Filter Extension - add Accent and Case-insensitive Comparison conform…

CHANGELOG.md

@@ -4,6 +4,23 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [v1.0.0-rc.1] - TBD
+
+### Added
+
+- The CQL2 Accent and Case-insensitive Comparison 
+    (`http://www.opengis.net/spec/cql2/1.0/conf/accent-case-insensitive-comparison`) conformance class
+    adds the ACCENTI and CASEI functions for case-insensitive comparison. These replace the UPPER and
+    LOWER psuedo-functions that were previously part of the Advanced Comparison Operators class.
+
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
 ## [v1.0.0-beta.5] - 2022-01-14
 
 ### Added

extensions.md

@@ -62,6 +62,7 @@ the service supports. This are listed at the top of each extension description,
   - <http://www.opengis.net/spec/cql2/1.0/conf/arithmetic>
   - <http://www.opengis.net/spec/cql2/1.0/conf/array-operators>
   - <http://www.opengis.net/spec/cql2/1.0/conf/property-property>
+  - <http://www.opengis.net/spec/cql2/1.0/conf/accent-case-insensitive-comparison>
 - [Context](item-search/README.md#context-extension)
   - <https://api.stacspec.org/v1.0.0-beta.5/item-search#context>
   - <https://api.stacspec.org/v1.0.0-beta.5/ogcapi-features#context>

fragments/filter/README.md

@@ -15,6 +15,7 @@
   - Arithmetic Expressions: <http://www.opengis.net/spec/cql2/1.0/conf/arithmetic>
   - Array Operators: <http://www.opengis.net/spec/cql2/1.0/conf/array-operators>
   - Property-Property Comparisons: <http://www.opengis.net/spec/cql2/1.0/conf/property-property>
+  - Accent and Case-insensitive Comparison: <http://www.opengis.net/spec/cql2/1.0/conf/accent-case-insensitive-comparison>
 - **Extension [Maturity Classification](../../README.md#maturity-classification):** Pilot
 - **Dependents:**
   - [Item Search](../../item-search)
@@ -62,6 +63,12 @@
     - [Example 11: Using LIKE](#example-11-using-like)
       - [Example 11: cql2-text (GET)](#example-11-cql2-text-get)
       - [Example 11: cql2-json (POST)](#example-11-cql2-json-post)
+    - [Example 12: Using the CASEI Case-insensitive Comparison Function](#example-12-using-the-casei-case-insensitive-comparison-function)
+      - [Example 12: cql2-text (GET)](#example-12-cql2-text-get)
+      - [Example 12: cql2-json (POST)](#example-12-cql2-json-post)
+    - [Example 13: Using the ACCENTI Accent-insensitive Comparison Function](#example-13-using-the-accenti-accent-insensitive-comparison-function)
+      - [Example 13: cql2-text (GET)](#example-13-cql2-text-get)
+      - [Example 13: cql2-json (POST)](#example-13-cql2-json-post)
 
 ## Overview
 
@@ -187,8 +194,10 @@ For additional capabilities, the following classes can be implemented:
   defines array operators (`A_EQUALS`, `A_CONTAINS`, `A_CONTAINED_BY`, and `A_OVERLAPS`).
 - Property-Property Comparisons: (`http://www.opengis.net/spec/cql2/1.0/conf/property-property`)
   allows the use of queryables (e.g., properties) in both positions of a clause, not just in the
-  first position. This allows predicates like `property1 == property2` be expressed, whereas the
+  first position. This allows predicates like `property1 = property2` be expressed, whereas the
   Basic CQL2 conformance class only requires comparisons against right-hand-side literals.
+- Accent and Case-insensitive Comparison: (`http://www.opengis.net/spec/cql2/1.0/conf/accent-case-insensitive-comparison`)
+  defines the UPPER and LOWER functions that can be used for case-insensitive comparison.
 
 Additionally, if an API implements the OGC API Features endpoint, it is **recommended** that the OAFeat Part 3 Filter,
 Features Filter, and Basic CQL2 conformance classes be implemented, which allow use of CQL2 filters against the
@@ -985,18 +994,23 @@ filter=mission LIKE 'sentinel%'
 }
 ```
 
-<!-- ### Example 12: Using Case-insensitive Comparison Functions
+### Example 12: Using the CASEI Case-insensitive Comparison Function
 
-The predefined function `CASEI` allows for case-insensitive comparisons.
+The predefined function `CASEI` allows for case-insensitive comparisons. This function is
+defined in the Accent and Case-insensitive Comparison conformance class.
+
+In the example using 'Straße', both the capitalized 'S' and Eszett ('ß') are converted to an
+insensitive representation whereby the expressions `CASEI('Straße')`, `CASEI('straße')`,
+`CASEI('Strasse')`, and `CASEI('strasse')` are all equal.
 
 #### Example 12: cql2-text (GET)
 
 ```http
-filter=CASEI(provider) = 'coolsat'
+filter=CASEI(provider) = CASEI('coolsat')
 ```
 
 ```http
-filter=CASEI(provider) = 'NASA'
+filter=CASEI(provider) = CASEI('Straße')
 ```
 
 #### Example 12: cql2-json (POST)
@@ -1007,10 +1021,14 @@ filter=CASEI(provider) = 'NASA'
   "filter": {
     "op": "=",
     "args": [
-      {
-        "lower" : { "property": "provider" }
+      { 
+        "function" : "casei", 
+        "args" : [ { "property": "provider" } ]
       },
-      "coolsat"
+      { 
+        "function" : "casei", 
+        "args" : [ "coolsat" ]
+      }
     ]
   }
 }
@@ -1022,11 +1040,48 @@ filter=CASEI(provider) = 'NASA'
   "filter": {
     "op": "=",
     "args": [
-      {
-        "upper": { "property": "provider" }
+      { 
+        "function" : "casei", 
+        "args" : [ { "property": "provider" } ]
+      },
+      { 
+        "function" : "casei", 
+        "args" : [ "Straße" ]
+      }
+    ]
+  }
+}
+```
+
+### Example 13: Using the ACCENTI Accent-insensitive Comparison Function
+
+The predefined function `ACCENTI` allows for accent-insensitive comparisons. This function is
+defined in the Accent and Case-insensitive Comparison conformance class. In the example below,
+`ACCENTI('tiburon')` and `ACCENTI('tiburón')` evaluate to be equal.
+
+#### Example 13: cql2-text (GET)
+
+```http
+filter=ACCENTI(provider) = ACCENTI('tiburón')
+```
+
+#### Example 13: cql2-json (POST)
+
+```json
+{
+  "filter-lang": "cql2-json",
+  "filter": {
+    "op": "=",
+    "args": [
+      { 
+        "function" : "accenti", 
+        "args" : [ { "property": "provider" } ]
       },
-      "NASA"
+      { 
+        "function" : "accenti", 
+        "args" : [ "tiburón" ]
+      }
     ]
   }
 }
-``` -->
+```