From 1df27928381eb21e043f57af019884aa27ad3aa0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Pant=C5=AF=C4=8Dek?=
 <dominik.pantucek@trustica.cz>
Date: Sun, 9 Apr 2023 19:34:27 +0200
Subject: [PATCH] Implement ldict-ref.

---
 doc/utils.md      | 11 +++++++++++
 src/util-dict.scm | 17 ++++++++++-------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/doc/utils.md b/doc/utils.md
index a5358fa..c992cbf 100644
--- a/doc/utils.md
+++ b/doc/utils.md
@@ -62,6 +62,17 @@ Returns ```#t``` if given dictionary contains no keys.
 
 Returns ```#t``` if given ```ld``` contains given key ```k```.
 
+    (ldict-ref ld k [default])
+
+* ```ld``` - a ldict instance
+* ```k``` - a compatible key
+* ```default``` - optional fallback value
+
+Retrieves the value associated with given key in given dictionary. If
+the dictionary does not contain it and no default is given, an
+exception is raised. Otherwise the default value is returned in case
+of missing key.
+
 ### IO
 
     (import util-io)
diff --git a/src/util-dict.scm b/src/util-dict.scm
index af91ba9..27448f9 100644
--- a/src/util-dict.scm
+++ b/src/util-dict.scm
@@ -97,13 +97,16 @@
  ;; is provided it is used as default value in case the key does not
  ;; exist. If only two arguments are given and the key does not exist,
  ;; raises an error.
- (define (dict-ref d k . r)
-   (let ((p (assq k d)))
-     (if p
-	 (cdr p)
-	 (if (null? r)
-	     (error 'dict-ref "Key does not exist" k)
-	     (car r)))))
+ (define (ldict-ref ld k . ds)
+   (let ((equality? (ldict-equality? ld)))
+     (let loop ((pairs (ldict-pairs ld)))
+       (if (null? pairs)
+	   (if (null? ds)
+	       (error 'ldict-ref "Key does not exist" k)
+	       (car ds))
+	   (if (equality? (caar pairs) k)
+	       (cdar pairs)
+	       (loop (cdr pairs)))))))
 
  ;; Returns a new dictionary based on d with key k removed. If it
  ;; doesn't contain the key, an error is raised.