参考：正则表达式（Regular Expression） — Chuanqi 的技术文档 

"	\"
\	\\
.	\.

一、函数细节

1. GlobalReplace()

RE2::GlobalReplace(str, pat, new_sub_str )：将句子str中匹配到的子串替换为new_sub_str 

std::string aInput = "~/Test (Folder)/";
RE2::GlobalReplace( &aInput, "(<|>|\\||\\:|\\(|\\)|&|;|\\s)", "\\\\0" );


~/Test\ \(Folder\)/
替换为
~/Test\0\0Folder\0

2. PartialMatch() 

RE2::PartialMatch("hello:1234", pattern, &s, &i)：将匹配的组内容放到s、i中

RE2 pattern("(\\w+):(\\d+)", RE2::Quiet);
assert(RE2::PartialMatch("hello:1234", pattern, &s, &i));  // 成功匹配

#include <re2/re2.h>
#include <iostream>
#include <assert.h>
 
int
main(void)
{
    int i;
    std::string s;
    assert(RE2::FullMatch("ruby:1234", "(\\w+):(\\d+)", &s, &i));
    assert(s == "ruby");
    assert(i == 1234);
 
    // Fails: "ruby" cannot be parsed as an integer.
    assert(!RE2::FullMatch("ruby", "(.+)", &i));
 
    // Success; does not extract the number.
    assert(RE2::FullMatch("ruby:1234", "(\\w+):(\\d+)", &s));
 
    // Success; skips NULL argument.
    assert(RE2::FullMatch("ruby:1234", "(\\w+):(\\d+)", (void*)NULL, &i));
 
    // Fails: integer overflow keeps value from being stored in i.
    assert(!RE2::FullMatch("ruby:123456789123", "(\\w+):(\\d+)", &s, &i));
 
    std::cout << "Ok" << std::endl;
    return 0;
}

3. re2::StringPiece

RE2返回的是匹配的字符串，如果需要知道匹配的偏移量，则将结果存储在re2::StringPiece而不是std::string中， .data()的值将指向原始字符串。

考虑这个程序。
在每个测试中，result.data()是指向原始const char*或std::string的指针。

二、Options设置

set_literal (3)

set_posix_syntax (3)

set_perl_classes (3)

set_log_errors (3)

set_case_sensitive (3)：大小写

Copy (2)

set_word_boundary (2)

set_never_nl (2)

set_max_mem (2)

set_one_line (1)："^$"开关可用