15 – Using SCAN
This section contains some basic examples that illustrate what
SCA can do to help you with your programs. The examples have very
little explanation. If you want a more detailed explanation of the
underlying concepts, see the Basic_Query_Concepts help topic. The
remainder of this section is written in terms that are specific to
SCAN programs.
If you want to follow along and try the examples, you will need to
have an SCA library available. If you do not know how to create
an SCA library, read the Building_An_SCA_Library help topic. The
examples use generic variable names (such as i). You will have to
substitute variable names that actually exist in your code when
trying the examples.
The first example is the easiest query: It lets you find all the
items in your SCA library named i, and shows you all the places
where they appear (all occurrences of i).
FIND i
You can search for any name in this manner, including using
wildcard characters (for example, FIND i*).
Now let's say you are looking for an occurrence, and you know
that it occurs in a particular file. The following query finds all
occurrences of items that are named i but will then limit them to
those which happen to occur in the file named 'PROG.SCN'.
FIND i AND FILE_SPEC="PROG.SCN"
Another typical question one might ask is "Find all the places
where this item is assigned to (or read from, called, declared,
and so forth)." The next example finds all occurrences of items
that are named i, but then limits them to only those occurrences
where i is assigned a value.
FIND i AND OCCURRENCE=WRITE
(SCA understands many occurrence classes other then WRITE. See the
help subtopics under Getting_Started for tables containing all the
SCA attributes and their corresponding meanings in SCAN.)
Often, you only want to know where (in what file or module) a
particular procedure is, so that you can go to it and edit it.
You could use the first query (where i would be the name of the
procedure) and then look through the output. The output would
include all occurrences of the procedure, one of which would be
its declaration, which you could then select. Or, you could ask
SCA to limit the search for you by typing the following query:
FIND i AND OCCURRENCE=PRIMARY
In SCA terms, a primary declaration is the most significant
declaration of an item. For a SCAN procedure, this means the
place where the procedure is actually implemented, that is, the
PROCEDURE declaration. This is in contrast to FORWARD or EXTERNAL
declarations, which are associated declarations
Another problem you might have is that there are many different
items in your system having a given name. Some may be variables;
others may be procedures, constants, labels, and so forth. Suppose
you want to find only the procedures named i. Again, the query
FIND i would give you what you wanted, but it would also give you
much more. It is preferable to issue the following query:
FIND i AND SYMBOL_CLASS=PROCEDURE
The last four examples have all selected information based on two
attributes. The last example selected information based on a name
attribute (in this case, i) and a symbol class attribute (in this
case, PROCEDURE). Note how the attributes are combined using the
boolean operator AND. In general, you can select items out of your
library based on any combination of attributes, using AND as well
as the other logical operators OR, XOR and NOT.
The next example shows another primary feature of SCA - the
ability to display relationships between items. The example
given here shows the most common use of this feature. It finds
the complete call tree (that is, all procedures called directly
and indirectly), of the procedure named i.
FIND CALLED_BY (i, DEPTH=ALL)
If you want to limit the depth of the call tree, you can replace
the keyword ALL by any positive integer.
The final part of this section describes how to go directly to the
source code once you have issued a query. After issuing the query
FIND i, for example, you can have an LSE query buffer containing
something that looks like the following:
I variable
SCAN_MODULE\60 variable declaration
SCAN_MODULE\75 write reference
SCAN_MODULE\79 read reference
SCAN_MODULE\122 read reference
SCAN_MODULE\144 write reference
SCAN_MODULE\146 read reference
SCAN_MODULE\149 write reference
SCAN_MODULE\149 read reference
SCAN_MODULE\150 read reference
SCAN_MODULE\166 read reference
The first two lines of this display will be highlighted. The first
line represents the item you looked for (i), and the rest of the
lines represent the different places in the code where this item
occurred (that is, the occurrences of i). By using the up and down
arrows on your keyboard, or by clicking on an occurrence with your
mouse, you can choose the occurrence you want to see. Then all
you have to do is type CTRL/G (the keyboard equivalent of the GOTO
SOURCE command), and LSE will bring the source file into a buffer
and position you at the occurrence you chose.
To obtain help on the following topics, request help as indicated.
o For help on query language, see the Basic_Query_Concepts help
topic.
o For help on libraries, see the Building_An_SCA_Library help
topic.
16 – SCAN Attributes Table
The following table lists the SCA symbol classes and their
corresponding meanings in SCAN.
SCA Symbol Classes and Equivalent SCAN Language Terminology
SCA Term SCAN Term Explanation
Argument Formal A routine or function formal
parameter parameter
Component, Leaf node A leaf node of a TREE variable
Field
Constant, Constant A CONSTANT definition
Literal
Exception N/A
File File A file used during compilation
Function, Procedure A Procedure
Procedure,
Program,
Routine,
Subroutine
Generic N/A
Keyword N/A
Label Label A statement label
Macro N/A
Module, Module A module
Package
Placeholder N/A
Psect Psect A psect name
Tag N/A
Task N/A
Type Type
Unbound N/A
Variable Variable
The following table lists the SCA occurrence classes and their
corresponding meanings in SCAN.
SCA Occurrence Classes and Equivalent SCAN Language Terminology
SCA Term SCAN Term Explanation
Primary Declaration Either a DECLARE or PROCEDURE
declaration
Associated Declaration Either a FORWARD or EXTERNAL
declaration
Declaration Declaration Either primary or associated
Read, Fetch Reference The value of a variable is
retrieved.
Write, Store Assignment A variable is assigned a value.
Address, Indirect
Pointer reference
Call Call
Command_line Command line A file specified on the command
line; for example, SCAN foo.scn.
Include Include A file included with the INCLUDE
statement
Precompiled N/A
Reference Reference Any nondeclaration
Explicit Explicit A variable or procedure explicitly
declared with DECLARE or PROCEDURE
statement
Implicit Implicit A variable declared by the compiler
on first reference, for example, a
picture variable
Visible N/A
Hidden N/A
Compilation_ Module
unit
The following table lists the SCA domain classes and their
corresponding meanings in SCAN.
SCA Domain Classes and Equivalent SCAN Language Terminology
SCA Term SCAN Term Explanation
Inheritable N/A
Global Global Declaration has GLOBAL attribute
Predefined Predefined
Multi_module Global or
predefined
Module_ Local to one module
specific