parser.ts•3.9 kB
// Page range parsing utilities
import { ErrorCode, McpError } from '@modelcontextprotocol/sdk/types.js';
const MAX_RANGE_SIZE = 10000; // Prevent infinite loops for open ranges
/**
* Parse a single range part (e.g., "1-3", "5", "7-")
*/
const parseRangePart = (part: string, pages: Set<number>): void => {
const trimmedPart = part.trim();
if (trimmedPart.includes('-')) {
const splitResult = trimmedPart.split('-');
const startStr = splitResult[0] || '';
const endStr = splitResult[1];
const start = parseInt(startStr, 10);
const end = endStr === '' || endStr === undefined ? Infinity : parseInt(endStr, 10);
if (Number.isNaN(start) || Number.isNaN(end) || start <= 0 || start > end) {
throw new Error(`Invalid page range values: ${trimmedPart}`);
}
const practicalEnd = Math.min(end, start + MAX_RANGE_SIZE);
for (let i = start; i <= practicalEnd; i++) {
pages.add(i);
}
if (end === Infinity && practicalEnd === start + MAX_RANGE_SIZE) {
console.warn(
`[PDF Reader MCP] Open-ended range starting at ${String(start)} was truncated at page ${String(practicalEnd)}.`
);
}
} else {
const page = parseInt(trimmedPart, 10);
if (Number.isNaN(page) || page <= 0) {
throw new Error(`Invalid page number: ${trimmedPart}`);
}
pages.add(page);
}
};
/**
* Parse page range string into array of page numbers
* @param ranges - Range string (e.g., "1-3,5,7-10")
* @returns Sorted array of unique page numbers
*/
export const parsePageRanges = (ranges: string): number[] => {
const pages = new Set<number>();
const parts = ranges.split(',');
for (const part of parts) {
parseRangePart(part, pages);
}
// This should never happen as parseRangePart would have thrown an error
// if no valid pages were found, but we keep this as a safety check
/* c8 ignore next */
if (pages.size === 0) {
throw new Error('Page range string resulted in zero valid pages.');
}
return Array.from(pages).sort((a, b) => a - b);
};
/**
* Get target pages from page specification
* @param sourcePages - Page specification (string or array)
* @param sourceDescription - Description for error messages
* @returns Array of page numbers or undefined
*/
export const getTargetPages = (
sourcePages: string | number[] | undefined,
sourceDescription: string
): number[] | undefined => {
if (!sourcePages) {
return undefined;
}
try {
if (typeof sourcePages === 'string') {
return parsePageRanges(sourcePages);
}
// Array of page numbers
if (sourcePages.some((p) => !Number.isInteger(p) || p <= 0)) {
throw new Error('Page numbers in array must be positive integers.');
}
const uniquePages = [...new Set(sourcePages)].sort((a, b) => a - b);
if (uniquePages.length === 0) {
throw new Error('Page specification resulted in an empty set of pages.');
}
return uniquePages;
} catch (error: unknown) {
const message = error instanceof Error ? error.message : String(error);
throw new McpError(
ErrorCode.InvalidParams,
`Invalid page specification for source ${sourceDescription}: ${message}`
);
}
};
/**
* Determine which pages to process based on target pages and document size
*/
export const determinePagesToProcess = (
targetPages: number[] | undefined,
totalPages: number,
includeFullText: boolean
): { pagesToProcess: number[]; invalidPages: number[] } => {
if (targetPages) {
const pagesToProcess = targetPages.filter((p) => p <= totalPages);
const invalidPages = targetPages.filter((p) => p > totalPages);
return { pagesToProcess, invalidPages };
}
if (includeFullText) {
const pagesToProcess = Array.from({ length: totalPages }, (_, i) => i + 1);
return { pagesToProcess, invalidPages: [] };
}
return { pagesToProcess: [], invalidPages: [] };
};