package def parsing

.clang-tidy

@@ -1 +1 @@
-Checks: '*,clang-analyzer-*,-llvmlibc-*,-fuchsia-*,-altera-*,-abseil-*,-android-*,-modernize-use-trailing-return-type,-readability-identifier-length,-*-readability-todo,-*-magic-numbers,-readability-function-cognitive-complexity,-*-easily-swappable-parameters'
+Checks: '*,clang-analyzer-*,-llvmlibc-*,-fuchsia-*,-altera-*,-abseil-*,-android-*,-modernize-use-trailing-return-type,-readability-identifier-length,-*-readability-todo,-*-magic-numbers,-readability-function-cognitive-complexity,-*-easily-swappable-parameters,-*-non-private-member-variables-in-classes,-*-no-recursion'

src/main.cc

@@ -1,3 +1,18 @@
+#include "parser.h"
+#include <fstream>
 #include <iostream>
+#include <sstream>
 
-int main() { std::cout << "Hello, World!\n"; }
+int main() {
+  std::ifstream file("zlib.shrap");
+  if (!file) {
+    std::cerr << "Error opening file\n";
+    return 1;
+  }
+
+  std::stringstream buffer;
+  buffer << file.rdbuf();
+
+  Expr pkg = Expr::parse(buffer.str());
+  std::cout << pkg.get("name").value << std::endl;
+}

src/parser.h

@@ -0,0 +1,141 @@
+#pragma once
+
+#include <sstream>
+#include <string>
+#include <vector>
+
+struct Expr {
+public:
+  enum class Type { Atom, String, List };
+
+  Type type = Type::Atom;
+  std::string value;
+  std::vector<Expr> children;
+
+  [[nodiscard]] Expr get(const std::string &key) const {
+    if (type != Type::List) {
+      throw std::runtime_error("get() called on non-list");
+    }
+    for (const auto &child : children) {
+      if (child.type == Type::List && child.children.size() >= 2 &&
+          child.children[0].type == Type::Atom &&
+          child.children[0].value == key) {
+        return child.children[1];
+      }
+    }
+    throw std::runtime_error("key not found: " + key);
+  }
+
+  static Expr parse(const std::string &input) {
+    std::istringstream in(input);
+    return parse_expr(in);
+  }
+
+private:
+  static std::string read_atom(std::istringstream &in) {
+    std::string atom;
+    while (true) {
+      int next = in.peek();
+      if (next == -1 || is_space(static_cast<char>(next)) || next == '(' ||
+          next == ')') {
+        break;
+      }
+      atom += static_cast<char>(in.get());
+    }
+    if (atom.empty()) {
+      throw std::runtime_error("empty atom");
+    }
+    return atom;
+  }
+
+  static Expr parse_list(std::istringstream &in) {
+    Expr result = {.type = Expr::Type::List};
+
+    in.get(); // consume bracket
+
+    while (true) {
+      while (is_space(static_cast<char>(in.peek()))) {
+        in.get();
+      }
+      if (!in) {
+        throw std::runtime_error("unexpected EOF");
+      }
+
+      if (in.peek() == ')') {
+        in.get();
+        break;
+      }
+
+      result.children.push_back(parse_expr(in));
+    }
+
+    return result;
+  }
+
+  static std::string read_string(std::istringstream &in) {
+    std::string result;
+
+    in.get(); // consume the quote
+
+    while (true) {
+      if (!in) {
+        throw std::runtime_error("unexpected EOF in string");
+      }
+
+      auto c = static_cast<char>(in.get());
+      if (c == '"') {
+        break;
+      }
+      result += c;
+    }
+    return result;
+  }
+
+  static Expr parse_expr(std::istringstream &in) {
+    while (is_space(static_cast<char>(in.peek()))) {
+      in.get();
+    }
+    if (!in) {
+      throw std::runtime_error("unexpected EOF");
+    }
+
+    if (in.peek() == '(') {
+      return parse_list(in);
+    }
+    if (in.peek() == ')') {
+      throw std::runtime_error("unexpected ')'");
+    }
+
+    if (in.peek() == '"') {
+      return {.type = Type::String, .value = read_string(in)};
+    }
+
+    return {.type = Type::Atom, .value = read_atom(in)};
+  }
+
+  static bool is_space(char c) {
+    return c == ' ' || c == '\t' || c == '\n' || c == '\v' || c == '\r';
+  }
+};
+
+inline std::ostream &operator<<(std::ostream &out, const Expr &e) {
+  switch (e.type) {
+  case Expr::Type::Atom:
+    out << e.value;
+    break;
+  case Expr::Type::String:
+    out << '"' << e.value << '"';
+    break;
+  case Expr::Type::List:
+    out << '(';
+    for (size_t i = 0; i < e.children.size(); ++i) {
+      if (i > 0) {
+        out << ' ';
+      }
+      out << e.children[i];
+    }
+    out << ')';
+    break;
+  }
+  return out;
+}

zlib.shrap

@@ -0,0 +1,7 @@
+(package
+    (name "zlib")
+    (version "1.3.1")
+    (homepage "https://zlib.net/")
+    (src (tar "https://zlib.net/zlib-1.3.1.tar.gz" "207c3b0862cb4e3686f8405f76a98c38dbad9c94bcf4be4b9efca0716aba51ec"))
+    (build
+        (configure_make)))