File: imatch.cpp
   1 /*
   2 The MIT License (MIT)
   3 
   4 Copyright © 2020-2025 pacman64
   5 
   6 Permission is hereby granted, free of charge, to any person obtaining a copy of
   7 this software and associated documentation files (the “Software”), to deal
   8 in the Software without restriction, including without limitation the rights to
   9 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
  10 of the Software, and to permit persons to whom the Software is furnished to do
  11 so, subject to the following conditions:
  12 
  13 The above copyright notice and this permission notice shall be included in all
  14 copies or substantial portions of the Software.
  15 
  16 THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22 SOFTWARE.
  23 */
  24 
  25 /*
  26 imatch [regular expressions...]
  27 
  28 Only keep lines which case-insensitively match any of the regexes given.
  29 When not given any regex, match non-empty lines by default.
  30 */
  31 
  32 // c++ -Wall -O3 -s -o imatch imatch.cpp
  33 
  34 #include <iostream>
  35 #include <regex>
  36 #include <string>
  37 #include <unistd.h>
  38 #include <vector>
  39 
  40 #ifdef RED_ERRORS
  41 #define ERROR_STYLE "\x1b[38;2;204;0;0m"
  42 #ifdef __APPLE__
  43 #define ERROR_STYLE "\x1b[31m"
  44 #endif
  45 #define RESET_STYLE "\x1b[0m"
  46 #else
  47 #define ERROR_STYLE ""
  48 #define RESET_STYLE ""
  49 #endif
  50 
  51 using namespace std;
  52 
  53 const auto regex_opts = regex_constants::ECMAScript | regex_constants::icase;
  54 
  55 int compile(int argc, char** argv, vector<regex>& res) {
  56     size_t errors = 0;
  57 
  58     for (int i = 1; i < argc; i++) {
  59         try {
  60             regex expr(argv[i], regex_opts);
  61             res.push_back(expr);
  62         } catch (const regex_error& e) {
  63             cerr << ERROR_STYLE << e.code() << ": " << e.what() << RESET_STYLE << endl;
  64             errors++;
  65         }
  66     }
  67 
  68     return errors;
  69 }
  70 
  71 bool match(string& s, const vector<regex>& expressions) {
  72     for (const regex& e : expressions) {
  73         if (regex_search(s, e)) {
  74             return true;
  75         }
  76     }
  77     return false;
  78 }
  79 
  80 int run(int argc, char** argv, bool live_lines) {
  81     if (argc == 1) {
  82         return 0;
  83     }
  84 
  85     vector<regex> expressions;
  86     size_t errors = compile(argc, argv, expressions);
  87     if (errors > 0) {
  88         return 3;
  89     }
  90 
  91     string line;
  92     size_t matches = 0;
  93 
  94     while (getline(cin, line)) {
  95         if (match(line, expressions)) {
  96             matches++;
  97             if (live_lines) {
  98                 cout << line << endl;
  99             } else {
 100                 cout << line << '\n';
 101             }
 102             if (cout.eof()) {
 103                 break;
 104             }
 105         }
 106     }
 107 
 108     if (!live_lines) {
 109         cout.flush();
 110     }
 111     return matches > 0 ? 0 : 1;
 112 }
 113 
 114 int main(int argc, char** argv) {
 115     const bool live_lines = lseek(fileno(stdout), 0, SEEK_CUR) != 0;
 116     if (!live_lines) {
 117         setvbuf(stdout, NULL, _IOFBF, 0);
 118     }
 119     cin.tie(NULL);
 120     ios_base::sync_with_stdio(false);
 121 
 122     try {
 123         if (argc == 1) {
 124             char* fallback[2] = {argv[0], (char*)"^[^\\r]"};
 125             argc = 2;
 126             argv = fallback;
 127         }
 128         return run(argc, argv, live_lines) == 0 ? 0 : 1;
 129     } catch (const bad_alloc& e) {
 130         cerr << ERROR_STYLE "out of memory" RESET_STYLE << endl;
 131         return 2;
 132     }
 133 }