Rough implementation of ASTPrinter complete with nasty shared_ptr syntax :)

headers/ASTPrinter.h

@@ -0,0 +1,18 @@
+#pragma once
+#include "Expression.h"
+#include <string>
+#include <initializer_list>
+
+class ASTPrinter : public Visitor<std::string>
+{
+    std::string visitBinaryExpr(BinaryExpr<std::string>* expression) override;
+//    std::string visitGroupingExpr(GroupingExpr<std::string> expression);
+    std::string visitLiteralExpr(LiteralExpr<std::string>* expression) override;
+    std::string visitUnaryExpr(UnaryExpr<std::string>* expression) override;
+public:
+    int test = 10;
+    std::string print(Expr<std::string>* expr);
+private:
+    std::string parenthesize(std::string name,  std::vector<std::shared_ptr<Expr<std::string> > > exprs);
+
+};

headers/Expression.h

@@ -5,45 +5,74 @@
 #pragma once
 #include "Lexer.h"
 #include <iostream>
+
+template <typename T>
+struct Visitor;
+
+template <typename T>
 struct Expr{
-    virtual ~Expr()
-    {
-
-    }
+    virtual T accept(Visitor<T>* visitor) = 0;
+    virtual ~Expr(){}
 };
 
-struct BinaryExpr : Expr
+template <typename T>
+struct BinaryExpr : Expr<T>
 {
-    const Expr left;
+    const std::shared_ptr<Expr<T> > left;
     const Token oper;
-    const Expr right;
+    const std::shared_ptr<Expr<T> > right;
 
-    BinaryExpr(Expr left, Token oper, Expr right) : left(left), oper(oper), right(right)
+    BinaryExpr(std::shared_ptr<Expr<T> > left, Token oper, std::shared_ptr<Expr<T> > right) : left(left), oper(oper), right(right)
     {
     }
-};
-struct GroupingExpr : Expr
-{
-    const Expr expression;
-
-    GroupingExpr(Expr expression) : expression(expression)
-    {
+    T accept(Visitor<T>* visitor) override{
+        return visitor->visitBinaryExpr(this);
     }
 };
-struct LiteralExpr : Expr
+//template <typename T>
+//struct GroupingExpr : Expr<T>, Visitor<T>
+//{
+//    Expr<T> expression;
+//
+//    GroupingExpr(Expr<T> expression) : expression(expression)
+//    {
+//    }
+//    T accept(Visitor<T> visitor){
+//        return visitor.visitGroupingExpr(this);
+//    }
+//};
+template <typename T>
+struct LiteralExpr : Expr<T>
 {
     const std::string value;
 
     LiteralExpr(std::string value) : value(value)
     {
     }
-};
-struct UnaryExpr : Expr
-{
-    const Token oper;
-    const Expr right;
-
-    UnaryExpr(Token oper, Expr right) : oper(oper), right(right)
-    {
+    T accept(Visitor<T>* visitor) override{
+        return visitor->visitLiteralExpr(this);
     }
 };
+template <typename T>
+struct UnaryExpr : Expr<T>
+{
+    const Token oper;
+    const std::shared_ptr<Expr<T> > right;
+
+    UnaryExpr(Token oper, std::shared_ptr<Expr<T> > right) : oper(oper), right(right)
+    {
+    }
+    T accept(Visitor<T>* visitor) override{
+        return visitor->visitUnaryExpr(this);
+    }
+};
+
+////
+template <typename T>
+struct Visitor
+{
+    virtual T visitBinaryExpr(BinaryExpr<T>* expression) = 0;
+//    virtual T visitGroupingExpr(GroupingExpr<T> expression){};
+    virtual T visitLiteralExpr(LiteralExpr<T>* expression) = 0;
+    virtual T visitUnaryExpr(UnaryExpr<T>* expression) = 0;
+};

headers/helperFunctions/HelperFunctions.h

@@ -37,4 +37,16 @@ std::string trim(const std::string& str) {
 
     // Extract the trimmed substring
     return str.substr(start, end - start + 1);
+}
+
+std::string replaceSubstring(const std::string& str, const std::string& findSubstring, const std::string& replacement) {
+    std::string result = str;
+    size_t startPos = result.find(findSubstring);
+
+    while (startPos != std::string::npos) {
+        result.replace(startPos, findSubstring.length(), replacement);
+        startPos = result.find(findSubstring, startPos + replacement.length());
+    }
+
+    return result;
 }

source/ASTPrinter.cpp

@@ -0,0 +1,43 @@
+//
+// Created by Bobby Lucero on 5/23/23.
+//
+#include "../headers/ASTPrinter.h"
+
+
+std::string ASTPrinter::visitBinaryExpr(BinaryExpr<std::string>* expression){
+    std::cout << expression->left << std::endl;
+    return parenthesize(expression->oper.lexeme, std::vector<std::shared_ptr<Expr<std::string> > >{expression->left, expression->right});
+}
+
+//std::string ASTPrinter::visitGroupingExpr(GroupingExpr<std::string> expression){
+//    return "hi";
+//}
+std::string ASTPrinter::visitLiteralExpr(LiteralExpr<std::string>* expression){
+    return expression->value;
+}
+std::string ASTPrinter::visitUnaryExpr(UnaryExpr<std::string>* expression){
+    return parenthesize(expression->oper.lexeme, std::vector<std::shared_ptr<Expr<std::string> > >{expression->right});
+}
+
+std::string ASTPrinter::print(Expr<std::string> *expr) {
+    return expr->accept(this);
+}
+
+std::string ASTPrinter::parenthesize(std::string name, std::vector<std::shared_ptr<Expr<std::string> > > exprs) {
+    std::string builder;
+
+    builder += "(" + name;
+
+    for(std::shared_ptr<Expr<std::string> > expr : exprs)
+    {
+        std::cout << expr << std::endl;
+
+        builder += " ";
+        builder += expr->accept(this);
+    }
+
+    builder += ")";
+
+    return builder;
+
+}

source/main.cpp

@@ -1,37 +1,44 @@
 //
 // Created by Bobby Lucero on 5/21/23.
 //
+
+
 #include "../headers/bob.h"
 #include "../headers/Expression.h"
 #include "../headers/Lexer.h"
+#include "../headers/ASTPrinter.h"
 int main(){
 
     Bob bobLang;
 
     //bobLang.runFile("source.bob");
 
+    ASTPrinter printer;
 
-    Expr a;
-    Expr b;
-    Token t = {PLUS, "+", 1};
-    Token t2 = {MINUS, "-", 1};
-    BinaryExpr e = BinaryExpr(a, t, b);
+    std::shared_ptr<Expr<std::string> > expression = std::make_shared<BinaryExpr<std::string> >(
+            std::make_shared<UnaryExpr<std::string> >(
+                Token{MINUS, "-", 0},
+                std::make_shared<LiteralExpr<std::string> >("123")
+            ),
+            Token{STAR, "*", 0},
+            std::make_shared<UnaryExpr<std::string> >(
+                    Token{MINUS, "+", 0},
+                    std::make_shared<LiteralExpr<std::string> >("987")
+            )
+            );
 
-    std::shared_ptr<Expr> any = std::make_shared<BinaryExpr>(a, t, b);
-    if(std::shared_ptr<BinaryExpr> binexpr = std::dynamic_pointer_cast<BinaryExpr>(any))
-    {
-        std::cout << binexpr->oper.lexeme;
-    }
+//    Expr<std::string>* e = new BinaryExpr<std::string>(
+//                new UnaryExpr<std::string>(Token{MINUS, "-", 0}, new LiteralExpr<std::string>("123")),
+//                Token{STAR, "*", 0},
+//                new UnaryExpr<std::string>(Token{PLUS, "+", 0}, new LiteralExpr<std::string>("535"))
+//            );
+    LiteralExpr<std::string>* le = new LiteralExpr<std::string>("123");
 
-    any = std::make_shared<BinaryExpr>(a, t2, b);
-    if(std::shared_ptr<BinaryExpr> binexpr = std::dynamic_pointer_cast<BinaryExpr>(any))
-    {
-        std::cout << binexpr->oper.lexeme;
-    }
+    std::cout << printer.print(expression.get());
 
     std::cout << std::endl;
 
-    bobLang.runPrompt();
+    //bobLang.runPrompt();
 
     return 0;
 }

testthing

@@ -1,35 +1,51 @@
-struct BinaryExpr : Expr
+template <typename T>
+struct BinaryExpr : Expr<T>, Visitor<T>
 {
-    const Expr left;
+    const Expr<T> left;
     const Token oper;
-    const Expr right;
+    const Expr<T> right;
 
-    BinaryExpr(Expr left, Token oper, Expr right) : left(left), oper(oper), right(right)
+    BinaryExpr(Expr<T> left, Token oper, Expr<T> right) : left(left), oper(oper), right(right)
     {
     }
+    T accept(Visitor<T> visitor){
+        return visitor.visitBinaryExpr(this);
+    }
 };
-struct GroupingExpr : Expr
+template <typename T>
+struct GroupingExpr : Expr<T>, Visitor<T>
 {
-    const Expr expression;
+    const Expr<T> expression;
 
-    GroupingExpr(Expr expression) : expression(expression)
+    GroupingExpr(Expr<T> expression) : expression(expression)
     {
     }
+    T accept(Visitor<T> visitor){
+        return visitor.visitGroupingExpr(this);
+    }
 };
-struct LiteralExpr : Expr
+template <typename T>
+struct LiteralExpr : Expr<T>, Visitor<T>
 {
     const std::string value;
 
     LiteralExpr(std::string value) : value(value)
     {
     }
-};
-struct UnaryExpr : Expr
-{
-    const Token oper;
-    const Expr right;
-
-    UnaryExpr(Token oper, Expr right) : oper(oper), right(right)
-    {
+    T accept(Visitor<T> visitor){
+        return visitor.visitLiteralExpr(this);
+    }
+};
+template <typename T>
+struct UnaryExpr : Expr<T>, Visitor<T>
+{
+    const Token oper;
+    const Expr<T> right;
+
+    UnaryExpr(Token oper, Expr<T> right) : oper(oper), right(right)
+    {
+    }
+    T accept(Visitor<T> visitor){
+        return visitor.visitUnaryExpr(this);
     }
 };

tools/GenerateAST.cpp

@@ -8,21 +8,29 @@
 
 void defineType(std::ofstream &out, std::string baseName, std::string className, std::string fieldList)
 {
-    out << "struct " << className << "Expr : " << baseName << "\n{\n";
+    out << "template <typename T>\n";
+    out << "struct " << className << "Expr : " << baseName << "<T>" << ", Visitor<T>" << "\n{\n";
     std::vector<std::string> fields = splitString(fieldList, ", ");
     for(std::string field : fields)
     {
-        out << "    const " << trim(field) << ";\n";
+        std::cout << trim(field) << std::endl;
+        std::string fieldClass = splitString(trim(field), " ")[0];
+        std::string fieldName = splitString(trim(field), " ")[1];
+        fieldClass = trim(fieldClass) == "Expr" ? "Expr<T>" : trim(fieldClass);
+        out << "    const " << fieldClass << " " << fieldName << ";\n";
     }
-
+    fieldList = replaceSubstring(fieldList, "Expr", "Expr<T>");
     out << "\n    " << className << "Expr(" << fieldList << ") : ";
 
     std::string explicitDeclaration;
     for(std::string field : fields)
     {
-        std::string name = splitString(trim(field), " ")[1];
+        std::cout << trim(field) << std::endl;
+        std::string fieldClass = splitString(trim(field), " ")[0];
+        std::string fieldName = splitString(trim(field), " ")[1];
+        fieldClass = trim(fieldClass) == "Expr" ? "Expr<T>" : trim(fieldClass);
 
-        explicitDeclaration += trim(name) + "(" + trim(name) + "), ";
+        explicitDeclaration += trim(fieldName) + "(" + trim(fieldName) + "), ";
     }
     explicitDeclaration = trim(explicitDeclaration);
     explicitDeclaration.pop_back();
@@ -31,6 +39,11 @@ void defineType(std::ofstream &out, std::string baseName, std::string className,
 
     out << "\n    {\n";
     out << "    }\n";
+
+    out << "    T accept(Visitor<T> visitor){\n";
+    out << "        return visitor.visit" << className << "Expr(this);\n";
+    out << "    }\n";
+
     out << "};" << std::endl;
 }