syntactic.js

syntactic.js provides an API for static analysis of javascript code intended for an educational setting. The API allows you to:

1. Whitelist and blacklist syntactic features (such as for loops, while loops, etc.)
2. Test that two code samples share the same general structure.

You can check out the demo here: https://github.com/eadlam/syntactic-demo

Installation

This library is currently built for the browser (the npm module may come in the future). You can install it with bower install syntactic.

Dependencies

syntactic.js relies on esprima for parsing javascript into an abstract syntax tree, and Q (for promises) allowing the analysis to run asynchronously in a non-blocking way.

Usage

###Template Structure Comparison

syntactic.outline(text) instantiates a SerializedStructure object which contains a parsed version of the input text. It can then be used to verify other text. The verify() method is currently synchronous but will soon be changed to be asynchronous by returning a promise.

#####example

// syntactic.outline(text1).verify(text2);

> var text = '// This is a hint \n' +
             'while(true){console.log("Hello")};'

> var template = syntactic.outline(text);
> console.log(template);

    SerializedStructure{
        hints: Array[3],
        serialized: {
            Program.WhileStatement: Object
            Program.WhileStatement.CallExpression: Object
            Program.WhileStatement.CallExpression.MemberExpression: {
                2: " This is a hint "
            }
        }
        ...
    }
> var text2 = 'while(true){};'
> var result = template.verify(text2);
> console.log(result)

    Object{
        hints:[
            "This is a hint."
        ],
        missing:[
            "Program.WhileStatement.CallExpression",
            "Program.WhileStatement.CallExpression.MemberExpression"
        ],
        status:false
    }

###Whitelist / Blacklist Specification (Asynchronous)

Unlike syntactic.outline().verify(), syntactic.specify().verify() is asynchronous. It returns a promise so that it can be run in a non-blocking way. In the future syntactic.outline().verify() will also use promises.

You instantiate a Requirements object with syntactic.specify(lists) where lists is an object containing either whitelist or blacklist or both. The contents of these options is in the form {TokenType:[token, token, etc., ...]}

Once instantiated, you can use the object to verify text. verify() returns the Requirements object with updated status, which equals false if the verification failed, and flags which contains the offending items.

#####example

> var text = 'while(true){};'
> syntactic.specify({
        whitelist:{Keyword: ['for']},
        blacklist:{Keyword: ['while']}
    }).verify(text2).then(function(res){
        console.log(res);
  });

    Requirements{
        flags:{
            blacklist:{
                Keyword:{
                    while: [
                        {
                            end:{...},
                            start:{
                                column:0,
                                line:1
                            }
                        }
                    ]
                }
            },
            whitelist:{
                Keyword:{
                    for: undefined
                }
            }
        },
        status: false
    }