Small improvements around List (#1216)

* * Improved fastRemoveAt
* Fixed off by one bug
* Fixed const safeness with List<>

* Made List begin and end const safe.

* Revert to previous RefPtr usage.

* Fix bug with casting.

* Tabs -> spaces.
Small fixes/improvements to List.

* Improve comment on List.

* hasContent -> isNonEmpty

5 files changed, 40 insertions, 44 deletions

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index f8df46ff7..a37d80ae8 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -2559,7 +2559,7 @@ namespace Slang
         }
         funcDecl->ReturnType = resultType;
 
-        for (auto & para : funcDecl->GetParameters())
+        for (auto& para : funcDecl->GetParameters())
         {
             ensureDecl(para, DeclCheckState::ReadyForReference);
         }
@@ -2779,11 +2779,7 @@ namespace Slang
         //      subscript(uint index) -> T { get; }
         //
 
-        bool anyAccessors = false;
-        for(auto accessorDecl : decl->getMembersOfType<AccessorDecl>())
-        {
-            anyAccessors = true;
-        }
+        bool anyAccessors = decl->getMembersOfType<AccessorDecl>().isNonEmpty();
 
         if(!anyAccessors)
         {
diff --git a/source/slang/slang-check-overload.cpp b/source/slang/slang-check-overload.cpp
index dc013b781..20d1af09a 100644
--- a/source/slang/slang-check-overload.cpp
+++ b/source/slang/slang-check-overload.cpp
@@ -440,11 +440,8 @@ namespace Slang
                     // A call may yield an l-value, and we should take a look at the candidate to be sure
                     if(auto subscriptDeclRef = candidate.item.declRef.as<SubscriptDecl>())
                     {
-                        for(auto setter : subscriptDeclRef.getDecl()->getMembersOfType<SetterDecl>())
-                        {
-                            callExpr->type.IsLeftValue = true;
-                        }
-                        for(auto refAccessor : subscriptDeclRef.getDecl()->getMembersOfType<RefAccessorDecl>())
+                        const auto& decl = subscriptDeclRef.getDecl();
+                        if (decl->getMembersOfType<SetterDecl>().isNonEmpty() || decl->getMembersOfType<RefAccessorDecl>().isNonEmpty())
                         {
                             callExpr->type.IsLeftValue = true;
                         }
diff --git a/source/slang/slang-lexer.cpp b/source/slang/slang-lexer.cpp
index 6d13a053d..9b3bed88e 100644
--- a/source/slang/slang-lexer.cpp
+++ b/source/slang/slang-lexer.cpp
@@ -12,18 +12,18 @@
 
 namespace Slang
 {
-    Token TokenReader::GetEndOfFileToken()
+    Token TokenReader::getEndOfFileToken()
     {
         return Token(TokenType::EndOfFile, UnownedStringSlice::fromLiteral(""), SourceLoc());
     }
 
-    Token* TokenList::begin() const
+    const Token* TokenList::begin() const
     {
         SLANG_ASSERT(m_tokens.getCount());
         return &m_tokens[0];
     }
 
-    Token* TokenList::end() const
+    const Token* TokenList::end() const
     {
         SLANG_ASSERT(m_tokens.getCount());
         SLANG_ASSERT(m_tokens[m_tokens.getCount() - 1].type == TokenType::EndOfFile);
@@ -59,7 +59,7 @@ namespace Slang
     Token TokenReader::advanceToken()
     {
         if (!m_cursor)
-            return GetEndOfFileToken();
+            return getEndOfFileToken();
 
         Token token = m_nextToken;
         if (m_cursor < m_end)
diff --git a/source/slang/slang-lexer.h b/source/slang/slang-lexer.h
index 0d19fe617..d1a1ba844 100644
--- a/source/slang/slang-lexer.h
+++ b/source/slang/slang-lexer.h
@@ -12,8 +12,8 @@ namespace Slang
 
     struct TokenList
     {
-        Token* begin() const;
-        Token* end() const;
+        const Token* begin() const;
+        const Token* end() const;
 
         SLANG_FORCE_INLINE void add(const Token& token) { m_tokens.add(token); }
 
@@ -29,13 +29,13 @@ namespace Slang
             , m_end  (tokenList.end  ())
         {}
 
-        Token* begin() const { return m_begin; }
-        Token* end  () const { return m_end  ; }
+        const Token* begin() const { return m_begin; }
+        const Token* end  () const { return m_end  ; }
 
         int getCount() { return (int)(m_end - m_begin); }
 
-        Token* m_begin;
-        Token* m_end;
+        const Token* m_begin;
+        const Token* m_end;
     };
 
     struct TokenReader
@@ -45,17 +45,17 @@ namespace Slang
         explicit TokenReader(TokenSpan const& tokens)
             : m_cursor(tokens.begin())
             , m_end   (tokens.end  ())
-            , m_nextToken(tokens.begin() ? *tokens.begin() : GetEndOfFileToken())
+            , m_nextToken(tokens.begin() ? *tokens.begin() : getEndOfFileToken())
         {}
         explicit TokenReader(TokenList const& tokens)
             : m_cursor(tokens.begin())
             , m_end   (tokens.end  ())
-            , m_nextToken(tokens.begin() ? *tokens.begin() : GetEndOfFileToken())
+            , m_nextToken(tokens.begin() ? *tokens.begin() : getEndOfFileToken())
         {}
         struct ParsingCursor
         {
             Token nextToken;
-            Token* tokenReaderCursor = nullptr;
+            const Token* tokenReaderCursor = nullptr;
         };
         ParsingCursor getCursor()
         {
@@ -78,9 +78,9 @@ namespace Slang
 
         int getCount() { return (int)(m_end - m_cursor); }
 
-        Token* m_cursor;
-        Token* m_end;
-        static Token GetEndOfFileToken();
+        const Token* m_cursor;
+        const Token* m_end;
+        static Token getEndOfFileToken();
     };
 
     typedef unsigned int LexerFlags;
diff --git a/source/slang/slang-syntax.h b/source/slang/slang-syntax.h
index c5160e47b..6177b894d 100644
--- a/source/slang/slang-syntax.h
+++ b/source/slang/slang-syntax.h
@@ -753,8 +753,8 @@ namespace Slang
 
         struct Iterator
         {
-            Element* m_cursor;
-            Element* m_end;
+            const Element* m_cursor;
+            const Element* m_end;
 
             bool operator!=(Iterator const& other)
             {
@@ -766,9 +766,9 @@ namespace Slang
                 m_cursor = adjust(m_cursor + 1, m_end);
             }
 
-            RefPtr<T>& operator*()
+            const RefPtr<T>& operator*()
             {
-                return *(RefPtr<T>*)m_cursor;
+                return  *(RefPtr<T>*)(m_cursor);
             }
         };
 
@@ -784,7 +784,7 @@ namespace Slang
             return iter;
         }
 
-        static Element* adjust(Element* cursor, Element* end)
+        static const Element* adjust(const Element* cursor, const Element* end)
         {
             while (cursor != end)
             {
@@ -797,7 +797,7 @@ namespace Slang
 
         // TODO(tfoley): It is ugly to have these.
         // We should probably fix the call sites instead.
-        RefPtr<T>& getFirst() { return *begin(); }
+        const RefPtr<T>& getFirst() { return *begin(); }
         Index getCount()
         {
             Index count = 0;
@@ -819,8 +819,11 @@ namespace Slang
             return result;
         }
 
-        Element* m_begin;
-        Element* m_end;
+        bool isEmpty() const { return m_end == m_begin; }
+        bool isNonEmpty() const { return m_end != m_begin; }
+
+        const Element* m_begin;
+        const Element* m_end;
     };
 
     struct TransparentMemberInfo
@@ -861,17 +864,17 @@ namespace Slang
         struct Iterator
         {
             FilteredMemberRefList const* list;
-            RefPtr<Decl>* ptr;
-            RefPtr<Decl>* end;
+            const RefPtr<Decl>* ptr;
+            const RefPtr<Decl>* end;
 
             Iterator() : list(nullptr), ptr(nullptr) {}
             Iterator(
-                FilteredMemberRefList const* list,
-                RefPtr<Decl>* ptr,
-                RefPtr<Decl>* end)
-                : list(list)
-                , ptr(ptr)
-                , end(end)
+                FilteredMemberRefList const* inList,
+                const RefPtr<Decl>* inPtr,
+                const RefPtr<Decl>* inEnd)
+                : list(inList)
+                , ptr(inPtr)
+                , end(inEnd)
             {}
 
             bool operator!=(Iterator other)
@@ -893,7 +896,7 @@ namespace Slang
         Iterator begin() const { return Iterator(this, Adjust(decls.begin(), decls.end()), decls.end()); }
         Iterator end() const { return Iterator(this, decls.end(), decls.end()); }
 
-        RefPtr<Decl>* Adjust(RefPtr<Decl>* ptr, RefPtr<Decl>* end) const
+        const RefPtr<Decl>* Adjust(const RefPtr<Decl>* ptr, const RefPtr<Decl>* end) const
         {
             for (; ptr != end; ptr++)
             {