Replace ciCompareLen with ciStartsWith where possible

`ciCompareLen(a, b, b.size()) == 0` expression is an equivalent of checking for
equality of `a` prefix with size `b.size()` with `b`.

`ciCompareLen(a, b, a.size()) == 0` is also the same thing but `a` is a prefix
`b` should start with.

apps/openmw/mwclass/misc.cpp

@@ -205,7 +205,7 @@ namespace MWClass
     {
         const std::string_view soulgemPrefix = "misc_soulgem";
 
-        if (::Misc::StringUtils::ciCompareLen(ptr.getCellRef().getRefId(), soulgemPrefix, soulgemPrefix.length()) == 0)
+        if (Misc::StringUtils::ciStartsWith(ptr.getCellRef().getRefId(), soulgemPrefix))
             return std::make_unique<MWWorld::ActionSoulgem>(ptr);
 
         return std::make_unique<MWWorld::NullAction>();

apps/openmw/mwscript/containerextensions.cpp

@@ -309,7 +309,7 @@ namespace MWScript
 
                     const std::string soulgemPrefix = "misc_soulgem";
 
-                    if (::Misc::StringUtils::ciCompareLen(item, soulgemPrefix, soulgemPrefix.length()) == 0)
+                    if (Misc::StringUtils::ciStartsWith(item, soulgemPrefix))
                     {
                         it = invStore.end();
 

apps/openmw/mwworld/store.cpp

@@ -147,10 +147,7 @@ namespace MWWorld
     {
         std::vector<const T*> results;
         std::copy_if(mShared.begin(), mShared.end(), std::back_inserter(results),
-                [&id](const T* item)
-                {
-                    return Misc::StringUtils::ciCompareLen(id, item->mId, id.size()) == 0;
-                });
+                [&id](const T* item) { return Misc::StringUtils::ciStartsWith(item->mId, id); });
         if(!results.empty())
             return results[Misc::Rng::rollDice(results.size(), prng)];
         return nullptr;

apps/openmw_test_suite/misc/test_stringops.cpp

@@ -151,4 +151,35 @@ namespace
     {
         EXPECT_FALSE(ciEqual(std::string("a"), std::string("aa")));
     }
+
+    TEST(MiscStringsCiStartsWith, empty_string_should_start_with_empty_prefix)
+    {
+        EXPECT_TRUE(ciStartsWith(std::string_view(), std::string_view()));
+    }
+
+    TEST(MiscStringsCiStartsWith, string_should_start_with_empty_prefix)
+    {
+        EXPECT_TRUE(ciStartsWith("foo", std::string_view()));
+    }
+
+    TEST(MiscStringsCiStartsWith, string_should_start_with_own_prefix)
+    {
+        std::string string = "some string";
+        EXPECT_TRUE(ciStartsWith(string, string.substr(0, 4)));
+    }
+
+    TEST(MiscStringsCiStartsWith, string_should_start_with_the_same_value)
+    {
+        EXPECT_TRUE(ciStartsWith("foo", "foo"));
+    }
+
+    TEST(MiscStringsCiStartsWith, string_should_not_start_with_not_its_prefix)
+    {
+        EXPECT_FALSE(ciStartsWith("some string", "foo"));
+    }
+
+    TEST(MiscStringsCiStartsWith, string_should_not_start_with_longer_string_having_matching_prefix)
+    {
+        EXPECT_FALSE(ciStartsWith("foo", "foo bar"));
+    }
 }

components/misc/strings/algorithm.hpp

@@ -28,6 +28,11 @@ namespace Misc::StringUtils
                           [] (char l, char r) { return toLower(l) == toLower(r); });
     }
 
+    inline bool ciStartsWith(std::string_view value, std::string_view prefix)
+    {
+        return ciEqual(value.substr(0, prefix.size()), prefix);
+    }
+
     inline int ciCompareLen(std::string_view x, std::string_view y, std::size_t len)
     {
         std::string_view::const_iterator xit = x.begin();

components/nifbullet/bulletnifloader.cpp

@@ -373,7 +373,7 @@ void BulletNifLoader::handleNode(const std::string& fileName, const Nif::Node& n
             // affecting the entire subtree of this node
             Nif::NiStringExtraData *sd = (Nif::NiStringExtraData*)e.getPtr();
 
-            if (Misc::StringUtils::ciCompareLen(sd->string, "NC", 2) == 0)
+            if (Misc::StringUtils::ciStartsWith(sd->string, "NC"))
             {
                 // NCC flag in vanilla is partly case sensitive: prefix NC is case insensitive but second C needs be uppercase
                 if (sd->string.length() > 2 && sd->string[2] == 'C')

components/sceneutil/attach.cpp

@@ -72,10 +72,11 @@ namespace SceneUtil
 
         bool filterMatches(std::string_view name) const
         {
-            if (Misc::StringUtils::ciCompareLen(name, mFilter, mFilter.size()) == 0)
+            if (Misc::StringUtils::ciStartsWith(name, mFilter))
                 return true;
-            if (Misc::StringUtils::ciCompareLen(name, "tri ", 4) == 0)
-                return Misc::StringUtils::ciCompareLen(name.substr(4), mFilter, mFilter.size()) == 0;
+            constexpr std::string_view prefix = "tri ";
+            if (Misc::StringUtils::ciStartsWith(name, prefix))
+                return Misc::StringUtils::ciStartsWith(name.substr(prefix.size()), mFilter);
             return false;
         }
 

components/sceneutil/visitor.cpp

@@ -144,8 +144,7 @@ namespace SceneUtil
 
     void RemoveTriBipVisitor::applyImpl(osg::Node& node)
     {
-        const std::string_view toFind = "tri bip";
-        if (Misc::StringUtils::ciCompareLen(node.getName(), toFind, toFind.size()) == 0)
+        if (Misc::StringUtils::ciStartsWith(node.getName(), "tri bip"))
         {
             osg::Group* parent = static_cast<osg::Group*>(*(getNodePath().end()-2));
             // Not safe to remove in apply(), since the visitor is still iterating the child list