| 'use strict' |
| |
| var codes = require('./character/codes.js') |
| var constants = require('./constant/constants.js') |
| |
| var search = /[\0\t\n\r]/g |
| |
| function preprocess() { |
| var start = true |
| var column = 1 |
| var buffer = '' |
| var atCarriageReturn |
| |
| return preprocessor |
| |
| function preprocessor(value, encoding, end) { |
| var chunks = [] |
| var match |
| var next |
| var startPosition |
| var endPosition |
| var code |
| |
| value = buffer + value.toString(encoding) |
| startPosition = 0 |
| buffer = '' |
| |
| if (start) { |
| if (value.charCodeAt(0) === codes.byteOrderMarker) { |
| startPosition++ |
| } |
| |
| start = undefined |
| } |
| |
| while (startPosition < value.length) { |
| search.lastIndex = startPosition |
| match = search.exec(value) |
| endPosition = match ? match.index : value.length |
| code = value.charCodeAt(endPosition) |
| |
| if (!match) { |
| buffer = value.slice(startPosition) |
| break |
| } |
| |
| if ( |
| code === codes.lf && |
| startPosition === endPosition && |
| atCarriageReturn |
| ) { |
| chunks.push(codes.carriageReturnLineFeed) |
| atCarriageReturn = undefined |
| } else { |
| if (atCarriageReturn) { |
| chunks.push(codes.carriageReturn) |
| atCarriageReturn = undefined |
| } |
| |
| if (startPosition < endPosition) { |
| chunks.push(value.slice(startPosition, endPosition)) |
| column += endPosition - startPosition |
| } |
| |
| if (code === codes.nul) { |
| chunks.push(codes.replacementCharacter) |
| column++ |
| } else if (code === codes.ht) { |
| next = Math.ceil(column / constants.tabSize) * constants.tabSize |
| chunks.push(codes.horizontalTab) |
| while (column++ < next) chunks.push(codes.virtualSpace) |
| } else if (code === codes.lf) { |
| chunks.push(codes.lineFeed) |
| column = 1 |
| } |
| // Must be carriage return. |
| else { |
| atCarriageReturn = true |
| column = 1 |
| } |
| } |
| |
| startPosition = endPosition + 1 |
| } |
| |
| if (end) { |
| if (atCarriageReturn) chunks.push(codes.carriageReturn) |
| if (buffer) chunks.push(buffer) |
| chunks.push(codes.eof) |
| } |
| |
| return chunks |
| } |
| } |
| |
| module.exports = preprocess |
