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Compiler/Preprocessor: Difference between revisions
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{{draft task}}
This task modifies the source code prior to the lexical analysis similar to the C built-in preprocessor. All design decisions go with as simple an example as possible to show concept and match the simple language the other tasks support.
{{task heading}}
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The program should treat any line starting with a hashtag (#) as a command to process. There are currently two valid commands, include and define. No space between the hashtag and its command. Multiple whitespace is treated the same as one.
The include command must be followed by whitespace and a double quoted string
The define command must be followed by whitespace and a new macro name. Redefinition is illegal. The same character convention for naming variables in the language is used for macro names. No whitespace is required in the arguments but is allowed between every token. When there are no parameters, both the definition or usage must either have an empty argument list or there must not be one. The empty list is required to avoid confusion when the definition needs parenthesizes to force precedence. If there is a close parenthesis, the whitespace trailing it is optional. Otherwise, it is required. From that point to end of line is the definition, whitespace removed from both the start and end of it. Whitespace within the definition between tokens must be maintained. Any names within the definition are treated as macro names first before it is assumed they are a variable in the language during the usage.
To make it easier to find, the usage will be within hashtags, and replaces its usage elsewhere in the files processed. These usages will be processed everywhere they are encountered without regard to the syntax of the sample language. The calling arguments replace the define's parameters as a simple string substitution. You may not assume the usage proceeds in an order to form complex combinations. Tokens detected during definition processing can remain separated during usage processing. If the contents within the double hashtags is not a valid macro usage, its entire text is written to the output as if it was not detected. It is not required to use the ending hashtag as the start of another macro usage.
There are three possible [optional] command line arguments, debug, input, and output. Debug is an implementer depended switch such as -d or --debug to allow the user to pick between the commands vanishing from the output or the commands appearing as comments in the output. Debug can be specified in any order on the command line beyond the command. Input is the file to process, when missing the console input is used. The Input is always specified before the Output. Output is the file to create, when missing the console output is used. If only one file is specified, it is the input file. If you wish to use an output file and console input, you must specify both arguments, who's usage is left up to the implementer. It is not required that there be a way to specify the console on the command line so you could use a file for the output and console for the input.
{{task heading|Input Specification}}
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__TOC__
=={{header|Julia}}==
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