This provides a compiler than translates high-level DM Script syntax to DMPL JSON.
Check out the dms-scratchpad for an example usage.
The DM Script language is bracket-based, making the structure clear and easy to parse.
The syntax is close to current mainstream languages, so it's familiar,
including infix operators, function calls, and if/else.
Frequently used statements, such as input and run, have a nice terse-ness to them.
To use the compiler CLI, run yarn to install dependencies and then run:
./bin/compile <file>
You can use a file in examples to see the output, like ./bin/compile examples/planet-trivia.dmpl.
To use the API, require the compiler and pass it a source string:
const compile = require('./compiler');
console.log(compile('X = "simple program"'))
The compiler uses snapshot testing to ensure correctness. The tests in compiler.test.js generate snapshots of the output which can be seen in the __snapshots__ directory. This provides a nice way to see the compiler output and verify that any changes in the output is intentional.
The parser uses the library Parsimmon for parsing. It provides parser combinators to construct a language out of many small parsers. The top-level parser is Program and it will break down the syntax from there.
To generate an output value, each parser uses map to map the output to an AST node. It takes a list of things matched by the parser combinator as an array and you can extract values from it.
You can use any of the builtin parsers from Parsimmon to create a parser, like P.string('+'), or use an existing parser from the language by reading off the value given to the parser, usually r, like r.Expression.
Reading the existing parsers should give you a good idea about how to work with it. The syntax can be tweaked by changing the parsers to match different syntax, and new forms can be added by adding new parsers to the object passed into P.createLanguage.
The compiler takes an AST and compiles it down to the JSON
representation. It recursively calls itself to compile down
expressions and statements. Each type of node implements its own compile function named after its type, for example compileUse.
The top-level function is compile, so you can recursively compile expressions by doing things like [node.target.name, this.compile(node.expression)]. When adding a new form, you need to implement a new compile* method on the Compiler class.
curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -
apt-get install -y nodejs
Original author: James Long
Current maintainer: Nishant Shukla