Snapdragon util and plugin for patching the position on an AST node.
Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your ❤️ and support.
Install with npm:
$ npm install --save snapdragon-positionAdds a .position object to tokens that looks something like this:
{
source: 'string',
start: { index: 0, column: 1, line: 1 },
end: { index: 3, column: 4, line: 1 },
range: [0, 3] // getter
}When used as snapdragon-lexer plugin, this adds a .position() method to the instance and patches the lexer.lex() and lexer.handle() methods to automatically add position objects to tokens.
There is a more detailed example below.
Heads up!
If you would prefer for the property name to be token.loc rather than token.position, use snapdragon-location instead.
The main export is a function that can be used as a plugin with snapdragon-lexer, or called directly with an instance of snapdragon-lexer.
Sets the start position and returns a function for setting the end position on a token.
Params
name{String|Object}: (optional) Snapdragon Lexer or Tokenizer instance, or the name to use for the position property on the token. Default isposition.target{Object}: Snapdragon Lexer or Tokenizer instancereturns{Function}: Returns a function that takes atokenas its only argument
Example
const position = require('snapdragon-position');
const Lexer = require('snapdragon-lexer');
const lexer = new Lexer('foo/bar');
lexer.capture('slash', /^\//);
lexer.capture('text', /^\w+/);
const pos = position(lexer);
const token = pos(lexer.advance());
console.log(token);Use as a plugin to add a .position method to your snapdragon-lexer or [snapdragon-tokenizer][] instance to automatically add a position object to tokens when the .lex() or .handle() methods are used.
Example
const Lexer = require('snapdragon-lexer');
const position = require('snapdragon-position');
const lexer = new Lexer();
lexer.use(position());Get the current source location, with index, column and line. Used by .position() to create the "start" and "end" locations.
returns{Object}: Returns an object with the current source location.
Example
const Lexer = require('snapdragon-lexer');
const lexer = new Lexer();
console.log(lexer.location());
//=> Location { index: 0, column: 0, line: 1 };Returns a function for getting the current position.
returns{Function}: Returns a function that takes atokenas its only argument, and patches a.positionproperty onto the token.
Example
const Lexer = require('snapdragon-lexer');
const lexer = new Lexer('foo/bar');
lexer.use(position());
lexer.set('text', function(tok) {
// get start position before advancing lexer
const pos = this.position();
const match = this.match(/^\w+/);
if (match) {
// get end position after advancing lexer (with .match)
return pos(this.token(match));
}
});Params
start{Object}: (required) Starting locationend{Object}: (required) Ending locationtarget{Object}: (optional) Snapdragon Lexer or Tokenizer instancereturns{Object}
Example
const Lexer = require('snapdragon-lexer');
const Location = require('snapdragon-position').Location;
const lexer = new Lexer('foo/bar');
lexer.capture('text', /^\w+/);
lexer.advance();
console.log(new Location(lexer));
//=> Location { index: 3, column: 4, line: 1 }Params
start{Object}: (required) Starting locationend{Object}: (required) Ending locationtarget{Object}: (optional) Snapdragon Lexer or Tokenizer instancereturns{Object}
Example
const Lexer = require('snapdragon-lexer');
const position = require('snapdragon-location');
const lexer = new Lexer('foo/bar')
.capture('slash', /^\//)
.capture('text', /^\w+/);
const start = new position.Location(lexer);
lexer.advance();
const end = new position.Location(lexer);
console.log(new position.Position(start, end, lexer));
// Position {
// source: undefined,
// start: Location { index: 0, column: 1, line: 1 },
// end: Location { index: 3, column: 4, line: 1 } }When used as a plugin, this adds a .position() method to a snapdragon-lexer instance, for adding position information to tokens.
Example
const position = require('snapdragon-position');
const Lexer = require('snapdragon-lexer');
const lexer = new Lexer('foo/bar');
lexer.use(position());
lexer.capture('slash', /^\//);
lexer.capture('text', /^\w+/);
var token = lexer.advance();
console.log(token);Adds a .position object to the token, like this:
Token {
type: 'text',
value: 'foo',
match: [ 'foo', index: 0, input: 'foo/*' ],
position: {
start: { index: 0, column: 1, line: 1 },
end: { index: 3, column: 4, line: 1 },
range: [0, 3] // getter
}
}See the Token documentation for more details about the Token object.
interface Token {
type: string;
value: string;
match: array | undefined;
position: Position;
}The token.position property contains source string position information on the token.
interface Position {
source: string | undefined;
start: Location;
end: Location;
range: array (getter)
}source{string|undefined} - the source position provided bylexer.options.source. Typically this is a filename, but could also bestringor any user defined value.start{object} - start location object, which is the location of the first character of the lexed source string.end{object} - end location object, which is the location of the last character of the lexed source string.range{array} - getter that returns an array with the following values:[position.start.index, position.end.index]
Each Location object consists of an index number (0-based), a column number (0-based), and a line number (1-based):
interface Location {
index: number; // >= 0
column: number; // >= 0,
line: number; // >= 1
}line{string|undefined} - the source position provided bylexer.options.source. Typically this is a filename, but could also bestringor any user defined value.column{object} - start location object, which is the location of the first character of the lexed source string.end{object} - end location object, which is the location of the last character of the lexed source string.
const Lexer = require('snapdragon-lexer');
const lexer = new Lexer('foo/*', { source: 'string' });
lexer.use(position());
lexer.capture('star', /^\*/);
lexer.capture('slash', /^\//);
lexer.capture('text', /^\w+/);
lexer.tokenize();
console.log(lexer.tokens);Results in:
[
{
type: 'text',
val: 'foo',
match: ['foo', index: 0, input: 'foo/*'],
position: {
source: 'string',
start: { index: 0, column: 1, line: 1 },
end: { index: 3, column: 4, line: 1 },
range: [0, 3]
}
},
{
type: 'slash',
val: '/',
match: ['/', index: 0, input: '/*'],
position: {
source: 'string',
start: { index: 3, column: 4, line: 1 },
end: { index: 4, column: 5, line: 1 },
range: [3, 4]
}
},
{
type: 'star',
val: '*',
match: ['*', index: 0, input: '*'],
position: {
source: 'string',
start: { index: 4, column: 5, line: 1 },
end: { index: 5, column: 6, line: 1 },
range: [4, 5]
}
}
]Contributing
Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.
Please read the contributing guide for advice on opening issues, pull requests, and coding standards.
Running Tests
Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
$ npm install && npm testBuilding docs
(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)
To generate the readme, run the following command:
$ npm install -g verbose/verb#dev verb-generate-readme && verbYou might also be interested in these projects:
- snapdragon-capture: Snapdragon plugin that adds a capture method to the parser instance. | homepage
- snapdragon-node: Snapdragon utility for creating a new AST node in custom code, such as plugins. | homepage
- snapdragon-util: Utilities for the snapdragon parser/compiler. | homepage
Jon Schlinkert
Copyright © 2018, Jon Schlinkert. Released under the MIT License.
This file was generated by verb-generate-readme, v0.6.0, on January 08, 2018.
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