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improving support for Hash and FileHash functions #1133

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Merged
rocky merged 1 commit into from
Feb 7, 2021
Merged

improving support for Hash and FileHash functions #1133

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25 changes: 10 additions & 15 deletions mathics/builtin/files.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3812,6 +3812,8 @@ 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"]
Expand Down Expand Up @@ -3840,19 +3842,20 @@ 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:
Expand All @@ -3865,7 +3868,7 @@ 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):
Expand Down Expand Up @@ -4803,6 +4806,7 @@ def apply(self, pathname, evaluation):
return SymbolTrue
return SymbolFalse


class Needs(Builtin):
"""
<dl>
Expand Down Expand Up @@ -4922,7 +4926,6 @@ 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, '`')
Expand All @@ -4932,19 +4935,11 @@ 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

32 changes: 24 additions & 8 deletions mathics/builtin/numeric.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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"]
Expand All @@ -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")
Expand All @@ -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):
Expand Down