CSS minifier

Author: px86

.gitignore

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+*.o
+example.min.css
+minify
+*~

LICENSE

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+Copyright 2022 Pushkar Raj <px86@protonmail.com>
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Makefile

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+CXX=g++
+CXXFLAGS=-Wall -Werror -Wpedantic -std=c++11
+LIBS=
+
+minify: minify.cpp
+	$(CXX) $(CXXFLAGS) -o $@ $^ $(LIBS)
+
+test: example.css minify
+	./minify example.css example.min.css
+
+clean:
+	rm -rf example.min.css minify

README.org

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+#+TITLE: Minify - A CSS minifier
+#+AUTHOR: Pushkar Raj
+#+DATE: [2022-02-03 Thu]
+
+Remove comments and unnecessary whitespaces from a CSS file.
+
+* Compilation
+
+It's very simple.
+
+#+begin_src shell
+  g++ -std=c++11 -o minify minify.cpp
+#+end_src
+
+or, if you have =GNU Make= installed, run =make= to compile the program, and =make test= for running the program on the =example.css= file.
+
+#+begin_src shell
+  make test
+#+end_src
+
+* Usage
+
+#+begin_src shell
+  minify <path-to-a-css-file> <ouput-file-path>
+#+end_src

example.css

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+/*
+  Don't look, you will hurt your eye.
+  It's horrible.
+*/
+
+
+
+    :root      {
+    margin:     0;
+     padding: 0;
+    box-sizing: border-box;
+    font-size: 16px;
+
+    --font-serif:
+	'Noto Serif', serif;
+    --font-sans-serif: 'Lato',
+		       sans-serif;
+    --font-monospace:  'Fantasque Sans Mono', monospace;
+
+
+
+  }
+
+body    ul     li   > a  {
+    background: var(--color-dark-primary);
+    color: #ffffff;
+    font-family: var(--font-sans-serif);
+    min-height: 100vh;
+    margin-left: 30ch;
+
+
+    border :  0   0   10px black ;
+}

minify.cpp

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+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <stdexcept>
+
+auto read_file(const char *path) -> std::string;
+void minify_file(const char *, const char *);
+auto minify(const std::string &css) -> std::string;
+
+int main(int argc, char **argv) {
+  if (argc != 3) {
+    std::cerr << "Usage: " << argv[0] << " CSSFILE OUTPUTFILE\n";
+    return 1;
+  }
+  const char *filepath = argv[1];
+  const char *outpath  = argv[2];
+
+  // TODO: add support for optional OUTFILE, where output filename is derieved from the css filename.
+  // Should print an error and exit if a file with the derieved name already exists.
+
+  minify_file(filepath, outpath);
+  return 0;
+}
+
+auto read_file(const char *path) -> std::string {
+  constexpr auto read_size = std::size_t(4096); // <- Exactly what a typical modern C++ programmer would do.
+  auto stream = std::ifstream(path);
+  stream.exceptions(std::ios_base::badbit);
+
+  auto out = std::string();
+  auto buf = std::string(read_size, '\0');
+  while (stream.read(&buf[0], read_size)) {
+    out.append(buf, 0, stream.gcount());
+  }
+  out.append(buf, 0, stream.gcount());
+
+  return out;
+}
+
+void minify_file(const char *cssfilepath, const char *outfilepath) {
+  auto css = read_file(cssfilepath);
+  auto minicss = minify(css);
+  auto out = std::ofstream(outfilepath);
+  out << minicss;
+}
+
+auto minify(const std::string& css) -> std::string {
+  auto minicss = std::string();
+  minicss.reserve(css.size());
+
+  bool last_was_space = true; // 'true' to deal with the whitespaces at the very beginning of the file.
+  char c;
+  try {
+      for (size_t i = 0; i < css.size(); ++i) {
+	c = css.at(i);
+	switch (c) {
+	case '\t':
+	case ' ' :
+	  {
+	    // Replace a sequence of whitespaces with a single space character.
+	    // Note: make sure to set last_was_space to false, everywhere else where a not whitespace
+	    // character has been appended to 'minicss'.
+	    if (!last_was_space) {
+	      minicss += ' ';
+	      last_was_space = true;
+	    }
+	  } break;
+	case '\n': break; // no newlines allowed!
+	case ':':
+	case ';':
+	case ',':
+	case '>':
+	case '{':
+	case '}':
+	  {
+	    // Make sure that no whitespace is present before the above characters.
+	    if (minicss.back() == ' ') minicss.back() = c;
+	    else minicss += c;
+	    // Consume all whitespace after the above characters.
+	    while (i < css.size()-1 && std::isspace(css.at(i+1))) i++;
+	    last_was_space = false;
+	  } break;
+	case '\'':
+	case '"' :
+	  {
+	    // Preseve the whitespaces in strings.
+	    // TODO: this fails if there is an escaped quote between the string. (Is it allowed?)
+	    minicss += c;
+	    while (i < css.size()-1 && css.at(++i) != c) minicss += css.at(i);
+	    minicss += c;
+	    last_was_space = false;
+	  } break;
+	case '/' :
+	  {
+	    // Consume the comment.
+	    if (css.at(++i) == '*') {
+	      while (!(css.at(++i) == '*' && css.at(++i) == '/')) {}
+	    }
+	    else minicss += '/';
+	  } break;
+
+	default: minicss += c; last_was_space = false;
+	}
+      }
+  } catch (std::out_of_range &e) {
+    std::cerr << "Unexpected end of file reached, possible syntax error.\n";
+    std::exit(1);
+  }
+
+  minicss.shrink_to_fit();
+  return minicss;
+}