[pure-lang-svn] SF.net SVN: pure-lang: [411] pure/trunk/examples

[<js...@us...>]

Revision: 411
          http://pure-lang.svn.sourceforge.net/pure-lang/?rev=411&view=rev
Author:   jspitz
Date:     2008-07-07 13:46:37 -0700 (Mon, 07 Jul 2008)

Log Message:
-----------
Add slicing operation

Modified Paths:
--------------
    pure/trunk/examples/array.pure
    pure/trunk/examples/dict.pure

Modified: pure/trunk/examples/array.pure
===================================================================
--- pure/trunk/examples/array.pure	2008-07-07 14:22:07 UTC (rev 410)
+++ pure/trunk/examples/array.pure	2008-07-07 20:46:37 UTC (rev 411)
@@ -37,6 +37,11 @@
    a!i			return ith member of a
    a!(i,j)		two-dimensional subscript
 
+   a!!is		slicing (get a list of values from a list
+			indices
+   a!!ijs		slicing of two-dimensional array (from a given
+			list of pairs (i, j):...:[])
+
    null a		tests whether a is the empty array
    members a		list of values stored in a
    members2 a		list of members in a two-dimensional array
@@ -100,6 +105,14 @@
 // get value by indices from two-dimensional array
 x@(Array _)!(i::int, j::int)	= x!i!j;
 
+// slicing (get list of values from list of indices)
+a@(Array _)!!is@(_::int:_)	= [a!i; i = is; (i >= 0) && (i < (#a))];
+
+// slicing of two-dimensional array
+a@(Array _)!!ijs@((_::int, _::int):_)
+				= [a!(i, j); (i, j) = ijs; (i >= 0) && (i < (#a))
+						 && (j >= 0) && (j < (#(a!i)))];
+
 // check for an empty array
 null (Array nil)		= 1;
 null (Array _)			= 0;

Modified: pure/trunk/examples/dict.pure
===================================================================
--- pure/trunk/examples/dict.pure	2008-07-07 14:22:07 UTC (rev 410)
+++ pure/trunk/examples/dict.pure	2008-07-07 20:46:37 UTC (rev 411)
@@ -52,6 +52,8 @@
 
 #d				size of dict or hdict d
 d!x:				get value from d by key x
+d!!xs				slicing (get a list of values
+				from a list of keys)
 
 null d				tests whether d is the empty dict or hdict
 member d x			tests whether d contains member with key x
@@ -421,7 +423,9 @@
 vals (Hdict d)	= vals d
 with
   vals nil			= [];
-  vals (bin _ xys _ d1 d2)	= vals d1 + map (\(_ => val) -> val) xys + vals d2
+  vals (bin _ xys _ d1 d2)	= vals d1 +
+				  map (\(_ => val) -> val) xys +
+				  vals d2
 end;
 
 // get a value by key from dict or hdict
@@ -453,6 +457,47 @@
   lookupk (       _ :xys) x	= lookupk xys x
 end;
 
+// slicing (get list of values from list of keys)
+(Dict d)!!xs			= slice d [] xs
+with
+  slice d ys (x:xs)		= slice d
+					(case mbr of nil = ys;
+					            (nonil y) = (y:ys) end) xs
+					when
+						mbr = d!x
+					end;
+  slice d ys []			= reverse ys;
+
+  nil!_				= nil;
+  (bin x::int    y _ d1 d2)!x1::int    |
+  (bin x::string y _ d1 d2)!x1::string |
+  (bin x         y _ d1 d2)!x1
+				= d1!x1 if x1 < x;
+				= d2!x1 if x1 > x;
+				= nonil y
+end;
+
+(Hdict d)!!xs			= slice d [] xs
+with
+  slice d ys (x:xs)		= slice d
+					(case mbr of nil = ys;
+					            (nonil y) = (y:ys) end) xs
+					when
+						mbr = lookup d (hash x) x
+					end;
+  slice d ys []			= reverse ys;
+
+  lookup nil _ _		= nil;
+  lookup (bin k::int xys _ d1 d2) k1::int x1
+				= lookup d1 k1 x1 if k > k1;
+				= lookup d2 k1 x1 if k < k1;
+				= lookupk xys x1;
+
+  lookupk []	       _	= nil;
+  lookupk ((xa => y):_  ) xb	= nonil y if xa === xb;
+  lookupk (       _ :xys) x	= lookupk xys x
+end;
+
 // curried version of insert for dict and hdict
 update d@(Dict  _) x::int    y |
 update d@(Dict  _) x::string y |


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