Add support for escape sequences in character symbols

src/lex.cpp

@@ -337,13 +337,67 @@ int lex_t::lex(parse_token_value_t *value) {
 			if (!next(true))
 				return syntax_error(value);
 
-			value->c = current();
+			if (current() == '\\') {
+				if (!next(true))
+					return syntax_error(value);
+
+				switch (current()) {
+				case 'a':
+					value->c = '\a';
+					break;
+
+				case 'b':
+					value->c = '\b';
+					break;
+
+				case 'f':
+					value->c = '\f';
+					break;
+
+				case 'n':
+					value->c = '\n';
+					break;
+
+				case 'r':
+					value->c = '\r';
+					break;
+
+				case 't':
+					value->c = '\t';
+					break;
+
+				case 'v':
+					value->c = '\v';
+					break;
+
+				case '\\':
+					value->c = '\\';
+					break;
+
+				case '\'':
+					value->c = '\'';
+					break;
+
+				case '"':
+					value->c = '"';
+					break;
+
+				case '?':
+					value->c = '?';
+					break;
+
+				default:
+					return syntax_error(value);
+				}
+			}
+			else {
+				value->c = current();
+			}
 
 			if (!next(true) || current() != '\'')
 				return syntax_error(value);
 
 			next(true);
-
 			consume(false);
 
 			return TOK_CHAR;
@@ -354,9 +408,6 @@ int lex_t::lex(parse_token_value_t *value) {
 		case '"':
 			return lex_string(value);
 
-		//case '0' ... '9':
-			//return lex_number(value);
-
 		case 'a' ... 'z':
 		case 'A' ... 'Z':
 			return lex_symbol(value);

src/output.cpp

@@ -64,6 +64,48 @@ void output_t::initialize() {
 	}
 }
 
+std::string output_t::symbol_case(const symbol_t &sym) {
+	if (sym.get_type() == SYMBOL_TYPE_CHAR) {
+		switch (sym.get_value()[0]) {
+		case '\a':
+			return "'\\a'";
+
+		case '\b':
+			return "'\\b'";
+
+		case '\f':
+			return "'\\f'";
+
+		case '\n':
+			return "'\\n'";
+
+		case '\r':
+			return "'\\r'";
+
+		case '\t':
+			return "'\\t'";
+
+		case '\v':
+			return "'\\v'";
+
+		case '\\':
+			return "'\\\\'";
+
+		case '\'':
+			return "'\\''";
+
+		default:
+			return "'" +  sym.get_value() + "'";
+		}
+	}
+	else {
+		if (sym.get_value().empty())
+			return "0";
+		else
+			return token_prefix_str + sym.get_value();
+	}
+}
+
 void output_t::emit_tokens() {
 	if (tokens.empty())
 		return;

src/output.hpp

@@ -57,6 +57,8 @@ protected:
 		return token_prefix_str.c_str();
 	}
 
+	std::string symbol_case(const symbol_t &sym);
+
 	void emit_tokens();
 	void emit_token_value();
 	void emit_header();

src/output_lr0.cpp

@@ -42,11 +42,7 @@ void output_lr0_t::emit_state_shift(unsigned i) {
 		if (it == generator->get_shifts().end())
 			continue;
 
-		if (token.get_type() == SYMBOL_TYPE_CHAR)
+		std::fprintf(source_file, "\t\t\tcase %s:\n", symbol_case(token).c_str());
-			std::fprintf(source_file, "\t\t\tcase '%c':\n", token.get_value()[0]);
-		else
-			std::fprintf(source_file, "\t\t\tcase %s%s:\n", token_prefix(), token.get_value().c_str());
-
 		std::fprintf(source_file, "\t\t\t\tparser->stack[parser->top].value.token = *value;\n");
 		std::fprintf(source_file, "\t\t\t\tparser->stack[++parser->top].state = %u;\n", unsigned(it->second));
 		std::fprintf(source_file, "\t\t\t\treturn 1;\n\n");

src/output_slr.cpp

@@ -38,25 +38,14 @@ void output_slr_t::emit_state_shift(unsigned i, const symbol_t &token) {
 	if (it == generator->get_shifts().end())
 		return;
 
-	if (token.get_type() == SYMBOL_TYPE_CHAR)
+	std::fprintf(source_file, "\t\t\tcase %s:\n", symbol_case(token).c_str());
-		std::fprintf(source_file, "\t\t\tcase '%c':\n", token.get_value()[0]);
-	else if (!token.get_value().empty())
-		std::fprintf(source_file, "\t\t\tcase %s%s:\n", token_prefix(), token.get_value().c_str());
-	else
-		std::fprintf(source_file, "\t\t\tcase 0:\n");
-
 	std::fprintf(source_file, "\t\t\t\tparser->stack[parser->top].value.token = *value;\n");
 	std::fprintf(source_file, "\t\t\t\tparser->stack[++parser->top].state = %u;\n", unsigned(it->second));
 	std::fprintf(source_file, "\t\t\t\treturn 1;\n\n");
 }
 
 void output_slr_t::emit_state_reduce(const item_t &item, const symbol_t &token, int rule_id) {
-	if (token.get_type() == SYMBOL_TYPE_CHAR)
+	std::fprintf(source_file, "\t\t\tcase %s:\n", symbol_case(token).c_str());
-		std::fprintf(source_file, "\t\t\tcase '%c':\n", token.get_value()[0]);
-	else if (!token.get_value().empty())
-		std::fprintf(source_file, "\t\t\tcase %s%s:\n", token_prefix(), token.get_value().c_str());
-	else
-		std::fprintf(source_file, "\t\t\tcase 0:\n");
 
 	const auto &rhs = item.get_rhs();
 	if (rhs.size())