26 lines
827 B
JavaScript
26 lines
827 B
JavaScript
export default function prefixStreamWrite(writableStream, prefix) {
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const oldWrite = writableStream.write
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function newWrite(...args) {
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const [chunk, encoding] = args
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// Prepend the prefix if the chunk is either a string or a Buffer.
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// Otherwise, just leave it alone to be safe.
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if (typeof chunk === 'string') {
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// Only prepend the prefix is the `encoding` is safe or not provided.
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// If it's a function, it is third arg `callback` provided as optional second
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if (!encoding || encoding === 'utf8' || typeof encoding === 'function') {
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args[0] = prefix + chunk
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}
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} else if (Buffer.isBuffer(chunk)) {
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args[0] = Buffer.concat([Buffer.from(prefix), chunk])
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}
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return oldWrite.apply(this, args)
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}
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writableStream.write = newWrite
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return writableStream
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}
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