Add an opt-in option to lowercase filter values

Filter values that only differ in case, like `Mint` and `mint`, came
through as separate values. The new `--lowercase-filters` option
(`lowercase_filters`, `PAGEFIND_LOWERCASE_FILTERS`, and
`lowercaseFilters` / `lowercase_filters` in the Node and Python
wrappers) lowercases filter values when indexing and merges values on
a page that become equal. Filter names are left as they are. Off by
default.

Fixes #737

wrappers/node/lib/index.js

@@ -59,6 +59,7 @@ export const createIndex = (config) => new Promise((resolve, reject) => {
                 keep_index_url: config?.keepIndexUrl,
                 write_playground: config?.writePlayground,
                 include_characters: config?.includeCharacters,
+                lowercase_filters: config?.lowercaseFilters,
             }
         }, (response) => {
             /** @type {function(InternalResponsePayload): Omit<NewIndexResponse, 'errors'>?} */

wrappers/node/types/index.d.ts

@@ -56,6 +56,10 @@ export interface PagefindServiceConfig {
      * @example "<>$"
      */
     includeCharacters?: string,
+    /**
+     * Lowercase filter values when indexing, so that values differing only in case are merged into one.
+     */
+    lowercaseFilters?: boolean,
 }
 
 

wrappers/node/types/internal.d.ts

@@ -34,6 +34,7 @@ export interface InternalPagefindServiceConfig {
     keep_index_url?: boolean,
     write_playground?: boolean,
     include_characters?: string,
+    lowercase_filters?: boolean,
 }
 
 export interface InternalAddFileRequest {

wrappers/python/src/pagefind/index/__init__.py

@@ -59,6 +59,8 @@ class IndexConfig(TypedDict, total=False):
 
     Useful for sites documenting technical topics such as programming languages.
     """
+    lowercase_filters: Optional[bool]
+    """Lowercase filter values when indexing, so that values differing only in case are merged into one."""
     output_path: Optional[str]
     """
     The folder to output the search bundle into, relative to the processed site.

wrappers/python/src/pagefind/service/types.py

@@ -22,6 +22,7 @@ class InternalPagefindServiceConfig(TypedDict, total=False):
     keep_index_url: Optional[bool]
     write_playground: Optional[bool]
     include_characters: Optional[str]
+    lowercase_filters: Optional[bool]
 
 
 class InternalNewIndexRequest(TypedDict):