Parsing tools: added GetArrayIndex function

Author: TheMostDiligent

Common/interface/ParsingTools.hpp

@@ -31,6 +31,7 @@
 
 #include <cstring>
 #include <sstream>
+#include <limits>
 
 #include "../../Primitives/interface/BasicTypes.h"
 #include "../../Primitives/interface/FlagEnum.h"
@@ -1155,6 +1156,75 @@ inline std::string RefinePreprocessorDirective(const char* Str, size_t Len = 0)
     return RefinePreprocessorDirective(Str, Str + Len);
 }
 
+static constexpr int InvalidArrayIndex = std::numeric_limits<int>::min();
+
+/// Returns the array index if the given variable name is an indexed array element.
+///
+/// \param [in]  Start   - starting position.
+/// \param [in]  End     - end of the input string.
+/// \param [out] NameEnd - ending position of the variable name.
+///
+/// \return     - Array index if the given variable name is an array element.
+///             - -1 if the given variable name is a valid identifier and is not an array element.
+///             - INT_MIN if the array index is invalid.
+template <typename InteratorType>
+inline int GetArrayIndex(const InteratorType& Start, const InteratorType& End, InteratorType& NameEnd)
+{
+    NameEnd = SkipIdentifier(Start, End);
+    // Empty name is not a valid identifier
+    if (NameEnd == Start)
+    {
+        //
+        //  ^
+        return InvalidArrayIndex;
+    }
+
+    if (NameEnd == End)
+    {
+        // MyArray
+        //        ^
+        return -1;
+    }
+    // MyArray [ 16 ]
+    //        ^
+
+    auto Pos = SkipDelimiters(NameEnd, End, " \t");
+    // MyArray [ 16 ]
+    //         ^
+    if (Pos == End || *Pos != '[')
+        return InvalidArrayIndex;
+
+    Pos = SkipDelimiters(Pos + 1, End, " \t");
+    // MyArray [ 16 ]
+    //           ^
+    if (Pos == End)
+        return InvalidArrayIndex;
+
+    int Index = InvalidArrayIndex;
+    Pos       = ParseInteger(Pos, End, Index);
+    // MyArray [ 16 ]
+    //             ^
+
+    Pos = SkipDelimiters(Pos, End, " \t");
+    // MyArray [ 16 ]
+    //              ^
+    return (Pos != End && *Pos == ']') ? Index : InvalidArrayIndex;
+}
+
+template <typename InteratorType>
+inline int GetArrayIndex(const InteratorType& Start, const InteratorType& End, std::string& NameWithoutBrackets)
+{
+    InteratorType NameEnd = End;
+    const auto    Index   = GetArrayIndex(Start, End, NameEnd);
+    NameWithoutBrackets.assign(Start, NameEnd);
+    return Index;
+}
+
+inline int GetArrayIndex(const std::string& Var, std::string& NameWithoutBrackets)
+{
+    return GetArrayIndex(Var.begin(), Var.end(), NameWithoutBrackets);
+}
+
 } // namespace Parsing
 
 } // namespace Diligent

Tests/DiligentCoreTest/src/Common/ParsingToolsTest.cpp

@@ -1405,4 +1405,41 @@ TEST(Common_ParsingTools, ParseInteger)
     }
 };
 
+
+TEST(Common_ParsingTools, GetArrayIndex)
+{
+    auto Test = [](const std::string Var, size_t RefNameEndPos, int RefIndex) {
+        std::string NameWOBrackets;
+        int         Index = GetArrayIndex(Var, NameWOBrackets);
+
+        EXPECT_EQ(NameWOBrackets, Var.substr(0, RefNameEndPos));
+        EXPECT_EQ(Index, RefIndex);
+    };
+
+    Test("", 0, InvalidArrayIndex);
+    Test(" ", 0, InvalidArrayIndex);
+    Test("1", 0, InvalidArrayIndex);
+    Test("?", 0, InvalidArrayIndex);
+    Test("x", 1, -1);
+    Test("abc", 3, -1);
+    Test("xy1 ", 3, InvalidArrayIndex);
+    Test("xy2[", 3, InvalidArrayIndex);
+    Test("xy3 [", 3, InvalidArrayIndex);
+    Test("xy4[ ", 3, InvalidArrayIndex);
+    Test("xy5 [ ", 3, InvalidArrayIndex);
+    Test("xy6[10]", 3, 10);
+    Test("xy7[11 ]", 3, 11);
+    Test("xy8[ 12]", 3, 12);
+    Test("xy9[ 13 ]", 3, 13);
+    Test("xy0 [14]", 3, 14);
+    Test("xy1 [ 15]", 3, 15);
+    Test("xy2 [16 ]", 3, 16);
+    Test("xy3 [ 18 ]", 3, 18);
+    Test("xy4[x]", 3, INT_MIN);
+    Test("xy5 [ x ] ", 3, INT_MIN);
+    Test("xy6[12x]", 3, INT_MIN);
+    Test("xy7[12", 3, INT_MIN);
+    Test("xy7[12 ", 3, INT_MIN);
+}
+
 } // namespace