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Text File | 1986-04-13 | 24.2 KB | 567 lines

DOCUMENTATION for BLED version 1.3 by Ken Goosens, 5020 Portsmouth Road, Fairfax, VA 22032 13 April 1986 CONTENTS What is BLED What Use is BLED What are the Advantages of BLED New Features of BLED How Does BLED Work How do you Identify Lines Line Number Merging How to Invoke BLED How BLED Runs The Major BLED Functions CONFIGURE FILE COMPARE LINE MERGE MERGE Stylistic Considerations What is BLED BLED is a Batch Line EDitor. Editor - because it changes text files. Line - because it operates on entire lines of text rather than individual characters or phrases. And batch - because the changes to be made are not specified interactively, but are pre-specified in a file describing the changes, which is created outside of BLED. What Use is BLED? BLED is most useful when different people have to communicate changes to a text file that they jointly maintain. The typical use of BLED is for producing modifications to source code for programs. Interactive Microsoft BASIC has long had a MERGE command which functions like BLED. It inserts, deletes, and replaces lines based on line numbers. Other public domain programs would compare two BASIC programs and produce a merge file to convert one to the other using the merge command. BLED is a generalized program that combines these two functions. What are the Advantages of BLED? o Lines of text do not have to be numbered. This means that BLED will work with source code that allows lines of code to have no numbers, including Mircosoft QuickBASIC, as well as Pascal and other languages. o Comment lines are supported. BLED comment lines are completely ignored when merging. This means that documentation can be included right inside a BLED merge file. One of the disadvantages of the BASIC merge command was that the only type of line possible was BASIC code, so that documentation for a merge always had to be included in a separate file. o Logical lines can span multiple physical lines. One of the more disagreeable features of old BASIC was that a single line of code (i.e. a line beginning with a number) had to be on one physical line. Newer languages like QuickBASIC support a line-continuation character (e.g the underscore) that allows the same logical line to span multiple physical lines. This greatly improves the readability of source code by allowing grouping by indentation. BLED recognizes and supports logical lines. o Can be run batch from DOS, or interactively. Commands telling BLED what to do can be specified as DOS arguments, and BLED has a batch mode in which it will run without further prompts and return automatically to DOS. BLED will prompt for any arguments it needs which are not specified. o Configurable. BLED comes pre-set to work with Microsoft QuickBASIC, but can be configured to work with different languages. New Features of BLED BLED 1.3 fixes a bug. If a line begins with a comment other than in column 1 and ends with a line continuation character (e.g. source code commented out), BLED would get not correctly identify the line as a comment and would get an illegal function call. BLED 1.2 has two two features: (1) autodocumenting merge, and (2) test run mode. AUTODOCUMENTING. When you do a file compare to produce a merge, BLED produces a header on what files were used to make the merge and date and time stamps the merge. Also, BLED produces a header comment for each change indicating whether the line is being INSERTED, DELETED, or REPLACED (changed). Also, for replacement lines longer than one line, BLED will insert a comment marking the first different line. TEST MODE. There is a new "T" (for Test) parameter. This limits the run to a specificed number of logical lines in the master file. You will not normally use this parameter. How Does BLED Work? Like a block editor. Think of how you would work with a full screen text editor, if you had to work from the top to the bottom of the file. You basically do two things: o Mark a block of lines. o Say what to do with the block - either keep, delete, or replace by another block of code; or insert a block of code. BLED has a BLOCK command to identify the block of text, followed by a disposition command of KEEP, DELETE, REPLACE, or INSERT. This is BLED's general MERGE. How do You Identify Lines? You have to specify what blocks of lines you want to work with. There are three ways. o By physical line number. The absolute physical line numbers are 1,2,3,etc. for each line of text. Relative lines can also be specified, e.g. from the current position in the file forward three lines. o By line labels. Line labels are identifiers or names for lines. BLED supports both numeric line labels (it calls them label numbers) and alphanumeric labels (simply labels). BLED ASSUMES THAT A LINE LABEL OCCURS ONLY AS THE FIRST WORD ON A LINE. Some languages allow labels to be put in the middle of a physical line, but this is bad practice because interior labels are hard to find. o By strings. Strings are just sequences of characters that can occur inside lines. So, in BLED, a block can be identified as beginning or ending with an absolute or relative line number, a line label, or a string. And so a block can be defined as the first five lines everything between label-1 and label-2 from line 50 to label-1 from label-1 to the line with "HELP" in it Line Number Merging BLED also supports a more specialized merge much like the BASIC merge. Details are given below. This line merge mode is just like the BASIC merge command except that logical blocks of physical lines replace the single physical line, and comment lines are supported. BLED supports the specialized line number merge because the assumptions greatly simplify the merge files. No special BLED commands are required: no blocks, no block dispositions. To insert a line, just give it a line number between the original line numbers. To delete, put only the line number in the merge file. To replace, use the same line number. The BLED line number merge treats all lines between line numbers as a single block, i.e. as if they are one single logical line, even if they are multiple physical and logical lines. For example, in the BASIC code 200 X = X+1 IF X>5 THEN_ Y=0 210 Y = Y+1 you might think that you could delete the first line 200 by having "200" alone in the merge. In fact, the first three lines would be deleted rather than the first only. How to Invoke BLED BLED is invoked at DOS by typing BLED[/options] [spec-1] [spec-2] [spec-3] [spec-4] [spec-5] where a spec has the format [drive:][\path\][filename] Everything in brackets is optional and may be omitted. The options after BLED are /B - run batch. Means to ask no questions and automatically return to DOS when done. Must be used with one of following options and requires first three specs. /F - file compare. Means to produce a merge file which will transform spec-1 (old version) into spec-2. Output is spec-3. /L - line number merge. Do a merge of spec-2 into spec-1, based on line number identifiers in both files, outputting to spec-3. /M - general merge based on BLED commands. Into spec-1 merge spec-2, producing spec-3. /T=XXX - test mode. Do not process all line from master (first) file. Instead, end the run after processing XXX (a number) of logical lines in the master file. Used mainly for testing BLED. So you can run against large real files without having to create smaller samples. Note: /F,/L,/M options are incompatible and at most one can be specified. BLED checks for consistency and required parameters and will abort with an error message and help. Optional parameters not specified at DOS are supplied using full screen prompts. Spec-4 is used when you want to override the default warning file name (WARNING is the default configuration value). BLED keeps appending to the warning file as long as you continue to run within it. Each time you reenter BLED from DOS, however, BLED will begin overwriting the warning file. The override is useful if you want to preserve previous warning files. Spec-5 is for overriding the default configuration file name of BLED.CFG. Note: the meaning of the first three file specs is different for the /F option. Merges mean [source file] [merges] [source+merge] But for the /F option the specs mean [old version] [new version] [merges] How BLED Runs BLED makes a single pass through the original file, doing comparisons to the second file. Therefor all references to line labels should be in the same order they occur in the original file. BLED gives an on- screen status report of what it is doing, the files it is using, as well as counts of the number of records it reads and writes at the bottom of the screen. The Major BLED Functions The four major BLED functions are o CONFIGURE. General configuration parameters. o FILE COMPARE. Create a merge file. o LINE MERGE. Merge based on line number labels. o MERGE. Merge using explicit BLED block and block disposition commands. The main menu in BLED uses the first letter of each choice. CONFIGURE BLED has 10 configuration parameters, which are stored in the configuration file BLED.CFG. If no configuration file exists, BLED uses as a default parameters suitable for QuickBASIC. (1) Default extension for source files. If no extension is given for source files, BLED will add this. Default for this option is BAS. Source files include spec-1, and also spec-3 for merges and spec-2 for file compares. (2) Default extension for changes to source. If no extension is given for this file, BLED will add this. Default for this option is MRG. In merges, this applies to spec-2. In file compares, this applies to spec-3. (3) Character using to begin remarks in source. Default character is the single quote ('). When looking for a line continuation character at the end of a line, BLED will ignore all text after the remark character. (4) BLED phrase indicating end of block. Used with INSERT BLOCK command. What follows is a block of code to be inserted. Tells BLED where the code ends. (5) Character beginning a line of BLED documentation. BLED will completely ignore a line beginning with this character when merging. Allows comments or documentation to be included right in a merge file to explain changes. The character need not be in column 1 - only the first non-blank character. Default is "*". The documentation character should never occur as the first character in your source text. (6) Character at end of every alphanumeric label. Default is ":". BLED assumes that line labels occur only as the first word in a line. Leading spaces are ignored, so that labels can begin in any column. This label character is used by BLED to help locate labels. When specifying blocks in a BLED command, you need not include the end-character. BLED knows, for example, what when you say "LABEL LOOPER" that "LOOPER:" is what actually occurs in the source code. (7) Character beginning BLED commands. Default is none. BLED can distinguish its commands from source code lines by when a command is needed and by key phrase. If confusion might result, however, you can specify that BLED commands begin with a character that will never occur at the beginning of a line of text, such as possibly "$" or "-". (8) Whether case is ignored in alphanumeric labels. Default is yes, so that "looper" and "LOOPER" are treated as the same. (9) Line continuation character. One way for a logical line to span multiple physical lines is to insert a special line continuation character at the end of a line that logically continues on the following line. Default is "_" (underscore). May differ in languages other than QuickBASIC. Many other freeform languages use a statement terminator character. Fortran puts a continuation character in column 6, which is not supported by BLED. (BLED can still work on FORTRAN files though.) (10) File that warning messages are written to. From the time you enter BLED until you exit DOS, BLED may issue warning messages based on its file comparison or merge. These messages are written to this file for perusal later. This way BLED can run completely batch with no loss of information. You can nullify these messages by making the file "NUL:" or send them to the screen using "SCRN:". BLED will report the number of warning messages during its operation. Sending messages to the screen will interfere with BLED's normal report of its progress on the screen. The default name for this warning is "WARNING". FILE COMPARE The function of this module is to produce a BLED merge file that will convert an old version of a file to a new, modified version. All that is in the merge are the necessary changes. This is a very complex and difficult programming task which is only partially implemented in the current version. The file comparison will only work for source with line number labels. Essentially, the assumption is that the line number labels are ordered from low to high in both versions of the file. A comparison utility must have some way to identify lines. Ideally, this constraint should be relaxed to apply to alphanumeric labels with no assumptions about order. Please send me your ideas or code changes if you think you can solve this problem. So, the ONLY TYPE OF MERGE FILE THAT FILE COMPARISON WILL PRODUCE IS ONE FOR LINE MERGING, and not for general merging. Operationally, this means that if you are not using line numbers in your source code, you should make your code changes directly in a merge file, and apply the merge file to produce the modified code. If you directly change the old version, there will be no way to isolate just the changes later. NOTE: the BLED file compare is NOT A GENERAL FILE COMPARE. General file compares, like the DOS utility, compare two files by relative byte position with a file. BLED does a logical line by logical line compare. Apply the BLED file compare ONLY TO COMPILEABLE SOURCE CODE, otherwise the result will be unpredictable. LINE MERGE This option is a generalization of the BASIC merge command. The assumptions are that o the lines of code are numbered at the beginning of a line. o Physical lines of text are to be blocked from a line number up to the next line number. The merge operates only on such blocks as a unit. o The line numbers are ordered from low to high in both the source and merge file. o Lines in the source not in the merge file are to be kept, lines in the merge not in the source are to be inserted, and lines in both are to be replaced by the line (i.e. block) in the merge file. o Lines in the merge file with only a line number are to be deleted from the source file. o The merge maintains the low to high line number order. MERGE The general merge in BLED allows merges even when there are no line numbers. The BLED commands are BLOCK, INSERT, DELETE, REPLACE, and KEEP. Each of these commands can be abbreviated by their first letter (e.g "B FROM LINE 1 TO LINE 5" means "BLOCK FROM LINE 1 TO LINE 5"). The syntax is BLOCK [FROM] [linetype] lineid [TO/UPTO/THRU] [linetype] lineid [block disposition] [lineid] where [linetype] is LINE/LABEL/LABEL#/STRING. The BLOCK command is for marking a block of text in the source file (spec-1). It must specify where the block begins and ends. The first three phrases after BLOCK identify the beginning, the last three the end. All phrases enclosed in brackets are optional. LINE is the default linetype if none is specified. Linetype has four options. o LINE means the physical line number, either absolute or relative. The lineid distinguishes the two. Absolute line numbers are positive integers, relative line numbers are "*+n", where n is a positive integer. o LABEL means an alphanumeric label. o LABEL# means a numeric line label (a positive integer). o STRING means a string of characters. LABELS must be the first word on a line, STRINGS can occur anywhere in a line. Lineid matches with the linetype. LABEL and STRING require a word with any characters. LABEL# requires a positive integer. And line requires either a positive integer, or the string "*+" to mean the current line in the text file plus" a positive number, or the word "END" to indicate thru the end of file. The phrase TO and UPTO are equivalent. They mean up to but not including. The phrase THRU means up to and include. TO is the default if no phrase is specified. There are three block dispositions: KEEP/DELETE/REPLACE. They tell BLED what to do with a defined block and therefor make sense only after a BLOCK command. DELETE deletes the block, KEEP keeps it. REPLACE [BLOCK/n] This replaces a defined block with another. The "n" means that the next n physical lines go in place of the defined block. And BLOCK means that all following lines up to the end-block phrase are the replacements. Another BLED command is to insert new lines. INSERT [BLOCK/n] This means to insert a block of lines at the current position in the source file, i.e. just before the current line that has been read. The "n" means to insert the following n physical lines. The BLOCK means to take all following lines up to the end-block phrase. EXAMPLES (SOURCE) (MERGES) CALL INITIALIZE BLOCK FROM LINE 1 TO STRING OPENFILES GOSUB OPENFILES REPLACE 1 LOOPER: CALL HELP IF X=1 THEN GOTO ALLDONE: BLOCK FROM LINE * THRU LABEL ALLDONE X = X+1 KEEP GOTO LOOPER INSERT BLOCK ALLDONE: CLOSE END ENDBLOCK (RESULT) CALL HELP GOSUB OPENFILES LOOPER: IF X=1 THEN GOTO ALLDONE: X = X+1 GOTO LOOPER ALLDONE: CLOSE END (SOURCE) (LINE MERGE) 110 IF GOT.COMMAND THEN_ 115 NO.HELP = -1 IF NO.HELP THEN_ 150 IF HELPFUL THEN_ PRINT "SORRY" WHILE X>5 AND NOT EOF(2):_ 120 GOSUB CHKFILES GOSUB CHECKER:_ 150 IF HELPFUL THEN_ WEND WHILE X>5:_ 200 GOSUB CHECKER:_ 220 END WEND 200 IF X>10 THEN X=12 (RESULT) 100 IF GOT.COMMAND THEN_ IF NO.HELP THEN_ PRINT "SORRY" 115 NO.HELP = -1 120 GOSUB CHKFILES 150 IF HELPFUL THEN_ WHILE X>5 AND NOT EOF(2):_ GOSUB CHECKER:_ WEND 220 END Stylistic Considerations A good merge file includes the following information at the top of the file. o author o date of merge o what merge is to be applied to o how to apply the merge (line number merge, general merge?) o a list of the general fixes or enhancements made, listed in order of most to least important coupled. In the body of the merge the following documentation should be included. o a line by line explanation of the changes made stating what is changed and why. The explanation should precede the line. o lines should be grouped together if they implement a common function. A Model Merge File ***************************************************************** * EXAMPLE.MRG * * by Ken Goosens Jan 1, 1986 * * * * to be applied to BLED.BAS version 1.1 * * using the general merge of BLED.EXE * * * * This merge makes two changes: * * (1) the defaults when no configuration exists are changed * * to be appropriate for TURBO Pascal rather than * * QuickBASIC. * * (2) The warning message when no configuration file exists * * is changed to beep and delay for 3 seconds rather * * than quietly and hurriedly display. * ***************************************************************** * reset extensions for original and new files to "PAS" BLOCK FROM LABEL USEDEFAULTS TO STRING ENDBLK REPLACE BLOCK USEDEFAULTS: DEORIGFILE$ = "PAS" DEBTCHCMDS$ = "MRG" DENEWFILE$ = "PAS" ENDBLOCK * Change call from EXPLAIN to EXPERR BLOCK FROM LABEL ERROPEN THRU STRING CALL REPLACE BLOCK ERROPEN: X$ = "Error"+STR$(ERR)+" opening file "+FF$ CALL EXPERR (X$) ENDBLOCK