Simple Text Parser

This is a dead simple text parser written in Javascript. It's based around strings and regular expressions so it's highly customizable, synchronous and relatively fast.

Install

Requires Node.js and NPM. Simply install it into your package of choice.

npm install simple-text-parser --save

The --save will tell npm to add it to your package.json.

Usage

The STP package is a Parser class. Create a new object from it.

var Parser = require("simple-text-parser"),
    parser = new Parser();

Examples

STP works by taking a plain text String and searching it for substrings and regular expressions. When a match is found, it is parsed out into a tree and replaced.

Let's start by defining a parsing rule. Say we want to parse some text for hash tags (#iamahashtag) and replace it with some custom html:

// Define a rule using a regular expression
parser.addRule(/\#[\S]+/ig, function(tag) {
    // Return the tag minus the `#` and surrond with html tags
    return "<span class=\"tag\">" + tag.substr(1) + "</span>";
});

Now lets parse some text and output the resulting string:

parser.parse("Some text #iamahashtag foo bar.");

becomes...

Some text <span class="tag">iamahashtag</span> foo bar.

Of course we can also parse some text into an Object tree for more custom handling and to retrieve the parsed data:

parser.toTree("Some text #iamahashtag foo bar.");

outputs...

[ { type: 'text', text: 'Some text ' },
  { type: 'text',
    text: '<span class="tag">iamahashtag</span>' },
  { type: 'text', text: ' foo bar.' } ]

Of course a type of text on a tag isn't helpful when specifically trying to parse out tags. Let's modify our parsing rule to be more specfic:

// Define a rule using a regular expression
parser.addRule(/\#[\S]+/ig, function(tag) {
    // Get the tag minus the `#`
    var clean_tag = tag.substr(1);
    
    // create the replacement text with surronding html tags
    var text = "<span class=\"tag\">" + clean_tag + "</span>";
    
    // return an object describing this tag
    return { type: "tag", text: text, tag: clean_tag };
});

Now lets rerun parse() and toTree() on the original text. Notice that parse() outputs the same thing as before, but toTree() includes the custom meta data.

Some text <span class="tag">iamahashtag</span> foo bar.

[ { type: 'text', text: 'Some text ' },
  { type: 'tag',
    text: '<span class="tag">iamahashtag</span>',
    tag: 'iamahashtag' },
  { type: 'text', text: ' foo bar.' } ]

API Documentation

Class Methods

These methods can be called directly from the Parser class.

Parser.registerPreset()

Register a new preset rule. This allows STP to be extended globally. Presets don't handle the replacing, only the matching. STP comes with three pre-included presets: tag, url, and email.

Parser.registerPreset(name, match);

name (String) - The string id of the preset. Also the type.
match (String, RegExp, Function) - The search to perform.

Instance Methods

These methods can be called on objects returned from new Parser().

parser.addRule()

Add a parsing rule.

parser.addRule(match, replace);

match (String, RegExp, Function) - The search to perform. If a String, it is searched for exactly. If RegExp, a simple match is performed. If Function, it is called with a single argument: the full string passed to parse().
replace (String, Function) - Replaces the match when found. When a String, it is replaces exactly. Functions are called with matched substring as first argument. All capture groups are passed as next parameters.

parser.addPreset()

Registers a preset rule within the instance.

parser.addPreset(name, replace);

name (String) - The string id of the preset. Also the type.
replace (String, Function) - Replaces the match when found.

parser.toTree()

Returns the parsed string as an array of objects describing each part. Every part includes at least a type and text key. type defaults to text. The text key is used to replaced the matched string.

parser.toTree(str);

str (String) - A plain text string to parse.

parser.parse()

Returns a parsed string with all rules replaced.

parser.parse(str);

str (String) - A plain text string to parse.