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The interface `cb_each()` iterates through a crit-bit tree and calls a specific callback function for each of the contained items. The callback function is expected to return either: - `CB_CONTINUE` in case iteration shall continue. - `CB_BREAK` to abort iteration. This is needlessly restrictive though, as callers may want to return arbitrary values and have them be bubbled up to the `cb_each()` call site. In fact, this is a rather common pattern we have: whenever such a callback function returns a non-zero error code, we abort iteration and bubble up the code as-is. Refactor both the crit-bit tree and oidtree subsystems to behave accordingly. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
/*
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* crit-bit tree implementation, does no allocations internally
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* For more information on crit-bit trees: https://cr.yp.to/critbit.html
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* Based on Adam Langley's adaptation of Dan Bernstein's public domain code
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* git clone https://github.com/agl/critbit.git
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*
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* This is adapted to store arbitrary data (not just NUL-terminated C strings
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* and allocates no memory internally. The user needs to allocate
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* "struct cb_node" and fill cb_node.k[] with arbitrary match data
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* for memcmp.
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* If "klen" is variable, then it should be embedded into "c_node.k[]"
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* Recursion is bound by the maximum value of "klen" used.
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*/
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#ifndef CBTREE_H
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#define CBTREE_H
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struct cb_node;
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struct cb_node {
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struct cb_node *child[2];
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/*
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* n.b. uint32_t for `byte' is excessive for OIDs,
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* we may consider shorter variants if nothing else gets stored.
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*/
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uint32_t byte;
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uint8_t otherbits;
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uint8_t k[FLEX_ARRAY]; /* arbitrary data, unaligned */
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};
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struct cb_tree {
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struct cb_node *root;
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};
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#define CBTREE_INIT { 0 }
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static inline void cb_init(struct cb_tree *t)
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{
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struct cb_tree blank = CBTREE_INIT;
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memcpy(t, &blank, sizeof(*t));
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}
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struct cb_node *cb_lookup(struct cb_tree *, const uint8_t *k, size_t klen);
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struct cb_node *cb_insert(struct cb_tree *, struct cb_node *, size_t klen);
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/*
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* Callback invoked by `cb_each()` for each node in the critbit tree. A return
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* value of 0 will cause the iteration to continue, a non-zero return code will
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* cause iteration to abort. The error code will be relayed back from
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* `cb_each()` in that case.
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*/
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typedef int (*cb_iter)(struct cb_node *, void *arg);
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int cb_each(struct cb_tree *, const uint8_t *kpfx, size_t klen,
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cb_iter, void *arg);
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#endif /* CBTREE_H */
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