Merge pull request #1133 from mathics/hashfunctions

improving support for Hash and FileHash functions

Author: rocky

mathics/builtin/files.py

@@ -3813,6 +3813,8 @@ class FileHash(Builtin):
     <dt>'FileHash[$file$, $type$]'
       <dd>returns an integer hash of the specified $type$ for the given $file$.</dd>
       <dd>The types supported are "MD5", "Adler32", "CRC32", "SHA", "SHA224", "SHA256", "SHA384", and "SHA512".</dd>
+    <dt>'FileHash[$file$, $type$, $format$]'
+      <dd>gives a hash code in the specified format.</dd>
     </dl>
 
     >> FileHash["ExampleData/sunflowers.jpg"]
@@ -3841,19 +3843,20 @@ class FileHash(Builtin):
     #> FileHash["ExampleData/sunflowers.jpg", xyzsymbol]
      = FileHash[ExampleData/sunflowers.jpg, xyzsymbol]
     #> FileHash["ExampleData/sunflowers.jpg", "xyzstr"]
-     = FileHash[ExampleData/sunflowers.jpg, xyzstr]
+     = FileHash[ExampleData/sunflowers.jpg, xyzstr, Integer]
     #> FileHash[xyzsymbol]
      = FileHash[xyzsymbol]
     """
 
     rules = {
-        "FileHash[filename_String]": 'FileHash[filename, "MD5"]',
+        "FileHash[filename_String]": 'FileHash[filename, "MD5", "Integer"]',
+        "FileHash[filename_String, hashtype_String]": 'FileHash[filename, hashtype, "Integer"]',
     }
 
     attributes = ("Protected", "ReadProtected")
 
-    def apply(self, filename, hashtype, evaluation):
-        "FileHash[filename_String, hashtype_String]"
+    def apply(self, filename, hashtype, format, evaluation):
+        "FileHash[filename_String, hashtype_String, format_String]"
         py_filename = filename.get_string_value()
 
         try:
@@ -3866,7 +3869,7 @@ def apply(self, filename, hashtype, evaluation):
             e.message(evaluation)
             return
 
-        return Hash.compute(lambda update: update(dump), hashtype.get_string_value())
+        return Hash.compute(lambda update: update(dump), hashtype.get_string_value(), format.get_string_value())
 
 
 class FileDate(Builtin):
@@ -4802,6 +4805,7 @@ def apply(self, pathname, evaluation):
             return SymbolTrue
         return SymbolFalse
 
+
 class Needs(Builtin):
     """
     <dl>
@@ -4921,7 +4925,6 @@ def apply(self, context, evaluation):
             curr_ctxt = evaluation.definitions.get_current_context()
             contextstr = curr_ctxt + contextstr[1:]
             context = String(contextstr)
-
         if not valid_context_name(contextstr):
             evaluation.message('Needs', 'ctx', Expression(
                 'Needs', context), 1, '`')
@@ -4931,19 +4934,11 @@ def apply(self, context, evaluation):
         if test_loaded.is_true():
             # Already loaded
             return SymbolNull
-
-        # TODO: Figure out why this raises the message:
-        # "Select::normal: Nonatomic expression expected."
-        already_loaded = Expression('MemberQ',
-                                    Symbol('System`$Packages'), context)
-        already_loaded = already_loaded.evaluate(evaluation).is_true()
-        if already_loaded:
-           return SymbolNull
-
         result = Expression('Get', context).evaluate(evaluation)
 
         if result == SymbolFailed:
             evaluation.message("Needs", "nocont", context)
             return SymbolFailed
 
         return SymbolNull
+

mathics/builtin/numeric.py

@@ -1340,6 +1340,8 @@ class Hash(Builtin):
     <dt>'Hash[$expr$, $type$]'
       <dd>returns an integer hash of the specified $type$ for the given $expr$.</dd>
       <dd>The types supported are "MD5", "Adler32", "CRC32", "SHA", "SHA224", "SHA256", "SHA384", and "SHA512".</dd>
+    <dt>'Hash[$expr$, $type$, $format$]'
+      <dd>Returns the hash in the  especified format.</dd>
     </dl>
 
     > Hash["The Adventures of Huckleberry Finn"]
@@ -1358,11 +1360,12 @@ class Hash(Builtin):
     = 58042316473471877315442015469706095084
 
     >> Hash[{a, b, c}, "xyzstr"]
-     = Hash[{a, b, c}, xyzstr]
+     = Hash[{a, b, c}, xyzstr, Integer]
     """
 
     rules = {
-        "Hash[expr_]": 'Hash[expr, "MD5"]',
+        "Hash[expr_]": 'Hash[expr, "MD5", "Integer"]',
+        "Hash[expr_, type_String]": 'Hash[expr, type, "Integer"]',
     }
 
     attributes = ("Protected", "ReadProtected")
@@ -1380,17 +1383,30 @@ class Hash(Builtin):
     }
 
     @staticmethod
-    def compute(user_hash, py_hashtype):
+    def compute(user_hash, py_hashtype, py_format):
         hash_func = Hash._supported_hashes.get(py_hashtype)
         if hash_func is None:  # unknown hash function?
             return  # in order to return original Expression
         h = hash_func()
         user_hash(h.update)
-        return from_python(int(h.hexdigest(), 16))
-
-    def apply(self, expr, hashtype, evaluation):
-        "Hash[expr_, hashtype_String]"
-        return Hash.compute(expr.user_hash, hashtype.get_string_value())
+        res = h.hexdigest()
+        if  py_format in ('HexString', "HexStringLittleEndian") :
+            return from_python(res)
+        res = int(res, 16)
+        if py_format == "DecimalString":
+            return from_python(str(res))
+        elif py_format == "ByteArray":
+            print("Not implemented. Return a string")
+            return from_python(str(res))
+        # Default: Integer
+        return from_python(res)
+        
+
+    def apply(self, expr, hashtype, outformat, evaluation):
+        "Hash[expr_, hashtype_String, outformat_String]"
+        return Hash.compute(expr.user_hash,
+                           hashtype.get_string_value(),
+                           outformat.get_string_value())
 
 
 class TypeEscalation(Exception):