Refactor interpreter: parse all files before executing them & improve error reporting

apps/interpreter/source/main.cpp

@@ -5,16 +5,45 @@
 #include <pslang/ast/print.hpp>
 
 #include <iostream>
+#include <fstream>
 #include <cstring>
+#include <cmath>
 
-int main(int argc, char ** argv) try
+std::string extract_nth_line(std::filesystem::path const & path, std::size_t n)
+{
+	std::ifstream file(path);
+	std::string line;
+
+	for (size_t i = 1; i <= n && std::getline(file, line); ++i) {
+		if (i == n) {
+			return line;
+		}
+	}
+
+	return {};
+}
+
+void print_error_context(std::filesystem::path const & file, pslang::ast::location const & location)
+{
+	if (location.begin.line == location.end.line)
+	{
+		std::size_t max_line_number_digits = std::floor(std::log10(location.begin.line)) + 1;
+
+		std::cerr << std::endl;
+		std::cerr << "line " << std::setw(max_line_number_digits) << std::right << location.begin.line << ": ";
+		std::cerr << extract_nth_line(file, location.begin.line) << std::endl;
+		std::cerr << std::string(std::max<std::size_t>(location.begin.column, 1) - 1 + max_line_number_digits + 7, ' ') << std::string(location.end.column - location.begin.column, '^') << std::endl;
+	}
+}
+
+int main(int argc, char ** argv)
 {
 	if (argc == 1)
 	{
 		std::cout << "Usage: psli [ options ] <file1> [ <file2> ... ]\n";
 		std::cout << "Available options:\n";
 		std::cout << "    -t, --trace        Trace each line of execution\n";
-		std::cout << "    -d, --dump         Dump all variables after processing each file\n";
+		std::cout << "    -d, --dump         Dump all variables after processing all files\n";
 		std::cout << "    -p, --print        Print the AST after parsing each file\n";
 		return 0;
 	}
@@ -26,6 +55,9 @@ int main(int argc, char ** argv) try
 	bool dump = false;
 	bool dump_ast = false;
 
+	std::vector<std::string> filenames;
+	std::vector<ast::statement_list_ptr> parsed;
+
 	for (int arg = 1; arg < argc; ++arg)
 	{
 		if (std::strcmp(argv[arg], "-d") == 0 || std::strcmp(argv[arg], "--dump") == 0)
@@ -46,21 +78,33 @@ int main(int argc, char ** argv) try
 			continue;
 		}
 
-		auto ast = parser::parse(argv[arg]);
+		try
-
-		if (dump_ast)
 		{
-			ast::print(std::cout, ast);
+			filenames.push_back(argv[arg]);
-			std::cout << std::flush;
+			parsed.push_back(parser::parse(argv[arg]));
 		}
+		catch (pslang::parser::parse_error const & error)
+		{
+			std::cerr << "Parse error at " << error.location() << ":\n    " << error.what() << std::endl;
+			print_error_context(argv[arg], error.location());
+			return EXIT_FAILURE;
+		}
+	}
 
+	if (dump_ast)
+	{
+		for (std::size_t i = 0; i < filenames.size(); ++i)
+		{
+			std::cout << "Input file " << filenames[i] << " AST dump:\n\n";
+			ast::print(std::cout, parsed[i]);
+			std::cout << "\n";
+		}
+		std::cout << std::flush;
+	}
+
+	for (auto const & ast : parsed)
 		interpreter::exec(context, ast);
 
-		if (dump)
+	if (dump)
-			interpreter::dump(std::cout, context);
+		interpreter::dump(std::cout, context);
-	}
-}
-catch (pslang::parser::parse_error const & error)
-{
-	std::cerr << "Parse error at " << error.location() << ":\n    " << error.what() << std::endl;
 }