Merge branch 'jk/argv-array' into maint

* jk/argv-array:
  run_hook: use argv_array API
  checkout: use argv_array API
  bisect: use argv_array API
  quote: provide sq_dequote_to_argv_array
  refactor argv_array into generic code
  quote.h: fix bogus comment
  add sha1_array API docs

2 files changed, 125 insertions, 0 deletions

diff --git a/Documentation/technical/api-argv-array.txt b/Documentation/technical/api-argv-array.txt
new file mode 100644
index 0000000000..49b3d52952
--- /dev/null
+++ b/Documentation/technical/api-argv-array.txt
@@ -0,0 +1,46 @@
+argv-array API
+==============
+
+The argv-array API allows one to dynamically build and store
+NULL-terminated lists.  An argv-array maintains the invariant that the
+`argv` member always points to a non-NULL array, and that the array is
+always NULL-terminated at the element pointed to by `argv[argc]`. This
+makes the result suitable for passing to functions expecting to receive
+argv from main(), or the link:api-run-command.html[run-command API].
+
+The link:api-string-list.html[string-list API] is similar, but cannot be
+used for these purposes; instead of storing a straight string pointer,
+it contains an item structure with a `util` field that is not compatible
+with the traditional argv interface.
+
+Each `argv_array` manages its own memory. Any strings pushed into the
+array are duplicated, and all memory is freed by argv_array_clear().
+
+Data Structures
+---------------
+
+`struct argv_array`::
+
+	A single array. This should be initialized by assignment from
+	`ARGV_ARRAY_INIT`, or by calling `argv_array_init`. The `argv`
+	member contains the actual array; the `argc` member contains the
+	number of elements in the array, not including the terminating
+	NULL.
+
+Functions
+---------
+
+`argv_array_init`::
+	Initialize an array. This is no different than assigning from
+	`ARGV_ARRAY_INIT`.
+
+`argv_array_push`::
+	Push a copy of a string onto the end of the array.
+
+`argv_array_pushf`::
+	Format a string and push it onto the end of the array. This is a
+	convenience wrapper combining `strbuf_addf` and `argv_array_push`.
+
+`argv_array_clear`::
+	Free all memory associated with the array and return it to the
+	initial, empty state.
diff --git a/Documentation/technical/api-sha1-array.txt b/Documentation/technical/api-sha1-array.txt
new file mode 100644
index 0000000000..4a4bae8109
--- /dev/null
+++ b/Documentation/technical/api-sha1-array.txt
@@ -0,0 +1,79 @@
+sha1-array API
+==============
+
+The sha1-array API provides storage and manipulation of sets of SHA1
+identifiers. The emphasis is on storage and processing efficiency,
+making them suitable for large lists. Note that the ordering of items is
+not preserved over some operations.
+
+Data Structures
+---------------
+
+`struct sha1_array`::
+
+	A single array of SHA1 hashes. This should be initialized by
+	assignment from `SHA1_ARRAY_INIT`.  The `sha1` member contains
+	the actual data. The `nr` member contains the number of items in
+	the set.  The `alloc` and `sorted` members are used internally,
+	and should not be needed by API callers.
+
+Functions
+---------
+
+`sha1_array_append`::
+	Add an item to the set. The sha1 will be placed at the end of
+	the array (but note that some operations below may lose this
+	ordering).
+
+`sha1_array_sort`::
+	Sort the elements in the array.
+
+`sha1_array_lookup`::
+	Perform a binary search of the array for a specific sha1.
+	If found, returns the offset (in number of elements) of the
+	sha1. If not found, returns a negative integer. If the array is
+	not sorted, this function has the side effect of sorting it.
+
+`sha1_array_clear`::
+	Free all memory associated with the array and return it to the
+	initial, empty state.
+
+`sha1_array_for_each_unique`::
+	Efficiently iterate over each unique element of the list,
+	executing the callback function for each one. If the array is
+	not sorted, this function has the side effect of sorting it.
+
+Examples
+--------
+
+-----------------------------------------
+void print_callback(const unsigned char sha1[20],
+		    void *data)
+{
+	printf("%s\n", sha1_to_hex(sha1));
+}
+
+void some_func(void)
+{
+	struct sha1_array hashes = SHA1_ARRAY_INIT;
+	unsigned char sha1[20];
+
+	/* Read objects into our set */
+	while (read_object_from_stdin(sha1))
+		sha1_array_append(&hashes, sha1);
+
+	/* Check if some objects are in our set */
+	while (read_object_from_stdin(sha1)) {
+		if (sha1_array_lookup(&hashes, sha1) >= 0)
+			printf("it's in there!\n");
+
+	/*
+	 * Print the unique set of objects. We could also have
+	 * avoided adding duplicate objects in the first place,
+	 * but we would end up re-sorting the array repeatedly.
+	 * Instead, this will sort once and then skip duplicates
+	 * in linear time.
+	 */
+	sha1_array_for_each_unique(&hashes, print_callback, NULL);
+}
+-----------------------------------------