完成Parser定义以及表达式解析

src/Parser/Parser.hpp

@@ -0,0 +1,154 @@
+/*!
+    @file src/Parser/Parser.hpp
+    @brief 语法分析器(Pratt + 手动递归下降) 定义
+    @author PuqiAR (im@puqiar.top)
+    @date 2026-02-14
+*/
+
+#pragma once
+
+#include <Ast/Ast.hpp>
+#include <Deps/Deps.hpp>
+#include <Error/Error.hpp>
+#include <Lexer/Lexer.hpp>
+#include <Token/Token.hpp>
+
+#include <cstddef>
+#include <cstdlib>
+
+#include <unordered_set>
+
+namespace Fig
+{
+
+    class Parser
+    {
+    private:
+        Lexer         &lexer;
+        SourceManager &srcManager;
+
+        size_t          index = 0; // token在buffer下标
+        DynArray<Token> buffer;
+
+        String fileName;
+
+        bool isEOF = false;
+
+        const Token &nextToken()
+        {
+            assert(!isEOF && "nextToken: eof but called nextToken");
+            if (index + 1 < buffer.size())
+            {
+                return buffer[++index];
+            }
+            const auto &result = lexer.NextToken();
+            if (!result)
+            {
+                ReportError(result.error(), srcManager);
+                std::exit(-1);
+            }
+            const Token &token = result.value();
+            if (token.type == TokenType::EndOfFile)
+            {
+                isEOF = true;
+            }
+            buffer.push_back(token);
+            index++;
+            return token;
+        }
+
+        inline const Token &prevToken()
+        {
+            return buffer[buffer.size() - 2];
+        }
+
+        inline const Token &currentToken()
+        {
+            if (buffer.empty())
+            {
+                return nextToken();
+            }
+            return buffer.back();
+        }
+
+        const Token &peekToken(size_t lookahead = 1)
+        {
+            assert(!isEOF && "peekToken: eof but called peekToken");
+
+            size_t peekIndex = index + lookahead;
+            while (peekIndex >= buffer.size() && !isEOF)
+            {
+                const auto &result = lexer.NextToken();
+                if (!result)
+                {
+                    ReportError(result.error(), srcManager);
+                    std::abort();
+                }
+                const Token &token = result.value();
+                if (token.type == TokenType::EndOfFile)
+                {
+                    isEOF = true;
+                }
+                buffer.push_back(token);
+            }
+            if (peekIndex >= buffer.size()) // 没有那么多token
+            {
+                return buffer.back(); // back是EOF Token
+            }
+            return buffer[peekIndex];
+        }
+
+        inline Token consumeToken()
+        {
+            if (isEOF)
+                return buffer.back();
+            Token current = currentToken();
+            nextToken();
+            return current;
+        }
+
+    public:
+        enum class State : std::uint8_t
+        {
+            Standby,
+
+            ParsingLiteralExpr,
+            ParsingIdentiExpr,
+
+            ParsingInfixExpr,
+            ParsingPrefixExpr,
+        } state;
+
+        Parser(Lexer &_lexer, SourceManager &_srcManager, String _fileName) :
+            lexer(_lexer), srcManager(_srcManager), fileName(std::move(_fileName))
+        {
+            state = State::Standby;
+        }
+
+    private:
+        SourceLocation makeSourcelocation(const Token &tok)
+        {
+            auto [line, column] = srcManager.GetLineColumn(tok.index);
+            return SourceLocation(
+                SourcePosition(
+                    line,
+                    column,
+                    tok.length
+                ), fileName, "[internal parser]", magic_enum::enum_name(state).data());
+        }
+
+        Result<LiteralExpr *, Error> parseLiteralExpr(); // 当前token为literal时调用
+        Result<IdentiExpr *, Error>  parseIdentiExpr();  // 当前token为Identifier调用
+
+        Result<InfixExpr *, Error>  parseInfixExpr(Expr *);  // 由 parseExpression递归调用, 当前token为op
+        Result<PrefixExpr *, Error> parsePrefixExpr(); // 由 parseExpression递归调用, 当前token为op
+
+        std::unordered_set<TokenType> getTerminators(); // 返回当前state的终止条件(终止符)
+        bool shouldTerminate(); // 通过state判断该不该终止表达式解析
+
+    public:
+        Result<Expr *, Error> parseExpression(BindingPower = 0);
+
+        DynArray<AstNode *> parseAll();
+    };
+}; // namespace Fig