improve fetchSSE (#532)

src/utils/eventsource-parser.mjs

@@ -0,0 +1,130 @@
+// https://www.npmjs.com/package/eventsource-parser/v/1.1.1
+
+function createParser(onParse) {
+  let isFirstChunk
+  let bytes
+  let buffer
+  let startingPosition
+  let startingFieldLength
+  let eventId
+  let eventName
+  let data
+  reset()
+  return {
+    feed,
+    reset,
+  }
+  function reset() {
+    isFirstChunk = true
+    bytes = []
+    buffer = ''
+    startingPosition = 0
+    startingFieldLength = -1
+    eventId = void 0
+    eventName = void 0
+    data = ''
+  }
+
+  function feed(chunk) {
+    bytes = bytes.concat(Array.from(chunk))
+    buffer = new TextDecoder().decode(new Uint8Array(bytes))
+    if (isFirstChunk && hasBom(buffer)) {
+      buffer = buffer.slice(BOM.length)
+    }
+    isFirstChunk = false
+    const length = buffer.length
+    let position = 0
+    let discardTrailingNewline = false
+    while (position < length) {
+      if (discardTrailingNewline) {
+        if (buffer[position] === '\n') {
+          ++position
+        }
+        discardTrailingNewline = false
+      }
+      let lineLength = -1
+      let fieldLength = startingFieldLength
+      let character
+      for (let index = startingPosition; lineLength < 0 && index < length; ++index) {
+        character = buffer[index]
+        if (character === ':' && fieldLength < 0) {
+          fieldLength = index - position
+        } else if (character === '\r') {
+          discardTrailingNewline = true
+          lineLength = index - position
+        } else if (character === '\n') {
+          lineLength = index - position
+        }
+      }
+      if (lineLength < 0) {
+        startingPosition = length - position
+        startingFieldLength = fieldLength
+        break
+      } else {
+        startingPosition = 0
+        startingFieldLength = -1
+      }
+      parseEventStreamLine(buffer, position, fieldLength, lineLength)
+      position += lineLength + 1
+    }
+    if (position === length) {
+      bytes = []
+      buffer = ''
+    } else if (position > 0) {
+      bytes = bytes.slice(new TextEncoder().encode(buffer.slice(0, position)).length)
+      buffer = buffer.slice(position)
+    }
+  }
+
+  function parseEventStreamLine(lineBuffer, index, fieldLength, lineLength) {
+    if (lineLength === 0) {
+      if (data.length > 0) {
+        onParse({
+          type: 'event',
+          id: eventId,
+          event: eventName || void 0,
+          data: data.slice(0, -1),
+          // remove trailing newline
+        })
+
+        data = ''
+        eventId = void 0
+      }
+      eventName = void 0
+      return
+    }
+    const noValue = fieldLength < 0
+    const field = lineBuffer.slice(index, index + (noValue ? lineLength : fieldLength))
+    let step = 0
+    if (noValue) {
+      step = lineLength
+    } else if (lineBuffer[index + fieldLength + 1] === ' ') {
+      step = fieldLength + 2
+    } else {
+      step = fieldLength + 1
+    }
+    const position = index + step
+    const valueLength = lineLength - step
+    const value = lineBuffer.slice(position, position + valueLength).toString()
+    if (field === 'data') {
+      data += value ? ''.concat(value, '\n') : '\n'
+    } else if (field === 'event') {
+      eventName = value
+    } else if (field === 'id' && !value.includes('\0')) {
+      eventId = value
+    } else if (field === 'retry') {
+      const retry = parseInt(value, 10)
+      if (!Number.isNaN(retry)) {
+        onParse({
+          type: 'reconnect-interval',
+          value: retry,
+        })
+      }
+    }
+  }
+}
+const BOM = [239, 187, 191]
+function hasBom(buffer) {
+  return BOM.every((charCode, index) => buffer.charCodeAt(index) === charCode)
+}
+export { createParser }