Added insert(iterator, char); method.

3 files changed, 59 insertions, 0 deletions

diff --git a/include/string b/include/string
index dccd5ac..428d1db 100644
--- a/include/string
+++ b/include/string
@@ -235,6 +235,13 @@ class string
         return string(&left, 1).append(right);
     }
 
+    // Insert a copy of c before the character referred to by pos.
+    // @param pos A valid iterator on *this.
+    // @return An iterator which refers to the copy of the inserted
+    // character. Because internally some reallocation may occur, the
+    // returned iterator may be different from 'pos'.
+    iterator insert(iterator pos, char c);
+
     // Find the position of a sub-string. The empty string is always
     // found at the requested position except when it's beyond the
     // string's end.
diff --git a/src/string.cpp b/src/string.cpp
index d2457fc..5c04c8e 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -516,6 +516,31 @@ string& string::assign(const value_type *array, size_type n)
     return *this;
 }
 
+string::iterator string::insert(iterator iter, char c) {
+    const size_type new_len = mLength + 1;
+    char *base = iter.base();
+
+    if (base < mData || base > mData + mLength || new_len < mLength) {
+        return iterator(&sDummy);  // out of bound || overflow
+    }
+
+    const size_type pos = base - mData;
+    if (new_len > mCapacity) {
+        reserve(new_len);
+        if (new_len > mCapacity) {
+            return iterator(&sDummy);  // not enough memory?
+        }
+    }
+    // At this point 'iter' and 'base' are not valid anymore since
+    // realloc could have taken place.
+    base = mData + pos;
+    std::memmove(base + 1, base, mLength - pos);
+    *base = c;
+    mLength = new_len;
+    mData[mLength] = 0;
+    return iterator(base);
+}
+
 string& string::operator=(char c)
 {
     clear();
diff --git a/tests/test_string.cpp b/tests/test_string.cpp
index c2405ae..0a9c1cc 100644
--- a/tests/test_string.cpp
+++ b/tests/test_string.cpp
@@ -1038,6 +1038,32 @@ bool testCharSearch() {
     return true;
 }
 
+
+bool testInsert() {
+    {
+        string::iterator res;
+        string str("zzzzzz");
+        res = str.insert(str.begin(), 'a');
+        EXPECT_TRUE(str == "azzzzzz");
+        EXPECT_TRUE(*res == 'a');
+
+        res = str.insert(str.begin() + 3, 'b');
+        EXPECT_TRUE(str == "azzbzzzz");
+        EXPECT_TRUE(*res == 'b');
+
+        res = str.insert(str.end(), 'c');
+        EXPECT_TRUE(str == "azzbzzzzc");
+        EXPECT_TRUE(*res == 'c');
+    }
+    {
+        string str;
+        string::iterator res = str.insert(str.begin(), 'a');
+        EXPECT_TRUE(str == "a");
+        EXPECT_TRUE(*res == 'a');
+    }
+    return true;
+}
+
 }  // namespace android
 
 int main(int argc, char **argv)
@@ -1067,5 +1093,6 @@ int main(int argc, char **argv)
     FAIL_UNLESS(testForwardIterator);
     FAIL_UNLESS(testSubstr);
     FAIL_UNLESS(testCharSearch);
+    FAIL_UNLESS(testInsert);
     return kPassed;
 }