dd-trace/packages/dd-trace/src/tagger.js

Datadog APM tracing client for JavaScript

'use strict'

// TODO: Rename and move file. This is a general purpose helper for adding tags to a carrier.

function addNonEmpty (carrier, key, value) {
  if (key !== '') {
    carrier[key] = value
  }
}

function add (carrier, keyValuePairs, valueSeparator = ':') {
  if (!carrier) return

  if (typeof keyValuePairs === 'string') {
    let valueStart = 0
    let keyStart = 0

    for (let i = 0; i < keyValuePairs.length; i++) {
      const char = keyValuePairs[i]

      if (char === valueSeparator) {
        if (valueStart === 0) {
          valueStart = i
        }
      } else if (char === ',') {
        valueStart ||= i
        addNonEmpty(
          carrier,
          keyValuePairs.slice(keyStart, valueStart).trim(),
          keyValuePairs.slice(valueStart + 1, i).trim()
        )
        keyStart = i + 1
        valueStart = 0
      }
    }

    if (keyValuePairs.at(-1) !== ',') {
      valueStart ||= keyValuePairs.length
      addNonEmpty(
        carrier,
        keyValuePairs.slice(keyStart, valueStart).trim(),
        keyValuePairs.slice(valueStart + 1).trim()
      )
    }
  } else if (Array.isArray(keyValuePairs)) {
    for (const tags of keyValuePairs) {
      add(carrier, tags)
    }
  } else {
    Object.assign(carrier, keyValuePairs)
  }
}

module.exports = { add }