procedure (tei-document->excerpt-max-allow-chars doc)

→ exact-positive-integer?

doc : tei-document?

method (send a-searchable-document-set do-term-search       norm-term       #:ricoeur-only? ricoeur-only?       #:languages languages       #:book/article book/article       #:exact? exact?)

→ (instance-set/c document-search-results?)

norm-term : normalized-term?

ricoeur-only? : any/c

languages : (set/c language-symbol/c #:cmp 'eq #:kind 'immutable)

book/article : (or/c 'any 'book 'article)

exact? : any/c

The method used to implement searchable-document-set-do-term-search.

There are a few notable differences between do-term-search and all of the higher-level search functions or methods:

1. All of the keyword arguments are mandatory. As there are several different classes that implement searchable-document-set<%>, copying the default values correctly to every definition would be unpleasant and error-prone.

2. The search term is passed as a normalized term value, rather than a string satisfying term/c. This prevents do-term-search from being called except by searchable-document-set-do-term-search, which allows the implementation of searchable-document-set-do-term-search to rely on the fact that it will be able to interpose on calls. In fact, the implementation does do some normalization when constructing a normalized term value, and it can guarantee that it will always have the chance to do so.

3. The languages argument is normalized: rather than being passed as a search-languages/c value, which is designed for the convienience of clients, it is given as an immutable set of language-symbol/c symbols. This allows searchable-document-set-do-term-search to take sole responsibility for handling 'any and lists with duplicate symbols, rather than placing that burden on every class that implements searchable-document-set<%>.

procedure (normalized-term? v) → any/c   v : any/c

procedure (normalized-term-string norm-term)  → (and/c term/c trimmed-string-px)   norm-term : normalized-term?

procedure (pregexp-quote-normalized-term   norm-term       #:exact? exact?)    → string-immutable/c   norm-term : normalized-term?   exact? : any/c

procedure (segment-make-search-results seg excerpts)

→ (listof search-result?)

seg : segment?

excerpts   :   (listof (maybe/c (and/c string-immutable/c                         #px"[^\\s]")))

procedure (search-result-nullify-excerpt result) → search-result?

result : search-result?

procedure (make-document-search-results info results)

→ document-search-results?

info : instance-info?

results : (non-empty-listof search-result?)

signature search^ : signature

value search-backend/c : contract?

A search^ unit should define search-backend/c as a contract recognizing the new type of search backend value it wants to support.

A search^ unit’s search backend implementation need only provide a basic contract and initialize it eagerly in initialize-search-backend. The additional variants permitted by the final, public search-backend/c (see lazy+eager-search-backend/c) are added using define-lazy-search-unit.

procedure (initialize-search-backend backend docs)

→ searchable-document-set?

backend : search-backend/c

docs : (instance-set/c tei-document?)

The search^ unit’s initialize-search-backend will be called with a backend search backend value satisfying the unit’s specific definiton of search-backend/c. The unit’s implementation of initialize-search-backend is responsible for returning a searchable document set: that is, an instance of a class that implements searchable-document-set<%>.

Typically, initialize-search-backend will be a wrapper around a constructor for a unit-specific searchable-document-set<%> class, and the unit’s notion of a search-backend/c value will to encapsulate all of the other data needed to initialize the class.

However, this is not mandatory. The implementation of initialize-search-backend from noop@, for example, ignores its arguments and always returns the singleton object noop-searchable-document-set.

value initialize-search-backend/c : contract?

=  (-> search-backend/c     (instance-set/c tei-document?)     searchable-document-set?)

The search^ signature uses define-values-for-export to define initialize-search-backend/c as the contract for that unit’s implementation of initialize-search-backend.

syntax (define-compound-search-unit compound-search-unit-id   member-search-unit-id ...+)

syntax (define-lazy-search-unit lazy-search-unit-id   eager-search-unit-id)

value noop@  :  (unit/c (import)         (export search^))

value regexp@  :  (unit/c (import)         (export search^))

value postgresql@  :  (unit/c (import)         (export search^))