next/dist/esm/shared/lib/router/utils/sortable-routes.js

The React Framework

/**
 * A route that can be sorted by specificity.
 */ /**
 * Determines the specificity of a route segment for sorting purposes.
 *
 * In Next.js routing, more specific routes should match before less specific ones.
 * This function returns a numeric value where lower numbers indicate higher specificity.
 *
 * Specificity order (most to least specific):
 * 1. Static segments (e.g., "about", "api") - return 0
 * 2. Dynamic segments (e.g., "[id]", "[slug]") - return 1
 * 3. Catch-all segments (e.g., "[...slug]") - return 2
 * 4. Optional catch-all segments (e.g., "[[...slug]]") - return 3
 *
 * @param segment - A single path segment (e.g., "api", "[id]", "[...slug]")
 * @returns A numeric specificity value (0-3, where 0 is most specific)
 */ export function getSegmentSpecificity(segment) {
    // Static segments are most specific - they match exactly one path
    if (!segment.includes('[')) {
        return 0;
    }
    // Optional catch-all [[...param]] is least specific - matches zero or more segments
    if (segment.startsWith('[[...') && segment.endsWith(']]')) {
        return 3;
    }
    // Catch-all [...param] is less specific - matches one or more segments
    if (segment.startsWith('[...') && segment.endsWith(']')) {
        return 2;
    }
    // Regular dynamic [param] is more specific than catch-all - matches exactly one segment
    if (segment.startsWith('[') && segment.endsWith(']')) {
        return 1;
    }
    // Default to static (fallback case)
    return 0;
}
/**
 * Compares two route paths using a depth-first traversal approach.
 *
 * This function implements a deterministic comparison that sorts routes by specificity:
 * 1. More specific routes come first (fewer dynamic segments)
 * 2. Shorter routes are more specific than longer ones
 * 3. Routes with same specificity are sorted lexicographically
 *
 * The comparison is done segment by segment, left to right, similar to how
 * you would traverse a route tree in depth-first order.
 *
 * @param pathA - First route path to compare (e.g., "/api/users/[id]")
 * @param pathB - Second route path to compare (e.g., "/api/[...slug]")
 * @returns Negative if pathA is more specific, positive if pathB is more specific, 0 if equal
 */ export function compareRouteSegments(pathA, pathB) {
    // Split paths into segments, removing empty strings from leading/trailing slashes
    const segmentsA = pathA.split('/').filter(Boolean);
    const segmentsB = pathB.split('/').filter(Boolean);
    // Compare segment by segment up to the length of the longer path
    const maxLength = Math.max(segmentsA.length, segmentsB.length);
    for(let i = 0; i < maxLength; i++){
        const segA = segmentsA[i] || '';
        const segB = segmentsB[i] || '';
        // Handle length differences: shorter routes are MORE specific
        // Example: "/api" is more specific than "/api/users"
        if (!segA && segB) return -1 // pathA is shorter, so more specific
        ;
        if (segA && !segB) return 1 // pathB is shorter, so more specific
        ;
        if (!segA && !segB) return 0 // Both paths ended, they're equal
        ;
        // Compare segment specificity using our specificity scoring
        const specificityA = getSegmentSpecificity(segA);
        const specificityB = getSegmentSpecificity(segB);
        // Lower specificity number = more specific route
        // Example: "api" (0) vs "[slug]" (1) - "api" wins
        if (specificityA !== specificityB) {
            return specificityA - specificityB;
        }
        // If segments have same specificity, compare lexicographically for determinism
        // Example: "[id]" vs "[slug]" - "[id]" comes first alphabetically
        if (segA !== segB) {
            return segA.localeCompare(segB);
        }
    // Segments are identical, continue to next segment
    }
    // All segments compared equally
    return 0;
}
/**
 * Compares two complete routes for sorting purposes.
 *
 * Routes are compared with a two-tier priority system:
 * 1. Primary: Compare by source path specificity
 * 2. Secondary: If sources are equal, compare by page path specificity
 *
 * This ensures that routes are primarily organized by their source patterns,
 * with page-specific variations grouped together.
 *
 * @param a - First route to compare
 * @param b - Second route to compare
 * @returns Negative if route a should come first, positive if route b should come first, 0 if equal
 */ function compareSortableRoutes(a, b) {
    // First compare by source specificity - this is the primary sorting criterion
    // Source represents the original route pattern and takes precedence
    const sourceResult = compareRouteSegments(a.sourcePage, b.sourcePage);
    if (sourceResult !== 0) return sourceResult;
    // If sources are identical, compare by page specificity as a tiebreaker
    // Page represents the final rendered route and provides secondary ordering
    return compareRouteSegments(a.page, b.page);
}
/**
 * Sorts an array of routes by specificity using a deterministic depth-first traversal approach.
 *
 * This function implements Next.js route matching priority where more specific routes
 * should be matched before less specific ones. The sorting is deterministic and stable,
 * meaning identical inputs will always produce identical outputs.
 *
 * Sorting criteria (in order of priority):
 * 1. Source path specificity (primary)
 * 2. Page path specificity (secondary)
 * 3. Lexicographic ordering (tertiary, for determinism)
 *
 * Examples of specificity order:
 * - "/api/users" (static) comes before "/api/[slug]" (dynamic)
 * - "/api/[id]" (dynamic) comes before "/api/[...slug]" (catch-all)
 * - "/api/[...slug]" (catch-all) comes before "/api/[[...slug]]" (optional catch-all)
 *
 * @param routes - Array of routes to sort
 * @returns New sorted array (does not mutate input)
 */ export function sortSortableRoutes(routes) {
    // Because sort is always in-place, we need to create a shallow copy to avoid
    // mutating the input array.
    return [
        ...routes
    ].sort(compareSortableRoutes);
}
/**
 * Sorts an array of pages by specificity using a deterministic depth-first
 * traversal approach.
 *
 * @param pages - Array of pages to sort
 * @returns New sorted array (does not mutate input)
 */ export function sortPages(pages) {
    // Because sort is always in-place, we need to create a shallow copy to avoid
    // mutating the input array.
    return [
        ...pages
    ].sort(compareRouteSegments);
}
/**
 * Sorts an array of objects by sourcePage and page using a deterministic
 * depth-first traversal approach.
 *
 * @param objects - Array of objects to sort
 * @param getter - Function to get the sourcePage and page from an object
 * @returns New sorted array (does not mutate input)
 */ export function sortSortableRouteObjects(objects, getter) {
    // Create a SortableRoute for each object.
    const routes = [];
    for (const object of objects){
        const route = getter(object);
        routes.push({
            ...route,
            object
        });
    }
    // In-place sort the SortableRoutes.
    routes.sort(compareSortableRoutes);
    // Map the sorted SortableRoutes back to the original objects.
    return routes.map(({ object })=>object);
}
/**
 * Sorts an array of objects by page using a deterministic depth-first traversal
 * approach.
 *
 * @param objects - Array of objects to sort
 * @param getter - Function to get the page from an object
 * @returns New sorted array (does not mutate input)
 */ export function sortPageObjects(objects, getter) {
    const indexes = {};
    const pages = new Set();
    for(let i = 0; i < objects.length; i++){
        const object = objects[i];
        const page = getter(object);
        indexes[page]?.push(i) || (indexes[page] = [
            i
        ]);
        pages.add(page);
    }
    // Sort the unique pages.
    const sortedPages = Array.from(pages).sort(compareRouteSegments);
    // Map the sorted pages back to the original objects.
    return sortedPages.reduce((sortedObjects, page)=>{
        // Add all objects for this page to the sorted array.
        for (const i of indexes[page]){
            sortedObjects.push(objects[i]);
        }
        // Return the sorted array.
        return sortedObjects;
    }, []);
}

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