ENH: SHA1Digest : Istream construction

src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.C

@@ -32,7 +32,37 @@ License
 
 //! @cond fileScope
 const char hexChars[] = "0123456789abcdef";
-//! @endcond
+//! @endcond fileScope
+
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+unsigned char Foam::SHA1Digest::readHexDigit(Istream& is)
+{
+    // Takes into account that 'a' (or 'A') is 10
+    static const label alphaOffset = toupper('A') - 10;
+    // Takes into account that '0' is 0
+    static const label zeroOffset = int('0');
+
+    char c = 0;
+    is.read(c);
+
+    if (!isxdigit(c))
+    {
+        FatalIOErrorIn("SHA1Digest::readHexDigit(Istream&)", is)
+            << "Illegal hex digit: '" << c << "'"
+            << exit(FatalIOError);
+    }
+
+    if (isdigit(c))
+    {
+        return int(c) - zeroOffset;
+    }
+    else
+    {
+        return toupper(c) - alphaOffset;
+    }
+}
 
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
@@ -43,6 +73,12 @@ Foam::SHA1Digest::SHA1Digest()
 }
 
 
+Foam::SHA1Digest::SHA1Digest(Istream& is)
+{
+    is  >> *this;
+}
+
+
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
 void Foam::SHA1Digest::clear()
@@ -75,6 +111,23 @@ bool Foam::SHA1Digest::operator!=(const SHA1Digest& rhs) const
 
 // * * * * * * * * * * * * * * Friend Operators * * * * * * * * * * * * * * //
 
+Foam::Istream& Foam::operator>>(Istream& is, SHA1Digest& dig)
+{
+    unsigned char *v = dig.v_;
+
+    for (unsigned i = 0; i < dig.length; ++i)
+    {
+        unsigned char c1 = SHA1Digest::readHexDigit(is);
+        unsigned char c2 = SHA1Digest::readHexDigit(is);
+
+        v[i] = (c1 << 4) + c2;
+    }
+
+    is.check("Istream& operator>>(Istream&, SHA1Digest&)");
+    return is;
+}
+
+
 Foam::Ostream& Foam::operator<<(Ostream& os, const SHA1Digest& dig)
 {
     const unsigned char *v = dig.v_;

src/OpenFOAM/primitives/hashes/SHA1/SHA1Digest.H

@@ -45,11 +45,13 @@ namespace Foam
 
 // Forward declaration of classes
 class Ostream;
+class Istream;
 
 // Forward declaration of friend functions and operators
 class SHA1;
 class SHA1Digest;
 Ostream& operator<<(Ostream&, const SHA1Digest&);
+Istream& operator>>(Istream&, SHA1Digest&);
 
 
 /*---------------------------------------------------------------------------*\
@@ -67,6 +69,9 @@ public:
     //- Construct a zero digest
     SHA1Digest();
 
+    //- Construct read a digest
+    SHA1Digest(Istream&);
+
     //- Reset the digest to zero
     void clear();
 
@@ -77,11 +82,14 @@ public:
     bool operator!=(const SHA1Digest&) const;
 
     friend Ostream& operator<<(Ostream&, const SHA1Digest&);
+    friend Istream& operator>>(Istream&, SHA1Digest&);
 
 private:
 
     //- The digest contents
     unsigned char v_[length];
+
+    static unsigned char readHexDigit(Istream&);
 };