(in-package #:fwoar.lisputils)
 
 (defmacro vector-destructuring-bind ((&rest symbols) vector &body body)
   (let ((mappings (loop for symbol in symbols
 		     for num from 0
 		     collect (list num symbol))))
     (once-only (vector)
       `(symbol-macrolet ,(mapcar (destructuring-lambda ((num symbol))
 				   `(,symbol (aref ,vector ,num)))
 				 mappings)
 	 ,@body))))
 
 (defun v-first (vector)
   (elt vector 0))
 
 (defun index-table (table &key (test 'eql) (key 'v-first))
   (declare (optimize (speed 0) (debug 3)))
   (check-type table (array * (* *)))
   (let ((table-index (cl-containers:make-container 'cl-containers:simple-associative-container :test test)))
     (loop for row-num from 0 to (1- (array-dimension table 0))
        for current-row = (make-array (array-dimension table 1)
 				     :displaced-to table
 				     :displaced-index-offset (apply #'array-row-major-index table (list row-num 0)))
        do (setf (cl-containers:item-at table-index (funcall key current-row)) row-num))
     table-index))
 
 (defun join-tables (table1 table2 &key (test 'eql) (key1 'v-first) (key2 'v-first))
   (declare (optimize (speed 0) (debug 3)))
   (check-type table1 (array * (* *)))
   (check-type table2 (array * (* *)))
   (let ((table2-index (index-table table2 :test test :key key2)))
     (loop for row-num from 0 to (1- (array-dimension table1 0))
        for current-row = (make-array (array-dimension table1 1)
 				     :displaced-to table1
 				     :displaced-index-offset (apply #'array-row-major-index table1 (list row-num 0)))
        for dest-index = (cl-containers:item-at table2-index (funcall key1 current-row))
        when dest-index
        collect (let* ((to-row (make-array (array-dimension table2 1)
 					  :displaced-to table2
 					  :displaced-index-offset (apply #'array-row-major-index table2 (list dest-index 0)))))
 		 (concatenate 'vector current-row to-row)))))