This is the AdaControl Programmer Manual. It is intended for those who want to add new rules to AdaControl, or more generally modify (and presumably improve!) AdaControl. Reading this manual is not necessary to use AdaControl. On the other hand, it is assumed that the reader is familiar with how to use AdaControl.
|• The framework and utilities packages|
|• Writing a new rule|
|• Plugging-in a new rule into the framework|
|• Testing and debugging a rule|
Commercial support is available for AdaControl. If you plan to use AdaControl for industrial projects, or if you want it to be customized or extended to match your own needs, please contact Adalog at firstname.lastname@example.org.
AdaControl is Copyright © 2005-2021 Eurocontrol/Adalog, except for some specific modules that are © 2006 Belgocontrol/Adalog, © 2006 CSEE/Adalog, © 2006 SAGEM/Adalog, or © 2015 Alstom/Adalog. AdaControl is free software; you can redistribute it and/or modify it under terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This unit is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License distributed with this program; see file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
As a special exception, if other files instantiate generics from this program, or if you link units from this program with other files to produce an executable, this does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU Public License.
This document is Copyright © 2005-2021 Eurocontrol/Adalog. This document may be copied, in whole or in part, in any form or by any means, as is or with alterations, provided that (1) alterations are clearly marked as alterations and (2) this copyright notice is included unmodified in any copy.
This programmer manual describes how to add new rules to AdaControl. Since AdaControl is based on ASIS, this manual assumes that the reader has some familiarity with ASIS programming.
Modifying AdaControl needs of course a source distribution. It is OK to work with the regular source distribution, but if you intend to submit your patches, it is appropriate to get the latest “bleeding edge” version from our GIT repository on SourceForge. Instructions on how to get AdaControl from GIT are here
Some terms have a precise definition in AdaControl, and will be used with that signification in the rest of this manual.
A rule is an AdaControl package whose purpose is to recognize occurrences of certain constructs in Ada programs. All rules are children of the “Rules” package. By extension, the term rule is also used to designate the check that is performed by the package. A rule has a name, and may have parameters.
A control defines a check to be performed on some Ada text. A control is defined by a rule, and the value of the parameters given to the rule.
A command is a statement in the command language interpreted by AdaControl.
A control command is a kind of command that describes a check to be performed. A control commmand includes a kind (“check”, “search” or “count”, see user’s guide), and a control (rule name and parameters).
A context is a set of values used by a rule to keep the characteristics associated with a control. Those values can, but need not necessarily, be the parameters of the control.
The AdaControl tool includes several main components. Those that are relevant for writing new rules are:
Framework.Plugs, where rules are plugged-in;
This clear distinction makes it easy to add new rules. Actually, the framework relieves the programmer from all the “dirty work”, and adding a new rule requires nothing else than caring about the rule itself.
The framework includes the package
Framework itself and its
public child packages. There are also some private child packages, but
they are of course not relevant to the users of the framework.
In each package, services (declarations, subprograms) that are relevant for writing rules appear at the beginning of the package specification. Other services that are used by the rest of the framework, but not intended to be called from a rule, appear below the following comment lines:
-- -- Declarations below this line are for the use of the framework --
This section provides an overview of the services that are made available by the framework and other utilities packages. It is not the purpose of this section to describe the syntax of every service provided : please refer to the comments in the specification of each package. Existing rules are also typical examples of how to use these functionnalities.
|• The package Adactl_Constants|
|• The package Framework|
|• The package Framework.Rules_Manager|
|• The package Framework.Reports|
|• The package Framework.Fixes|
|• The package Framework.Language|
|• The package Framework.Variables|
|• The package Framework.Plugs|
|• The package Scope_Manager|
|• The package Rules|
|• The package Utilities|
|• The packages Thick_Queries and Framework.Queries|
|• The packages Linear_Queue and Binary_Map|
|• The package A4G_Bugs|
AdaControl has some fixed size structures that limit the complexity of the programs it can handle, like for example the maximum numbers of parameters that subprograms can have, the maximum nesting of loops, etc.
These limits are set as constants in the package
Adactl_Constants. These values are large enough to accomodate
any reasonable program, but should you hit one of these limits, you
can safely change them here. No other change is required.
If a rule needs to set a fixed dimension to some tables for example, it should use the constants defined in this package. If no existing constant is appropriate, add a new one to the package, don’t define dimensioning constants in the rule itself.
The package Framework includes general services, needed by most rules. These include:
search Entities (Blah); Strictly_Forbidden: check entities (Ada.Unchecked_Conversion)
the rule Entities must associate that
Blah is the target of a
search, and that
Ada.Unchecked_Deallocation is the target of a
check with label
Framework.Rules_Manager is used to register and
Register declares the name of the rule and the
Note that there is nothing else to do to make a rule known to the system: once it is registered, it will be recognized on the command line, help command will work, etc.
Enter is used to let the system know which rule is
Framework.Reports is used to report error or found
messages when a rule matches. It deals automatically with things like
rules being temporarily disabled, therefore the rule does not have to
The main service provided by this package is the
which comes in two flavors. This is the only allowed way for a rule to
report its findings, never use
Wide_Text_IO or any other
mean. The specifications of the Report procedures are:
procedure Report (Rule_Id : in Wide_String; Rule_Label : in Wide_String; Ctl_Type : in Control_Kinds; Loc : in Location; Msg : in Wide_String); procedure Report (Rule_Id : in Wide_String; Context : in Root_Context'class; Loc : in Location; Msg : in Wide_String);
The first procedure expects the label and type to be given
explicitely, while the second one gets them from a
object (see comments in the package).
Note that there is only one string for the message. Please do not try to “improve” the presentation by introducing line breaks in the report message: the output of AdaControl should remain parseable by rather naive tools, therefore it is necessary to ensure that one output line = one message.
In addition, there is an
Uncheckable procedure, with the following profile:
procedure Uncheckable (Rule_Id : in Wide_String; Risk : in Uncheckable_Consequence; Loc : in Location; Msg : in Wide_String);
This procedure is called each time a rule encounters some dynamic
construct that prevents normal checking. The parameter
False_Positive if the consequence of not being able to analyze
the construct would result in wrong error messages, and
False_Negative if it would result in not detecting something
that could be an error. It is important to call this procedure for any
non-checkable construct, since it is what allows the rule
“Uncheckable” to work.
Framework.Reports.Fixes provides functionalities
for generating fixes to the source code.
The functionalities provided here allow to insert, delete, or replace elements of the source text. See the specification for details.
If your rule knows how to fix a violation, just call the corresponding subprograms from this package. Always call the fixes subprograms after the corresponding report subprograms, because it’s the report subprogram that determines if the rule is enabled or disabled.
Note that it is better to delete some text than to replace it if
possible, because the fixing tool (
conflicts between deletions better than conflicts between
insertions/replacements. For example, to remove unnecessary
parentheses, the rule
removes the opening and closing parentheses, rather than replace the
A_Parenthesized_Expression with its content (the
Framework.Language provides functionalities
for parsing parameters, as well as the rest of the command language;
but of course only the subprograms used to parse parameters are
relevant to the writing of rules.
The functionalities provided here allow a good deal of freedom for defining the syntax of a rule’s parameters (although it is a good idea to stay as close as possible to the syntax of other rules). Look at the syntax of various rules to see what can be accomplished.
The package provides a
Parameter_Exists function that returns
True if there are parameters left to parse. The kind of the
next parameter can be checked with the
functions. The corresponding parameter value can be retrieved with the
functions. The latter function returns an entity specification, i.e. a
descriptor for something which is expected to be a general
specification for an Ada entity (including overloading information,
for example). Such an entity can be used as a key for a context.
There is a generic package
Flag_Utilities to help manage flags
(keywords) parameters defined by an enumerated type. An instantiation
of this package provides a
Get_Flag_Parameter procedure to
parse the flags, an
Image function to get a string
representation of a flag, and a
Help_On_Flags function to print
the help message that enumerates all possible flag values.
There is a
Get_Modifier to process modifiers (things like
“not” or “case_sensitive” in front of a parameter). For more
sophisticated modifiers, you can instantiate the generic package
Modifier_Utilities, which works like
also provides the notion of sets of modifiers.
Note that if you instantiate
Modifier_Utilities in a library package (as will be the case
most of the time), you must put a
(Framework.Language); on top of the package. Failing to do so will
result in circular elaboration problems; (
as implicitely provided by GNAT, does not work).
This package manages rule variables (the ones that can be set with
set command of the language).
A rule may use any number of rule variables for adjusting its behaviour. A rule variable holds a value, and various subprograms are provided for setting and getting the associated value.
Rule variables are extensions of
Framework.Variables.Object. Typically, they extend this type
with a value that can be of any type. Abstract subprograms that need
to be overriden include
Value_Image for setting
and getting a value from/to a string and
All_Values to give
possible values for help messages.
Generic packages are provided to make it easier to define variable
types associated to enumerated types and integer types. In addition,
Framework.Variables.Shared_Types provides variable
types for commonly used associated types.
When a rule needs a rule variable, it declares an object of the
appropriate type, and registers it to the framework by calling
Framework.Variables.Register, passing a pointer to the object
and the name used to refer to it. This name must be given in upper
case, and start with the rule’s name, like
EXPRESSIONS.CALLED_INFO” for example. Of course, it is
better to use
Rule_Id for building the name, like in:
Framework.Variables.Register (Called_Info'Access, Variable_Name => Rule_Id & ".CALLED_INFO");
This call is typically put in the initalization part of the rule’s package, after the registration of the rule itself.
Expressions (in file
includes a typical usage of a rule variable.
Procedures in the package
Framework.Plugs are called during the
traversal of the Ada source code. Unlike the rest of the framework,
this package does not provide services to rules, but instead calls
processing procedures defined in the rules packages. Therefore, it is
necessary to plug the corresponding calls in this package. This is
described in details in Plugging-in a new rule into the framework.
Scope_Manager provides facilities for rules that
need to follow scoping rules (i.e. which identifiers are visible at a
given place). It provides subprograms to query currently active
scopes, and a generic package that allows associating any kind of
information to a scope. Scopes are automatically managed: the
information will disappear when the corresponding scope is exited,
except for information associated to package specifications that will
be restored when the corresponding body is entered.
The scope manager follows strictly the visibility rules for child units: when entering a public child unit, the scope from the visible part of the parent is restored, and when entering the private part of the child, the scope of the private part of the parent is restored. In the case of a private child, the full scope of the parent is restored upon entering.
See the package specification for more details.
Note: this package used to be a child of
Framework in previous
versions of AdaControl. This has been changed to be an autonomous
package to make it reusable by other programs.
Rules is (almost) empty. It’s purpose is to serve as the
parent package of all rules.
It simply provides an empty state type (
Null_State), and a null procedure that can
be used for instantiating
Traverse_Element in simple cases.
This package provides various general facilities that are not specific to AdaControl. The main elements provided are:
User_Log. Both procedures output a message, the difference being that
User_Logoutputs its message only in verbose mode.
User_Messageis used to print help messages.
User_Logcould be used if some rule wanted to print some extra information in verbose mode. Note that these procedures should not be used to report the result of a check or search (use
Errorprocedure is not to be called directly, use
Framework.Language.Parameter_Errorinstead to report errors in user provided parameters. In most cases, parameters are checked in the
Add_Controlprocedure of the rule (see Writing a new rule), and therefore errors are reported during the parsing of the commands. In some cases, incorrect parameters are discovered while traversing the code. It is acceptable to call
Framework.Language.Parameter_Errorat any time, but be aware that this will immediately stop all analysis. See the
Rules.Unsafe_Paired_Callsfor an example of this.
Failure procedure is used to report internal failures. It
is frequent in ASIS programming to have a big case statement over the
various kinds of elements, of which only a few values are interesting
or possible given the context. We strongly encourage to call
Failure in the when others part of the case statement to
trap unexpected cases. Note that the procedure is overloaded with a
version that allows to print information about the failing element.
Traceprocedures allow you to output a message, possibly with a boolean value, or the context of an ASIS element or element list. There is also an
Assertprocedure that calls
Failureif its condition is false; well placed
Assertcalls are very helpfull in debugging. Note that traces are output only in debug mode.
These packages contain high level services that are built on top of Asis queries, and can therefore be quite useful to the writing of rules. The queries are documented in the specification of the packages.
The difference between the packages is that
not depend in any way on the other parts of AdaControl (and notably on
the framework); it is therefore directly reusable for any ASIS
application. On the other hand,
facilities provided by the framework, and is therefore not directly
reusable outside of AdaControl.
These packages provide simple generic containers that are needed by several rules.
The generic package
Linear_Queue can be instantiated with any
Component type, and provides a simple queue of
elements. Note that this queue has value semantics: when a queue
is assigned, its content is duplicated. Queues are controlled, and
therefore all internal storage allocations are internally managed. The
Framework.Element_Queue is an instantiation of
Linear_Queue with the type
The generic package
Binary_Map can be instantiated with a
Key_Type and a
Value_Type, and associates values of
Value_Type to values of the
Key_Type. The mapping uses a
binary tree; if you use it to keep user information, it is appropriate
to rebalance the tree before starting the actual
processing. See Prepare.
See existing rules for examples of using this package.
AdaControl is quite demanding on the ASIS implementation, and we found some bugs in ASIS-for-GNAT during its development. These have been reported to ACT, and are fixed in the wavefront version of GNAT, or should be fixed very soon.
However, many people do not have access to the wavefront version, or prefer to stay with the stable version. This package provides replacements for some ASIS subprograms that do not behave as expected. Subprograms in this package have specifications identical to the corresponding ASIS subprograms, and are designed in such a way that there is no harm in using them with a version of ASIS that does not exhibit the bug. Therefore, it is strongly recommended to use the subprograms in this package rather than their ASIS equivalent.
Note that if you run the rules file
src/verif.aru on your code,
it will spot any use of an ASIS function for which there is a
There are two kinds of rules: semantic rules, which operate on Ada
elements, and textual rules, which operate on the source text. In
some rare cases, a rule can be of both kinds at the same time; see the
rule “Style” for an example of this. Note that a semantic rule can
still access the text of an Ada construct with the facilities provided
by the package
Asis.Text, this does not require the rule to be
All rules currently provided follow a common pattern, described below; it is recommended that new rules do the same, in order to make maintenance easier.
The first thing to do before adding a new rule is to read the source
for existing rules, as they provide good examples of how a rule is
implemented. For an example of a simple rule, see
for an example of a sophisticated one, see
Rules.Unnecessary_Use. For an example of a textual rule, see
Rules.Max_Line_Length. Note that
Rules.Entity can be
used as a template for writing new semantic rules, as most rules will
follow the same general structure, just making more elaborated
processing of relevant entities.
A rule is implemented as a child package of package
following sections describe the structure of the specification and
body of a rule package.
It is good practice to use only one string type all over a program,
and since ASIS is based on
Wide_String, a rule should not use
String, but rather use
The specification of a rule package must contain the following elements:
Rule_ID is a constant of type
Wide_String. It is the unique
rule identifier of a rule. It is used by the package
Framework.Rules_Manager as the key in the rules list to
dispatch to the corresponding registered operation, and as the rule
name used by the user on the command line to parameterize and use the
rule. The name of the rule must be given in upper-case (to allow for
Rule_Id : constant Wide_String := "PRAGMAS";
Note that from a language point of view, this declaration could be in the body of the package; however, for identification purposes, it is more convenient to put it in the specification.
One (or more) procedure(s) may be necessary to process the rule
(collectively named the
Process procedures in this
document). These procedures are called from
appropriate places, and therefore must be declared in the
specification of the rule. See Plugging-in a new rule into the framework.
Process procedures of a semantic rule take one parameter of type
Asis.Element. Although all element kinds are equivalent from
the point of view of Ada’s type checking, it is recommended to follow
general ASIS practice, and to define the parameter with the ASIS
element kind expected by the procedure.
Process procedures of a textual rule take two parameters: an input line, and the corresponding location.
-- Semantic rule: procedure Process_Pragma (Pragma_Element : in Asis.Pragma_Element); -- Textual rule: procedure Process_Line (Line : in Asis.Program_Text; Loc : in Framework.Location);
It is a good habit to start the body of a rule by giving a comment explaining the general principles of the algorithm used, especially if the algorithm is not trivial. To be honest, not all current rules do provide this information, and some crucial information may be missing in the rules that do... You are more than welcome to improve these comments, especially if you think that some fundamental information should have been provided here.
The body must contain a
Add_Control, and a
Command procedure. It may also optionnally contain a
Prepare and a
Finalize procedure. These procedures are
call-backs that are registered to the framework by calling
Framework.Rules_Manager.Register in the statements part of the
body. Note that there is a parameter to this procedure that tells
whether the rule is semantic, textual, or both. This procedure has
null defaults for the optional subprograms.
Help is a procedure that displays a short help message to the standard output for the rule. It takes no parameter.
Help is called when the user specifies a “-h” option
for the rule. It must display a useful message by calling
Utilities.User_Message. In order to have a uniform presentation
for all rules, the message must be structured as follows:
Help_On_Flagprocedure that formats automatically the values.
If the different parameters have different meanings, you can use the form “Parameter(1):”, “Parameter(2):” etc. instead. If the rule has no parameters, just say “Parameters: none”.
Note that the command:
adactl -h all
outputs the help messages for all rules, providing examples of how you should write your own help messages.
procedure Help is use Utilities; begin User_Message ("Rule: " & Rule_Id); User_Message ("Control occurrences of aspect specifications"); User_Message; User_Message ("Parameter(s): <Aspect_Mark> | implicit_true | all"); User_Message (" (optional, default = all)"); end Help;
Add_Control is a procedure which is called by the rules parser
when it finds a control command that refers to the corresponding
rule. It is passed the corresponding label (an empty string if there
is no label), and the control’s kind (
Count). It will typically loop over the parameters with the
Get_XXX_Parameters from package
to process the parameters.
If for some reason a parameter is not appropriate to the rule, the
rule should call
Rules.Language.Parameter_Error with an
appropriate message. This procedure will raise the exception
User_Error, and the
Add_Control procedure should not handle
it; the exception will be processed by the framework.
Add_Control may be called several times if the same rule
is activated with different parameters in a rules file. If a rule can
be specified only once, it is up to the rule to check this and call
Parameter_Error in case it is given more than once.
procedure Add_Control (Label : in Label; Ctl_Type : in Control_Kinds) is begin while Parameter_Exists loop -- process parameter end loop; end Add_Control;
There is no special requirement on the implementation of the
procedure. The programmer is free to interpret the parameters as
necessary and do whatever initialisation processing they
imply. Typically, for a rule that searches for the occurrence of an
identifier, this procedure would add the identifier to some internal
Command is a procedure used by the framework to send
“commands” to the rule in order to change its state. It has a
parameter of an enumeration type that can take the values
Commandis called with this value whenever a “clear” command is given. The rule must reset the rule to the “not used” state, and free any allocated data structure.
Commandis called with this value whenever the rule is inhibited. The rule must preserve its current “used” state, and enter the “not used” state.
Commandis called with this value whenever the rule is no more inhibited. The rule must restore its state from the copy saved by the previous
This procedure is required, since it must at least deal with the
Rule_Used flag (see Process). Note that it is guaranteed
Resume are properly paired, and that
Suspend is not called on an already suspended rule. Therefore,
a simple variable can be used to save the current state.
procedure Command (Action : Framework.Rules_Manager.Rule_Action) is use Framework.Rules_Manager; begin case Action is when Clear => Rule_Used := False; -- Free internal data structures if necessary when Suspend => Save_Used := Rule_Used; Rule_Used := False; when Resume => Rule_Used := Save_Used; end case; end Command;
Prepare is a procedure that performs some initialisations that
must be done after all controls refering to the rule have been parsed,
and before processing the units. It is optional (i.e. a
null pointer can be passed for it to the
procedure, or simply not mentionned since
null is the
A typical use of
Prepare is to balance the tree from a binary
map to improve efficiency.
There is no special requirement on the implementation of the
Process procedure(s). The programmer is free to do whatever is
necessary to the rule. It is possible to use ASIS query functions, or
any other service deemed appropriate.
It is also possible to have several
Process procedures (e.g. if
the programmer wants to do some processing when going down the ASIS
tree, and some other processing when going up).
Process procedure should return immediately if no
Add_Control has ever been called. In most cases, this
is conveniently done by having a
Rule_Used global boolean
variable which is set to
Add_Control, and checked at
the beginning of
Process. For efficiency reasons, avoid doing
any call to the ASIS library before this check. This means that if you
need objects initialized with such calls, they should be declared in a
block after the test, rather than in the declarative part of the
After this test, the rule should immediately call
Rules_Manager.Enter (with the rule name as the parameter). In
case of a problem, this allows the system to report which rule failed.
A special case arises for rules that follow the call graph. Such rules
may traverse elements outside the current unit, but should avoid
analyzing units to which an
inhibit all applies (so-called
banned units). The framework features an
that tells if an element should not be traversed due to it being
declared in a banned unit. See
Rules.Global_References for an
example of this.
Finalize is called at the end of a "Go" command, after all
units have been processed. It is useful for rules that report on
global usage of entities, and therefore can report findings only at
the end. It is optionnal (i.e. a
null pointer can be passed
for it to the
Register procedure, or simply not mentionned
null is the default).
procedure Finalize is begin -- Report findings end Finalize;
The package body statements part should include a call to
Framework.Rules_Manager.Register in order to register
the rule and its associated
Command, and optionally
procedures. Note that the second parameter of
whether it is a semantic, textual, or semantic_textual rule.
begin Framework.Rules_Manager.Register (Rule_Id, Rules_Manager.Semantic, Help => Help'Access, Add_Control => Add_Control'Access, Command => Command'Access, Prepare => Prepare'Access); end Rules.Pragmas;
We try to maintain a consistent style in AdaControl, therefore the code you write should
match the style of the rest of the program. Have a look at other rules, and run
on your code. In addition, please note the following:
useclause is allowed, but its scope should be restricted to the innermost declarative region where it is useful. Use a
useclause for ASIS units, and another one for other units. Sort units alphabetically in the clause.
Report. Especially, no rule should use
Framework.Reports.Uncheckableto warn the user.
Each time you want the name of something, remember that the name may
be given in selected notation. In most cases, you should call
Thick_Queries.Simple_Name on the result of any query that
returns a name to get rid of the possible selectors. Otherwise, you
should inspect the returned expression to see if its
A_Selected_Component, and take the
Selector if it is.
When designing a rule, consider the implications of renamings and generics.
If you want to output the Element_Image of some element, beware that
it will be preceded by spaces. Do not use
Ada.Strings.Wide_Fixed.Trim to eliminate them, since it
wont remove tab characters. Use
Utilities.trim_all, which will
do the right thing.
Remember that ASIS queries can be costly. Declare local variables (or constants) rather than evaluating several times the same query.
There are issues with some ASIS queries. The rule whose label is
verif.aru will remind you if you use one of
There might be confusion with
Asis.Subtype_Mark; moreover, you
normally want to get rid of selected components (see above). Use
This query return a
Nil_Element if any type in the derivation
chain is a
'Base attribute (to be honnest, versions of ASIS
before the latest 5.05 will loop indefinitely in this case). Use
Thick_Queries.Corresponding_Root_Type_Name instead, and consider what
you want to do if there is a
'Base in the derivation chain.
This query suffers from the same problem as
Corresponding_Root_Type. Don’t use it, rather take
Subtype_Simple_name of the
and do your own analysis, depending on whether the returned
An_Attribute_Reference or not.
A frequent cause of inefficiencies in ASIS for Gnat arises from tree
swapping. Read the section about tree swapping in the ASIS-for-GNAT
User Guide. Passing “
-iargs -do -dt” as an ASIS
option to AdaControl can be handy in evaluating the effect of tree
|• Normal case|
|• Specific rules|
|• User documentation|
Adding a new rule to the tool requires only simple modifications to
Framework.Plugs contains several procedures that
are called during the traversal of the code under the following
Enter_Unit: Called when entering a compilation unit, before any other processing.
Exit_Unit: Called when leaving a compilation unit, after any other processing.
Enter_Scope: Called when entering a new scope (i.e. a construct that can contain declarations).
Exit_Scope: Called when leaving a scope.
Pre_Procedure: Called when entering a syntax node (this is like the usual
Pre_Procedureused in the instantiation of
ASIS.Iterator.Traverse_Element, except that there is no
Post_Procedure: Called when leaving a syntax node.
True_Identifier: Called when entering an
An_Enumeration_Literalnode that corresponds to a real identifier, i.e. not to a pragma name or other forms of irrelevant names. This avoids special cases in rules dealing with identifiers.
Text_Analysis: Called on every source line of the code.
These procedures have the usual "big case" structure of an ASIS
application (i.e. a first level case statement on
with each case alternative containing other case statements to further
refine the kind of node that is being dealt with).
The following modifications must be done to the body of this package:
Processprocedure(s) at the appropriate place(s) in the body of the provided procedures. For textual rules,
Text_Analysisis the only appropriate place.
procedure Pre_Procedure (Element : in Asis.Element) is use Asis; use Asis.Elements; begin case Element_Kind (Element) is when A_Pragma => Rules.Pragmas.Process_Pragma (Element); ... end Pre_Procedure;
Many alternatives of the big case statement cover a number of
values. It may happen that a new rule requires calling its
Process procedure for some, but not all of these values. In
this case, the case alternative must be split. This is not a problem,
but do not forget to duplicate the statements from the original
alternative before adding the new calls, to make sure that the split
does not break existing rules.
It is always possible to plug a
Process procedure in
Pre_Procedure or in
Post_Procedure. However, some
“natural” places for plugging rules correspond to many branches of
the big case statement. For example, there are many places where you
enter a scope. That’s why the package
other procedures that are called in “interesting” contexts. If
appropriate, it is better practice to plug calls to
procedures here, rather than all over the place in various
alternatives of the big case statement.
In some cases, you may want to keep your rules separate from the general purpose ones. This may happen if you have developped some very specific rules that take the structure of your project into account, and hence would not be of interest to anybody else. Or it may be that your local lawyer does not allow you to publish your rules as free software.
This should not prevent you from using AdaControl. Just write the
rules as usual, but instead of plugging them in
Framework.Plugs, use the package
Framework.Specific_Plugs instead. This package has subprograms
identical to those described above for plugging-in rules, and they are
called in the same contexts. But it is guaranteed that no rule from
the public release of AdaControl will ever be plugged-in into this
package. This way, you can keep your rules separate from the public
ones, and you can upgrade to a new version of AdaControl without
needing to merge the modifications for your rules.
If you have specific rules plugged into
Framework.Specific_Plugs, change the constant
Specific_Version in the specification of the package to
something that identifies the specific version (like your company’s
name for example). This way, the version number of AdaControl will
show that it is a specific version.
Of course, you should update the user’s guide with the information about your rules. This guide is written in Texinfo, see http://www.gnu.org/software/texinfo/. Note however that you don’t need to understand all the possibilities of Texinfo to update the manual; look at the description of other rules, the few commands you need will be quite straightforward to understand.
|• Debugging aids|
|• Integrating the test in the test suite|
Once the rule is written, you will test it. Of course, you’ll first write a small test case to make sure that it works as expected. But that’s not enough.
Our experience with existing rules has shown that getting the rule 90% right is quite easy, but the last 10% can be tricky. Ada offers constructs that you often didn’t think about when writing the rule; for example, if you are expecting a name at some place, did you take care of selected names (we got trapped by this one several times)? Therefore, it is extremely important that you check your rule against as much code as you can, the minimum being the code of AdaControl itself.
Note that if your rule encountered some uncheckable cases, you should
add a child for your rule to the test
t_uncheckable, and also
t_uncheckable.aru file accordingly. Look at how it
is done currently, and do the same.
As mentionned above, it is often the case when writing a new rule, as well as with any kind of ASIS programming, that one comes across unexpected contexts. This is due to the rich features of Ada, but it is sometimes difficult to understand what is happenning.
The framework provides some facilities that help in debugging. Don’t
hesitate to use the
utilities. See The package Utilities. Note that the
procedures may be given an element (or an element list) whose basic
characteritics are printed. If the
With_Source parameter is
True, the source correponding to the element is also printed.
In the case where AdaControls enters an endless loop, the first thing
to do is to determine the place where the loop is happening. To ease
this, AdaControl may be compiled in “interruptible” mode. In normal
mode, the package
Framework.Interrupt is a renaming of
Framework.Interrupt_Std, a dummy package that does
Framework.Interrupt to make it a renaming of
Framework.Interrupt_Dbg (instructions provided in the package)
Now, when you hit Ctrl-C while AdaControl is running with the “-d” option, execution of the current “go” command is interrupted with a message telling which rule is active, and on which compilation unit. If the “-x” option is also given, the whole execution is stopped.
Of course, when you are done, reestablish the normal package by doing the inverse manipulation. The reason we didn’t put the debug version in the regular version is that it drags in the whole tasking run-time, with a measurable impact on efficiency (we measured 18% extra time for running AdaControl on the ACATS).
In addition, a small stand-alone utility called
provided. It prints the logical nesting of ASIS elements for a
unit. The syntax of Ptree is:
ptree [-sS] [-p <project_file>] <unit>[:<span>] -- <ASIS_Options> <span> ::= <line_number> | [<first_line>]-[<last_line>] | <line_number>:<column_number>
If the “-s” option is given,
ptree processes the
specification of the unit, otherwise it processes the body. If the
“-S” option is given, the span of each element is also printed. The
“-p” option has the same meaning as in AdaControl itself. ASIS
options can be passed, like for AdaControl, after a “--” (but
-FS is the default).
The <unit> is given either as an Ada unit, or as a file name, provided the extension is “.ads” or “.adb” (as in AdaControl). If a span is mentionned behind the unit name, only the constructs that cover the indicated span are output. The syntax of the span is the same used by pfni. This is useful if you are interested in just one particular structure in a big unit.
If you come across a situation where you don’t understand the logical
nesting of elements, try to reduce it to a very simple example, then
ptree on it. It can be quite instructive!
Of course, a more elaborated, but less convenient solution is to use Asistant. Please refer to your ASIS documentation to learn how to use Asistant.
Finally, if you come to suspect that you get a strange result from an
ASIS provided operation, check whether there is an equivalent
operation in the package
A4G_Bugs, and if yes, use it
instead. See The package A4G_Bugs.
When your rule has been carefully tested and is ready for integration,
run the rule file
src/verif.aru on every unit that you have
written or changed. This will control that you match the programming
rules for AdaControl. There can be some “found” messages (try to
minimize them if possible), but there should be no “Error”
message. Then, the last thing you have to do is to write a test for
non-regression verification purpose. Don’t forget to include examples
of the tricky cases in the test.
Go to the
test directory. You’ll notice that all test programs
have a name of the form
t_name.adb (or in some rare cases,
name is the rule name. You’ll notice
also that some units have a name like
tfw_name.adb; these are
tests for the framework, you should normally ignore them. Name your
test file according to this convention, normally using
unless the test requires some weird parameters that prevent it from
being run normally, in which case it should use
stands for special). It is OK for your test to have child units (whose
names will be dictated by the Gnat naming convention). If your test
requires other units, name them like
x_name_complement. Then, go to the
and put your rule file under the name
t_name.aru (with the same
name of course).
Go back to the
test directory, and run
tests should report PASSED, except the
tfw_check tests. Your test will not be reported, because its
expected output is not yet in the directory
tfw_help will report FAILED because this test prints all help
messages, and that the help message for your rule has been added; test
tfw_check will report FAILED because there is now one extra
message (from the extra rule file) saying “No error found”.
Check that the result of your test is OK (in the file
test/res/t_name.txt), and copy this file to the directory
test/ref/. Do the following command:
diff test/ref/tfw_help.txt test/res/tfw_help.txt
and check that the only difference is the addition of the help message from your rule.
Do the following command:
diff test/ref/tfw_check.txt test/res/tfw_check.txt
and check that the only difference is the addition of one “No error found” message.
test/res/tfw_check.txt to the directory
test.sh again: it should print PASSED for all tests, including
yours. Pay special attention to the last test, called
tfw_stress. This test runs all rules against all test units. If
it fails, the file
res/tfw_stress.txt contains the whole
listing of the run (with
-dv options), so you’ll find all the
context of the problem.
In case of problems, note that options can be passed to
test.sh; check the comments at the top of the file for details.
When everything is OK, all you have to do is send your modifications (including the tests) to email@example.com, for inclusion in the next release of AdaControl!