(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)))))