Tokenizer 

A simple Deno library

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Examples

import { Tokenizer } from 'https://deno.land/x/tokenizer/mod.ts';

const input = 'abc 123 HELLO [a cool](link)';

const rules = [{ 
    type : 'HELLO' ,
    pattern : 'HELLO' 
},{ 
    type : 'WORD' ,
    pattern : /[a-zA-Z]+/ 
},{ 
    type : 'DIGITS' ,
    pattern : /\d+/ ,
    value : m => Number.parseInt(m.match)
},{ 
    type : 'LINK' ,
    pattern : /\[([^\[]+)\]\(([^\)]+)\)/
},{ 
    type : 'SPACE' , 
    pattern : / / ,
    ignore: true // Or leave type blank and remove "ignore: true"
}];

const tokenizer = new Tokenizer(input,rules);

Option A

console.log(...tokenizer);

{ type: "WORD", match: "abc", value: "abc", groups: [], position: { start: 0, end: 3 } },
{ type: "DIGITS", match: "123", value: 123, groups: [], position: { start: 4, end: 7 } },
{ type: "HELLO", match: "HELLO", value: "HELLO", groups: [], position: { start: 8, end: 13 } },
{ type: "LINK", match: "[a cool](link)", value: "[a cool](link)", groups: [ "a cool", "link" ], position: { start: 14, end: 28 } }

Option B

while(!tokenizer.done)
    console.log(tokenizer.next().value);

{ type: "WORD", match: "abc", value: "abc", groups: [], position: { start: 0, end: 3 } }

{ type: "DIGITS", match: "123", value: 123, groups: [], position: { start: 4, end: 7 } }

{ type: "HELLO", match: "HELLO", value: "HELLO", groups: [], position: { start: 8, end: 13 } }

{ type: "LINK", match: "[a cool](link)", value: "[a cool](link)", groups: [ "a cool", "link" ], position: { start: 14, end: 28 } }

Option C

// Add a parameter to the tokenize method to override the source string
console.log(tokenizer.tokenize());

[{ type: "WORD", match: "abc", value: "abc", groups: [], position: { start: 0, end: 3 } },
 { type: "DIGITS", match: "123", value: 123, groups: [], position: { start: 4, end: 7 } },
 { type: "HELLO", match: "HELLO", value: "HELLO", groups: [], position: { start: 8, end: 13 } },
 { type: "LINK", match: "[a cool](link)", value: "[a cool](link)", groups: [ "a cool", "link" ], position: { start: 14, end: 28 } } ]

TODO

• Custom patterns using functions
• Add position information to Token
• Array patterns (Multiple patterns for the same rule)
• Documentation
• Better error handling
• Group matching
• Value transform
• More and better tests for everything
• Examples
• Line and column information? Or just a helper function to get line and column from index
• BNF / EBNF ?
• Generate a tokenizer