forked from NUDT-compiler/nudt-compiler-cpp
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115 lines
3.3 KiB
115 lines
3.3 KiB
// 将 parse tree 转换为 AST。
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#include "frontend/AstBuilder.h"
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#include <any>
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#include <stdexcept>
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#include <string>
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#include <utility>
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#include <vector>
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#include "SysYBaseVisitor.h"
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#include "SysYParser.h"
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#include "ast/AstNodes.h"
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#include "antlr4-runtime.h"
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namespace {
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using ast::BinaryExpr;
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using ast::BinaryOp;
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using ast::Block;
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using ast::CompUnit;
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using ast::FuncDef;
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using ast::NumberExpr;
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using ast::ReturnStmt;
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using ast::VarDecl;
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using ast::VarExpr;
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template <typename T>
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T Take(std::any&& value) {
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if (auto* ptr = std::any_cast<T>(&value)) {
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return std::move(*ptr);
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}
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throw std::runtime_error("AST 构建失败：类型不匹配");
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}
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class Builder : public SysYBaseVisitor {
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public:
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std::any visitCompUnit(SysYParser::CompUnitContext* ctx) override {
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auto func = Take<std::shared_ptr<FuncDef>>(visit(ctx->funcDef()));
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return std::make_shared<CompUnit>(std::move(func));
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}
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std::any visitFuncDef(SysYParser::FuncDefContext* ctx) override {
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auto body = Take<std::shared_ptr<Block>>(visit(ctx->block()));
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return std::make_shared<FuncDef>("main", std::move(body));
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}
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std::any visitBlock(SysYParser::BlockContext* ctx) override {
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auto block = std::make_shared<Block>();
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for (auto stmtCtx : ctx->stmt()) {
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if (stmtCtx->varDecl()) {
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block->varDecls.emplace_back(
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Take<std::shared_ptr<VarDecl>>(visit(stmtCtx->varDecl())));
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} else if (stmtCtx->returnStmt()) {
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block->stmts.emplace_back(
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Take<std::shared_ptr<ReturnStmt>>(visit(stmtCtx->returnStmt())));
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}
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}
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return block;
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}
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std::any visitVarDecl(SysYParser::VarDeclContext* ctx) override {
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std::shared_ptr<ast::Expr> init;
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if (ctx->exp()) {
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init = Take<std::shared_ptr<ast::Expr>>(visit(ctx->exp()));
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}
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return std::make_shared<VarDecl>(ctx->Ident()->getText(), std::move(init));
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}
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std::any visitReturnStmt(SysYParser::ReturnStmtContext* ctx) override {
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auto expr = Take<std::shared_ptr<ast::Expr>>(visit(ctx->exp()));
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return std::make_shared<ReturnStmt>(std::move(expr));
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}
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std::any visitExp(SysYParser::ExpContext* ctx) override {
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return visit(ctx->addExp());
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}
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std::any visitAddExp(SysYParser::AddExpContext* ctx) override {
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auto node = Take<std::shared_ptr<ast::Expr>>(visit(ctx->primary(0)));
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for (size_t i = 1; i < ctx->primary().size(); ++i) {
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auto rhs = Take<std::shared_ptr<ast::Expr>>(visit(ctx->primary(i)));
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auto opToken = ctx->AddOp(i - 1);
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BinaryOp op = BinaryOp::Add;
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if (opToken->getText() == "-") op = BinaryOp::Sub;
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node = std::make_shared<BinaryExpr>(op, std::move(node), std::move(rhs));
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}
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return node;
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}
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std::any visitPrimary(SysYParser::PrimaryContext* ctx) override {
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if (ctx->Number()) {
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std::shared_ptr<ast::Expr> expr =
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std::make_shared<NumberExpr>(std::stoi(ctx->Number()->getText()));
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return expr;
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}
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if (ctx->Ident()) {
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std::shared_ptr<ast::Expr> expr =
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std::make_shared<VarExpr>(ctx->Ident()->getText());
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return expr;
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}
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return visit(ctx->exp());
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}
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};
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} // namespace
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std::shared_ptr<ast::CompUnit> BuildAst(antlr4::tree::ParseTree* tree) {
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if (!tree) {
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throw std::runtime_error("parse tree 为空");
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}
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Builder visitor;
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auto result = visitor.visit(tree);
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return Take<std::shared_ptr<ast::CompUnit>>(std::move(result));
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}
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