Add characters-read-out for Introspection reading

This allows reading multiple structs from the same file.

src/Dictionary.cake

@@ -364,7 +364,7 @@
          (memset new-element 0 (path (path field > field-type-metadata) > struct-size))
          (unless (read-introspect-struct-s-expr (path field > field-type-metadata)
                                                 new-element
-                                                argument-start string-allocate)
+                                                argument-start string-allocate null)
            (fprintf stderr "error: failed to read element into dictionary: ")
            (print-string-range argument-start argument-end true)
            (free-introspect-struct-fields (path field > field-type-metadata)
@@ -611,7 +611,7 @@
          (fclose in-file)
 
          (unless (read-introspect-struct-s-expr my-dict--metadata (addr read-struct)
-                                                file-contents malloc)
+                                                file-contents malloc null)
            (free-introspect-struct-fields
             my-dict--metadata (addr read-struct) free)
            (free (type-cast file-contents (* void)))
@@ -658,7 +658,7 @@
          (fclose in-file)
 
          (unless (read-introspect-struct-s-expr my-strdict--metadata (addr read-struct)
-                                                file-contents malloc)
+                                                file-contents malloc null)
            (free-introspect-struct-fields
             my-strdict--metadata (addr read-struct) free)
            (free (type-cast file-contents (* void)))

src/DynamicArray.cake

@@ -299,7 +299,7 @@
          (memset current-element 0 (path (path field > field-type-metadata) > struct-size))
          (unless (read-introspect-struct-s-expr (path field > field-type-metadata)
                                                 current-element
-                                                argument-start string-allocate)
+                                                argument-start string-allocate null)
            (fprintf stderr "error: failed to read element at %d: " current-index)
            (print-string-range argument-start argument-end true)
            (dynarray-free (deref dynarray-ptr-read))

src/Introspection.cake

@@ -893,7 +893,11 @@
      (return (read-introspect-struct-s-expr (path field > field-type-metadata)
                                             substruct-out
                                             in-string
-                                            string-allocate)))
+                                            string-allocate
+                                            ;; Why can this be null? Because in a valid S-expression
+                                            ;; file, our parent should be able to find the number of
+                                            ;; characters read via scanning and counting parentheses
+                                            null)))
 
     (true
      (fprintf stderr "error: do not know how to parse field '%s' with type %d from string \"%s\"\n"
@@ -975,11 +979,16 @@
             (set (deref end-out) (+ 1 current-char))
             (break))))))))
 
+;; characters-read-out signals the end of this struct, which enables many potentially different
+;; structs to be in the same file, one after another. null is okay if you don't care
 (defun read-introspect-struct-s-expr (struct-metadata (* (const metadata-struct))
                                       struct-out (* void)
                                       in-string (* (const char))
                                       string-allocate allocate-string-function
+                                      characters-read-out (* (unsigned int))
                                       &return bool)
+  (when characters-read-out
+    (set (deref characters-read-out) 0))
   ;; Find the start of the struct; validates we are parsing the struct we expect via checking the
   ;; type name after the first opening paren
   (var struct-member-start (* (const char)) null)
@@ -1021,6 +1030,7 @@
   (set state state-read-member-name)
   (var argument-start (* (const char)) null)
   (var argument-end (* (const char)) null)
+  (var last-valid-argument-end (* (const char)) null)
   (var current-char (* (const char)) struct-member-start)
   (s-expr-get-next-argument-start-end current-char (addr argument-start) (addr argument-end))
   (while (and argument-start argument-end)
@@ -1028,6 +1038,8 @@
     ;; (print-string-range argument-start argument-end false)
     ;; (fprintf stderr "'\n")
 
+    (set last-valid-argument-end argument-end)
+
     (cond
       ((= state state-read-member-name)
        (unless (= (deref argument-start) ':')
@@ -1115,6 +1127,11 @@
              (return false))))
        (set state state-read-member-name)))
     (s-expr-get-next-argument-start-end argument-end (addr argument-start) (addr argument-end)))
+  (when characters-read-out
+    (set (deref characters-read-out)
+         ;; Add one to eat the final closing paren
+         (+ 1 (type-cast (- last-valid-argument-end in-string)
+          (unsigned int)))))
   (return true))
 
 (defun free-introspect-struct-fields (struct-metadata (* (const metadata-struct))
@@ -1339,12 +1356,16 @@
     (unless in-file (return false))
     (var file-contents (* (const char)) (read-file-into-memory in-file))
     (fclose in-file)
+    (var num-characters-read (unsigned int) 0)
     (unless (read-introspect-struct-s-expr struct-metadata read-struct
-                                           file-contents malloc)
+                                           file-contents malloc (addr num-characters-read))
       (free (type-cast file-contents (* void)))
       (free read-struct)
       (return false))
 
+    ;; (fprintf stderr "Read %d characters. Last char: %c Rest: \"%s\"\n"
+    ;;          num-characters-read (deref (+ file-contents num-characters-read))
+    ;;          (+ file-contents num-characters-read))
     (free (type-cast file-contents (* void))))
 
    (fprintf stderr "Read-in struct:\n")
@@ -1503,7 +1524,7 @@
       (fclose in-file)
       (fprintf stderr "note: I expect there to be an error to read struct from Errors.cakedata -- ")
       (when (read-introspect-struct-s-expr my-struct--metadata (addr read-struct)
-                                           file-contents malloc)
+                                           file-contents malloc null)
         (fprintf stderr "error: expected to fail to read struct from Errors.cakedata\n")
         (free-introspect-struct-fields
          my-struct--metadata (addr read-struct) free)