Adding another example.

cyclichash.h

@@ -55,7 +55,6 @@ class CyclicHash {
      // this is a convenience function, use eat,update and .hashvalue to use as a rolling hash function 
     template<class container>
     hashvaluetype  hash(container & c) {
-    	assert(c.size()==static_cast<uint>(n));
     	hashvaluetype answer(0);
     	for(uint k = 0; k<c.size();++k) {
     		fastleftshift(answer, 1) ;
@@ -81,7 +80,8 @@ class CyclicHash {
     }
 
     uint32 hashvalue;
-    const int n, wordsize;
+    int n;
+    const int wordsize;
     CharacterHash hasher;
     const hashvaluetype mask1;
     const int myr;

example2.cpp

@@ -0,0 +1,34 @@
+#include <string>
+#include <vector>
+#include <memory>
+#include <iostream>
+
+    // given hash value of "ABCD", can I have value of 
+    // "ABCDE", without computing the whole hash value?
+
+#include "cyclichash.h"
+
+
+int main(int argc, char * argv[])
+{
+    CyclicHash hf(5,19);
+    string input = "ABCDE";
+    hf.eat(input[0]);//A
+    hf.eat(input[1]);//B
+    hf.eat(input[2]);//C
+    hf.eat(input[3]);//D
+    cout<<"Hash value of ABCD is " << hf.hashvalue << endl;
+    // we check the answer going the long way...
+    const std::vector<unsigned char> charvectslice(input.begin(), input.begin()+4);
+    uint32_t trueanswerslice  = hf.hash(charvectslice);
+    if(trueanswerslice != hf.hashvalue ) throw runtime_error("bug");
+    // we continue
+    hf.eat(input[4]);//E
+    cout<<"Hash value of ABCDE is " << hf.hashvalue << endl;
+    // we check the answer going the long way
+    const std::vector<unsigned char> charvect(input.begin(), input.end());
+    uint32_t trueanswer  = hf.hash(charvect);
+    if(trueanswer != hf.hashvalue ) throw runtime_error("bug");
+    return 0;
+
+}

generalhash.h

@@ -105,7 +105,6 @@ class GeneralHash {
     // this is a convenience function, use eat,update and .hashvalue to use as a rolling hash function 
     template<class container>
     hashvaluetype  hash(container & c) const {
-    	assert(c.size()==static_cast<uint>(n));
     	hashvaluetype answer(0);
     	for(uint k = 0; k<c.size();++k) {
     		fastleftshift(answer, 1) ;
@@ -116,7 +115,7 @@ class GeneralHash {
 
     hashvaluetype hashvalue;
     const int wordsize;
-    const int n;
+    int n;
     hashvaluetype irreduciblepoly;
     CharacterHash hasher;
     const hashvaluetype lastbit;

rabinkarphash.h

@@ -64,7 +64,8 @@ class KarpRabinHash {
     } 
 
     hashvaluetype hashvalue;
-    const int n, wordsize;
+    int n;
+    const wordsize;
     CharacterHash hasher;
     const hashvaluetype HASHMASK;
     hashvaluetype BtoN;

threewisehash.h

@@ -75,7 +75,8 @@ class ThreeWiseHash {
     }
 
     hashvaluetype hashvalue;
-    const int n, wordsize;
+    int n;
+    const int wordsize;
     deque<chartype> ngram;
     vector<CharacterHash> hashers;
     CharacterHash hasher;//placeholder

unit.cpp

@@ -43,6 +43,10 @@ bool isItAFunction(uint L = 7) {
 	return true;
 }
 
+
+
+
+
 template<class hashfunction>
 bool isItRandom(uint L = 19) {
   cout<<"checking that it is randomized "<<endl;