eventsource-parser
Version:
Streaming, source-agnostic EventSource/Server-Sent Events parser
107 lines (106 loc) • 3.76 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: !0 });
class ParseError extends Error {
constructor(message, options) {
super(message), this.name = "ParseError", this.type = options.type, this.field = options.field, this.value = options.value, this.line = options.line;
}
}
function noop(_arg) {
}
function createParser(callbacks) {
if (typeof callbacks == "function")
throw new TypeError(
"`callbacks` must be an object, got a function instead. Did you mean `{onEvent: fn}`?"
);
const { onEvent = noop, onError = noop, onRetry = noop, onComment } = callbacks;
let incompleteLine = "", isFirstChunk = !0, id, data = "", eventType = "";
function feed(newChunk) {
const chunk = isFirstChunk ? newChunk.replace(/^\xEF\xBB\xBF/, "") : newChunk, [complete, incomplete] = splitLines(`${incompleteLine}${chunk}`);
for (const line of complete)
parseLine(line);
incompleteLine = incomplete, isFirstChunk = !1;
}
function parseLine(line) {
if (line === "") {
dispatchEvent();
return;
}
if (line.startsWith(":")) {
onComment && onComment(line.slice(line.startsWith(": ") ? 2 : 1));
return;
}
const fieldSeparatorIndex = line.indexOf(":");
if (fieldSeparatorIndex !== -1) {
const field = line.slice(0, fieldSeparatorIndex), offset = line[fieldSeparatorIndex + 1] === " " ? 2 : 1, value = line.slice(fieldSeparatorIndex + offset);
processField(field, value, line);
return;
}
processField(line, "", line);
}
function processField(field, value, line) {
switch (field) {
case "event":
eventType = value;
break;
case "data":
data = `${data}${value}
`;
break;
case "id":
id = value.includes("\0") ? void 0 : value;
break;
case "retry":
/^\d+$/.test(value) ? onRetry(parseInt(value, 10)) : onError(
new ParseError(`Invalid \`retry\` value: "${value}"`, {
type: "invalid-retry",
value,
line
})
);
break;
default:
onError(
new ParseError(
`Unknown field "${field.length > 20 ? `${field.slice(0, 20)}\u2026` : field}"`,
{ type: "unknown-field", field, value, line }
)
);
break;
}
}
function dispatchEvent() {
data.length > 0 && onEvent({
id,
event: eventType || void 0,
// If the data buffer's last character is a U+000A LINE FEED (LF) character,
// then remove the last character from the data buffer.
data: data.endsWith(`
`) ? data.slice(0, -1) : data
}), id = void 0, data = "", eventType = "";
}
function reset(options = {}) {
incompleteLine && options.consume && parseLine(incompleteLine), isFirstChunk = !0, id = void 0, data = "", eventType = "", incompleteLine = "";
}
return { feed, reset };
}
function splitLines(chunk) {
const lines = [];
let incompleteLine = "", searchIndex = 0;
for (; searchIndex < chunk.length; ) {
const crIndex = chunk.indexOf("\r", searchIndex), lfIndex = chunk.indexOf(`
`, searchIndex);
let lineEnd = -1;
if (crIndex !== -1 && lfIndex !== -1 ? lineEnd = Math.min(crIndex, lfIndex) : crIndex !== -1 ? lineEnd = crIndex : lfIndex !== -1 && (lineEnd = lfIndex), lineEnd === -1) {
incompleteLine = chunk.slice(searchIndex);
break;
} else {
const line = chunk.slice(searchIndex, lineEnd);
lines.push(line), searchIndex = lineEnd + 1, chunk[searchIndex - 1] === "\r" && chunk[searchIndex] === `
` && searchIndex++;
}
}
return [lines, incompleteLine];
}
exports.ParseError = ParseError;
exports.createParser = createParser;
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