scriptlang: start on structs

meson.build

@@ -11,6 +11,11 @@ project(
 fmt_dep = dependency('fmt')
 sdl2_dep = dependency('sdl2')
 
+add_project_arguments(
+    '-Wno-gnu-statement-expression-from-macro-expansion',
+    language: 'cpp',
+)
+
 common_sources = []
 subdir('utils')
 subdir('scriptlang')
@@ -18,7 +23,6 @@ subdir('markup')
 
 browser_sources = common_sources
 subdir('browser')
-browser_sources
 
 executable(
     'web-browser',

scriptlang/error.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+namespace scriptlang {
+
+enum class Errors {
+    NotImplemented,
+    LexerNoTokenYet,
+    LexerStringNotTerminated,
+    LexerUnexpectedCharacer,
+    LexerMultilineCommentNotTerminated,
+    NoLexerOutput,
+    ParserExhausted,
+    ParserMalformedStringLiteral,
+    ParserStructNotTerminated,
+};
+
+}

scriptlang/lexer.cpp

@@ -1,13 +1,14 @@
 #include "lexer.hpp"
+#include "error.hpp"
 #include <cctype>
 #include <string_view>
 
 namespace scriptlang {
 
-auto constexpr Lexer::next() noexcept -> Result<Token, void>
+auto Lexer::make_token() noexcept -> Result<Token, Errors>
 {
     if (done())
-        return token(Tokens::Eof, index);
+        return token(Tokens::Eof, index, current_location());
     if (std::isdigit(current()) != 0)
         return make_number();
     if (std::isalpha(current()) != 0 or current() == '_')
@@ -17,32 +18,34 @@ auto constexpr Lexer::next() noexcept -> Result<Token, void>
     return make_static();
 }
 
-auto constexpr Lexer::make_number() noexcept -> Result<Token, void>
+auto Lexer::make_number() noexcept -> Result<Token, Errors>
 {
     auto begin = index;
+    auto span_from = current_location();
     while (!done() and std::isdigit(current()) != 0)
         step();
     if (current() == '.') {
         step();
         while (!done() and std::isdigit(current()) != 0)
             step();
-        return token(Tokens::Float, begin);
+        return token(Tokens::Float, begin, span_from);
     }
-    return token(Tokens::Int, begin);
+    return token(Tokens::Int, begin, span_from);
 }
 
-auto constexpr Lexer::make_id() noexcept -> Result<Token, void>
+auto Lexer::make_id() noexcept -> Result<Token, Errors>
 {
     auto begin = index;
+    auto span_from = current_location();
     while (!done()
         and (std::isalpha(current()) != 0 or std::isdigit(current()) != 0
             or current() == '_'))
         step();
-    return token(id_or_keyword_type(text.substr(begin, index - begin)), begin);
+    return token(id_or_keyword_type(text.substr(begin, index - begin)), begin,
+        span_from);
 }
 
-auto constexpr Lexer::id_or_keyword_type(std::string_view substring) noexcept
-    -> Tokens
+auto Lexer::id_or_keyword_type(std::string_view substring) noexcept -> Tokens
 {
     if (substring.compare("if") == 0)
         return Tokens::If;
@@ -75,9 +78,10 @@ auto constexpr Lexer::id_or_keyword_type(std::string_view substring) noexcept
     return Tokens::Id;
 }
 
-auto constexpr Lexer::make_string() noexcept -> Result<Token, void>
+auto Lexer::make_string() noexcept -> Result<Token, Errors>
 {
     auto begin = index;
+    auto span_from = current_location();
     step();
     auto escaped = false;
     while (!done() and (current() != '"' or escaped)) {
@@ -85,22 +89,23 @@ auto constexpr Lexer::make_string() noexcept -> Result<Token, void>
         step();
     }
     if (current() != '"')
-        return {};
+        return Errors::LexerStringNotTerminated;
     step();
-    return token(Tokens::String, begin);
+    return token(Tokens::String, begin, span_from);
 }
 
-auto constexpr Lexer::make_static() noexcept -> Result<Token, void>
+auto Lexer::make_static() noexcept -> Result<Token, Errors>
 {
     auto begin = index;
+    auto span_from = current_location();
     auto type = static_token_type();
     if (!type)
-        return {};
-    return token(*type, begin);
+        return type.transform<Token>();
+    return token(*type, begin, span_from);
 }
 
 // NOLINTNEXTLINE(readability-function-cognitive-complexity)
-auto constexpr Lexer::static_token_type() noexcept -> Result<Tokens, void>
+auto Lexer::static_token_type() noexcept -> Result<Tokens, Errors>
 {
     using TT = Tokens;
     auto stepped = [&](Tokens v) {
@@ -202,10 +207,10 @@ auto constexpr Lexer::static_token_type() noexcept -> Result<Tokens, void>
             return stepped(TT::GreaterEqual);
         return TT::Greater;
     }
-    return {};
+    return Errors::LexerUnexpectedCharacer;
 }
 
-auto constexpr Lexer::skip_multiline_comment() noexcept -> Result<Tokens, void>
+auto Lexer::skip_multiline_comment() noexcept -> Result<Tokens, Errors>
 {
     step();
     auto last = current();
@@ -213,12 +218,12 @@ auto constexpr Lexer::skip_multiline_comment() noexcept -> Result<Tokens, void>
     while (!done() and last != '*' and current() != '/')
         step();
     if (last != '*' or current() != '/')
-        return {};
+        return Errors::LexerMultilineCommentNotTerminated;
     step();
     return Tokens::MultilineComment;
 }
 
-auto constexpr Lexer::skip_singleline_comment() noexcept -> Result<Tokens, void>
+auto Lexer::skip_singleline_comment() noexcept -> Result<Tokens, Errors>
 {
     step();
     while (!done() and current() != '\n')

scriptlang/lexer.hpp

@@ -1,3 +1,4 @@
+#include "error.hpp"
 #include "utils/all.hpp"
 #include <optional>
 #include <string_view>
@@ -80,10 +81,14 @@ struct Location {
     int line, column;
 };
 
+struct Span {
+    Location from, to;
+};
+
 struct Token {
     Tokens type;
     size_t index, length;
-    Location location;
+    Span span;
 };
 
 class Lexer {
@@ -91,29 +96,39 @@ public:
     Lexer(std::string_view text)
         : text { text }
     { }
-    auto constexpr next() noexcept -> Result<Token, void>;
-    auto peek() noexcept -> Result<Token, void>
+    auto next() noexcept -> Result<Token, Errors> { return make_token(); }
+    auto peek() noexcept -> Result<Token, Errors>
     {
         if (last_token)
-            return Result<Token, void>::create_ok(*last_token);
-        return {};
+            return Result<Token, Errors>::create_ok(*last_token);
+        return Errors::LexerNoTokenYet;
     }
 
 private:
-    auto constexpr make_number() noexcept -> Result<Token, void>;
-    auto constexpr make_id() noexcept -> Result<Token, void>;
-    auto constexpr id_or_keyword_type(std::string_view substring) noexcept
-        -> Tokens;
-    auto constexpr make_string() noexcept -> Result<Token, void>;
-    auto constexpr make_static() noexcept -> Result<Token, void>;
-    auto constexpr static_token_type() noexcept -> Result<Tokens, void>;
-    auto constexpr skip_multiline_comment() noexcept -> Result<Tokens, void>;
-    auto constexpr skip_singleline_comment() noexcept -> Result<Tokens, void>;
+    auto make_token() noexcept -> Result<Token, Errors>;
+    auto make_number() noexcept -> Result<Token, Errors>;
+    auto make_id() noexcept -> Result<Token, Errors>;
+    auto id_or_keyword_type(std::string_view substring) noexcept -> Tokens;
+    auto make_string() noexcept -> Result<Token, Errors>;
+    auto make_static() noexcept -> Result<Token, Errors>;
+    auto static_token_type() noexcept -> Result<Tokens, Errors>;
+    auto skip_multiline_comment() noexcept -> Result<Tokens, Errors>;
+    auto skip_singleline_comment() noexcept -> Result<Tokens, Errors>;
 
-    [[nodiscard]] auto constexpr inline token(
-        Tokens type, size_t begin) noexcept -> Token
+    [[nodiscard]] auto constexpr inline current_location() const noexcept
+        -> Location
     {
-        auto token = Token { type, begin, index - begin, { line, column } };
+        return { line, column };
+    }
+    [[nodiscard]] auto constexpr inline token(
+        Tokens type, size_t begin, Location span_from) noexcept -> Token
+    {
+        auto token = Token {
+            type,
+            begin,
+            index - begin,
+            { span_from, { line, column } },
+        };
         last_token = token;
         return token;
     }

scriptlang/meson.build

@@ -1,5 +1,5 @@
 
 common_sources += files(
-    'parser.cpp',
     'lexer.cpp',
+    'parser.cpp',
 )

scriptlang/parser.cpp

@@ -1,14 +1,110 @@
 #include "parser.hpp"
+#include "error.hpp"
+#include <cstdlib>
+#include <memory>
 
 namespace scriptlang {
 
-auto Parser::parse_value() noexcept -> Result<std::unique_ptr<Expression>, void>
+auto parse_expression(bool strictly_values) noexcept
+    -> Result<std::unique_ptr<Expression>, Errors>
 {
-    switch (lexer.peek()->type) {
+    if (strictly_values)
+        return parse_expression(true);
+    return Errors::NotImplemented;
+}
+
+auto Parser::parse_struct(bool strictly_values) noexcept
+    -> Result<std::unique_ptr<Expression>, Errors>
+{
+    auto values = std::map<std::string, std::unique_ptr<Expression>> {};
+    auto first_brace = TRY(lexer.peek());
+    if (TRY(lexer.peek()).type == Tokens::LBrace) {
+        TRY(lexer.next());
+        auto last_brace = TRY(lexer.peek());
+        if (last_brace.type != Tokens::RBrace)
+            return Errors::ParserStructNotTerminated;
+        return {
+            std::make_unique<Struct>(
+                token_span(first_brace, last_brace), std::move(values)),
+        };
+    }
+    return parse_atom();
+}
+
+auto Parser::parse_atom() noexcept
+    -> Result<std::unique_ptr<Expression>, Errors>
+{
+    auto token = TRY(lexer.peek());
+    switch (token.type) {
         case Tokens::Id:
+            return {
+                std::make_unique<Id>(token_span(token, token),
+                    token_text(lexer.peek()->index, lexer.peek()->length)),
+            };
+        case Tokens::Int:
+            return {
+                std::make_unique<Int>(token_span(token, token),
+                    std::atol(
+                        token_text(lexer.peek()->index, lexer.peek()->length)
+                            .c_str())),
+            };
+        case Tokens::Float:
+            return {
+                std::make_unique<Float>(token_span(token, token),
+                    std::atof(
+                        token_text(lexer.peek()->index, lexer.peek()->length)
+                            .c_str())),
+            };
+        case Tokens::False:
+            return {
+                std::make_unique<Bool>(token_span(token, token), false),
+            };
+        case Tokens::True:
+            return {
+                std::make_unique<Bool>(token_span(token, token), true),
+            };
+        case Tokens::String:
+            return {
+                std::make_unique<String>(token_span(token, token),
+                    *parse_string_value(
+                        token_text(lexer.peek()->index, lexer.peek()->length))),
+            };
         default:
-            return {};
+            return Errors::ParserExhausted;
     }
 }
 
+[[nodiscard]] auto Parser::parse_string_value(std::string_view literal) noexcept
+    -> Result<std::string, Errors>
+{
+    if (literal.size() < 2)
+        return Errors::ParserMalformedStringLiteral;
+    auto value = std::string {};
+    auto escaped = false;
+    for (const auto c : literal.substr(1, literal.size() - 2)) {
+        if (escaped) {
+            value.push_back([&] {
+                switch (c) {
+                    case 'n':
+                        return '\n';
+                    case 'r':
+                        return '\r';
+                    case 't':
+                        return '\t';
+                    case 'v':
+                        return '\n';
+                    default:
+                        return c;
+                }
+            }());
+            escaped = false;
+        } else if (c == '\\') {
+            escaped = true;
+        } else {
+            value.push_back(c);
+        }
+    }
+    return value;
+}
+
 }

scriptlang/parser.hpp

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "error.hpp"
 #include "lexer.hpp"
 #include "utils/all.hpp"
 #include "utils/result.hpp"
@@ -12,10 +13,6 @@
 
 namespace scriptlang {
 
-struct Span {
-    Location from, to;
-};
-
 enum class Expressions {
     Binary,
     Negate,
@@ -25,6 +22,7 @@ enum class Expressions {
     Call,
     Operator,
 
+    Struct,
     Id,
     Int,
     Float,
@@ -47,66 +45,101 @@ public:
 private:
 };
 
-class Id final : public Expression {
+class Struct final : public Expression {
 public:
-    Id(std::string value)
-        : m_value { std::move(value) }
+    Struct(Span span, std::map<std::string, std::unique_ptr<Expression>> values)
+        : m_span { span }
+        , m_values { std::move(values) }
     { }
     [[nodiscard]] auto expression_type() const noexcept -> Expressions override
     {
         return Expressions::Id;
     }
+    [[nodiscard]] auto span() const noexcept -> Span override { return m_span; }
+    [[nodiscard]] auto values() const noexcept -> auto& { return m_values; }
+
+private:
+    Span m_span;
+    std::map<std::string, std::unique_ptr<Expression>> m_values;
+};
+
+class Id final : public Expression {
+public:
+    Id(Span span, std::string value)
+        : m_span { span }
+        , m_value { std::move(value) }
+    { }
+    [[nodiscard]] auto expression_type() const noexcept -> Expressions override
+    {
+        return Expressions::Id;
+    }
+    [[nodiscard]] auto span() const noexcept -> Span override { return m_span; }
     [[nodiscard]] auto value() const noexcept { return m_value; }
 
 private:
+    Span m_span;
     std::string m_value;
 };
+
 class Int final : public Expression {
 public:
-    Int(int64_t value)
-        : m_value { value }
+    Int(Span span, int64_t value)
+        : m_span { span }
+        , m_value { value }
     { }
     [[nodiscard]] auto expression_type() const noexcept -> Expressions override
     {
         return Expressions::Int;
     }
+    [[nodiscard]] auto span() const noexcept -> Span override { return m_span; }
     [[nodiscard]] auto value() const noexcept { return m_value; }
 
 private:
+    Span m_span;
     int64_t m_value;
 };
+
 class Float final : public Expression {
 public:
-    Float(double value)
-        : m_value { value }
+    Float(Span span, double value)
+        : m_span { span }
+        , m_value { value }
     { }
     [[nodiscard]] auto expression_type() const noexcept -> Expressions override
     {
         return Expressions::Float;
     }
     [[nodiscard]] auto value() const noexcept { return m_value; }
+    [[nodiscard]] auto span() const noexcept -> Span override { return m_span; }
 
 private:
+    Span m_span;
     double m_value;
 };
+
 class Bool final : public Expression {
 public:
-    Bool(bool value)
-        : m_value { value }
+    Bool(Span span, bool value)
+        : m_span { span }
+        , m_value { value }
     { }
     [[nodiscard]] auto expression_type() const noexcept -> Expressions override
     {
         return Expressions::Bool;
     }
     [[nodiscard]] auto value() const noexcept { return m_value; }
+    [[nodiscard]] auto span() const noexcept -> Span override { return m_span; }
 
 private:
+    Span m_span;
     bool m_value;
 };
+
 class String final : public Expression {
 public:
-    String(std::string value)
-        : m_value { std::move(value) }
+    String(Span span, std::string value)
+        : m_span { span }
+        , m_value { std::move(value) }
     { }
     [[nodiscard]] auto expression_type() const noexcept -> Expressions override
     {
@@ -116,8 +149,10 @@ public:
     {
         return m_value;
     }
+    [[nodiscard]] auto span() const noexcept -> Span override { return m_span; }
 
 private:
+    Span m_span;
     std::string m_value;
 };
 
@@ -127,11 +162,25 @@ public:
         : text { text }
         , lexer(text)
     { }
-    auto parse_expression() noexcept
-        -> Result<std::unique_ptr<Expression>, void>;
-    auto parse_value() noexcept -> Result<std::unique_ptr<Expression>, void>;
+    auto parse_expression(bool strictly_values) noexcept
+        -> Result<std::unique_ptr<Expression>, Errors>;
+    auto parse_struct(bool strictly_values) noexcept
+        -> Result<std::unique_ptr<Expression>, Errors>;
+    auto parse_atom() noexcept -> Result<std::unique_ptr<Expression>, Errors>;
 
 private:
+    [[nodiscard]] static auto parse_string_value(
+        std::string_view literal) noexcept -> Result<std::string, Errors>;
+    [[nodiscard]] auto token_text(size_t index, size_t length) const noexcept
+        -> std::string
+    {
+        return std::string { text.substr(index, length) };
+    }
+    [[nodiscard]] static auto token_span(Token from, Token to) noexcept -> Span
+    {
+        return { from.span.from, to.span.to };
+    }
+
     std::string_view text;
     Lexer lexer;
 };

utils/result.hpp

@@ -157,6 +157,15 @@ public:
         return unwrap();
     }
 
+    // Transforms `Result<T, E>` into `Result<Y, E>`.
+    // Requries result to be an error.
+    template <typename NewValue>
+    [[nodiscard]] constexpr auto transform() const noexcept
+        -> Result<NewValue, Error>
+    {
+        return Result<NewValue, Error>::create_error(unwrap_error());
+    }
+
     [[nodiscard]] constexpr auto map(auto func) noexcept
     {
         using NewValue = decltype(func(unwrap()));
@@ -643,3 +652,12 @@ private:
 };
 
 }
+
+// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define TRY(expr)                                                              \
+    ({                                                                         \
+        auto result = (expr);                                                  \
+        if (result.is_error())                                                 \
+            return { std::move(result.unwrap_error()) };                       \
+        std::move(result.unwrap());                                            \
+    })