This tool parses an FPP model, performs semantic checking on it, and writes out the model in JavaScript Object Notation (JSON) format.

Options:

1. -d dir: Set the output directory to dir. If this option is not present, then the output directory is the current directory.

2. -s: Emit syntax only (location map and abstract syntax tree).

Input:

1. A list fl of files to translate: either the single file stdin or a list of files specified on the command line.

Output:

Fpp-to-json generates the following files:

1. A file fpp-ast.json containing a JSON representation of the abstract syntax tree (AST).

2. A file fpp-loc.json containing a JSON representation of the location map.

3. If the flag -s is not present, then a file fpp-analysis.json containing a JSON representation of the Analysis Data Structure.

Procedure:

1. Parse each of the files in fl, generating a list tul of translation units. When parsing, recursively resolve include specifiers.

2. Convert the abstract syntax tree (AST) and the location map to JSON objects.

3. If -s is not present, then

   1. Perform semantic checking on tul.

   2. Convert the Analysis Data Structure to a JSON object.

4. Write the JSON objects to files.

JSON AST Parser

The fpp-ast.json output from this tool can be quite tedious to parse, but is a very useful source for programatically interpreting the fpp model files. As such, a barebones Python-based JSON AST parser is provided as a utility of [fprime-tools](https://github.com/nasa/fprime-tools/pull/207), as well as an fpp syntax writer.

Examples for utilizing both tools are provided in the fprime-tools utility folder.