Implement dynstr_first_string.

2 files changed, 118 insertions, 0 deletions

diff --git a/dynstr.c b/dynstr.c
index b160b58..076f277 100644
--- a/dynstr.c
+++ b/dynstr.c
@@ -231,3 +231,19 @@ size_t dynstr_last_byte(Dynstr *dynstr, size_t offset, int byte)
     return (size_t) (p - dynstr->mem);
 }
 
+
+size_t dynstr_first_string(Dynstr *dynstr, size_t offset, Dynstr *pattern)
+{
+    const unsigned char *p;
+    
+    if (offset >= dynstr->size)
+        return DYNSTR_NOT_FOUND;
+    if (pattern->size == 0)
+        return DYNSTR_NOT_FOUND;
+    p = memmem(dynstr->mem + offset, dynstr->size - offset, 
+               pattern->mem, pattern->size);
+    if (p == NULL)
+        return DYNSTR_NOT_FOUND;
+    return (size_t) (p - dynstr->mem);
+}
+
diff --git a/unittests.c b/unittests.c
index 24935ad..4004eec 100644
--- a/unittests.c
+++ b/unittests.c
@@ -681,6 +681,102 @@ static int test_last_byte_only_finds_byte_inside_range(void)
 }
 
 
+static int test_first_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_first_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, 2);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_first_string_only_finds_first_pattern(void)
+{
+    Dynstr *dynstr;
+    Dynstr *pattern;
+    size_t offset;
+    
+    dynstr = dynstr_new_from_cstring("123123");
+    pattern = dynstr_new_from_cstring("123");
+    offset = dynstr_first_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, 0);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_first_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_first_string(dynstr, 0, pattern);
+    FAIL_UNLESS_EQUAL(offset, DYNSTR_NOT_FOUND);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_first_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_first_string(dynstr, 3, pattern);
+    FAIL_UNLESS_EQUAL(offset, DYNSTR_NOT_FOUND);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_first_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_first_string(dynstr, 3, pattern);
+    FAIL_UNLESS_EQUAL(offset, 5);
+    dynstr_free(dynstr);
+    dynstr_free(pattern);
+    return true;
+}
+
+
+static int test_first_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_first_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();
@@ -746,6 +842,12 @@ static const struct test tests[] = {
     TEST(test_last_byte_does_not_find_nonexistent_byte),
     TEST(test_last_byte_does_not_find_byte_outside_range),
     TEST(test_last_byte_only_finds_byte_inside_range),
+    TEST(test_first_string_finds_pattern),
+    TEST(test_first_string_only_finds_first_pattern),
+    TEST(test_first_string_does_not_find_nonexistent_pattern),
+    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),
 };
 static const int num_tests = sizeof(tests) / sizeof(tests[0]);