brando - npm Package Compare versions

Comparing version 0.0.34 to 0.0.35

example/brando-stream-example.js

@@ -5,3 +5,3 @@ var log = console.log
     , input = fs.createReadStream( './example/test-data.txt' )
-    , sts = new require( '../lib/streams/sequence-transform' )( 10, 10, {} )
+    , sts = new require( '../lib/streams/sequence-transform' )( 16, 10, {} )
     , dstream = input.pipe( sts )
@@ -12,3 +12,3 @@ , onRead = function () {
             ;
-        while ( data = me.read( 3 ) ) log( 'data:', data );
+        while ( data = me.read(3) ) log( 'data:', data );
     }
@@ -15,0 +15,0 @@ , onEnd = function () {

lib/brando.js

@@ -19,4 +19,2 @@ /*
         , transform = require( './streams/' )
-        // mask to appy for restricting items
-        // , imask = 0xffffffff
         ;
@@ -31,3 +29,2 @@ return {
                 ;
-            // restrict items with mask: i &= imask;
             // with no repetition, items should be always <= range
@@ -46,3 +43,2 @@ return seq ? new random.sequence( i, r ) :
                 ;
-            // restrict items with mask : i &= imask;
             // with no repetition, items should be always <= range
@@ -49,0 +45,0 @@ return seq ? new transform.sequence( i, r, stream_opt ) :

lib/filters/partperm.js

@@ -106,3 +106,3 @@ /*
      * algo checks for values with p+1 bits, but those values are in the range 0 to 2^(p + 1),
-     * so the probability to find a value in the correct range is:
+     * so, on the average, the probability to find a value in the correct range is:
      *
@@ -112,3 +112,4 @@ * (2^(p) + 1) / 2^(p + 1), or 1/2 + 2^-(p+1) ~ 1/2
      * Then, using result from the previous case, the probability to find the k-th value, is
-     * 1/2 - (k - 1)/(range*2).
+     * (1/2) - (1/2)*(k - 1)/range. When we set items ~ range/2, the probability to find the
+     * last value is, on the average, =~ 1/4 + 1/(2*r) or ~ 25%.
      *
@@ -115,0 +116,0 @@ */

lib/streams/sequence-transform.js

 /*
-* Transform Stream for Random Sequence, unlimited repetitions.
+ * Transform Stream for Random Sequence, unlimited repetitions.
  */
@@ -11,5 +11,3 @@
         , dlog = Math.log
-        , floor = Math.floor
         , max = Math.max
-        , random = Math.random
         , log2 = dlog( 2 )
@@ -21,3 +19,2 @@ , util = require( 'util' )
         , compare = Bice.compare
-        , swap = Bice.swap
         , clone = Bolgia.clone
@@ -47,3 +44,4 @@ , improve = Bolgia.improve
             var range = r >>> 0 ? abs( r ) : 1
-                , items = i >>> 0 ? abs( i ) : 1
+                // 0 items means no limits.
+                , items = abs( i ) >>> 0
                 // , repeat = Infinity
@@ -53,8 +51,5 @@ , bits = max( ceil( dlog( range ) / log2 ), 1 )
                 , ibits = ibytes << 3 >>> 0
-                , tbytes = ibytes * items
                 // choose appropriate method for reading/writing ints/uints from 8 to 32 bits
                 , ruint = [ 'readUInt' + ibits + ( ibytes > 1 ? 'BE' : '' ) ]
                 , wuint = [ 'writeUInt' + ibits + ( ibytes > 1 ? 'BE' : '' ) ]
-                // current writing position in the result Buffer, when parsing random data
-                , wpos = 0
                 // use a Buffer for range value, for faster comparisons when parsing data.
@@ -64,3 +59,2 @@ , brange = new Buffer( ibytes )
                 , bcompare = compare.bind( me, brange, 0 )
-                , bsize = 8 * 1024
                 ;
@@ -74,13 +68,11 @@
                 , items : items
+                , left : items ? items : -1
                 , bits : bits
                 , ibytes : ibytes
                 , ibits : ibits
-                , tbytes : tbytes
                 , runit : ruint
                 , wuint : wuint
-                , bcompare : bcompare
+                , cmask : masks[ ibits - bits ]
+                , compare : bcompare
                 , brange : brange
-                , buffer : new Buffer( bsize )
-                , bsize : bsize
-                , bpos : 0
             };
@@ -99,38 +91,32 @@
             , seq = me._sequence
-            , bcomp = seq.bcompare
-            , brange = seq.brange
-            , result = seq.result
+            , bcomp = seq.compare
             , ibytes = seq.ibytes
-            , tbytes = seq.tbytes
+            , ibits = seq.ibits
             , bits = seq.bits
-            , ibits = seq.ibits
-            , cmask = masks[ ibits - bits ]
+            , cmask = seq.cmask
             , dlen = data.length
             , l = dlen - ibytes
             , o = 0
+            , s = 0
             ;
-        /*
-         * Bufferize the incoming random data.
-         *
-         * NOTE: without buffering, push could be:
-         *      if ( ~ bcomp( data, o ) )
-         *          me.push( data.slice( o, o + ibytes ) );
-         */
         for ( ; o <= l; o += ibytes ) {
             data[ o ] &= cmask;
             if ( ~ bcomp( data, o ) ) {
-                if ( seq.bpos + ibytes >= seq.bsize ) {
-                    // current buffer is not big enough, create a new one,
-                    me.push( seq.buffer.slice( 0, seq.bpos ) );
-                    seq.bpos = 0;
-                    seq.buffer = new Buffer( seq.bsize );
+                // value is in the selected range
+                if ( ( ~ seq.left ) && ( --seq.left <= 0 ) ) {
+                    // items limit was reached, push data
+                    if ( s <= o ) me.push( data.slice( s, o + ibytes ) );
+                    // reset the counter for left items
+                    seq.left = seq.items ? seq.items : -1
+                    // end the stream
+                    return me.push( null ) & done();
                 }
-                // TODO: it's better to copy a slice, not a value at a time.
-                data.copy( seq.buffer, seq.bpos, o, o + ibytes );
-                seq.bpos += ibytes;
-                // limit result to items.
-                if ( seq.bpos === tbytes )
-                    me.push( seq.buffer.slice( 0, tbytes ) );
+                continue;
             }
+            // value is out of range, slice all good values
+            if ( s < o ) me.push( data.slice( s, o ) );
+            s = o + ibytes;
         }
+        // before calling done(), check for previous skipped values to push
+        if ( s + ibytes < o ) me.push( data.slice( s, dlen ) );
         done();
@@ -142,7 +128,3 @@ };
             , seq = me._sequence
-            , bpos = seq.bpos
-            , ibytes = seq.ibytes
-            , buff = seq.buffer
             ;
-        seq.bpos = 0;
         done();
@@ -149,0 +131,0 @@ };

package.json

 {
   "name": "brando"
-  , "version": "0.0.34"
+  , "version": "0.0.35"
   , "description": "Brando."
@@ -5,0 +5,0 @@ , "homepage": "https://github.com/rootslab/brando"

Readme.md

@@ -58,5 +58,3 @@ ### Brando
 /*
- * A simple factory method, it returns a Sequence EventEmitter,for filling a
- * random (Buffer) sequence/permutation only with values the current selected
- * range.
+ * A simple factory method, it returns a Sequence EventEmitter.
  *
@@ -63,0 +61,0 @@ * NOTE:

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Worsened metrics

Total package byte prevSize

46915

decreased by-1.55%

Lines of code

915

decreased by-2.24%

Number of lines in readme file

106

decreased by-1.85%

No dependency changes