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73 lines
1.5 KiB
73 lines
1.5 KiB
module.exports = function bufferIndexOf(buff, search, offset, encoding){ |
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if (!Buffer.isBuffer(buff)) { |
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throw TypeError('buffer is not a buffer'); |
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} |
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// allow optional offset when providing an encoding |
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if (encoding === undefined && typeof offset === 'string') { |
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encoding = offset; |
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offset = undefined; |
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} |
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if (typeof search === 'string') { |
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search = new Buffer(search, encoding || 'utf8'); |
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} else if (typeof search === 'number' && !isNaN(search)) { |
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search = new Buffer([search]) |
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} else if (!Buffer.isBuffer(search)) { |
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throw TypeError('search is not a bufferable object'); |
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} |
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if (search.length === 0) { |
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return -1; |
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} |
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if (offset === undefined || (typeof offset === 'number' && isNaN(offset))) { |
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offset = 0; |
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} else if (typeof offset !== 'number') { |
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throw TypeError('offset is not a number'); |
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} |
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if (offset < 0) { |
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offset = buff.length + offset |
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} |
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if (offset < 0) { |
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offset = 0; |
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} |
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var m = 0; |
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var s = -1; |
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for (var i = offset; i < buff.length ; ++i) { |
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if(buff[i] != search[m]){ |
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s = -1; |
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// <-- go back |
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// match abc to aabc |
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// 'aabc' |
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// 'aab' |
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// ^ no match |
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// a'abc' |
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// ^ set index here now and look at these again. |
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// 'abc' yay! |
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i -= m-1 |
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m = 0; |
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} |
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if(buff[i] == search[m]) { |
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if(s == -1) { |
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s = i; |
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} |
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++m; |
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if(m == search.length) { |
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break; |
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} |
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} |
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} |
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if (s > -1 && buff.length - s < search.length) { |
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return -1; |
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} |
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return s; |
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} |
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