Mercurial > hg > mercurial-crew-with-dirclash
view mercurial/ancestor.py @ 5197:55860a45bbf2
Enable demandimport only in scripts, not in importable modules (issue605)
This way other applications can choose if and when they want this feature,
because it might be problematic if those applications rely on ImportError.
author | Thomas Arendsen Hein <thomas@intevation.de> |
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date | Sat, 18 Aug 2007 11:37:08 +0200 |
parents | eb0b4a2d70a9 |
children |
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# ancestor.py - generic DAG ancestor algorithm for mercurial # # Copyright 2006 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms # of the GNU General Public License, incorporated herein by reference. import heapq def ancestor(a, b, pfunc): """ return the least common ancestor of nodes a and b or None if there is no such ancestor. pfunc must return a list of parent vertices """ if a == b: return a # find depth from root of all ancestors visit = [a, b] depth = {} while visit: vertex = visit[-1] pl = pfunc(vertex) if not pl: depth[vertex] = 0 visit.pop() else: for p in pl: if p == a or p == b: # did we find a or b as a parent? return p # we're done if p not in depth: visit.append(p) if visit[-1] == vertex: depth[vertex] = min([depth[p] for p in pl]) - 1 visit.pop() # traverse ancestors in order of decreasing distance from root def ancestors(vertex): h = [(depth[vertex], vertex)] seen = {} while h: d, n = heapq.heappop(h) if n not in seen: seen[n] = 1 yield (d, n) for p in pfunc(n): heapq.heappush(h, (depth[p], p)) def generations(vertex): sg, s = None, {} for g, v in ancestors(vertex): if g != sg: if sg: yield sg, s sg, s = g, {v:1} else: s[v] = 1 yield sg, s x = generations(a) y = generations(b) gx = x.next() gy = y.next() # increment each ancestor list until it is closer to root than # the other, or they match try: while 1: if gx[0] == gy[0]: for v in gx[1]: if v in gy[1]: return v gy = y.next() gx = x.next() elif gx[0] > gy[0]: gy = y.next() else: gx = x.next() except StopIteration: return None