feat(post): add alphanumeric postcodes post-processing script

Document.js

@@ -41,6 +41,7 @@ function Document( source, layer, source_id ){
   // define default post-processing scripts
   this.addPostProcessingScript( require('./post/intersections') );
   this.addPostProcessingScript( require('./post/seperable_street_names').post );
+  this.addPostProcessingScript( require('./post/alphanumeric_postcodes') );
   this.addPostProcessingScript( require('./post/deduplication') );
   this.addPostProcessingScript( require('./post/language_field_trimming') );
   this.addPostProcessingScript( require('./post/popularity') );

post/alphanumeric_postcodes.js

@@ -0,0 +1,51 @@
+const _ = require('lodash');
+const ADDRESS_LAYER_NAME = 'address';
+const ALPHANUMERIC_POSTCODE = /^(\d{4})\s*([^\d]{2})$/;
+
+/**
+ * Alphanumeric postcodes post-processing script ensures that both the expanded
+ * and contracted version of alphanumeric postcodes are indexed.
+ *
+ * Without this script a postcode such as '1383GN' would not be matched to the
+ * query '1383'.
+ * 
+ * The script is intended to detect these alphanumeric postcodes and index both
+ * permutations, ie. '1383GN' = ['1383GN', '1383 GN'].
+ * 
+ * The inverse case should also be covered. ie. '1383 GN' = ['1383 GN', '1383GN'].
+ * 
+ * Note: the regex is currently restrictive by design, the UK for instance uses
+ * alphanumeric postcodes in the format 'E81DN' which could cause error when splitting
+ * with this method, they are currently ignored. Future work should consider global
+ * postcode formats.
+ * 
+ * Note: this script is intended to run *before* the 'deduplication' post processing
+ * script that prior aliases don't generate duplicate terms.
+ */
+
+function postcodes( doc ){
+
+  // only apply to docs from the address layer
+  if( doc.getLayer() !== ADDRESS_LAYER_NAME ){ return; }
+
+  // ensure postcode is set
+  let postcode = doc.getAddress('zip');
+  if( !_.isString(postcode) || _.isEmpty(postcode) ){ return; }
+
+  // ensure postcode is alphanumeric
+  let matches = postcode.match(ALPHANUMERIC_POSTCODE);
+  if( matches.length !== 3 ){ return; }
+
+  // generate postcode aliases for the postcode.
+  let [ match, numeric, alpha ] = matches;
+
+  // detect if the existing postcode is expanded or not
+  let isExpanded = /\s/.test(match);
+  if ( isExpanded ) {
+    doc.setAddressAlias('zip', `${numeric}${alpha}`); // add contracted form as alias
+  } else {
+    doc.setAddressAlias('zip', `${numeric} ${alpha}`); // add expanded form as alias
+  }
+}
+
+module.exports = postcodes;

test/document/post.js

@@ -2,10 +2,14 @@
 const Document = require('../../Document');
 const intersections = require('../../post/intersections');
 const seperable_street_names = require('../../post/seperable_street_names').post;
+const alphanumeric_postcodes = require('../../post/alphanumeric_postcodes');
 const deduplication = require('../../post/deduplication');
 const language_field_trimming = require('../../post/language_field_trimming');
 const popularity = require('../../post/popularity');
-const DEFAULT_SCRIPTS = [intersections, seperable_street_names, deduplication, language_field_trimming, popularity];
+const DEFAULT_SCRIPTS = [
+  intersections, seperable_street_names, alphanumeric_postcodes, 
+  deduplication, language_field_trimming, popularity
+];
 
 module.exports.tests = {};
 

test/post/alphanumeric_postcodes.js

@@ -0,0 +1,76 @@
+const Document = require('../../Document');
+const postcodes = require('../../post/alphanumeric_postcodes');
+
+module.exports.tests = {};
+
+module.exports.tests.alias = function(test) {
+  test('expand', function(t) {
+    const doc = new Document('mysource','address','myid');
+
+    // zip not set
+    postcodes(doc);
+    t.deepEqual(doc.getAddressAliases('zip'), [], 'no alias set');
+
+    // set postcode
+    doc.setAddress('zip', '1383GN');
+
+    // add expanded version
+    postcodes(doc);
+    t.deepEqual(doc.getAddressAliases('zip'), ['1383 GN'], 'alias set');
+
+    t.end();
+  });
+  test('contract', function(t) {
+    const doc = new Document('mysource','address','myid');
+
+    // zip not set
+    postcodes(doc);
+    t.deepEqual(doc.getAddressAliases('zip'), [], 'no alias set');
+
+    // set postcode
+    doc.setAddress('zip', '1383 GN');
+
+    // add contracted version
+    postcodes(doc);
+    t.deepEqual(doc.getAddressAliases('zip'), ['1383GN'], 'alias set');
+
+    t.end();
+  });
+};
+
+module.exports.tests.noop = function(test) {
+  test('noop: invalid layer != "address"', function(t) {
+    const doc = new Document('mysource','not_address','myid');
+
+    // set postcode
+    doc.setAddress('zip', '1383GN');
+
+    // no alias added
+    t.deepEqual(doc.getAddressAliases('zip'), [], 'no alias set');
+
+    t.end();
+  });
+
+  test('noop: postcode doesnt match regex', function(t) {
+    const doc = new Document('mysource','address','myid');
+
+    // set postcode
+    doc.setAddress('zip', 'E81DN');
+
+    // no alias added
+    t.deepEqual(doc.getAddressAliases('zip'), [], 'no alias set');
+
+    t.end();
+  });
+};
+
+module.exports.all = function (tape, common) {
+
+  function test(name, testFunction) {
+    return tape('post/alphanumeric_postcodes: ' + name, testFunction);
+  }
+
+  for( var testCase in module.exports.tests ){
+    module.exports.tests[testCase](test, common);
+  }
+};

test/run.js

@@ -1,7 +1,7 @@
-var tape = require('tape');
-var common = {};
+const tape = require('tape');
+const common = {};
 
-var tests = [
+const tests = [
   require('./Document.js'),
   require('./errors.js'),
   require('./document/centroid.js'),
@@ -23,6 +23,7 @@ var tests = [
   require('./document/toESDocument.js'),
   require('./document/post.js'),
   require('./post/intersections.js'),
+  require('./post/alphanumeric_postcodes.js'),
   require('./post/deduplication.js'),
   require('./post/seperable_street_names.js'),
   require('./post/language_field_trimming.js'),