Add actual dependency checking.

helpers.py

@@ -1,12 +1,6 @@
 import sys, os, errno
 
 
-def log(s):
-    sys.stdout.flush()
-    sys.stderr.write(s)
-    sys.stderr.flush()
-
-
 def unlink(f):
     """Delete a file at path 'f' if it currently exists.
 
@@ -20,3 +14,21 @@ def unlink(f):
             pass  # it doesn't exist, that's what you asked for
 
 
+def mkdirp(d, mode=None):
+    """Recursively create directories on path 'd'.
+
+    Unlike os.makedirs(), it doesn't raise an exception if the last element of
+    the path already exists.
+    """
+    try:
+        if mode:
+            os.makedirs(d, mode)
+        else:
+            os.makedirs(d)
+    except OSError, e:
+        if e.errno == errno.EEXIST:
+            pass
+        else:
+            raise
+
+

redo.py

@@ -6,7 +6,9 @@ from helpers import *
 optspec = """
 redo [targets...]
 --
-ifchange   something something
+d,debug    print dependency checks as they happen
+ifchange   only redo if the file is modified or deleted
+ifcreate   only redo if the file is created
 """
 o = options.Options('redo', optspec)
 (opt, flags, extra) = o.parse(sys.argv[1:])
@@ -14,41 +16,137 @@ o = options.Options('redo', optspec)
 targets = extra or ['it']
 
 
-def find_do_file(t):
-    p = '%s.do' % t
-    if os.path.exists(p):
-        return p
-    else:
-        return None
+def log(s):
+    sys.stdout.flush()
+    sys.stderr.write('redo: %s%s' % (REDO_DEPTH, s))
+    sys.stderr.flush()
+
+
+def debug(s):
+    if REDO_DEBUG:
+        log(s)
+
+
+def add_dep(t, mode, dep):
+    open('.redo/dep.%s' % t, 'a').write('%s %s\n' % (mode, dep))
     
 
+def find_do_file(t):
+    dofile = '%s.do' % t
+    if os.path.exists(dofile):
+        add_dep(t, 'm', dofile)
+        if dirty_deps(dofile, depth = ''):
+            build(dofile)
+        return dofile
+    else:
+        add_dep(t, 'c', dofile)
+        return None
+
+
+def _dirty_deps(t, depth):
+    debug('%s?%s\n' % (depth, t))
+    if not os.path.exists('.redo/stamp.%s' % t):
+        debug('%s-- DIRTY (no stamp)\n' % depth)
+        return True
+
+    stamptime = os.stat('.redo/stamp.%s' % t).st_mtime
+    try:
+        realtime = os.stat(t).st_mtime
+    except OSError:
+        realtime = 0
+
+    if stamptime != realtime:
+        debug('%s-- DIRTY (mtime)\n' % depth)
+        return True
+    
+    for sub in open('.redo/dep.%s' % t).readlines():
+        assert(sub[0] in ('c','m'))
+        assert(sub[1] == ' ')
+        assert(sub[-1] == '\n')
+        mode = sub[0]
+        name = sub[2:-1]
+        if mode == 'c':
+            if os.path.exists(name):
+                debug('%s-- DIRTY (created)\n' % depth)
+                return True
+        elif mode == 'm':
+            if dirty_deps(name, depth + '  '):
+                #debug('%s-- DIRTY (sub)\n' % depth)
+                return True
+    return False
+
+
+def dirty_deps(t, depth):
+    if _dirty_deps(t, depth):
+        unlink('.redo/stamp.%s' % t)  # short circuit future checks
+        return True
+    return False
+
+
+def stamp(t):
+    stampfile = '.redo/stamp.%s' % t
+    open(stampfile, 'w').close()
+    try:
+        mtime = os.stat(t).st_mtime
+    except OSError:
+        mtime = 0
+    os.utime(stampfile, (mtime, mtime))
+
+
 def build(t):
+    unlink('.redo/dep.%s' % t)
+    open('.redo/dep.%s' % t, 'w').close()
     dofile = find_do_file(t)
     if not dofile:
         if os.path.exists(t):  # an existing source file
+            stamp(t)
             return  # success
         else:
             raise Exception('no rule to make %r' % t)
     unlink(t)
     os.putenv('REDO_TARGET', t)
-    depth = os.getenv('REDO_DEPTH', '')
-    os.putenv('REDO_DEPTH', depth + '  ')
+    os.putenv('REDO_DEPTH', REDO_DEPTH + '  ')
     tmpname = '%s.redo.tmp' % t
     unlink(tmpname)
     f = open(tmpname, 'w+')
     argv = ['sh', '-e', dofile, t, 'FIXME', tmpname]
-    log('redo: %s%s\n' % (depth, t))
+    log('%s\n' % t)
     rv = subprocess.call(argv, stdout=f.fileno())
     st = os.stat(tmpname)
     #log('rv: %d (%d bytes) (%r)\n' % (rv, st.st_size, dofile))
-    if rv==0 and st.st_size:
-        os.rename(tmpname, t)
-        #log('made %r\n' % t)
+    stampfile = '.redo/stamp.%s' % t
+    if rv==0:
+        if st.st_size:
+            os.rename(tmpname, t)
+        else:
+            unlink(tmpname)
+        stamp(t)
     else:
         unlink(tmpname)
+        unlink(stampfile)
     f.close()
     if rv != 0:
         raise Exception('non-zero return code building %r' % t)
 
+
+mkdirp('.redo')
+REDO_TARGET = os.getenv('REDO_TARGET', '')
+REDO_DEPTH = os.getenv('REDO_DEPTH', '')
+
+assert(not (opt.ifchange and opt.ifcreate))
+if opt.debug:
+    REDO_DEBUG = 1
+    os.putenv('REDO_DEBUG', '1')
+else:
+    REDO_DEBUG = os.getenv('REDO_DEBUG', '') and 1 or 0
+
 for t in targets:
-    build(t)
+    if REDO_TARGET:
+        add_dep(REDO_TARGET, opt.ifcreate and 'c' or 'm', t)
+    if opt.ifcreate:
+        pass # just adding the dependency (above) is enough
+    elif opt.ifchange:
+        if dirty_deps(t, depth = ''):
+            build(t)
+    else:
+        build(t)