9.2 – Placeholders
Placeholders are syntactic character strings that hold the place of
program language constructs. When a placeholder name is expanded, it
expands to either an actual value (terminal node) or another
construct (nonterminal node) requiring further expansion (see also
Topics "Tokens_and_Placeholders").
The LSE commands used for the manipulation of placeholders are:
DEFINE PLACEHOLDER name
specifies placeholder characteristics for the current
language.
DELETE PLACEHOLDER name
cancels the effect of a DEFINE PLACEHOLDER command.
END DEFINE
terminates a DEFINE command.
ERASE PLACEHOLDER
deletes the text of a selected placeholder.
EXPAND
expands the placeholder-name at the current cursor postion.
EXTRACT PLACEHOLDER placeholder-name
selects the definition of the named placeholder and formats
it as a command.
GOTO PLACEHOLDER
moves the cursor to the next placeholder.
SAVE ENVIRONMENT [file-spec]
writes all user-defined placeholders to the specified file.
SHOW PLACEHOLDER [name | * ]
displays the characteristics of the specified placeholder.
UNEXPAND
reverses the effect of the last EXPAND command.
9.3 – Aliases
Aliases are abbreviated reference names for long identifiers that
have been entered in the source code. To define an alias for an
identifier on which the cursor is currently located, press the
GOLD-CTRL/A key sequence and type the abbreviation at the prompt:
_Alias name: name
Whenever the abbreviated reference name is typed and expanded
(CTRL/E), the original identifier string will appear in the buffer.
The LSE commands used for the manipulation of aliases are:
EXTRACT ALIAS alias-name
selects the definition of the alias name and formats
it as a command.
DEFINE ALIAS name [value]
specifies the alias name to be assigned and the value
of the string to be referenced.
DELETE ALIAS name
specifies the alias name to be deleted.
9.4 – New Files
To edit a new file in one of the supported languages, the following
commands are required for the manipulation of tokens and
placeholders:
o ERASE PLACEHOLDER/FORWARD (CTRL/K)
o EXPAND (CTRL/E)
o GOTO PLACEHOLDER/FORWARD (CTRL/N)
o GOTO PLACEHOLDER/REVERSE (CTRL/P)
o UNERASE PLACEHOLDER (PF1-CTRL/K)
o UNEXPAND (PF1-CTRL/E)
When you press the EXPAND key (CTRL/E), while the cursor is on a
placeholder name, one of the following will occur:
o The placeholder will be replaced automatically with a template
consisting of language constructs. This type of placeholder is
called a "nonterminal placeholder" because it will insert a
template into the buffer when expanded.
o Text will appear in a separate window to aid you in supplying a
value. This type of placeholder is called a "terminal
placeholder" because it does not insert a template into the
buffer when expanded. Instead, you must supply the necessary
text. You can press the spacebar to remove the window.
o A menu will appear that provides you with options that can be
selected and expanded into templates. This type of placeholder
is called a "menu placeholder".
In any of these three cases, you may type in the desired text over
the placeholder, and the placeholder will be erased automatically.
When expanding a menu placeholder, you can move through the options
by using the up and down arrow keys. To select an option, you press
the EXPAND key, the RETURN key, or the ENTER key. To exit the menu
without selecting an option, you press the spacebar.
You can construct a complete program by repeatedly expanding
templates. You do not have to continuously expand templates until
you reach a terminal placeholder. Rather, you may find it more
appropriate to type in the desired value yourself at a higher level
(see also topics "Tokens_and_Placeholders" and "Getting_Started").
9.5 – Old Files
To edit an existing file, in one of the supported languages, you use tokens. Since tokens exist for many reserved words, simply type the token name and press the EXPAND key (CTRL/E). For example, typing IF followed by a CTRL/E causes a template for an IF construct to appear on your screen. (Use the SHOW TOKEN command to acquire a listing of all the predefined tokens.)
10 – Compiling
While writing your program, you can use the COMPILE and REVIEW
commands to compile your code and review compilation errors without
leaving the editing session.
Supported VMS language compilers generate a file of compile-time
diagnostic information that LSE can use to review compilation errors.
The diagnostic information is generated with the /DIAGNOSTICS
qualifier.
The COMPILE command issues a DCL command in a subprocess to invoke
the appropriate compiler. LSE checks to see if the language provides
/DIAGNOSTICS capabilities. If so, LSE appends the /DIAGNOSTICS
qualifier onto the compilation command.
For example, if you issue the COMPILE command while in the buffer
TEST.ADA, the resulting DCL command is as follows:
$ ADA DEV:[DIRECTORY]TEST.ADA/DIAGNOSTICS=DEV:[DIRECTORY]TEST.DIA
LSE supports all of the compiler's command qualifiers as well as
user-supplied command procedures. You can specify DCL qualifiers,
such as /LIBRARY, when invoking the compiler from LSE. (See the
Command Dictionary for details on the COMPILE command.)
The REVIEW command displays any diagnostic messages that resulted
from a compilation. LSE displays the compilation errors in one
window, with the corresponding source code displayed in a second
window.
This multiwindow capability allows you to review your errors while
examining the associated source code. This eliminates tedious steps
in the error correction process and helps ensure that all the errors
are fixed before looping back through the compilation process.
LSE provides several commands to help you review errors and exam your
source code. The following lists these commands and their default
key bindings.
COMPILE/REVIEW
compiles and reviews the content of the current buffer.
END REVIEW
terminates the current review session.
GOTO SOURCE
uses the current cursor position in $REVIEW to select
the diagnostic in the source buffer. This command is
bound to CTRL/G.
NEXT ERROR
selects the next diagnostic message from $REVIEW.
NEXT STEP
selects the next diagnostic message from $REVIEW.
This command is bound to CTRL/F.
PREVIOUS ERROR
selects the previous diagnostic message from $REVIEW.
PREVIOUS STEP
selects the previous diagnostic message from $REVIEW.
This command is bound to CTRL/B.
REVIEW
displays the diagnostic messages resulting from a
compilation.
11 – CMS Interface
LSE V3.0 provides for invoking CMS from the LSE command line using
the CMS command. Also, when LSE must access a file from the
directory that is the user's CMS library, LSE will automatically use
CMS to FETCH the file. LSE also has a RESERVE command to reserve the
element in your current CMS library that has the same name and type
as the file associated with your current buffer. The UNRESERVE and
REPLACE commands also provide the corresonding CMS operation for the
file in your current buffer.
See the manual for information "File Manipulation" and for
descriptions of the following new or enhanced commands related to
source code management and CMS:
CMS
GOTO FILE
GOTO SOURCE
READ
REPLACE
RESERVE
SET CMS
UNRESERVE
12 – Patterns
The three pattern styles VMS, ULTRIX and TPU can be used in search and substitute commands. The pattern style is set by the SET SEARCH command.
12.1 – VMS
The VMS pattern style enables the special interpretation of wildcard
characters and a quote character in the search-string parameter as
shown below:
VMS-Style Wildcards
Wildcard Matches
* One or more characters of any kind on a line.
** One or more characters of any kind crossing lines.
% A single character.
\< Beginning of a line.
\> End of a line.
\[set-of- Any character in the specified set. For example,
characters] \[abc] matches any letter in the set "abc" and
\[c-t] matches any letter in the set "c" through
"t."
\[~set-of- Anything not in the specified set of characters.
characters]
\ Lets you specify the characters \,*,% or ] within
wildcard expressions. For example, \\ matches the
backslash character (\).
\. Repeats the previous pattern zero or more times,
including the original.
\: Repeats the previous pattern at least once,
including the original; that is, a null occurrence
does not match.
\w Any empty space created by the space bar or tab
stops, including no more than one line break.
\d Any decimal digit.
\o Any octal digit.
\x Any hexadecimal digit.
\a Any alphabetic character, including accented
letters, other marked letters, and non-English
letters.
\n Any alphanumeric character.
\s Any character that can be used in a symbol:
alphanumeric, dollar sign, and underscore.
\l Any lowercase letter.
\u Any uppercase letter.
\p Any punctuation character.
\f Any formatting characters: backspace, tab, line
feed, vertical tab, form feed, and carriage return.
\^ Any control character.
\+ Any character with bit 7 set; that is, ASCII decimal
values from 128 through 255.
For example the following command will find a line starting with an
uppercase letter:
SEARCH/PATTERN "\<\u"
12.2 – ULTRIX
The ULTRIX pattern style enables the special interpretation of
wildcard characters and a quote character in the search-string
parameter as shown below:
ULTRIX-Style Wildcards
Wildcard Matches
. A single character.
^ Beginning of a line.
$ End of a line.
[set-of- Any character in the specified set. For example,
characters] [abc] matches any letter in the set "abc" and [c-t]
matches any letter in the set "c" through "t."
[^set-of- Anything not in the specified set of characters.
characters]
\ Lets you specify the characters \,.,^,$,[,],or * in
wildcard expressions. For example, \\ matches the
backslash character (\).
* Repeats the previous pattern zero or more times,
including the original.
+ Repeats the previous pattern at least once,
including the original; that is, a null occurrence
does not match.
For example the following command will find a line starting with
a, b or c:
SEARCH/PATTERN "^[abc]"
12.3 – TPU
The TPU pattern style enables the use of TPU patterns. For full
details of TPU patterns see the DEC Text Processing Utility Manual.
1. Simple examples
The first example searches for abc or def and the second example
substitutes all occurrences of abc or def by ghi:
SEARCH/PATTERN "'abc' | 'def'"
SUBSTITUTE/PATTERN/ALL "'abc' | 'def'" "'ghi'"
In the examples 'abc', 'def' and 'ghi' are TPU
strings and | is the TPU pattern alternation operator.
The outermost quotes in the examples must be omitted
if the parameters are prompted for or if a dialog box is
used.
2. Search string
The search string is a TPU expression that must evaluate to a
TPU pattern.
3. Replace string
The replace string is a TPU expression that must evaluate to a
TPU string.
4. Partial pattern assignment variables
Partial pattern assignment variables allow a substitution
to be a function of the found pattern.
For example, the following command replaces a date of the
form yyyy/mm/dd with one of the form dd/mm/yyyy:
SUBSTITUTE/PATTERN -
"(_year@_v1)+'/'+(_month@_v2)+'/'+(_day@_v3)" -
"str(_v3)+'/'+str(_v2)+'/'+ str(_v1)"
when applied to: 1998/04/21 generates: 21/04/1998
In the above example _year, _month and _day are TPU
variables holding patterns that match the year, month
and day parts of a date, for details of how to set up
these variables see Section 8.
@ is the TPU partial pattern assignment operator and _v1,
_v2 and _v3 are partial pattern assignment variables that
are set to the found year, date and day.
A partial pattern assignment variable holds a TPU range
and when used in the replacement string must be converted
to a string using the TPU procedure STR.
For example, the following command will prefix any lines
that start with any three characters from ABCDEFGHI with
XYZ_ :
SUBSTITUTE/PATTERN/ALL -
"LINE_BEGIN + (ANY('ABCDEFGHI',3)@_v1)" -
"'XYZ_'+ str(_v1)"
when applied to: abc generates: XYZ_abc
012 012
defghi XYZ_defghi
In the above example LINE_BEGIN is a TPU keyword that
matches the beginning of a line and ANY is a TPU pattern
procedure that matches a specified number of characters
from a specified set of characters.
5. New line
A new line will be generated for each line feed character
in the replacement string, a line feed character can be
introduced by means of the TPU procedure ASCII with the
value 10 as a parameter.
For example, to replace any numbers at the end of lines
with the string 'xxx' (a line feed is necessary because
the search pattern includes the end of the line):
SUBSTITUTE/PATTERN/ALL -
"_n + LINE_END" -
"'xxx' + ASCII(10)"
when applied to: 123 456 generates: 123 xxx
789 xxx
In the above example LINE_END is a TPU keyword that
matches the end of a line and _n is TPU variable holding a
pattern that matches a number.
When a partial pattern assignment variable is converted
to a string by the TPU procedure STR an optional second
parameter can be set to ASCII(10) to cause any end
of lines in the range described by the variable to be
converted to line feed characters (without the parameter
they are represented by the null string). For example:
SUBSTITUTE/PATTERN/ALL -
"(LINE_BEGIN + _n + LINE_END + _n + LINE_END)@_v1" -
"STR(_v1, ASCII(10)) + STR(_v1, ASCII(10))"
when applied to: 123 generates: 123
456 456
123
456
Carriage return characters adjacent to line feed characters
in the replacement string are ignored.
6. Errors
The search and replace strings are TPU expressions
which have to be evaluated and may generate various TPU
compilation / evaluation error messages.
The following error messages are generated for invalid
search or replace strings:
Error in search pattern
Error in replacement string
These messages will normally be preceded by various TPU
error messages. For example, the search string "'aaa' +
bbb" would result in the following error messages:
Undefined procedure call BBB
Operand combination STRING + INTEGER unsupported
Error in search pattern
7. Global variables
Partial pattern assignment variables and pattern variables
(such as _year in an earlier example) need to be global
and must not clash with any TPU global variables used by
LSE. This can be achieved by starting any such variable
names with an underscore character.
8. Pattern variables
Any complicated search or substitution is likely to need
various pattern variables to have already been set up.
This can be achieved in various ways.
The definitions can be setup by issuing DO/TPU commands,
for example:
DO/TPU "_digits:='0123456789'"
DO/TPU "_digit:=any(_digits)"
DO/TPU "_year:=any(_digits,4)"
DO/TPU "_month:=any('01',1)+_digit"
DO/TPU "_day:=any('0123',1)+_digit"
DO/TPU "_n:=span(_digits)"
The file LSE$PATTERNS.TPU in the LSE$EXAMPLE directory
contains some examples of patterns which can be added to
LSE by means of the following commands:
GOTO FILE LSE$EXAMPLE:LSE$PATTERNS.TPU
EXTEND *
DO/TPU "LSE$PATTERNS_MODULE_INIT"
9. Use for developing DTM user filters
The user defined filters global replace feature introduced
in Digital Test Manager for OpenVMS Version V4.0 can
be simulated using the SUBSTITUTE/PATTERN/ALL command.
This allows DTM user defined filters to be developed
interactively using LSE.
For example, to replace any numbers at the end of lines
with the string 'xxx':
global_replace(
_n + LINE_END,
'xxx' + ASCII(10),
NO_EXACT,
OFF,
ON);
The LSE equivalent (assuming that the current search
attributes are equivalent to NO_EXACT) is:
SUBSTITUTE/PATTERN/ALL -
"_n + LINE_END" -
"'xxx' + ASCII(1O)"
The LSE equivalent of the pattern to replace parameter
(first parameter of the global_replace routine) is the
same except that the parameter has to be in quotes.
The LSE equivalent of the replacement string parameter
(second parameter) is the same if the evaluate replacement
parameter (fourth parameter) is set to ON and is the
same except that the parameter has to be in quotes if
the evaluate replacement parameter is set to OFF.
The LSE equivalent of the search mode parameter (third
parameter) is the setting of the search options (set by
the SET SEARCH command).
LSE does not have equivalents of the evaluate replacement
parameter (fourth parameter) or the convert linefeeds
parameter (fifth parameter). It always evaluates the
replacement string parameter and it always converts
linefeed characters (and ignores adjacent carriage return
characters).