lib: rework uc_index() implementation

 - Fix segfault on passing string haystack with non-string needle argument
 - Perform strict equality tests against array haystacks
 - Make string searches binary safe
 - Improve left index string search performance
 - Improve right index array search performance
 - Add missing test coverage for index() and rindex()

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

3 files changed, 124 insertions, 0 deletions

diff --git a/tests/custom/03_stdlib/58_index b/tests/custom/03_stdlib/58_index
new file mode 100644
index 0000000..30c5146
--- /dev/null
+++ b/tests/custom/03_stdlib/58_index
@@ -0,0 +1,48 @@
+The `index()` function locates an element within a given array or a substring
+position within a given string, depending on the type of arguments given.
+
+Returns `null` if the given haystack argument is neither an array nor a string,
+returns `-1` if the element was not found within the array or the substring was
+not found within the string.
+
+Returns the first found index position in all other cases.
+
+-- Testcase --
+{%
+	let o = {};
+
+	printf("%.J\n", [
+		index([ 1, 2, "abc", 3, "abc", 1, 2 ], "abc"),	// should return 2
+		index([ 1, 2, 3 ], 4),							// should return -1
+		index([ [], {} ], {}),							// should return -1 (strict equality)
+		index([ [], o ], o),							// should return 1 (strict equality)
+
+		index("foobarfoobarfoobar", "arf"),				// should return 4
+		index("test", "hello"),							// should return -1
+		index("test", "test"),							// should return 0 (needle = haystack length special case)
+		index("test", ""),								// should return 0 (zero length needle special case)
+		index("", ""),									// should return 0 (zero length special case)
+		index("foo\0foo\0foo", "o\0f"),					// should return 2 (binary safe)
+
+		index({ test: true }, true),					// should return null
+		index(1234, 3),									// should return null
+	]);
+%}
+-- End --
+
+-- Expect stdout --
+[
+	2,
+	-1,
+	-1,
+	1,
+	4,
+	-1,
+	0,
+	0,
+	0,
+	2,
+	null,
+	null
+]
+-- End --
diff --git a/tests/custom/03_stdlib/59_rindex b/tests/custom/03_stdlib/59_rindex
new file mode 100644
index 0000000..35f8d2d
--- /dev/null
+++ b/tests/custom/03_stdlib/59_rindex
@@ -0,0 +1,48 @@
+The `rindex()` function locates an element within a given array or a substring
+position within a given string, depending on the type of arguments given.
+
+Returns `null` if the given haystack argument is neither an array nor a string,
+returns `-1` if the element was not found within the array or the substring was
+not found within the string.
+
+Returns the last found index position in all other cases.
+
+-- Testcase --
+{%
+	let o = {};
+
+	printf("%.J\n", [
+		rindex([ 1, 2, "abc", 3, "abc", 1, 2 ], "abc"),	// should return 4
+		rindex([ 1, 2, 3 ], 4),							// should return -1
+		rindex([ [], {} ], {}),							// should return -1 (strict equality)
+		rindex([ [], o ], o),							// should return 1 (strict equality)
+
+		rindex("foobarfoobarfoobar", "arf"),			// should return 10
+		rindex("test", "hello"),						// should return -1
+		rindex("test", "test"),							// should return 0 (needle = haystack length special case)
+		rindex("test", ""),								// should return 4 (zero length needle special case)
+		rindex("", ""),									// should return 0 (zero length special case)
+		rindex("foo\0foo\0foo", "o\0f"),				// should return 6 (binary safe)
+
+		rindex({ test: true }, true),					// should return null
+		rindex(1234, 3),								// should return null
+	]);
+%}
+-- End --
+
+-- Expect stdout --
+[
+	4,
+	-1,
+	-1,
+	1,
+	10,
+	-1,
+	0,
+	4,
+	0,
+	6,
+	null,
+	null
+]
+-- End --
diff --git a/tests/custom/04_bugs/38_index_segfault b/tests/custom/04_bugs/38_index_segfault
new file mode 100644
index 0000000..e29b99f
--- /dev/null
+++ b/tests/custom/04_bugs/38_index_segfault
@@ -0,0 +1,28 @@
+When index() or rindex() was invoked with a string haystack and a non-
+string needle argument, a segmentation fault occurred due to an internal
+strlen() invocation on a NULL pointer.
+
+-- Testcase --
+print(index("abc", []), "\n")
+-- End --
+
+-- Args --
+-R
+-- End --
+
+-- Expect stdout --
+-1
+-- End --
+
+
+-- Testcase --
+print(rindex("abc", []), "\n")
+-- End --
+
+-- Args --
+-R
+-- End --
+
+-- Expect stdout --
+-1
+-- End --