Move 'redo --ifchange' into 'redo-ifchange' to match djb's style.

It does simplify the logic of both redo.py and redo-ifchange.py, I suppose.

redo.py

@@ -8,8 +8,6 @@ redo [targets...]
 --
 d,debug    print dependency checks as they happen
 v,verbose  print commands as they are run
-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:])
@@ -17,90 +15,24 @@ o = options.Options('redo', optspec)
 targets = extra or ['it']
 
 
-def relpath(t, base):
-    t = os.path.abspath(t)
-    tparts = t.split('/')
-    bparts = base.split('/')
-    for tp,bp in zip(tparts,bparts):
-        if tp != bp:
-            break
-        tparts.pop(0)
-        bparts.pop(0)
-    while bparts:
-        tparts.insert(0, '..')
-        bparts.pop(0)
-    return '/'.join(tparts)
-
-
-def sname(typ, t):
-    # FIXME: t.replace(...) is non-reversible and non-unique here!
-    tnew = relpath(t, vars.BASE)
-    #log('sname: (%r) %r -> %r\n' % (vars.BASE, t, tnew))
-    return vars.BASE + ('/.redo/%s^%s' % (typ, tnew.replace('/', '^')))
-
-
-def add_dep(t, mode, dep):
-    open(sname('dep', 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(sname('stamp', t)):
-        debug('%s-- DIRTY (no stamp)\n' % depth)
-        return True
-
-    stamptime = os.stat(sname('stamp', 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(sname('dep', 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(sname('stamp', t))  # short circuit future checks
-        return True
-    return False
-
-
 def stamp(t):
     stampfile = sname('stamp', t)
+    depfile = sname('dep', t)
     if not os.path.exists(vars.BASE + '/.redo'):
         # .redo might not exist in a 'make clean' target
         return
     open(stampfile, 'w').close()
+    open(depfile, 'a').close()
     try:
         mtime = os.stat(t).st_mtime
     except OSError:
@@ -126,6 +58,7 @@ def build(t):
             return  # success
         else:
             raise Exception('no rule to make %r' % t)
+    stamp(dofile)
     unlink(t)
     tmpname = '%s.redo.tmp' % t
     unlink(tmpname)
@@ -158,7 +91,6 @@ if opt.debug:
     os.environ['REDO_DEBUG'] = '1'
 if opt.verbose:
     os.environ['REDO_VERBOSE'] = '1'
-assert(not (opt.ifchange and opt.ifcreate))
 
 if not os.environ.get('REDO_BASE', ''):
     base = os.path.commonprefix([os.path.abspath(os.path.dirname(t))
@@ -173,6 +105,7 @@ if not os.environ.get('REDO_BASE', ''):
 
 import vars
 from log import *
+from libdo import *
 
 if not vars.DEPTH:
     # toplevel call to redo
@@ -188,11 +121,5 @@ for t in targets:
     os.chdir(startdir)
     
     if vars.TARGET:
-        add_dep(vars.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)
+        add_dep(vars.TARGET, 'm', t)
+    build(t)