Write matchers using C++ regex to match (and test the match) for C++ - style doubles and identifiers Using the template

[answerhappygod]

Write matchers using C++ regex to match (and test the match) for
C++ - style doubles and identifiers Using the template below.
//Begin of code
// Goal - match C++ decimal (base 10) integer strings.
// Digit = r(0|..|9)
// PositiveDigit=r(1|..|9)
// Decimal = r(0|(PositiveDigit((|')Digit)*))
#include "gtest/gtest.h"
#include <regex>
#include <string>
using namespace std;
bool IsDecimal(const std::string &candidate) {
regex
matcher("(-?(0|([1-9]('?[0-9])*))|\\((0|([1-9]('?[0-9])*))\\))");
return regex_match(candidate,matcher);
}
bool IsDouble(const std::string &candidate) {
return true;
}
bool IsIdentifier(const std::string &candidate) {
return true;
}
TEST(RegEx,DecimalInteger) {
ASSERT_TRUE(IsDecimal("0"));
ASSERT_TRUE(IsDecimal("1"));
ASSERT_TRUE(IsDecimal("1'2'3"));
ASSERT_TRUE(IsDecimal("1'000'000"));
ASSERT_TRUE(IsDecimal("-0"));
ASSERT_TRUE(IsDecimal("-1"));
ASSERT_TRUE(IsDecimal("-1'2'3"));
ASSERT_TRUE(IsDecimal("-1'000'000"));
ASSERT_FALSE(IsDecimal("-"));
ASSERT_FALSE(IsDecimal("00"));
ASSERT_FALSE(IsDecimal("00"));
ASSERT_FALSE(IsDecimal("0001"));
ASSERT_FALSE(IsDecimal("1''000''000"));
ASSERT_FALSE(IsDecimal(".20"));
ASSERT_FALSE(IsDecimal("20."));
}
TEST(RegEx,Double) {
}
TEST(RegEx,Identifier) {
}
#end of code