Parsing tools: added ParseInteger function

Common/interface/ParsingTools.hpp

@@ -75,9 +75,9 @@ inline bool IsDigit(Char Symbol) noexcept
 
 /// Skips all characters until the end of the line.
 
-/// \param[inout] Pos          - starting position.
-/// \param[in]    End          - end of the input string.
-/// \param[in]    GoToNextLine - whether to go to the next line.
+/// \param[in] Start        - starting position.
+/// \param[in] End          - end of the input string.
+/// \param[in] GoToNextLine - whether to go to the next line.
 ///
 /// \return       If GoToNextLine is true, the position following the
 ///               new line character at the end of the string.
@@ -124,9 +124,9 @@ DEFINE_FLAG_ENUM_OPERATORS(SKIP_COMMENT_FLAGS)
 
 /// Skips single-line and multi-line comments starting from the given position.
 
-/// \param[inout] Start - starting position.
-/// \param[in]    End   - end of the input string.
-/// \param[in]    Flags - flags controlling what kind of comments to skip.
+/// \param[in] Start - starting position.
+/// \param[in] End   - end of the input string.
+/// \param[in] Flags - flags controlling what kind of comments to skip.
 ///
 /// \return     if the comment is found, the position immediately following
 ///             the end of the comment; starting position otherwise.
@@ -211,9 +211,9 @@ InteratorType SkipComment(const InteratorType& Start, const InteratorType& End,
 
 /// Skips all delimiters starting from the given position.
 
-/// \param[inout] Pos        - starting position.
-/// \param[in]    End        - end of the input string.
-/// \param[in]    Delimiters - optional string containing custom delimiters.
+/// \param[in] Start      - starting position.
+/// \param[in] End        - end of the input string.
+/// \param[in] Delimiters - optional string containing custom delimiters.
 ///
 /// \return       position of the first non-delimiter character.
 template <typename InteratorType>
@@ -236,10 +236,10 @@ InteratorType SkipDelimiters(const InteratorType& Start, const InteratorType& En
 
 /// Skips all comments and all delimiters starting from the given position.
 
-/// \param[inout] Pos          - starting position.
-/// \param[in]    End          - end of the input string.
-/// \param[in]    Delimiters   - optional string containing custom delimiters.
-/// \param[in]    CommentFlags - optional flags controlling what kind of comments to skip.
+/// \param[in] Start        - starting position.
+/// \param[in] End          - end of the input string.
+/// \param[in] Delimiters   - optional string containing custom delimiters.
+/// \param[in] CommentFlags - optional flags controlling what kind of comments to skip.
 ///
 /// \return true  position of the first non-comment non-delimiter character.
 ///
@@ -270,8 +270,8 @@ IteratorType SkipDelimitersAndComments(const IteratorType& Start,
 
 /// Skips one identifier starting from the given position.
 
-/// \param[inout] Pos - starting position.
-/// \param[in]    End - end of the input string.
+/// \param[in] Start - starting position.
+/// \param[in] End   - end of the input string.
 ///
 /// \return     position immediately following the last character of identifier.
 template <typename IteratorType>
@@ -295,8 +295,8 @@ IteratorType SkipIdentifier(const IteratorType& Start, const IteratorType& End)
 
 /// Skips a floating point number starting from the given position.
 
-/// \param[inout] Pos - starting position.
-/// \param[in]    End - end of the input string.
+/// \param[in] Start - starting position.
+/// \param[in] End   - end of the input string.
 ///
 /// \return     position immediately following the last character of the number.
 template <typename IteratorType>
@@ -385,6 +385,38 @@ IteratorType SkipFloatNumber(const IteratorType& Start, const IteratorType& End)
     return Pos;
 }
 
+/// Parses an integer starting from the given position.
+///
+/// \param[in]  Start - starting position.
+/// \param[in]  End   - end of the input string
+/// \param[out] Value - parsed integer value.
+/// \return     position immediately following the last character of the number.
+template <typename IteratorType, typename ValueType>
+IteratorType ParseInteger(const IteratorType& Start, const IteratorType& End, ValueType& Value) noexcept
+{
+    auto Pos = Start;
+    if (Pos == End)
+        return Pos;
+
+    const bool IsNegative = *Pos == '-';
+    if (*Pos == '+' || *Pos == '-')
+        ++Pos;
+
+    if (Pos == End || !IsNum(*Pos))
+        return Start;
+
+    Value = 0;
+    while (Pos != End && IsNum(*Pos))
+    {
+        Value = Value * 10 + (*Pos - '0');
+        ++Pos;
+    }
+
+    if (IsNegative)
+        Value = -Value;
+
+    return Pos;
+}
 
 /// Splits string into chunks separated by comments and delimiters.
 ///

Tests/DiligentCoreTest/src/Common/ParsingToolsTest.cpp

@@ -1369,4 +1369,38 @@ TEST(Common_ParsingTools, RefinePreprocessorDirective)
     TestRefine("#  \t /* Comment*/ define", "define");
 }
 
+
+TEST(Common_ParsingTools, ParseInteger)
+{
+    auto Test = [](const std::string Str, size_t RefPos, int RefValue) {
+        int  Value = INT_MAX;
+        auto Pos   = ParseInteger(Str.begin(), Str.end(), Value);
+        EXPECT_EQ(Pos, Str.begin() + RefPos);
+        EXPECT_EQ(Value, RefValue);
+    };
+
+    Test("", 0, INT_MAX);
+    Test(" ", 0, INT_MAX);
+    Test("+", 0, INT_MAX);
+    Test("-", 0, INT_MAX);
+    Test("x", 0, INT_MAX);
+    Test("abcd", 0, INT_MAX);
+    Test("+x", 0, INT_MAX);
+    Test("-y", 0, INT_MAX);
+    Test("x123", 0, INT_MAX);
+    Test("+0", 2, 0);
+    Test("-0", 2, 0);
+    Test("234", 3, 234);
+    Test("+468", 4, 468);
+    Test("-135", 4, -135);
+    Test("234x567", 3, 234);
+    Test("+468x087", 4, 468);
+    Test("-135x124", 4, -135);
+    for (int i = -100; i <= 100; ++i)
+    {
+        std::string Str = std::to_string(i);
+        Test(Str, Str.length(), i);
+    }
+};
+
 } // namespace