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#### 8.8.2 The ptop configuration file

Creating and distributing a configuration file for ptop is not necessary, unless you want to modify the standard behaviour of ptop. The configuration file is never preloaded, so if you want to use it you should always specify it with a -c ptop.cfg parameter.

The structure of a ptop configuration file is a simple building block repeated several (20-30) times, for each Pascal keyword known to the ptop program. (See the default configuration file or ptopu.pp source to find out which keywords are known).

The basic building block of the configuration file consists of one or two lines, describing how ptop should react on a certain keyword. First comes a line without square brackets with the following format:

keyword=option1,option2,option3,...

If one of the options is ”dindonkey” (see further below), a second line - with square brackets - is needed:

[keyword]=otherkeyword1,otherkeyword2,otherkeyword3,...

As you can see the block contains two types of identifiers: keywords (keyword and otherkeyword1..3 in above example) and options, (option1..3 above).

Keywords are the built-in valid Pascal structure-identifiers like BEGIN, END, CASE, IF, THEN, ELSE, IMPLEMENTATION. The default configuration file lists most of these.

Besides the real Pascal keywords, some other codewords are used for operators and comment expressions as in table (8.1).

Table 8.1: Keywords for operators

Name of codeword | Operator

casevar | : in a case label ( unequal ’colon’)
becomes | :=
delphicomment | //
opencomment | { or (*
closecomment | } or *)
semicolon | ;
colon | :
equals | =
openparen | [
closeparen | ]
period | .

The options codewords define actions to be taken when the keyword before the equal sign is found, as listed in table (8.2).

Table 8.2: Possible options

Option | does what

crsupp | Suppress CR before the keyword.
crbefore | Force CR before keyword.
| (do not use with crsupp.)
blinbefore | Blank line before keyword.
dindonkey | De-indent on associated keywords.
| (see below)
dindent | Deindent (always)
spbef | Space before
spaft | Space after
gobsym | Print symbols which follow a
| keyword but which do not
| affect layout. prints until
| terminators occur.
| (terminators are hard-coded in pptop,
| still needs changing)
inbytab | Indent by tab.
crafter | Force CR after keyword.
upper | Prints keyword all uppercase
lower | Prints keyword all lowercase
capital | Capitalizes keyword: 1st letter
| uppercase, rest lowercase.

The option ”dindonkey” given in table table (8.2) requires some further explanation. ”dindonkey” is a contraction of ”DeINDent ON associated KEYword”. When it is present as an option in the first line, then a second, square-bracketed, line is required. A de-indent will be performed when any of the other keywords listed in the second line are encountered in the source.

Example: The lines

else=crbefore,dindonkey,inbytab,upper
[else]=if,then,else

mean the following:

- The keyword this block is about is else because it’s on the LEFT side of both equal signs.
- The option crbefore signals not to allow other code (so just spaces) before the ELSE keyword on the same line.
- The option dindonkey de-indents if the parser finds any of the keywords in the square brackets line (if,then,else).
- The option inbytab means indent by a tab.
- The option upper uppercase the keyword (else or Else becomes ELSE)

Try to play with the configfile step by step until you find the effect you desire. The configurability and possibilities of ptop are quite large. E.g. I like all keywords uppercased instead of capitalized, so I replaced all capital keywords in the default file by upper.

ptop is still development software. So it is wise to visually check the generated source and try to compile it, to see if ptop hasn’t introduced any errors.

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