feat(furc/parser): add function calls

furc/include/furc/front/ast.hpp

@@ -116,10 +116,16 @@ struct var_decl_node final : public decl_node {
 struct func_decl_node final : public decl_node {
     decl_type_e decl_type() const override { return Function; }
 
-    std::string                   name;
-    ast_type                      type;
-    std::vector<var_decl_node>    params;
-    std::optional<comp_stmt_node> body;
+    struct def_s {
+        comp_stmt_node          body;
+        std::vector<expr_node*> preConds;
+        std::vector<expr_node*> postConds;
+    };
+
+    std::string                name;
+    ast_type                   type;
+    std::vector<var_decl_node> params;
+    std::optional<def_s>       def;
 };
 
 class expr_node : public stmt_node {
@@ -128,9 +134,11 @@ public:
         Literal,
 
         VarRead,
+        FunctionCall,
         Group,
         BinaryOp,
         UnaryOp,
+        If,
     };
 public:
     category_e category() const override { return ast_node_cat::Expression; }
@@ -149,6 +157,13 @@ struct var_read_expr_node final : public expr_node {
       : name(std::move(name)) {}
 };
 
+struct func_call_expr_node final : public expr_node {
+    expr_type_e expr_type() const override { return FunctionCall; }
+
+    expr_node*              lhs = nullptr;
+    std::vector<expr_node*> args;
+};
+
 struct group_expr_node final : public expr_node {
     expr_type_e expr_type() const override { return Group; }
 
@@ -208,6 +223,14 @@ struct unary_op_expr_node final : public expr_node {
     unary_op_type type = Positive;
 };
 
+struct if_expr_node final : public expr_node {
+    expr_type_e expr_type() const override { return If; }
+
+    expr_node* cond     = nullptr;
+    expr_node* thenExpr = nullptr;
+    expr_node* elseExpr = nullptr;
+};
+
 class lit_node : public expr_node {
 public:
     enum lit_type_e {

furc/include/furc/front/lexer.hpp

@@ -4,7 +4,7 @@
 #include "furc/front/token.hpp"
 
 #include <cstddef>
-#include <optional>
+#include <deque>
 #include <string_view>
 
 namespace furc {
@@ -23,9 +23,10 @@ public:
     lexer& operator=(const lexer&) = delete;
 public:
     token next_token();
-    token peek_token();
-    token skip_token();
+    token peek_token(std::size_t offset = 0);
 private:
+    token get_token();
+
     void           next();
     constexpr char get(std::size_t offset = 0) const;
     void           skip_spaces();
@@ -38,7 +39,7 @@ private:
     std::size_t      m_row       = 0;
     std::size_t      m_lineStart = 0;
 
-    std::optional<token> m_peekToken;
+    std::deque<token> m_peekToken;
 };
 
 } // namespace furc

furc/include/furc/front/token.hpp

@@ -76,6 +76,8 @@ struct token {
         While,   /**< `while` */
         Public,  /**< `public` */
         Private, /**< `private` */
+        Pre,     /**< `pre` */
+        Post,    /**< `post` */
 
         Pointerof, /**< `pointerof` */
         Sizeof,    /**< `sizeof` */
@@ -186,6 +188,8 @@ struct token {
         case token::While: return os << "while";
         case token::Public: return os << "public";
         case token::Private: return os << "private";
+        case token::Pre: return os << "pre";
+        case token::Post: return os << "post";
         case token::Pointerof: return os << "pointerof";
         case token::Sizeof: return os << "sizeof";
         case token::Lengthof: return os << "lengthof";

furc/src/front/lexer.cpp

@@ -8,12 +8,23 @@
 namespace furc {
 
 token lexer::next_token() {
-    if (m_peekToken.has_value()) {
-        auto tok    = m_peekToken.value();
-        m_peekToken = {};
-        return tok;
-    }
+    if (m_peekToken.empty()) return get_token();
+    auto tok = m_peekToken.front();
+    m_peekToken.pop_front();
+    return tok;
+}
 
+token lexer::peek_token(std::size_t offset) {
+    if (m_peekToken.size() <= offset) {
+        while (m_peekToken.size() <= offset) {
+            auto tok = get_token();
+            m_peekToken.push_back(tok);
+        }
+    }
+    return m_peekToken[offset];
+}
+
+token lexer::get_token() {
     skip_spaces();
 
     if (m_cursor >= m_content.size()) return { location(), token::EndOfFile };
@@ -52,6 +63,8 @@ token lexer::next_token() {
             { "while", token::While },
             { "public", token::Public },
             { "private", token::Private },
+            { "pre", token::Pre },
+            { "post", token::Post },
             { "pointerof", token::Pointerof },
             { "sizeof", token::Sizeof },
             { "lengthof", token::Lengthof },
@@ -169,18 +182,6 @@ token lexer::next_token() {
     return { loc, token::UnexpectedCharacter, get() };
 }
 
-token lexer::peek_token() {
-    if (m_peekToken.has_value()) return m_peekToken.value();
-    auto tok    = next_token();
-    m_peekToken = tok;
-    return tok;
-}
-
-token lexer::skip_token() {
-    m_peekToken = {};
-    return next_token();
-}
-
 void lexer::next() {
     if (m_cursor < m_content.size()) ++m_cursor;
 }
@@ -190,8 +191,12 @@ constexpr char lexer::get(std::size_t offset) const {
 }
 
 void lexer::skip_spaces() {
-    while (m_cursor < m_content.size() && std::isspace(get()) != 0)
-        ++m_cursor;
+    while (m_cursor < m_content.size() && std::isspace(get()) != 0) {
+        if (m_content[m_cursor++] == '\n') {
+            ++m_row;
+            m_lineStart = m_cursor;
+        }
+    }
 }
 
 constexpr token::location lexer::location() const {

furc/src/front/parser.cpp

@@ -58,11 +58,81 @@ stmt_node* parser::parse_stmt() {
     default: break;
     }
 
-    try {
-        return parse_decl();
-    } catch (...) {
-        return parse_expr();
+    if (m_lexer.peek_token().type == token::Func) {
+        eat_token(token::Func);
+        func_decl_node func;
+
+        func.name = std::string(eat_token(token::Identifier).value.string);
+        eat_token(token::LParen);
+        if (m_lexer.peek_token().type != token::RParen) {
+            do {
+                var_decl_node param;
+
+                param.name = std::string(eat_token(token::Identifier).value.string);
+                eat_token(token::Colon);
+                param.type = parse_type();
+                if (m_lexer.peek_token().type == token::Equals) {
+                    m_lexer.next_token();
+                    param.init = parse_expr();
+                }
+                func.params.emplace_back(std::move(param));
+            } while (eat_token(token::Comma, token::RParen).type == token::Comma);
+        } else {
+            eat_token(token::RParen);
+        }
+
+        if (m_lexer.peek_token().type == token::SlimArrow) {
+            m_lexer.next_token();
+            func.type = parse_type();
+        }
+
+        if (m_lexer.peek_token().type == token::Semicolon) {
+            m_lexer.next_token();
+            return m_arena->allocate<func_decl_node>(std::move(func));
+        }
+
+        func_decl_node::def_s def;
+
+        while (m_lexer.peek_token().type == token::Pre || m_lexer.peek_token().type == token::Post) {
+            auto token = m_lexer.next_token();
+            eat_token(token::LParen);
+            auto* expr = parse_expr();
+            eat_token(token::RParen);
+
+            switch (token.type) {
+            case token::Pre: {
+                def.preConds.push_back(expr);
+            } break;
+            case token::Post: {
+                def.postConds.push_back(expr);
+            } break;
+            default: throw std::runtime_error("unreachable");
+            }
+        }
+
+        def.body = parse_comp();
+        func.def = std::move(def);
+
+        return m_arena->allocate<func_decl_node>(std::move(func));
     }
+
+    if (m_lexer.peek_token().type == token::Identifier &&
+        (m_lexer.peek_token(1).type == token::Colon || m_lexer.peek_token(1).type == token::Equals)) {
+        var_decl_node var;
+        var.name = std::string(eat_token(token::Identifier).value.string);
+        eat_token(token::Colon); // TODO: Auto-deduce the type
+        var.type = parse_type();
+        if (eat_token(token::Equals, token::Semicolon).type == token::Equals) {
+            var.init = parse_expr();
+            eat_token(token::Semicolon);
+        }
+
+        return m_arena->allocate<var_decl_node>(std::move(var));
+    }
+
+    auto* expr = parse_expr();
+    eat_token(token::Semicolon);
+    return expr;
 }
 
 decl_node* parser::parse_decl() {
@@ -99,7 +169,27 @@ decl_node* parser::parse_decl() {
             return m_arena->allocate<func_decl_node>(std::move(func));
         }
 
-        func.body = parse_comp();
+        func_decl_node::def_s def;
+
+        while (m_lexer.peek_token().type == token::Pre || m_lexer.peek_token().type == token::Post) {
+            auto token = m_lexer.next_token();
+            eat_token(token::LParen);
+            auto* expr = parse_expr();
+            eat_token(token::RParen);
+
+            switch (token.type) {
+            case token::Pre: {
+                def.preConds.push_back(expr);
+            } break;
+            case token::Post: {
+                def.postConds.push_back(expr);
+            } break;
+            default: throw std::runtime_error("unreachable");
+            }
+        }
+
+        def.body = parse_comp();
+        func.def = std::move(def);
 
         return m_arena->allocate<func_decl_node>(std::move(func));
     }
@@ -149,7 +239,7 @@ comp_stmt_node parser::parse_comp() {
 }
 
 expr_node* parser::parse_expr_primary() {
-    auto token = eat_token(token::Identifier, token::LParen, token::Integer, token::Char);
+    auto token = eat_token(token::Identifier, token::LParen, token::If, token::Integer, token::Char);
     switch (token.type) {
     case token::Identifier: {
         return m_arena->allocate<var_read_expr_node>(std::string(token.value.string));
@@ -160,6 +250,16 @@ expr_node* parser::parse_expr_primary() {
         eat_token(token::RParen);
         return m_arena->allocate<group_expr_node>(std::move(group));
     }
+    case token::If: {
+        if_expr_node ifExpr;
+        eat_token(token::LParen);
+        ifExpr.cond = parse_expr();
+        eat_token(token::RParen);
+        ifExpr.thenExpr = parse_expr();
+        eat_token(token::Else);
+        ifExpr.elseExpr = parse_expr();
+        return m_arena->allocate<if_expr_node>(std::move(ifExpr));
+    }
     case token::Integer: {
         return m_arena->allocate<int_lit_node>(int_lit_node(token.value.integer));
     }
@@ -214,30 +314,37 @@ expr_node* parser::parse_expr_unary() {
 
 expr_node* parser::parse_expr_right(expr_node* lhs, std::uint32_t precedence) {
     struct op_info {
-        binary_op_expr_node::binary_op_type type;
-        std::uint32_t                       precedence;
-        bool                                right = false;
+        enum type_e {
+            Binary = 0,
+            FunctionCall,
+        } type;
+        std::uint32_t precedence;
+        union {
+            binary_op_expr_node::binary_op_type binary;
+        };
+        bool right = false;
     };
 
     static std::unordered_map<token_t, op_info> s_ops = {
-        { token::Plus, { binary_op_expr_node::Add, 4 } },
-        { token::Minus, { binary_op_expr_node::Sub, 4 } },
-        { token::Star, { binary_op_expr_node::Mul, 3 } },
-        { token::Slash, { binary_op_expr_node::Div, 3 } },
-        { token::Percent, { binary_op_expr_node::Mod, 3 } },
-        { token::DblLT, { binary_op_expr_node::Shl, 5 } },
-        { token::DblGT, { binary_op_expr_node::Shr, 5 } },
-        { token::Ampersand, { binary_op_expr_node::BinAnd, 8 } },
-        { token::Pipe, { binary_op_expr_node::BinOr, 10 } },
-        { token::Hat, { binary_op_expr_node::BinXor, 9 } },
-        { token::DblAmpersand, { binary_op_expr_node::And, 11 } },
-        { token::DblPipe, { binary_op_expr_node::Or, 12 } },
-        { token::DblEquals, { binary_op_expr_node::Equals, 7 } },
-        { token::ExEquals, { binary_op_expr_node::NotEquals, 7 } },
-        { token::LessThan, { binary_op_expr_node::LessThan, 6 } },
-        { token::LessEquals, { binary_op_expr_node::LessEquals, 6 } },
-        { token::GreaterThan, { binary_op_expr_node::GreaterThan, 6 } },
-        { token::GreaterEquals, { binary_op_expr_node::GreaterEquals, 6 } },
+        { token::Plus, { op_info::Binary, 4, binary_op_expr_node::Add } },
+        { token::Minus, { op_info::Binary, 4, binary_op_expr_node::Sub } },
+        { token::Star, { op_info::Binary, 3, binary_op_expr_node::Mul } },
+        { token::Slash, { op_info::Binary, 3, binary_op_expr_node::Div } },
+        { token::Percent, { op_info::Binary, 3, binary_op_expr_node::Mod } },
+        { token::DblLT, { op_info::Binary, 5, binary_op_expr_node::Shl } },
+        { token::DblGT, { op_info::Binary, 5, binary_op_expr_node::Shr } },
+        { token::Ampersand, { op_info::Binary, 8, binary_op_expr_node::BinAnd } },
+        { token::Pipe, { op_info::Binary, 10, binary_op_expr_node::BinOr } },
+        { token::Hat, { op_info::Binary, 9, binary_op_expr_node::BinXor } },
+        { token::DblAmpersand, { op_info::Binary, 11, binary_op_expr_node::And } },
+        { token::DblPipe, { op_info::Binary, 12, binary_op_expr_node::Or } },
+        { token::DblEquals, { op_info::Binary, 7, binary_op_expr_node::Equals } },
+        { token::ExEquals, { op_info::Binary, 7, binary_op_expr_node::NotEquals } },
+        { token::LessThan, { op_info::Binary, 6, binary_op_expr_node::LessThan } },
+        { token::LessEquals, { op_info::Binary, 6, binary_op_expr_node::LessEquals } },
+        { token::GreaterThan, { op_info::Binary, 6, binary_op_expr_node::GreaterThan } },
+        { token::GreaterEquals, { op_info::Binary, 6, binary_op_expr_node::GreaterEquals } },
+        { token::LParen, { op_info::FunctionCall, 1 } },
     };
 
     while (true) {
@@ -246,17 +353,32 @@ expr_node* parser::parse_expr_right(expr_node* lhs, std::uint32_t precedence) {
         auto op = it->second;
         m_lexer.next_token();
 
-        expr_node* rhs    = parse_expr_unary();
-        auto       nextIt = s_ops.find(m_lexer.peek_token().type);
-        if (nextIt != s_ops.end()) {
-            rhs = parse_expr_right(rhs, op.precedence + (op.right ? 1 : 0));
-        }
+        if (op.type == op_info::FunctionCall) {
+            func_call_expr_node funcCall;
+            funcCall.lhs = lhs;
 
-        binary_op_expr_node binary;
-        binary.lhs  = lhs;
-        binary.rhs  = rhs;
-        binary.type = op.type;
-        lhs         = m_arena->allocate<binary_op_expr_node>(std::move(binary));
+            if (m_lexer.peek_token().type != token::RParen) {
+                do {
+                    funcCall.args.push_back(parse_expr());
+                } while (eat_token(token::Comma, token::RParen).type == token::Comma);
+            } else {
+                m_lexer.next_token();
+            }
+
+            lhs = m_arena->allocate<func_call_expr_node>(std::move(funcCall));
+        } else {
+            binary_op_expr_node binary;
+            binary.lhs  = lhs;
+            binary.rhs  = parse_expr_unary();
+            binary.type = op.binary;
+
+            auto nextIt = s_ops.find(m_lexer.peek_token().type);
+            if (nextIt != s_ops.end()) {
+                binary.rhs = parse_expr_right(binary.rhs, op.precedence + (op.right ? 1 : 0));
+            }
+
+            lhs = m_arena->allocate<binary_op_expr_node>(std::move(binary));
+        }
     }
 }
 

furc/src/main.cpp

@@ -6,10 +6,10 @@ int main(void) {
     furlang::arena arena;
 
     std::string_view content = R"(
-        func main(argc: u64) -> s32 {
+        func main(argc: u64) -> s32 pre(arc > 1) {
             x: s32 = 1 + 2 * 3;
-            if (x == 9) return 1;
-            else return 0;
+            println(x);
+            return if (x == 9) 1 else 0;
         }
     )";