adding hvcat 2d concatenation function

  called as hvcat((rows...), arguments...) where the first argument is
  a tuple giving the number of arguments in each block row
addresses issue #122
also related to issue #38

Author: JeffBezanson

j/abstractarray.j

@@ -961,6 +961,18 @@ end
 
 ## Other array functions ##
 
+# fallback definition of hvcat in terms of hcat and vcat
+function hvcat(rows::(Size...), as...)
+    nbr = length(rows)  # number of block rows
+    rs = cell(nbr)
+    a = 1
+    for i = 1:nbr
+        rs[i] = hcat(as[a:a-1+rows[i]]...)
+        a += rows[i]
+    end
+    vcat(rs...)
+end
+
 function repmat(a::AbstractMatrix, m::Size, n::Size)
     o,p = size(a)
     b = similar(a, o*m, p*n)

j/array.j

@@ -261,6 +261,8 @@ function cat(catdim::Int, X...)
         dimsC = nargs
     elseif catdim == 2
         dimsC = (1, nargs)
+    else
+        # TODO
     end
     C = Array(typeC, dimsC)
 
@@ -317,3 +319,35 @@ end
 
 vcat(A::Array...) = cat(1, A...)
 hcat(A::Array...) = cat(2, A...)
+
+# 2d concatenation
+
+function hvcat{T}(rows::(Size...), as::Array{T,2}...)
+    nbr = length(rows)  # number of block rows
+
+    nc = mapreduce(+, a->size(a,2), as[1:rows[1]])
+    nr = 0
+
+    a = 1
+    for i = 1:nbr
+        nr += size(as[a],1)
+        a += rows[i]
+    end
+
+    out = Array(T, nr, nc)
+
+    a = 1
+    r = 1
+    for i = 1:nbr
+        c = 1
+        szi = size(as[a],1)
+        for j = 1:rows[i]
+            szj = size(as[a+j-1],2)
+            out[r:r-1+szi, c:c-1+szj] = as[a+j-1]
+            c += szj
+        end
+        r += szi
+        a += rows[i]
+    end
+    out
+end

src/julia-parser.scm

@@ -769,6 +769,22 @@
 	    (else
 	     (error "missing separator in array expression")))))))
 
+(define (cat-to-hvcat closer e)
+  (if (and
+       (eqv? closer #\])
+       (eq? (car e) 'vcat)
+       (any (lambda (x) (and (pair? x) (eq? (car x) 'hcat))) (cdr e)))
+      ;; convert nested hcat inside vcat to hvcat
+      (let ((rows (map (lambda (x)
+			 (if (and (pair? x) (eq? (car x) 'hcat))
+			     (cdr x)
+			     (list x)))
+		       (cdr e))))
+	`(call (top hvcat)
+	       (tuple ,@(map length rows))
+	       ,@(apply nconc rows)))
+      e))
+
 (define (parse-matrix s first closer)
   (define (fix head v) (cons head (reverse v)))
   (define (update-outer v outer)
@@ -782,11 +798,13 @@
 		  (require-token s))))
       (if (eqv? t closer)
 	  (begin (take-token s)
-		 (if (pair? outer)
-		     (fix 'vcat (update-outer vec outer))
-		     (if (or (null? vec) (null? (cdr vec)))
-			 (fix 'vcat vec)    ; [x]   => (vcat x)
-			 (fix 'hcat vec)))) ; [x y] => (hcat x y)
+		 (cat-to-hvcat
+		  closer
+		  (if (pair? outer)
+		      (fix 'vcat (update-outer vec outer))
+		      (if (or (null? vec) (null? (cdr vec)))
+			  (fix 'vcat vec)     ; [x]   => (vcat x)
+			  (fix 'hcat vec))))) ; [x y] => (hcat x y)
 	  (case t
 	    ((#\; #\newline)
 	     (take-token s) (loop '() (update-outer vec outer)))