strvec: introduce new `strvec_splice()` function

Introduce a new `strvec_splice()` function that can replace a range of
strings in the vector with another array of strings. This function will
be used in subsequent commits.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/strvec.c b/strvec.c
index f712070f5745d5f998d0846ac4009441dddfa500..d1cf4e2496a564c878f4b81207efe275abed72cf 100644 (file)
--- a/strvec.c
+++ b/strvec.c
@@ -56,6 +56,25 @@ void strvec_pushv(struct strvec *array, const char **items)
                strvec_push(array, *items);
 }
 
+void strvec_splice(struct strvec *array, size_t idx, size_t len,
+                  const char **replacement, size_t replacement_len)
+{
+       if (idx + len > array->nr)
+               BUG("range outside of array boundary");
+       if (replacement_len > len)
+               ALLOC_GROW(array->v, array->nr + (replacement_len - len) + 1,
+                          array->alloc);
+       for (size_t i = 0; i < len; i++)
+               free((char *)array->v[idx + i]);
+       if (replacement_len != len) {
+               memmove(array->v + idx + replacement_len, array->v + idx + len,
+                       (array->nr - idx - len + 1) * sizeof(char *));
+               array->nr += (replacement_len - len);
+       }
+       for (size_t i = 0; i < replacement_len; i++)
+               array->v[idx + i] = xstrdup(replacement[i]);
+}
+
 const char *strvec_replace(struct strvec *array, size_t idx, const char *replacement)
 {
        char *to_free;

diff --git a/strvec.h b/strvec.h
index 4b73c1f092e9b016ce3299035477713c6267cdae..f74e061e1419bce7c3f3730d4dfdf081c8db094e 100644 (file)
--- a/strvec.h
+++ b/strvec.h
@@ -67,6 +67,15 @@ void strvec_pushl(struct strvec *, ...);
 /* Push a null-terminated array of strings onto the end of the array. */
 void strvec_pushv(struct strvec *, const char **);
 
+/*
+ * Replace `len` values starting at `idx` with the provided replacement
+ * strings. If `len` is zero this is effectively an insert at the given `idx`.
+ * If `replacement_len` is zero this is effectively a delete of `len` items
+ * starting at `idx`.
+ */
+void strvec_splice(struct strvec *array, size_t idx, size_t len,
+                  const char **replacement, size_t replacement_len);
+
 /**
  * Replace the value at the given index with a new value. The index must be
  * valid. Returns a pointer to the inserted value.

diff --git a/t/unit-tests/strvec.c b/t/unit-tests/strvec.c
index bf4c0cb172e1f01c452b8744084cc45bf3aa86fa..855b602337169f6fffcadf91e0734db44ceccb16 100644 (file)
--- a/t/unit-tests/strvec.c
+++ b/t/unit-tests/strvec.c
@@ -88,6 +88,71 @@ void test_strvec__pushv(void)
        strvec_clear(&vec);
 }
 
+void test_strvec__splice_with_same_size_replacement(void)
+{
+       struct strvec vec = STRVEC_INIT;
+       const char *replacement[] = { "1" };
+
+       strvec_pushl(&vec, "foo", "bar", "baz", NULL);
+       strvec_splice(&vec, 1, 1, replacement, ARRAY_SIZE(replacement));
+       check_strvec(&vec, "foo", "1", "baz", NULL);
+       strvec_clear(&vec);
+}
+
+void test_strvec__splice_with_smaller_replacement(void)
+{
+       struct strvec vec = STRVEC_INIT;
+       const char *replacement[] = { "1" };
+
+       strvec_pushl(&vec, "foo", "bar", "baz", NULL);
+       strvec_splice(&vec, 1, 2, replacement, ARRAY_SIZE(replacement));
+       check_strvec(&vec, "foo", "1", NULL);
+       strvec_clear(&vec);
+}
+
+void test_strvec__splice_with_bigger_replacement(void)
+{
+       struct strvec vec = STRVEC_INIT;
+       const char *replacement[] = { "1", "2", "3" };
+
+       strvec_pushl(&vec, "foo", "bar", "baz", NULL);
+       strvec_splice(&vec, 0, 2, replacement, ARRAY_SIZE(replacement));
+       check_strvec(&vec, "1", "2", "3", "baz", NULL);
+       strvec_clear(&vec);
+}
+
+void test_strvec__splice_with_empty_replacement(void)
+{
+       struct strvec vec = STRVEC_INIT;
+
+       strvec_pushl(&vec, "foo", "bar", "baz", NULL);
+       strvec_splice(&vec, 0, 2, NULL, 0);
+       check_strvec(&vec, "baz", NULL);
+       strvec_clear(&vec);
+}
+
+void test_strvec__splice_with_empty_original(void)
+{
+       struct strvec vec = STRVEC_INIT;
+       const char *replacement[] = { "1", "2" };
+
+       strvec_pushl(&vec, "foo", "bar", "baz", NULL);
+       strvec_splice(&vec, 1, 0, replacement, ARRAY_SIZE(replacement));
+       check_strvec(&vec, "foo", "1", "2", "bar", "baz", NULL);
+       strvec_clear(&vec);
+}
+
+void test_strvec__splice_at_tail(void)
+{
+       struct strvec vec = STRVEC_INIT;
+       const char *replacement[] = { "1", "2" };
+
+       strvec_pushl(&vec, "foo", "bar", NULL);
+       strvec_splice(&vec, 2, 0, replacement, ARRAY_SIZE(replacement));
+       check_strvec(&vec, "foo", "bar", "1", "2", NULL);
+       strvec_clear(&vec);
+}
+
 void test_strvec__replace_at_head(void)
 {
        struct strvec vec = STRVEC_INIT;