From d5cb498ba37949193fecafa8c1f15d70ade79515 Mon Sep 17 00:00:00 2001
From: Dimitar Trendafilov <dimitar@coherent-labs.com>
Date: Sun, 21 Oct 2018 21:27:36 +0300
Subject: Added a tree interpreter

---
 JSImpl/src/ASTInterpreter.cpp | 154 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)
 create mode 100644 JSImpl/src/ASTInterpreter.cpp

(limited to 'JSImpl/src/ASTInterpreter.cpp')

diff --git a/JSImpl/src/ASTInterpreter.cpp b/JSImpl/src/ASTInterpreter.cpp
new file mode 100644
index 0000000..7ce6d59
--- /dev/null
+++ b/JSImpl/src/ASTInterpreter.cpp
@@ -0,0 +1,154 @@
+#include "ASTInterpreter.h"
+#include "Expression.h"
+#include <cassert>
+#include <iostream>
+
+ASTInterpreter::ASTInterpreter()
+{}
+
+ASTInterpreter::~ASTInterpreter()
+{}
+
+ASTInterpreter::ValueStack ASTInterpreter::Run(Expression* program)
+{
+    program->Accept(*this);
+    ValueStack result;
+    m_Evaluation.swap(result);
+    return result;
+}
+
+void ASTInterpreter::RunExpression(const ExpressionPtr& e)
+{
+    if (e) {
+        e->Accept(*this);
+    }
+}
+
+bool ASTInterpreter::EvalToBool(const ExpressionPtr& e)
+{
+    e->Accept(*this);
+    auto result = m_Evaluation.top();
+    m_Evaluation.pop();
+    return result != 0.0;
+}
+
+#define NOT_IMPLEMENTED (void)e; assert(0 && "not-implemented")
+
+void ASTInterpreter::Visit(LiteralNull* e) {
+   NOT_IMPLEMENTED; 
+}
+
+void ASTInterpreter::Visit(LiteralUndefined* e) {
+   NOT_IMPLEMENTED; 
+}
+void ASTInterpreter::Visit(LiteralString* e) {
+   NOT_IMPLEMENTED; 
+}
+
+void ASTInterpreter::Visit(LiteralNumber* e) {
+    m_Evaluation.push(e->GetValue());
+}
+void ASTInterpreter::Visit(LiteralBoolean* e) {
+    m_Evaluation.push(e->GetValue());
+}
+
+void ASTInterpreter::Visit(BinaryExpression* e) {
+    e->GetLeft()->Accept(*this);
+    e->GetRight()->Accept(*this);
+    auto right = m_Evaluation.top();
+    m_Evaluation.pop();
+
+    auto left = m_Evaluation.top();
+    m_Evaluation.pop();
+
+    switch (e->GetOperator()) {
+        case TokenType::Plus:
+            std::cout << "PLUS:" << left << ':' << right << std::endl;
+            m_Evaluation.push(left + right);
+            break;
+        case TokenType::Minus:
+            m_Evaluation.push(left - right);
+            break;
+        case TokenType::Star:
+            m_Evaluation.push(left * right);
+            break;
+        case TokenType::Division:
+            m_Evaluation.push(left / right);
+            break;
+        default:
+            NOT_IMPLEMENTED;
+    }
+}
+
+void ASTInterpreter::Visit(UnaryExpression* e) {
+    NOT_IMPLEMENTED;
+}
+
+void ASTInterpreter::Visit(IdentifierExpression* e) {
+    auto values = m_Variables.find(e->GetName());
+    if (values != m_Variables.end()) {
+        m_Evaluation.push(values->second.top());
+    } else {
+        throw "Not-defined";
+    }
+}
+void ASTInterpreter::Visit(ListExpression* e) {
+    for (const auto& stmt: e->GetValues()) {
+        stmt->Accept(*this);
+    }
+}
+
+void ASTInterpreter::Visit(VariableDefinitionExpression* e) {
+    e->GetValue()->Accept(*this);
+    m_Variables[e->GetName()].push(m_Evaluation.top());
+    m_Evaluation.pop();
+}
+
+void ASTInterpreter::Visit(BlockStatement* e) {
+    for (const auto& stmt: e->GetValues()) {
+        stmt->Accept(*this);
+    }
+}
+
+void ASTInterpreter::Visit(LabeledStatement* e) {
+    RunExpression(e->GetStatement());
+}
+
+void ASTInterpreter::Visit(IfStatement* e) {
+    if (EvalToBool(e->GetCondition())) {
+        RunExpression(e->GetIfStatement());
+    } else {
+        RunExpression(e->GetElseStatement());
+    }
+}
+
+void ASTInterpreter::Visit(SwitchStatement* e) { NOT_IMPLEMENTED;}
+void ASTInterpreter::Visit(CaseStatement *e) { NOT_IMPLEMENTED;}
+
+void ASTInterpreter::Visit(WhileStatement* e) {
+    if (e->GetDoWhile()) {
+        RunExpression(e->GetBody());
+    }
+    while (EvalToBool(e->GetCondition())) {
+        RunExpression(e->GetBody());
+    }
+}
+
+void ASTInterpreter::Visit(ForStatement* e) {
+    for (RunExpression(e->GetInitialization());
+            EvalToBool(e->GetCondition());
+            RunExpression(e->GetIteration())) {
+        RunExpression(e->GetBody());
+    }
+}
+
+void ASTInterpreter::Visit(FunctionDeclaration* e) { NOT_IMPLEMENTED;}
+void ASTInterpreter::Visit(TopStatements* e) {
+    for (const auto& stmt: e->GetValues()) {
+        stmt->Accept(*this);
+    }
+}
+
+void ASTInterpreter::Visit(EmptyExpression* e) {
+    NOT_IMPLEMENTED;
+}
-- 
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