLtree version 1.2)
[4] => SCOPEREF
Some IDL types are representable as a simple numeric constant;
they do not require nodes. We'll call these types "elementary".
Elementary types are the scalar types, e.g. boolean, short,
unsigned long long, any, string.
Other IDL types cannot be represented in this way, they require
more information. An enum, for example, requires the enumeration
literals. These types are represented as nodes. The TYPE element
contains a numeric ID identifying what IDL type the node represents.
The NAME element, unless specified otherwise, simply holds the name string
of the respective IDL syntactic item.
The SUBORDINATES element depends on the node type.
Sometimes an item in the SUBORDINATES may contain either a type ID or
a reference to the defining node; we will call that a `type descriptor'.
Which of the two alternatives is in effect can be determined via the
isnode() function.
Contents of SUBORDINATES:
MODULE or Reference to an array of nodes (symbols) which are defined
INTERFACE within the module or interface. In the case of INTERFACE,
element [0] in this array will contain a reference to a
further array which in turn contains references to the
parent interface(s) if inheritance is used, or the null
value if the current interface is not derived by
inheritance. Element [1] is the "abstract" flag which is
non-zero for interfaces declared abstract.
INTERFACE_FWD Reference to the node of the full interface declaration.
STRUCT or Reference to an array of node references representing the
EXCEPTION member components of the struct or exception.
Each member representative node is a quadruplet consisting
of (TYPE, NAME, <dimref>, COMMENT).
The <dimref> is a reference to a list of dimension numbers,
or is 0 if no dimensions were given.
UNION Similar to STRUCT/EXCEPTION, reference to an array of
nodes. For union members, the member node has the same
structure as for STRUCT/EXCEPTION.
However, the first node contains a type descriptor for
the discriminant type.
The TYPE of a member node may also be CASE or DEFAULT.
For CASE, the NAME is unused, and the SUBORDINATE contains
a reference to a list of the case values for the following
member node.
For DEFAULT, both the NAME and the SUBORDINATE are unused.
ENUM Reference to the array of enum value literals.
TYPEDEF Reference to a two-element array: element 0 contains a
reference to the type descriptor of the original type;
element 1 contains a reference to an array of dimension
numbers, or the null value if no dimensions are given.
SEQUENCE As a special case, the NAME element of a SEQUENCE node
does not contain a name (as sequences are anonymous
types), but instead is used to hold the bound number.
If the bound number is 0, then it is an unbounded
sequence. The SUBORDINATES element contains the type
descriptor of the base type of the sequence. This
descriptor could itself be a reference to a SEQUENCE
defining node (that is, a nested sequence definition.)
Bounded strings are treated as a special case of sequence.
They are represented as references to a node that has
BOUNDED_STRING or BOUNDED_WSTRING as the type ID, the bound
number in the NAME, and the SUBORDINATES element is unused.
CONST Reference to a two-element array. Element 0 is a type
descriptor of the const's type; element 1 is a reference
to an array containing the RHS expression symbols.
FIXED Reference to a two-element array. Element 0 contains the
digit number and element 1 contains the scale factor.
The NAME component in a FIXED node is unused.
VALUETYPE [0] => $is_abstract (boolean)
[1] => reference to a tuple (two-element list) containing
inheritance related information:
[0] => $is_truncatable (boolean)
[1] => \@ancestors (reference to array containing
references to ancestor nodes)
[2] => \@members: reference to array containing references
to tuples (two-element lists) of the form:
[0] => 0|PRIVATE|PUBLIC
A zero for this value means the element [1]
contains a reference to a METHOD or ATTRIBUTE.
In case of METHOD, the first element in the
method node subordinates (i.e., the return
type) may be FACTORY.
[1] => reference to the defining node.
VALUETYPE_BOX Reference to the defining type node.
VALUETYPE_FWD Subordinates unused.
NATIVE Subordinates unused.
ATTRIBUTE Reference to a two-element array; element 0 is the read-
only flag (0 for read/write attributes), element 1 is a
type descriptor of the attribute's type.
METHOD Reference to a variable length array; element 0 is a type
descriptor for the return type. Elements 1 and following
are references to parameter descriptor nodes with the
following structure:
[0] => parameter type descriptor
[1] => parameter name
[2] => parameter mode (IN, OUT, or INOUT)
The last element in the variable-length array is a
reference to the "raises" list. This list contains
references to the declaration nodes of exceptions raised,
or is empty if there is no "raises" clause.
INCFILE Reference to an array of nodes (symbols) which are defined
within the include file. The Name element of this node
contains the include file name.
PRAGMA_PREFIX Subordinates unused.
PRAGMA_VERSION Version string.
PRAGMA_ID ID string.
PRAGMA This is for the general case of pragmas that are none
of the above, i.e. pragmas unknown to IDLtree.
The NAME holds the pragma name, and SUBORDINATES
holds a reference to all further text appearing after
the pragma name, if any.
The COMMENT element holds the comment text that precedes an IDL item
or appears on the same line as the IDL item.
Note that comments that relate to an IDL item, but appear on lines
*after* the IDL item, are not handled correctly: They are associated with
the following IDL item. Comment text appearing after the last IDL item
is lost.
The comment text is stored as a list to accomodate multi-line comments.
The lines in this list are not newline terminated. The COMMENT field is a
reference to this list, or contains the value 0 if no comment is present
at the IDL item.
The SCOPEREF element is a reference back to the node of the module or
interface enclosing the current node. If the current node is already
at the global scope level, then the SCOPEREF is 0. If the current node
is inside an INCFILE, the SCOPEREF element points to the corresponding
INCFILE node (the INCFILE reference was introduced in IDLtree version
1.3.) All nodes have this element except for the parameter nodes of
methods and the component nodes of structs/unions/exceptions.
-- Last updated: 2002/12/01
-- okellogg@users.sourceforge.net