rollsum: make a tree out of the splits

clients/go/camput/camput.go

@@ -17,7 +17,6 @@ limitations under the License.
 package main
 
 import (
-	"bufio"
 	"crypto/sha1"
 	"flag"
 	"fmt"
@@ -29,7 +28,6 @@ import (
 
 	"camli/blobref"
 	"camli/client"
-	"camli/rollsum"
 	"camli/schema"
 	"camli/jsonsign"
 )
@@ -357,38 +355,3 @@ func main() {
 		os.Exit(2)
 	}
 }
-
-func showSplits() {
-	file := flag.Arg(0)
-	f, err := os.Open(file)
-	if err != nil {
-		panic(err.String())
-	}
-	bufr := bufio.NewReader(f)
-
-	rs := rollsum.New()
-	n := 0
-	lastSplit := map[int]int{}
-	last := 0
-	for {
-		c, err := bufr.ReadByte()
-		if err != nil {
-			if err == os.EOF {
-				break
-			}
-			panic(err.String())
-		}
-		n++
-		rs.Roll(c)
-		if rs.OnSplit() {
-			bits := rs.Bits()
-			log.Printf("split at %d (after %d), bits=%d", n, n - last, bits)
-			last = n
-			for bits, last := range lastSplit {
-				log.Printf("  since %d = %d", bits, n - last)
-			}
-			lastSplit[bits] = n
-		}
-	}
-
-}

clients/go/camput/splits.go

@@ -0,0 +1,96 @@
+/*
+Copyright 2011 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"os"
+	"log"
+	"strings"
+
+	"camli/rollsum"
+)
+
+type span struct {
+	from, to int64
+	bits     int
+	children []span
+}
+
+func showSplits() {
+	file := flag.Arg(0)
+	f, err := os.Open(file)
+	if err != nil {
+		panic(err.String())
+	}
+	bufr := bufio.NewReader(f)
+
+	spans := []span{}
+	rs := rollsum.New()
+	n := int64(0)
+	last := n
+
+	for {
+		c, err := bufr.ReadByte()
+		if err != nil {
+			if err == os.EOF {
+				if n != last {
+					spans = append(spans, span{from: last, to: n})
+				}
+				break
+			}
+			panic(err.String())
+		}
+		n++
+		rs.Roll(c)
+		if rs.OnSplit() {
+			bits := rs.Bits()
+			sliceFrom := len(spans)
+			for sliceFrom > 0 && spans[sliceFrom-1].bits < bits {
+				sliceFrom--
+			}
+			nCopy := len(spans) - sliceFrom
+			var children []span
+			if nCopy > 0 {
+				children = make([]span, nCopy)
+				nCopied := copy(children, spans[sliceFrom:])
+				if nCopied != nCopy {
+					panic("n wrong")
+				}
+				spans = spans[:sliceFrom]
+			}
+			spans = append(spans, span{from: last, to: n, bits: bits, children: children})
+
+			log.Printf("split at %d (after %d), bits=%d", n, n-last, bits)
+			last = n
+		}
+	}
+
+	var dumpSpans func(s []span, indent int)
+	dumpSpans = func(s []span, indent int) {
+		in := strings.Repeat(" ", indent)
+		for _, sp := range s {
+			fmt.Printf("%sfrom=%d, to=%d (len %d) bits=%d\n", in, sp.from, sp.to, sp.to - sp.from, sp.bits)
+			if len(sp.children) > 0 {
+				dumpSpans(sp.children, indent + 4)
+			}
+		}
+	}
+	dumpSpans(spans, 0)
+}