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Change lexer code to use an option instead of ignoring the variant when no value is needed

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This commit is contained in:
Emin Arslan
2025-10-02 17:19:51 +03:00
committed by Emin Arslan
parent d0eae97771
commit 47f33f3dc0
3 changed files with 12 additions and 11 deletions
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3
src/include/lex.hpp
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@@ -3,6 +3,7 @@
#include <vector>
#include <stdint.h>
#include <variant>
#include <optional>
enum TokenType {
OpenParen,
@@ -18,7 +19,7 @@ enum TokenType {
// Plain Old Data
struct Token {
enum TokenType type;
std::variant<int64_t, double, std::string> value;
std::optional<std::variant<int64_t, double, std::string>> value;
};
bool operator==(Token const& one, Token const& other);
std::ostream &operator<<(std::ostream &os, Token const &t);

16
src/lex.cpp
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@@ -12,10 +12,10 @@ std::ostream &operator<<(std::ostream &os, Token const &t) {
case TokenType::OpenParen: os << "OpenParen)"; break;
case TokenType::CloseParen: os << "CloseParen)"; break;
case TokenType::Dollar: os << "Dollar)"; break;
case TokenType::Symbol: os << "Symbol, " << get<string>(t.value) << ")"; break;
case TokenType::String: os << "String, \"" << get<string>(t.value) << "\")"; break;
case TokenType::Int: os << "Int, " << get<int64_t>(t.value) << ")"; break;
case TokenType::Double: os << "Double, " << get<double>(t.value) << ")"; break;
case TokenType::Symbol: os << "Symbol, " << get<string>(*t.value) << ")"; break;
case TokenType::String: os << "String, \"" << get<string>(*t.value) << "\")"; break;
case TokenType::Int: os << "Int, " << get<int64_t>(*t.value) << ")"; break;
case TokenType::Double: os << "Double, " << get<double>(*t.value) << ")"; break;
case TokenType::End: os << "END)"; break;
default:
os << ")";
@@ -131,14 +131,14 @@ Token Lexer::next() {
// character while at EOF, even if we have exhausted the stream.
char c = ss.get();
if (ss.eof())
return {TokenType::End};
return {TokenType::End, nullopt};
if (isspace(c))
continue;
switch (c) {
case '(': return {TokenType::OpenParen};
case ')': return {TokenType::CloseParen};
case '$': return {TokenType::Dollar};
case '(': return {TokenType::OpenParen, nullopt};
case ')': return {TokenType::CloseParen, nullopt};
case '$': return {TokenType::Dollar, nullopt};
default:
ss.unget();
return lexNonSpecial();

4
src/tests/test.cpp
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@@ -6,7 +6,7 @@ TEST_CASE("Lexer lexes doubles correctly", "[Lexer]") {
SECTION("double and negative syntax") {
Lexer l("(1.0 0.1 -.1 -1. . - -. .-)");
REQUIRE(l.next() == Token({OpenParen}));
REQUIRE(l.next() == Token({OpenParen, nullopt}));
REQUIRE(l.next() == Token({Double, 1.0}));
REQUIRE(l.next() == Token({Double, 0.1}));
REQUIRE(l.next() == Token({Double, -0.1}));
@@ -15,7 +15,7 @@ TEST_CASE("Lexer lexes doubles correctly", "[Lexer]") {
REQUIRE(l.next() == Token({Symbol, "-"}));
REQUIRE(l.next() == Token({Symbol, "-."}));
REQUIRE(l.next() == Token({Symbol, ".-"}));
REQUIRE(l.next() == Token({CloseParen}));
REQUIRE(l.next() == Token({CloseParen, nullopt}));
}
}