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61 lines
2.5 KiB
Markdown
61 lines
2.5 KiB
Markdown
7 years ago
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# linebreak
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An implementation of the Unicode Line Breaking Algorithm (UAX #14)
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> Line breaking, also known as word wrapping, is the process of breaking a section of text into lines such that it will fit in the
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> available width of a page, window or other display area. The Unicode Line Breaking Algorithm performs part of this process.
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> Given an input text, it produces a set of positions called "break opportunities" that are appropriate points to begin a new line.
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> The selection of actual line break positions from the set of break opportunities is not covered by the Unicode Line Breaking Algorithm,
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> but is in the domain of higher level software with knowledge of the available width and the display size of the text.
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This is a JavaScript/CoffeeScript implementation of the
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[Unicode Line Breaking Algorithm](http://www.unicode.org/reports/tr14/#SampleCode) for Node.js
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(and browsers I guess). It is used by [PDFKit](http://github.com/devongovett/pdfkit/) for
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line wrapping text in PDF documents, but since the algorithm knows nothing about the actual
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visual appearance or layout of text, it could be used for other things as well.
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## Installation
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You can install via npm
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npm install linebreak
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## Example
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```javascript
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var LineBreaker = require('linebreak');
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var lorem = 'lorem ipsum...';
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var breaker = new LineBreaker(lorem);
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var last = 0;
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var bk;
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while (bk = breaker.nextBreak()) {
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// get the string between the last break and this one
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var word = lorem.slice(last, bk.position);
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console.log(word);
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// you can also check bk.required to see if this was a required break...
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if (bk.required) {
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console.log('\n\n');
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}
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}
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```
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## Development Notes
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In order to use the library, you shouldn't need to know this, but if you're interested in
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contributing or fixing bugs, these things might be of interest.
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* The `src/classes.coffee` file is automatically generated from `LineBreak.txt` in the Unicode
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database by `src/generate_data.coffee`. It should be rare that you need to run this, but
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you may if, for instance, you want to change the Unicode version.
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* You can run the tests using `npm test`. They are written using `mocha`, and generated from
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`LineBreakTest.txt` from the Unicode database, which is included in the repository for performance
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reasons while running them. About 150 of the over 6000 tests are currently skipped due to
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implementation differences. It appears that some of the tests may be wrong or use different
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tailoring from the spec.
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## License
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MIT
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