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notes/node_modules/doiuse/stream.js

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2017-03-09 13:16:08 -05:00
var through = require('through2')
var duplexer = require('duplexer2')
var rules = require('css-rule-stream')
var sourcemap = require('source-map')
var postcss = require('postcss')
var doiuse = require('./')
module.exports = stream
/**
* @param {Object} options (browsers, ignore, etc.)
* @param {string} [filename] Filename for outputting source code locations.
*/
function stream (options, filename) {
var inp = rules()
filename = filename || '<streaming css input>'
var processor
var out = through.obj(write)
var duplex = duplexer(inp, out)
try {
processor = postcss([doiuse({
browsers: options.browsers,
ignore: options.ignore,
onFeatureUsage: pushUsage
})])
inp.pipe(out)
} catch (e) {
setImmediate(function () { duplex.emit('error', e) })
}
return duplex
function write (rule, enc, next) {
try {
var mapper = new sourcemap.SourceMapGenerator()
var lines = rule.content.split('\n')
var oline = rule.line
var ocol = rule.column
for (var line = 0; line < lines.length; line++) {
mapper.addMapping({
generated: { line: line + 1, column: 1 },
original: { line: oline, column: ocol },
source: filename
})
mapper.addMapping({
generated: { line: line + 1, column: lines[line].length },
original: { line: oline, column: ocol + lines[line].length },
source: filename
})
oline++
ocol = 1
}
processor.process(rule.content, { map: { prev: mapper.toString() } })
.then(function (result) { next() })
.catch(handleError)
} catch (e) {
handleError(e)
}
function handleError (error) {
if (options.skipErrors) {
duplex.emit('warning', error)
next()
} else {
next(error)
}
}
}
function pushUsage (usage) {
out.push(usage)
}
}