Added simple string table for creating IDs

ReadMe.org

@@ -109,6 +109,7 @@ Here are the known compatibility results, where blank means untested/unknown:
 | FileSystem.cake             | Yes          | Yes          | Yes         |       |
 | FreeType.cake               | Yes          |              | Yes         |       |
 | Hash.cake                   | Yes          | Yes          | Yes         | Yes   |
+| HashStringTable.cake        | Yes          | Yes          | Yes         | Yes   |
 | Image.cake                  | Yes          | Yes          | Yes         |       |
 | ImGui.cake                  | Yes          | No[1]        | Yes         |       |
 | ImGuiSDLOpenGL.cpp          | Yes          | No[1]        | Yes         |       |

src/HashStringTable.cake

@@ -0,0 +1,46 @@
+;; HashStringTable.cake: Hash a string then store in a central table
+;; The strings will be copied for the table to ensure it will stick around until
+;; free-string-table is called.
+(import "Hash.cake" "Dictionary.cake")
+(c-import &with-decls "<stdint.h>" "<stddef.h>")
+
+(defstruct hash-string-pair
+  key uint32_t
+  ;; Owned by the string table
+  str (addr char))
+
+(def-type-alias-global string-table (addr hash-string-pair)) ;; dictionary
+(def-type-alias-global string-id uint32_t)
+
+(defun id-from-string (interned-strings (addr string-table)
+                       str (addr (const char))
+                       string-length size_t
+                       &return string-id)
+  (var hash uint32_t 0)
+  (hash-crc32 str string-length (addr hash))
+  (unless (dict-ptr-at (deref interned-strings) hash)
+    (var new-pair hash-string-pair
+      (array hash
+             ;; TODO: better memory allocation strategy
+             (strdup str)))
+    (dict-set-struct (deref interned-strings) new-pair))
+  (return hash))
+
+;; For safe comparison to quickly determine whether the string was not found
+(var-global c-string-missing-from-string-table (const (addr (const char)))
+  "<String not in table>")
+
+;; May return null if the string has never been added to the string table
+(defun string-from-string-id (interned-strings (addr string-table)
+                              id string-id
+                              &return (addr (const char)))
+  (var pair (addr hash-string-pair) (dict-ptr-at (deref interned-strings) id))
+  (unless pair
+    (return c-string-missing-from-string-table))
+  (return (path pair > str)))
+
+(defun free-string-table (table (addr string-table))
+  (each-item-in-dict (deref table) i entry (addr hash-string-pair)
+    (free (path entry > str)))
+  (dict-free (deref table))
+  (set (deref table) null))