1 \section{Traversal phase --- algorithm}
3 (In general, unless stated otherwise below, when we generate a new
4 commit $C$ using one of the commit kind algorith, we update
5 $W \assign C$. In any such case where we say we're going to Merge
6 with $L = W$, if $R \ge W$ we do not Merge but instead simply set
10 For each patch $\pc \in \allpatches$ in topological order by $\hasdep$,
15 \item Optionally, attempt
16 $\alg{Merge-Base}(\pc)$. This may or may not succeed.
18 \item If this didn't succeed, or was not attempted, execute
19 $\alg{Recreate-Base}(\pc)$.
21 \item Then in any case, execute
22 $\alg{Merge-Tip}(\pc)$.
26 After processing each $\pc$ we will have created:
30 \item $\tipcn$ and $\tipcy$ such that $\baseof{\tipcy} = \tipcn$.
34 \subsection{$\alg{Merge-Base}(\pc)$}
36 This algorithm attempts to construct a suitably updated version of the
37 base branch $\pcn$ using some existing version of $\pcn$ as a starting
40 It should be executed noninteractively. Specifically, if any step
41 fails with a merge conflict, the whole thing should be abandoned.
42 This avoids asking the user to resolve confusing conflicts. It also
43 avoids asking the user to pointlessly resolve conflicts in situations
44 where we will later discover that $\alg{Merge-Base}$ wasn't feasible
47 If $\pc$ has only one direct dependency, this algorithm should not be
48 used as in that case $\alg{Recreate-Base}$ is trivial and guaranteed
49 to generate a perfect answer, whereas this algorithm might involve
50 merges and therefore might not produce a perfect answer if the
51 situation is complicated.
53 Initially, set $W \iassign W^{\pcn}$.
55 \subsubsection{Bases and sources}
57 In some order, perhaps interleaving the two kinds of merge:
61 \item For each $\pd \isdirdep \pc$, find a merge base
62 $M \le W,\; \le \tipdy$ and merge $\tipdy$ into $W$.
63 That is, use $\alg{Merge}$ with $L = W,\; R = \tipdy$.
66 \item For each $S \in S^{\pcn}_i$, merge it into $W$.
67 That is, use $\alg{Merge}$ with $L = W,\; R = S,\; M = M^{\pcn}_i$.
74 Execute $\alg{Fixup-Base}(W,\pc)$.
77 \subsection{$\alg{Recreate-Base}(\pc)$}
83 Choose a $\hasdep$-maximal direct dependency $\pd$ of $\pc$.
87 Use $\alg{Create Base}$ with $L$ = $\pdy,\; \pq = \pc$ to generate $C$
88 and set $W \iassign C$. (Recreate Base Beginning.)
92 Execute the subalgorithm $\alg{Recreate-Recurse}(\pc)$.
96 Declare that we contain all of the relevant information from the
97 sources. That is, use $\alg{Pseudo-merge}$ with $L = W, \;
98 \set R = \{ W \} \cup \set S^{\pcn}$.
99 (Recreate Base Final Declaration.)
103 \subsubsection{$\alg{Recreate-Recurse}(\pd)$}
107 \item Is $W \haspatch \pd$ ? If so, there is nothing to do: return.
109 \item TODO what about non-Topbloke base branches
111 \item Use $\alg{Pseudo-Merge}$ with $L = W,\; \set R = \{ \tipdn \}$.
112 (Recreate Base Dependency Base Declaration.)
114 \item For all $\hasdep$-maximal $\pd' \isdirdep \pd$,
115 execute $\alg{Recreate-Recurse}(\pd')$.
117 \item Use $\alg{Merge}$ to apply $\pd$ to $W$. That is,
118 $L = W, \; R = \tipdy, \; M = \baseof{R} = \tipdn$.
124 \subsection{$\alg{Merge-Tip}(\pc)$}
128 \item TODO CHOOSE/REFINE W AND S as was done during Ranking for bases
130 \item $\alg{Merge}$ from $\tipcn$. That is, $L = W, \;
131 R = \tipcn$ and choose any suitable $M$. (Tip Base Merge.)
133 \item For each source $S \in \set S^{\pcy}$,
134 $\alg{Merge}$ with $L = W, \; R = S$ and any suitable $M$.