Merge pull request #18 from sriharivishnu/fix-list-assignment

list indexing assignment working (fixes #15)
sriharivishnu · Oct 8, 2020 · 501b51c · 501b51c
2 parents 99eabf7 + 9b002eb
commit 501b51c
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Showing 7 changed files with 66 additions and 4 deletions.
diff --git a/include/Expression.h b/include/Expression.h
@@ -105,6 +105,21 @@ class UpdateExpression : public Expression {
         shared_ptr<Expression> right;
 };
 
+class ObjectIndexUpdateExpression : public Expression {
+    public:
+        ObjectIndexUpdateExpression(
+            const Token& tok, 
+            shared_ptr<Expression> objToUpdate,
+            shared_ptr<Expression> index, 
+            shared_ptr<Expression> newVal);
+        shared_obj accept(Context& context, Visitor& v) override;
+        std::string toString() override;
+        Token tok;
+        shared_ptr<Expression> objToUpdate;
+        shared_ptr<Expression> index;
+        shared_ptr<Expression> newVal;
+};
+
 class ConditionalExpression : public Expression {
     public:
         ConditionalExpression(

diff --git a/include/Interpreter.h b/include/Interpreter.h
@@ -23,6 +23,7 @@ class StringExpression;
 class ListExpression;
 class AssignmentExpression;
 class UpdateExpression;
+class ObjectIndexUpdateExpression;
 class NameExpression;
 class ConditionalExpression;
 class CallFunctionExpression;
@@ -42,6 +43,7 @@ class Visitor {
         shared_obj visit(Context& context, ListExpression* e);
         shared_obj visit(Context& context, AssignmentExpression* e);
         shared_obj visit(Context& context, UpdateExpression* e);
+        shared_obj visit(Context& context, ObjectIndexUpdateExpression* e);
         shared_obj visit(Context& context, NameExpression* e);
         shared_obj visit(Context& context, ConditionalExpression* e);
         shared_obj visit(Context& context, CallFunctionExpression* e);

diff --git a/include/types.h b/include/types.h
@@ -33,6 +33,7 @@ struct object {
     virtual shared_obj lshift(const shared_obj& obj);
     virtual shared_obj rshift(const shared_obj& obj);
     virtual shared_obj index(const shared_obj& obj);
+    virtual shared_obj indexUpdate(const shared_obj& index, const shared_obj& newObj);
     virtual shared_obj bnot();
     virtual shared_obj inc();
     virtual shared_obj dec();
@@ -121,6 +122,7 @@ struct list_type : object {
     shared_obj multBy(const shared_obj& obj) override;
     shared_obj toBool() override;
     shared_obj index(const shared_obj& obj) override;
+    shared_obj indexUpdate(const shared_obj& obj, const shared_obj& newObj) override;
     shared_obj dot(const std::string& name, const std::vector<shared_obj>& args) override;
     std::string toString() override;
 };

diff --git a/src/Expression.cpp b/src/Expression.cpp
@@ -151,6 +151,20 @@ shared_obj UpdateExpression::accept(Context& context, Visitor& v) {
     return v.visit(context, this);
 }
 
+ObjectIndexUpdateExpression::ObjectIndexUpdateExpression(
+            const Token& tok, 
+            shared_ptr<Expression> objToUpdate,
+            shared_ptr<Expression> index, 
+            shared_ptr<Expression> newVal) : 
+            tok(tok), objToUpdate(objToUpdate), index(index), newVal(newVal)
+{}
+shared_obj ObjectIndexUpdateExpression::accept(Context& context, Visitor& v) {
+    return v.visit(context, this);
+}
+std::string ObjectIndexUpdateExpression::toString() {
+    return tok.getValue() + index->toString() + "]" + " = " + newVal->toString();
+}
+
 //Conditional
 ConditionalExpression::ConditionalExpression(
             Token tok_, 

diff --git a/src/Interpreter.cpp b/src/Interpreter.cpp
@@ -135,6 +135,16 @@ shared_obj Visitor::visit(Context& context, UpdateExpression* e) {
     throw UndefinedVariable(make_shared<Context>(context), e->name, e->getToken().startPos);
 }
 
+shared_obj Visitor::visit(Context& context, ObjectIndexUpdateExpression* e) {
+    shared_obj res = e->newVal->accept(context, *this);
+    shared_obj obj = e->objToUpdate->accept(context, *this);
+    shared_obj index = e->index->accept(context, *this);
+    shared_obj newValue = e->newVal->accept(context, *this);
+
+    return obj->indexUpdate(index, newValue);
+}
+
+
 shared_obj Visitor::visit(Context& context, NameExpression* e) {
     std::optional<shared_obj> value = context.symbols->get(e->name);
     if (value) {

diff --git a/src/Parser.cpp b/src/Parser.cpp
@@ -142,11 +142,11 @@ shared_ptr<Expression> Parser::getInfixExpression(const shared_ptr<Expression>&
         case Token::Type::BOR:
             return make_shared<BinOpExpression>(left, tok, parseExpression(Precedence::SUM - 1));
         case Token::Type::EQUALS: {
-            if (!left->getToken().is(Token::Type::IDENTIFIER)) {
-                throw SyntaxError(left->getToken().startPos, "Expected an identifier");
+            if (left->getToken().is(Token::Type::IDENTIFIER)) {
+                shared_ptr<Expression> right = parseExpression(Precedence::ASSIGNMENT - 1);
+                return make_shared<UpdateExpression>(left->getToken().getValue(), right, tok);
             }
-            shared_ptr<Expression> right = parseExpression(Precedence::ASSIGNMENT - 1);
-            return make_shared<UpdateExpression>(left->getToken().getValue(), right, tok);
+            throw SyntaxError(left->getToken().startPos, "Expected an identifier but instead got " + left->getToken().getValue());
         }
         case Token::Type::INC:
         case Token::Type::DEC:
@@ -168,6 +168,12 @@ shared_ptr<Expression> Parser::getInfixExpression(const shared_ptr<Expression>&
         case Token::Type::LSQUARE: {
             shared_ptr<Expression> index = parseExpression();
             consume(Token::Type::RSQUARE, ", expected ']'");
+            if (lookAhead(0).is(Token::Type::EQUALS)) {
+                consume(Token::Type::EQUALS);
+                shared_ptr<Expression> newObj = parseExpression();
+                return make_shared<ObjectIndexUpdateExpression>(tok, left, index, newObj);
+            }
+
             return make_shared<IndexExpression>(left, tok, index);
         }
         case Token::Type::LPAREN: {

diff --git a/src/types.cpp b/src/types.cpp
@@ -73,6 +73,9 @@ shared_obj object::rshift(const shared_obj& obj) {
 shared_obj object::index(const shared_obj& obj) {
     UNDEFINED_OP
 }
+shared_obj object::indexUpdate(const shared_obj& obj, const shared_obj& newObj) {
+    UNDEFINED_OP
+}
 shared_obj object::bnot() {
     UNDEFINED_UNARY("~")
 }
@@ -444,6 +447,16 @@ shared_obj list_type::index(const shared_obj& obj) {
     }
     return getValue<std::vector<shared_obj>>()[toAccess];
 }
+shared_obj list_type::indexUpdate(const shared_obj& obj, const shared_obj& newObj) {
+    if (!obj->value.isType<int>()) UNDEFINED_OP
+    int toAccess = obj->getValue<int>();
+    int size = getValue<std::vector<shared_obj>>().size();
+    if (toAccess >=  size || toAccess < 0) {
+        throw Error("Index Out of Bounds", "Attempted to access index: " + std::to_string(toAccess) + ", with list size: " + std::to_string(size));
+    }
+    getValue<std::vector<shared_obj>>()[toAccess] = newObj;
+    return std::make_shared<null_type>();
+}
 std::string list_type::toString() {
     auto values = getValue<std::vector<shared_obj>>();
     std::string str("[");