Implement dynstr_last_string.

2 files changed, 121 insertions, 0 deletions

diff --git a/dynstr.c b/dynstr.c
index 076f277..66da740 100644
--- a/dynstr.c
+++ b/dynstr.c
@@ -247,3 +247,22 @@ size_t dynstr_first_string(Dynstr *dynstr, size_t offset, Dynstr *pattern)
     return (size_t) (p - dynstr->mem);
 }
 
+
+size_t dynstr_last_string(Dynstr *dynstr, size_t offset, Dynstr *pattern)
+{
+    size_t result;
+    size_t new_result;
+
+    /* GNU libc lacks a memrmem function, so we loop to the last
+     * dynstr_first_string match. */
+    result = DYNSTR_NOT_FOUND;    
+    for (;;) {
+        new_result = dynstr_first_string(dynstr, offset, pattern);
+        if (new_result == DYNSTR_NOT_FOUND)
+            break;
+        result = new_result;
+        offset = result + 1;
+    }
+    return result;
+}
+
diff --git a/unittests.c b/unittests.c
index 4004eec..d9b14d3 100644
--- a/unittests.c
+++ b/unittests.c
@@ -777,6 +777,102 @@ static int test_first_string_does_not_find_empty_pattern(void)
 }
 
 
+static int test_last_string_finds_pattern(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123456");
+    pattern = dynstr_new_from_cstring("345");
+    offset = dynstr_last_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, 2);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_last_string_only_finds_last_pattern(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123123");
+    pattern = dynstr_new_from_cstring("123");
+    offset = dynstr_last_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, 3);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_last_string_does_not_find_nonexistent_pattern(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123456");
+    pattern = dynstr_new_from_cstring("x");
+    offset = dynstr_last_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, DYNSTR_NOT_FOUND);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_last_string_does_not_find_pattern_outside_range(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123456");
+    pattern = dynstr_new_from_cstring("123");
+    offset = dynstr_last_string(dynstr, 3, pattern);
+    FAIL_UNLESS_EQUAL(offset, DYNSTR_NOT_FOUND);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_last_string_only_finds_pattern_inside_range(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123123");
+    pattern = dynstr_new_from_cstring("3");
+    offset = dynstr_last_string(dynstr, 3, pattern);
+    FAIL_UNLESS_EQUAL(offset, 5);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_last_string_does_not_find_empty_pattern(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123123");
+    pattern = dynstr_new_from_cstring("");
+    offset = dynstr_last_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, DYNSTR_NOT_FOUND);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
 static void setup(void)
 {
     dynstr_init();
@@ -848,6 +944,12 @@ static const struct test tests[] = {
     TEST(test_first_string_does_not_find_pattern_outside_range),
     TEST(test_first_string_only_finds_pattern_inside_range),
     TEST(test_first_string_does_not_find_empty_pattern),
+    TEST(test_last_string_finds_pattern),
+    TEST(test_last_string_only_finds_last_pattern),
+    TEST(test_last_string_does_not_find_nonexistent_pattern),
+    TEST(test_last_string_does_not_find_pattern_outside_range),
+    TEST(test_last_string_only_finds_pattern_inside_range),
+    TEST(test_last_string_does_not_find_empty_pattern),
 };
 static const int num_tests = sizeof(tests) / sizeof(tests[0]);