Base hash-table convenience functionality

2 files changed, 43 insertions, 0 deletions

diff --git a/src/hash-table.lisp b/src/hash-table.lisp
new file mode 100644
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--- /dev/null
+++ b/src/hash-table.lisp
@@ -0,0 +1,37 @@
+(in-package #:substrate/hash-table)
+
+(defmacro hash (&rest pairs)
+  "Convenience macro for hash-table creation.
+Combines `make-hash-table` action with `(setf (gethash key table) val)` in one call.
+Arguments have to be in even numbers forming pairs, e.g.: `(% :x 1 :y 2)`."
+  (unless (evenp (length pairs))
+    (error "% - hash table requires an even number of arguments for key-value pairs."))
+  `(load-time-value
+    (let ((table (make-hash-table :test 'equal)))
+      ,@(loop for (key val) on pairs by #'cddr
+	      collect `(setf (gethash ,key table) ,val))
+      table)))
+
+(defun keys (hash-table)
+  "Convenience function which returns all keys of hash-table."
+  (loop for key being the hash-keys of hash-table
+	collect key))
+
+(defun vals (hash-table)
+  "Convenience function which returns all values from hash-table."
+  (loop for val being the hash-values of hash-table
+	collect val))
+
+(defun get-in (lookup-item keys &key default)
+  "Returns the value in nested associative structure (hash-table, list vector)"
+  (loop for key in keys
+	for current = lookup-item then next
+	for next = (cond
+		     ((hash-table-p current) (gethash key current))
+		     ((listp current) (nth key current))
+		     ((vectorp current) (elt current key))
+		     (t nil))
+	while next
+	finally (return (if (and default (not next))
+			    default
+			    next))))
diff --git a/src/package.lisp b/src/package.lisp
new file mode 100644
index 0000000..c0af7dc
--- /dev/null
+++ b/src/package.lisp
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+(defpackage #:substrate/hash-table
+  (:use #:cl)
+  (:export #:hash
+	   #:keys
+	   #:vals
+	   #:get-in))