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"""SCons.Sig
The Signature package for the scons software construction utility.
"""
__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"
import os.path
import string
class SConsignFile:
"""
Encapsulates reading and writing a .sconsign file.
"""
def __init__(self, dir, module):
"""
dir - the directory for the file
module - the signature module being used
"""
self.path = os.path.join(dir, '.sconsign')
self.entries = {}
try:
file = open(self.path, 'rt')
except:
pass
else:
for line in file.readlines():
filename, rest = map(string.strip, string.split(line, ":"))
time, signature = map(string.strip, string.split(rest, " "))
self.entries[filename] = (int(time), module.from_string(signature))
def get(self, filename):
"""
Get the signature for a file
filename - the filename whose signature will be returned
returns - (timestamp, signature)
"""
try:
return self.entries[filename]
except KeyError:
return (0, None)
def set(self, filename, timestamp, signature, module):
"""
Set the signature for a file
filename - the filename whose signature will be set
timestamp - the timestamp
signature - the signature
module - the signature module being used
"""
self.entries[filename] = (timestamp, module.to_string(signature))
def write(self):
"""
Write the .sconsign file to disk.
"""
file = open(self.path, 'wt')
for item in self.entries.items():
file.write("%s: %d %s\n" % (item[0], item[1][0], item[1][1]))
class Calculator:
"""
Encapsulates signature calculations and .sconsign file generating
for the build engine.
"""
def __init__(self, module):
"""
Initialize the calculator.
module - the signature module to use for signature calculations
"""
self.module = module
self.sig_files = {}
def collect(self, node, signatures):
"""
Collect the signatures of the node's sources.
node - the node whose sources will be collected
signatures - the dictionary that the signatures will be
gathered into.
"""
for source_node in node.sources + node.depends:
if not signatures.has_key(source_node):
signature = self.signature(source_node)
signatures[source_node] = signature
self.collect(source_node, signatures)
def get_sig_file(self, dir):
"""
Get a sconsign file from the cache, or add it to the cache.
dir - the dir for the sconsign file
returns - the sconsign file
"""
if self.sig_files.has_key(dir):
return self.sig_files[dir]
else:
self.sig_files[dir] = SConsignFile(dir, self.module)
return self.sig_files[dir]
def signature(self, node):
"""
Get the signature for a node.
node - the node
returns - the signature or None if the signature could not
be computed.
This method also stores the signature in the node and
in the .sconsign file.
"""
if node.has_signature():
sig = node.get_signature()
elif node.derived:
signatures = {}
self.collect(node, signatures)
signatures = filter(lambda x: not x is None, signatures.values())
sig = self.module.collect(signatures)
else:
if not node.exists():
return None
# XXX handle nodes that are not under the source root
sig = self.module.signature(node)
node.set_signature(sig)
dir, filename = os.path.split(node.path)
if node.exists():
timestamp = node.get_timestamp()
else:
timestamp = 0
self.get_sig_file(dir).set(filename,
timestamp,
sig,
self.module)
return sig
def current(self, node):
"""
Check if a node is up to date.
node - the node whose signature will be checked
returns - 0 if the signature has changed since the last invocation,
and 1 if it hasn't
"""
if not node.exists():
return 0
dir, filename = os.path.split(node.path)
oldtime, oldsig = self.get_sig_file(dir).get(filename)
newtime = node.get_timestamp()
if not node.derived and newtime == oldtime:
newsig = oldsig
else:
newsig = self.signature(node)
return newsig == oldsig
def write(self, nodes):
"""
Write out all of the signature files.
nodes - the nodes whose signatures may have changed durring
the build
"""
# make sure all the signatures have been calculated:
for node in nodes:
self.signature(node)
for sig_file in self.sig_files.values():
sig_file.write()
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