1 files changed, 131 insertions, 0 deletions
diff --git a/code/Interpreter2/src/Interpreter/Interpreter.java b/code/Interpreter2/src/Interpreter/Interpreter.java
new file mode 100644
index 0000000..65cdeb4
--- /dev/null
+++ b/code/Interpreter2/src/Interpreter/Interpreter.java
@@ -0,0 +1,131 @@
+package Interpreter;
+
+import java.util.List;
+
+import Interpreter.Expression.*;
+import Interpreter.Statement.ExpressionStatement;
+import Interpreter.Statement.PrintStatement;
+import Interpreter.Statement.VariableDeclaration;
+
+public class Interpreter {
+
+    private Environment environment = new Environment();
+
+    void interpret(List<Statement> statements){
+        try{
+            for (Statement statement: statements){
+                evaluateStatement(statement);
+            }
+        } catch (Error e){
+
+        }
+    }
+
+    private Object evaluateStatement(Statement statement){
+        switch(statement.getStatmentType()){
+            case "exprStmt":
+                return evalExpressionStatement((ExpressionStatement)statement);
+            case "vardec":
+                return evalVariableDeclaration((VariableDeclaration)statement);
+            case "print":
+                return evalPrintStatement((PrintStatement)statement);
+            default:
+                return null;
+        }
+    } 
+    private Object evalExpressionStatement(ExpressionStatement stmt){
+        return evaluateExpression(stmt.expr);
+    }
+
+    private Object evalVariableDeclaration(VariableDeclaration vardec){
+        environment.defineVariable(vardec.name.text, null);
+        return null;
+    }
+
+    private Object evalPrintStatement(PrintStatement print){
+        System.out.println(evaluateExpression(print.expr));
+        return null;
+    }
+
+    private Object evaluateExpression(Expression expression){
+        switch(expression.getExpressionType()){
+            case "binary":
+                return evaluateBinaryExpression((Binary)expression);
+            case "literal":
+                return evaluateLiteralExpression((Literal)expression);
+            case "bracket":
+                return evaluateBracketedExpression((BracketedExpression)expression);
+            case "assign":
+                return evaluateAssignmentExpression((AssignmentExpression)expression);
+            case "var":
+                return evaluateVariableExpression((Variable)expression);
+            default:
+                return null;
+        }
+    }
+
+    private Object evaluateBinaryExpression(Binary expr){
+        Object leftEval = evaluateExpression(expr.left);
+        Object rightEval = evaluateExpression(expr.right);
+        switch (expr.op.type){
+            case PLUS:
+                if (checkOperandsNum(leftEval, leftEval)){
+                    return (double)leftEval + (double)rightEval;
+                } 
+            case STAR:
+                if (checkOperandsNum(leftEval, leftEval)){
+                    return (double)leftEval * (double)rightEval;
+                } 
+            case MINUS:
+                if (checkOperandsNum(leftEval, leftEval)){
+                    return (double)leftEval - (double)rightEval;
+                }
+            case SLASH:
+                if (checkOperandsNum(leftEval, leftEval)){
+                    return (double)leftEval / (double)rightEval;
+                }
+
+            case GREATER:
+                if (checkOperandsNum(leftEval, leftEval)){
+                    return (double)leftEval > (double)rightEval;
+                }
+            case LESS:
+                if (checkOperandsNum(leftEval, leftEval)){
+                    return (double)leftEval < (double)rightEval;
+                }
+            
+            case EQUALITY:
+                return leftEval.equals(rightEval);
+            default:
+                break;
+        }
+        return null;
+    }
+
+    private Object evaluateLiteralExpression(Literal expr){
+        return expr.value.value;
+    }
+
+    private Object evaluateBracketedExpression(BracketedExpression expr){
+        return evaluateExpression(expr.expr);
+    }
+
+    private Object evaluateAssignmentExpression(AssignmentExpression expr){
+        Object assignedValue = evaluateExpression(expr.value);
+        environment.assignVariable(expr.name.text, assignedValue);
+        return null;
+    }
+
+    private Object evaluateVariableExpression(Variable expr){
+        return environment.getVariable(expr.name.text);
+    }
+
+    private boolean checkOperandsNum(Object left, Object right){
+        if (left instanceof Double && right instanceof Double){
+            return true;
+        } else {
+            Language.displayError("Operands must be numbers");
+            throw new Error();
+        }
+    }
+}