A more flexible app structure.
Goal
In this tutorial chapter, we'll refactor the apps we built in so that they look exactly the same from the end user's point of view, but offer the developer greater possibilites for expansion.
To achieve this, we'll ditch Lucy::Simple and replace it with the classes that it uses internally:
- - Plan out your index.
- - Field type for full text search.
- - A one-size-fits-all parser/tokenizer.
- - Manipulate index content.
- - Search an index.
- - Iterate over hits returned by a Searcher.
Adaptations to indexer.pl
After we load our modules...
``` c
include
include
include
include
define CFISH_USE_SHORT_NAMES
define LUCY_USE_SHORT_NAMES
include "Clownfish/String.h"
include "Lucy/Analysis/EasyAnalyzer.h"
include "Lucy/Document/Doc.h"
include "Lucy/Index/Indexer.h"
include "Lucy/Plan/FullTextType.h"
include "Lucy/Plan/StringType.h"
include "Lucy/Plan/Schema.h"
const char path_to_index[] = "/path/to/index"; const char uscon_source[] = "/usr/local/apache2/htdocs/us_constitution"; ```
perl
use Lucy::Plan::Schema;
use Lucy::Plan::FullTextType;
use Lucy::Analysis::EasyAnalyzer;
use Lucy::Index::Indexer;
... the first item we're going need is a .
The primary job of a Schema is to specify what fields are available and how they're defined. We'll start off with three fields: title, content and url.
``` c static Schema* S_create_schema() { // Create a new schema. Schema *schema = Schema_new();
// Create an analyzer.
String *language = Str_newf("en");
EasyAnalyzer *analyzer = EasyAnalyzer_new(language);
// Specify fields.
FullTextType *type = FullTextType_new((Analyzer*)analyzer);
{
String *field_str = Str_newf("title");
Schema_Spec_Field(schema, field_str, (FieldType*)type);
DECREF(field_str);
}
{
String *field_str = Str_newf("content");
Schema_Spec_Field(schema, field_str, (FieldType*)type);
DECREF(field_str);
}
{
String *field_str = Str_newf("url");
Schema_Spec_Field(schema, field_str, (FieldType*)type);
DECREF(field_str);
}
DECREF(type);
DECREF(analyzer);
DECREF(language);
return schema;
} ```
``` perl
Create Schema.
my $schema = Lucy::Plan::Schema->new; my $easyanalyzer = Lucy::Analysis::EasyAnalyzer->new( language => 'en', ); my $type = Lucy::Plan::FullTextType->new( analyzer => $easyanalyzer, ); $schema->spec_field( name => 'title', type => $type ); $schema->spec_field( name => 'content', type => $type ); $schema->spec_field( name => 'url', type => $type ); ```
All of the fields are spec'd out using the FieldType, indicating that they will be searchable as "full text" -- which means that they can be searched for individual words. The "analyzer", which is unique to FullTextType fields, is what breaks up the text into searchable tokens.
Next, we'll swap our Lucy::Simple object out for an . The substitution will be straightforward because Simple has merely been serving as a thin wrapper around an inner Indexer, and we'll just be peeling away the wrapper.
First, replace the constructor:
``` c int main() { // Initialize the library. lucy_bootstrap_parcel();
Schema *schema = S_create_schema();
String *folder = Str_newf("%s", path_to_index);
Indexer *indexer = Indexer_new(schema, (Obj*)folder, NULL,
Indexer_CREATE | Indexer_TRUNCATE);
```
``` perl
Create Indexer.
my $indexer = Lucy::Index::Indexer->new( index => $path_to_index, schema => $schema, create => 1, truncate => 1, ); ```
Next, have the indexer
object where we
were having the lucy
object adding the document before:
``` c DIR *dir = opendir(uscon_source); if (dir == NULL) { perror(uscon_source); return 1; }
for (struct dirent *entry = readdir(dir);
entry;
entry = readdir(dir)) {
if (S_ends_with(entry->d_name, ".txt")) {
Doc *doc = S_parse_file(entry->d_name);
Indexer_Add_Doc(indexer, doc, 1.0);
DECREF(doc);
}
}
closedir(dir);
```
perl
foreach my $filename (@filenames) {
my $doc = parse_file($filename);
$indexer->add_doc($doc);
}
There's only one extra step required: at the end of the app, you must call commit() explicitly to close the indexing session and commit your changes. (Lucy::Simple hides this detail, calling commit() implicitly when it needs to).
``` c Indexer_Commit(indexer);
DECREF(indexer);
DECREF(folder);
DECREF(schema);
return 0;
} ```
perl
$indexer->commit;
Adaptations to search.cgi
In our search app as in our indexing app, Lucy::Simple has served as a thin wrapper -- this time around and . Swapping out Simple for these two classes is also straightforward:
``` c
include
include
include
define CFISH_USE_SHORT_NAMES
define LUCY_USE_SHORT_NAMES
include "Clownfish/String.h"
include "Lucy/Document/HitDoc.h"
include "Lucy/Search/Hits.h"
include "Lucy/Search/IndexSearcher.h"
const char path_to_index[] = "/path/to/index";
int main(int argc, char *argv[]) { // Initialize the library. lucy_bootstrap_parcel();
if (argc < 2) {
printf("Usage: %s <querystring>\n", argv[0]);
return 0;
}
const char *query_c = argv[1];
printf("Searching for: %s\n\n", query_c);
String *folder = Str_newf("%s", path_to_index);
IndexSearcher *searcher = IxSearcher_new((Obj*)folder);
String *query_str = Str_newf("%s", query_c);
Hits *hits = IxSearcher_Hits(searcher, (Obj*)query_str, 0, 10, NULL);
String *title_str = Str_newf("title");
String *url_str = Str_newf("url");
HitDoc *hit;
int i = 1;
// Loop over search results.
while (NULL != (hit = Hits_Next(hits))) {
String *title = (String*)HitDoc_Extract(hit, title_str);
char *title_c = Str_To_Utf8(title);
String *url = (String*)HitDoc_Extract(hit, url_str);
char *url_c = Str_To_Utf8(url);
printf("Result %d: %s (%s)\n", i, title_c, url_c);
free(url_c);
free(title_c);
DECREF(url);
DECREF(title);
DECREF(hit);
i++;
}
DECREF(url_str);
DECREF(title_str);
DECREF(hits);
DECREF(query_str);
DECREF(searcher);
DECREF(folder);
return 0;
} ```
``` perl use Lucy::Search::IndexSearcher;
my $searcher = Lucy::Search::IndexSearcher->new( index => $path_to_index, ); my $hits = $searcher->hits( # returns a Hits object, not a hit count query => $q, offset => $offset, num_wanted => $page_size, ); my $hit_count = $hits->total_hits; # get the hit count here
...
while ( my $hit = $hits->next ) { ... } ```
Hooray!
Congratulations! Your apps do the same thing as before... but now they'll be easier to customize.
In our next chapter, , we'll explore how to assign different behaviors to different fields.