使用re2库实现简单的正则表达式匹配

Posted 2020-12-18 jackie-astro

reg_test.cpp内容如下：

#include <vector>
#include <fmt/format.h>
#include <console_color.h>
#include <re2/re2.h>

using namespace re2;
using namespace std;
using namespace fmt;
using namespace concol;

int main(int argc, char **argv)
{
    concol::init();

    //seperate text and int from a string
    int i = 0;
    string s("");
    if (RE2::FullMatch("My name is	Jackie:1234", "([0-9A-Za-z\\s]+):(\\d+)", &s, &i))
        cout << s << endl << i << endl;
    print_cyan_line();

    // find first number in a string
    int number = 0;
    const char* string_with_two_num = "x*100 + 200";
    if (RE2::PartialMatch(string_with_two_num, "(\\d+)", &number))
        cout << "first number in "" << string_with_two_num << "" is " << number << endl;
    // find second number in a string
    if (RE2::PartialMatch(string_with_two_num, "\\d+[^\\d]+(\\d+)", &number))
        cout << "second number in "" << string_with_two_num << "" is " << number << endl;
    print_cyan_line();

    // find all numbers in a string
    cout << "All numbers in string "" << string_with_two_num << "" are as follow: " << endl;
    StringPiece stringPieceWith2Num(string_with_two_num);
    while (RE2::FindAndConsume(&stringPieceWith2Num, "(\\d+)", &number))
        cout << number << endl;
    print_cyan_line();

    // extract int to string when integer overflow causes failure
    string digitStr("123456789123456789");
    string strInt;
    if (!RE2::FullMatch(digitStr, "(\\d+)", &number))
        cout << "Parse integer failed" << endl;
    if (RE2::FullMatch(digitStr, "(\\d+)", &strInt))
        cout << strInt << endl;
    print_cyan_line();

    // precompile pattern for faster matching, which is faster than sscanf.
    vector<string> strings;
    strings.push_back("Hello");
    strings.push_back("hello");
    strings.push_back("heLLo");
    strings.push_back("h_e_l_l_o");
    strings.push_back("H2 O");
    RE2 re("h.*o");
    for (auto& x : strings)
        if (RE2::FullMatch(x, re))
            cout << x << endl;
    print_cyan_line();

    // case-insensitive match
    RE2::Options opts;
    opts.set_case_sensitive(false);
    RE2 re2("h.*o", opts);
    for (auto & x : strings)
        if (RE2::FullMatch(x, re2))
            cout << x << endl;
    print_cyan_line();

    // scanning text incrementally
    string contents("foo = 3
bar = 5
foobar=foo+bar
jackie = 7
");
    StringPiece input(contents);
    string var;
    int value;
    while (RE2::FindAndConsume(&input, "(\\w+) = (\\d+)
", &var, &value))
        cout << "var: " << var << ", value: " << value << endl;
    print_cyan_line();
	
    // extract all words from a string
    StringPiece line("My name is Jackie");
    string word;
    while (RE2::FindAndConsume(&line, "(\\w+)", &word))
        cout << word << endl;
    print_cyan_line();

    // parse hex/octal/c-radix numbers
    int a, b, c, d;
    if (RE2::FullMatch("100 40 0100 0x40", "(.*) (.*) (.*) (.*)",
        RE2::Octal(&a), RE2::Hex(&b), RE2::CRadix(&c), RE2::CRadix(&d)))
        cout << a << ", " << b << ", " << c << ", " << d << endl;
    print_cyan_line();


    cout << "Press any key to exit..." << endl;
    get_char();
    return 0;
}

运行结果如下图所示：