14 The GNAT Pretty-Printer gnatpp

The gnatpp tool is an ASIS-based utility for source reformatting / pretty-printing. It takes an Ada source file as input and generates a reformatted version as output. You can specify various style directives via switches; e.g., identifier case conventions, rules of indentation, and comment layout.

To produce a reformatted file, gnatpp generates and uses the ASIS tree for the input source and thus requires the input to be syntactically and semantically legal. If this condition is not met, gnatpp will terminate with an error message; no output file will be generated.

gnatpp cannot process sources that contain preprocessing directives.

If the compilation unit contained in the input source depends semantically upon units located outside the current directory, you have to provide the source search path when invoking gnatpp, if these units are contained in files with names that do not follow the GNAT file naming rules, you have to provide the configuration file describing the corresponding naming scheme; see the description of the gnatpp switches below. Another possibility is to use a project file and to call gnatpp through the gnat driver (see The GNAT Driver and Project Files).

The gnatpp command has the form

     
     
     $ gnatpp [switches] filename [-cargs gcc_switches]

where

• switches is an optional sequence of switches defining such properties as the formatting rules, the source search path, and the destination for the output source file
• filename is the name (including the extension) of the source file to reformat; “wildcards” or several file names on the same gnatpp command are allowed. The file name may contain path information; it does not have to follow the GNAT file naming rules
• ‘gcc_switches’ is a list of switches for gcc. They will be passed on to all compiler invocations made by gnatelim to generate the ASIS trees. Here you can provide -I switches to form the source search path, use the -gnatec switch to set the configuration file, use the -gnat05 switch if sources should be compiled in Ada 2005 mode etc.

• Switches for gnatpp
• Formatting Rules