BigUnsignedInABase(std::string): Reject digits too big for the base.

[bigint/bigint.git] / BigUnsignedInABase.cc

diff --git a/BigUnsignedInABase.cc b/BigUnsignedInABase.cc
index 762f14e..999faaf 100644 (file)
--- a/BigUnsignedInABase.cc
+++ b/BigUnsignedInABase.cc
@@ -1,18 +1,19 @@
-/*
-* Matt McCutchen's Big Integer Library
-* http://hashproduct.metaesthetics.net/bigint/
-*/
+#include "BigUnsignedInABase.hh"
 
-/*
-* Milan Tomic had trouble compiling this file on Microsoft
-* Visual C++ 6 because, in the libraries that come with
-* Visual C++ 6, the `std::string::push_back' method apparently
-* does not exist.  To get around the problem, I rewrote
-* `BigUnsignedInABase::operator std::string' (at the bottom
-* of this file) so it doesn't use `push_back'.
-*/
+BigUnsignedInABase::BigUnsignedInABase(const Digit *d, Index l, Base base)
+       : NumberlikeArray<Digit>(d, l), base(base) {
+       // Check the base
+       if (base < 2)
+               throw "BigUnsignedInABase::BigUnsignedInABase(const Digit *, Index, Base): The base must be at least 2";
 
-#include "BigUnsignedInABase.hh"
+       // Validate the digits.
+       for (Index i = 0; i < l; i++)
+               if (blk[i] >= base)
+                       throw "BigUnsignedInABase::BigUnsignedInABase(const Digit *, Index, Base): A digit is too large for the specified base";
+
+       // Eliminate any leading zeros we may have been passed.
+       zapLeadingZeros();
+}
 
 namespace {
        unsigned int bitLen(unsigned int x) {
@@ -29,34 +30,31 @@ namespace {
 }
 
 BigUnsignedInABase::BigUnsignedInABase(const BigUnsigned &x, Base base) {
-
        // Check the base
        if (base < 2)
                throw "BigUnsignedInABase(BigUnsigned, Base): The base must be at least 2";
-       // Save the base.
-       // This pattern is seldom seen in C++, but the analogous ``this.'' is common in Java.
        this->base = base;
-       
+
        // Get an upper bound on how much space we need
        int maxBitLenOfX = x.getLength() * BigUnsigned::N;
        int minBitsPerDigit = bitLen(base) - 1;
        int maxDigitLenOfX = ceilingDiv(maxBitLenOfX, minBitsPerDigit);
-       len = maxDigitLenOfX; // Another change to comply with `staying in bounds'; see `BigUnsigned::divideWithRemainder'.
+       len = maxDigitLenOfX; // Another change to comply with `staying in bounds'.
        allocate(len); // Get the space
-       
+
        BigUnsigned x2(x), buBase(base);
        Index digitNum = 0;
-       
+
        while (!x2.isZero()) {
                // Get last digit.  This is like `lastDigit = x2 % buBase, x2 /= buBase'.
                BigUnsigned lastDigit(x2);
                lastDigit.divideWithRemainder(buBase, x2);
                // Save the digit.
-               blk[digitNum] = Digit(lastDigit); // invokes `BigUnsigned ==> unsigned short' converter
+               blk[digitNum] = lastDigit.toUnsignedShort();
                // Move on.  We can't run out of room: we figured it out above.
                digitNum++;
        }
-       
+
        // Save the actual length.
        len = digitNum;
 }
@@ -79,12 +77,12 @@ BigUnsignedInABase::BigUnsignedInABase(const std::string &s, Base base) {
        // Save the base.
        // This pattern is seldom seen in C++, but the analogous ``this.'' is common in Java.
        this->base = base;
-       
+
        // `s.length()' is a `size_t', while `len' is a `NumberlikeArray::Index',
        // also known as an `unsigned int'.  Some compilers warn without this cast.
        len = Index(s.length());
        allocate(len);
-       
+
        Index digitNum, symbolNumInString;
        for (digitNum = 0; digitNum < len; digitNum++) {
                symbolNumInString = len - 1 - digitNum;
@@ -97,6 +95,9 @@ BigUnsignedInABase::BigUnsignedInABase(const std::string &s, Base base) {
                        blk[digitNum] = theSymbol - 'a' + 10;
                else
                        throw "BigUnsignedInABase(std::string, Base): Bad symbol in input.  Only 0-9, A-Z, a-z are accepted.";
+
+               if (blk[digitNum] >= base)
+                       throw "BigUnsignedInABase::BigUnsignedInABase(const Digit *, Index, Base): A digit is too large for the specified base";
        }
        zapLeadingZeros();
 }
@@ -106,6 +107,7 @@ BigUnsignedInABase::operator std::string() const {
                throw "BigUnsignedInABase ==> std::string: The default string conversion routines use the symbol set 0-9, A-Z and therefore support only up to base 36.  You tried a conversion with a base over 36; write your own string conversion routine.";
        if (len == 0)
                return std::string("0");
+       // Some compilers don't have push_back, so use a char * buffer instead.
        char *s = new char[len + 1];
        s[len] = '\0';
        Index digitNum, symbolNumInString;
@@ -118,6 +120,6 @@ BigUnsignedInABase::operator std::string() const {
                        s[symbolNumInString] = char('A' + theDigit - 10);
        }
        std::string s2(s);
-       delete s;
+       delete [] s;
        return s2;
 }