PreProc is a command line tool to run preprocessor directives in a file. It's pretty simple, and is meant to be an analogue to the C preprocessor; but less fixated on C.
preproc [options] <input file> -o <output file>
The <input file> is the file to run the preprocessor on. The -o option
specifies the output file. If the output file is not specified, the output will
be written to stdout.
The input file should be a UTF-8 text file. Each line is processed separately;
if the line starts with a preprocessor directive prefix, the line is parsed
as a preprocessor directive. Otherwise, the line is written to the output
file. The preprocessor directive prefix is # by default, though is
determined by the file extension, but can be changed with the -c/--comment
option.
There are two main tables of values: the definition table, and the replacement
table. The definition table is a table of variables and their values, when
used in expressions. The replacement table is a table of variables and their
values, and the corresponding patterns in the non-directive text are replaced
with the value of the variable. By default, definitions are not replacements;
however, you can declare a replacement with #replace.
The current available preprocessor directives are:
#if <expr>: If the expression evaluates to true, the following lines are passed through. Otherwise, they are ignored.#elsif <expr>: If all of the previous#ifor#elsifevaluated to false, and this expression evaluates to true, the following lines are passed through. Otherwise, they are ignored.#else: If all of the previous#ifor#elsifevaluated to false, the following lines are passed through. Otherwise, they are ignored.#endif: Ends the previous#if,#elsif, or#elseblock.#replace <name>: Replaces all instances ofnamewith the value of the variablename. If the variable is not defined, it is replaced with the empty string.#replace <name> <expr>: Replaces all instances ofnamein the text with the value of the expressionexpr. If the expression cannot be evaluated, it is replaced with the empty string.#unrep <name>: Stops substitution ofnamein the current scope.#define <name> <expr>: Defines the variablenameto be the value of the expressionexpr. If the expression cannot be evaluated, the variable is set to null.#error <expr>: Marks the current line as an error. If the expression cannot be evaluated, the error is marked asnull. This will cause the preprocessor to exit with an error code, after processing the whole file.
To demonstrate the definitions and replacements as expressed above, an example input file is:
#define WORLD "world"
hello, WORLD!
#replace WORLD
hello, WORLD!
#replace WORLD null
hello, WORLD!
The output of processing this file is:
hello, WORLD!
hello, world!
hello, !
Because.
I wanted to write it.
Yes.