* This stateful pass hides content from an opening tag through the matching

* closing tag, or to end-of-string if the stream was truncated mid-tag.

*/

const TOOL_CALL_QUICK_RE = /<\s*\/?\s*(?:tool_call|tool_result|function_calls?|tool_calls)\b/i;

const TOOL_CALL_QUICK_RE =

/<\s*\/?\s*(?:tool_call|tool_result|function_calls?|function|tool_calls)\b/i;

const TOOL_CALL_TAG_NAMES = new Set([

"tool_call",

"tool_result",

"function_call",

"function_calls",

"function",

"tool_calls",

]);

const TOOL_CALL_JSON_PAYLOAD_START_RE =

/^(?:\s+[A-Za-z_:][-A-Za-z0-9_:.]*\s*=\s*(?:"[^"]*"|'[^']*'|[^\s"'=<>`]+))*\s*(?:\r?\n\s*)?[[{]/;

const TOOL_CALL_XML_PAYLOAD_START_RE =

/^\s*(?:\r?\n\s*)?<(?:function|invoke|parameters?|arguments?)\b/i;

type ToolCallPayloadKind = "json" | "xml" | null;

function endsInsideQuotedString(text: string, start: number, end: number): boolean {

let quoteChar: "'" | '"' | null = null;

let isEscaped = false;

return -1;

}

function looksLikeToolCallPayloadStart(text: string, start: number): boolean {

function detectToolCallPayloadKind(text: string, start: number): ToolCallPayloadKind {

const rest = text.slice(start);

return TOOL_CALL_JSON_PAYLOAD_START_RE.test(rest) || TOOL_CALL_XML_PAYLOAD_START_RE.test(rest);

if (TOOL_CALL_JSON_PAYLOAD_START_RE.test(rest)) {

return "json";

}

if (TOOL_CALL_XML_PAYLOAD_START_RE.test(rest)) {

return "xml";

}

return null;

}

function isLikelyStandaloneFunctionToolCall(

text: string,

tagStart: number,

tag: ParsedToolCallTag,

): boolean {

if (tag.tagName !== "function" || tag.isClose || tag.isSelfClosing || tag.isTruncated) {

return false;

}

if (!/\bname\s*=/.test(text.slice(tag.contentStart, tag.end))) {

return false;

}

let idx = tagStart - 1;

while (idx >= 0 && (text[idx] === " " || text[idx] === "\t")) {

idx -= 1;

}

return idx < 0 || text[idx] === "\n" || text[idx] === "\r" || /[.!?:]/.test(text[idx]);

}

function parseToolCallTagAt(text: string, start: number): ParsedToolCallTag | null {

let result = "";

let lastIndex = 0;

let inToolCallBlock = false;

let toolCallContentStart = 0;

let toolCallBlockContentStart = 0;

let toolCallBlockNeedsQuoteBalance = false;

let toolCallBlockStart = 0;

let toolCallBlockTagName: string | null = null;

const visibleTagBalance = new Map<string, number>();

continue;

}

const payloadStart = tag.isTruncated ? tag.contentStart : tag.end;

const hasToolCallPayloadStart =

tag.tagName === "tool_call"

? looksLikeToolCallPayloadStart(text, payloadStart)

: TOOL_CALL_JSON_PAYLOAD_START_RE.test(text.slice(payloadStart));

if (!tag.isClose && hasToolCallPayloadStart) {

const payloadKind =

tag.tagName === "tool_call" || tag.tagName === "function"

? detectToolCallPayloadKind(text, payloadStart)

: TOOL_CALL_JSON_PAYLOAD_START_RE.test(text.slice(payloadStart))

? "json"

: null;

const shouldStripStandaloneFunction =

tag.tagName !== "function" || isLikelyStandaloneFunctionToolCall(text, idx, tag);

if (!tag.isClose && payloadKind && shouldStripStandaloneFunction) {

inToolCallBlock = true;

toolCallContentStart = tag.end;

toolCallBlockContentStart = tag.end;

toolCallBlockNeedsQuoteBalance = payloadKind === "json";

toolCallBlockStart = idx;

toolCallBlockTagName = tag.tagName;

if (tag.isTruncated) {

lastIndex = text.length;

tag.isClose &&

(tag.tagName === toolCallBlockTagName ||

(toolCallBlockTagName === "tool_result" && tag.tagName === "tool_call")) &&

!endsInsideQuotedString(text, toolCallContentStart, idx)

(!toolCallBlockNeedsQuoteBalance ||

!endsInsideQuotedString(text, toolCallBlockContentStart, idx))

) {

inToolCallBlock = false;

toolCallBlockNeedsQuoteBalance = false;

toolCallBlockTagName = null;

}

if (!inToolCallBlock) {

result += text.slice(lastIndex);

} else if (toolCallBlockTagName === "function") {

result += text.slice(toolCallBlockStart);

}

return result;