A configurable parser to parse whatever you want
This module is basically a class that provides general mechanisms for parsing strings. It works with my tokenizer although it can be used with pretty much anything emitting tokens the same way. The parser works with a queue of functions. For each token the next function in the queue is called.
Only one thing is required for the parser to work : a tokenizer. These concepts are very different and that is why they are implemented separately. The easiest solution is to use my tokenizer
The default behaviour upon receiving a new token is ignoring it. It prints a warning when reaching EOF with the number of tokens that have been ignored. However this is probably not what you want to do!
In order to parse what you need to parse you have to provide the parser with the functions which will be called for each token. Let's call these functions 'handlers'. This can be achieved through configuration of the basic parser or through inheritance.
var Parser = require'parser';var util = require'util';var MyTokenizer = require'./MyTokenizer';// MyTokenizer is the tokenizer we configured// but it's not the subject of this moduleParserapplythis ;// override the default behaviourthisdefaultHandlerthisdefault;// specify the function that will be called on the first tokenthisinitialHanderthisinitial;utilinheritsMyParser Parser;/*** Of course you will have to define these functions somewhere*/
This is very theoretic but you can have a look at what is in the example folder
tokenthe actual token emitted by the tokenizer
typethe type of this token (i.e.
nexta function to specify what needs to be called on the next token(s)
next function takes a random number of handlers which will be pushed
in front of the handlers queue (they will be next!).
true from a handler causes the same token to be reemitted
to the next handler.
This allows you to define handlers doing some kind of "sniffing" if you find
yourself in a state in which you cannot determine what will come next.
This kind of handlers expand themselves to a greater number of handlers that
will effectively parse the following tokens. They do that by adding a few handlers
to the queue with
next and returning
true to notify the parser that the token
should be reemitted.
there are a few handlers factories provided by this module.
checkType(type)returns a handler that only checks the type of the token without doing anything so the same token is pass down to the next handler
expect(type)returns a handler that checks for the specified type and consumes the token
list(separator, element, end)returns a handler expanding to the handlers needed to parse a list of elements able to be parsed by
elementand separated by tokens of type
separator. The list should end by a token of type
- more robustness / better error handling
- features requests
- Support for asynchronous handlers
- allow for complex separator an ending tokens for handler utilities
If you'd like the parser to do something that it doesn't do or want to report a bug please use the github issue tracker on github
You are very welcome to send patches or pull requests