From 11e99c393b9c9b799c5c620ee391f093ea609548 Mon Sep 17 00:00:00 2001
From: aziz-mu <aziz20019@gmail.com>
Date: Wed, 23 Nov 2022 11:24:48 -0500
Subject: [PATCH] refactor transformer code

---
 src/parser/include/transformer.h |  8 +++
 src/parser/transformer.cpp       | 86 ++++++++++++++++++--------------
 2 files changed, 57 insertions(+), 37 deletions(-)

diff --git a/src/parser/include/transformer.h b/src/parser/include/transformer.h
index da2f24f6836..e67293966df 100644
--- a/src/parser/include/transformer.h
+++ b/src/parser/include/transformer.h
@@ -128,6 +128,14 @@ class Transformer {
         CypherParser::OC_ListOperatorExpressionContext& ctx,
         unique_ptr<ParsedExpression> propertyExpression);
 
+    unique_ptr<ParsedExpression> transformListSliceOperatorExpression(
+        CypherParser::KU_ListSliceOperatorExpressionContext& ctx,
+        unique_ptr<ParsedExpression> propertyExpression);
+
+    unique_ptr<ParsedExpression> transformListExtractOperatorExpression(
+        CypherParser::KU_ListExtractOperatorExpressionContext& ctx,
+        unique_ptr<ParsedExpression> propertyExpression);
+
     unique_ptr<ParsedExpression> transformNullOperatorExpression(
         CypherParser::OC_NullOperatorExpressionContext& ctx,
         unique_ptr<ParsedExpression> propertyExpression);
diff --git a/src/parser/transformer.cpp b/src/parser/transformer.cpp
index ba44722ccbc..883bab84158 100644
--- a/src/parser/transformer.cpp
+++ b/src/parser/transformer.cpp
@@ -498,50 +498,62 @@ unique_ptr<ParsedExpression> Transformer::transformListOperatorExpression(
     CypherParser::OC_ListOperatorExpressionContext& ctx,
     unique_ptr<ParsedExpression> propertyExpression) {
     auto rawExpression = propertyExpression->getRawName() + " " + ctx.getText();
+    unique_ptr<ParsedExpression> listOperator;
     if (ctx.kU_ListSliceOperatorExpression()) {
-        auto listSlice =
-            make_unique<ParsedFunctionExpression>(LIST_SLICE_FUNC_NAME, move(rawExpression));
-        listSlice->addChild(move(propertyExpression));
-        if (ctx.kU_ListSliceOperatorExpression()->children[1]->getText() == ":") {
-            listSlice->addChild(getZeroLiteral());
-            if (ctx.kU_ListSliceOperatorExpression()->oC_Expression(0)) {
-                listSlice->addChild(
-                    transformExpression(*ctx.kU_ListSliceOperatorExpression()->oC_Expression(0)));
-            } else {
-                listSlice->addChild(getZeroLiteral());
-            }
-        } else {
-            if (ctx.kU_ListSliceOperatorExpression()->oC_Expression(1)) {
-                listSlice->addChild(
-                    transformExpression(*ctx.kU_ListSliceOperatorExpression()->oC_Expression(0)));
-                listSlice->addChild(
-                    transformExpression(*ctx.kU_ListSliceOperatorExpression()->oC_Expression(1)));
-            } else {
-                listSlice->addChild(
-                    transformExpression(*ctx.kU_ListSliceOperatorExpression()->oC_Expression(0)));
-                listSlice->addChild(getZeroLiteral());
-            }
-        }
-        if (ctx.oC_ListOperatorExpression()) {
-            return transformListOperatorExpression(
-                *ctx.oC_ListOperatorExpression(), move(listSlice));
+        listOperator = transformListSliceOperatorExpression(
+            *ctx.kU_ListSliceOperatorExpression(), move(propertyExpression));
+    } else {
+        listOperator = transformListExtractOperatorExpression(
+            *ctx.kU_ListExtractOperatorExpression(), move(propertyExpression));
+    }
+    if (ctx.oC_ListOperatorExpression()) {
+        return transformListOperatorExpression(
+            *ctx.oC_ListOperatorExpression(), move(listOperator));
+    } else {
+        return listOperator;
+    }
+}
+
+unique_ptr<ParsedExpression> Transformer::transformListSliceOperatorExpression(
+    CypherParser::KU_ListSliceOperatorExpressionContext& ctx,
+    unique_ptr<ParsedExpression> propertyExpression) {
+    auto rawExpression = propertyExpression->getRawName() + " " + ctx.getText();
+    auto listSlice =
+        make_unique<ParsedFunctionExpression>(LIST_SLICE_FUNC_NAME, move(rawExpression));
+    listSlice->addChild(move(propertyExpression));
+    if (ctx.children[1]->getText() == ":") {
+        listSlice->addChild(getZeroLiteral());
+        // Parsing [:right] syntax.
+        if (ctx.oC_Expression(0)) {
+            listSlice->addChild(transformExpression(*ctx.oC_Expression(0)));
+            // Parsing [:] syntax.
         } else {
-            return listSlice;
+            listSlice->addChild(getZeroLiteral());
         }
     } else {
-        auto listExtract =
-            make_unique<ParsedFunctionExpression>(LIST_EXTRACT_FUNC_NAME, move(rawExpression));
-        listExtract->addChild(move(propertyExpression));
-        listExtract->addChild(
-            transformExpression(*ctx.kU_ListExtractOperatorExpression()->oC_Expression()));
-        if (ctx.oC_ListOperatorExpression()) {
-            return transformListOperatorExpression(
-                *ctx.oC_ListOperatorExpression(), move(listExtract));
+        // Parsing [left:right] syntax.
+        if (ctx.oC_Expression(1)) {
+            listSlice->addChild(transformExpression(*ctx.oC_Expression(0)));
+            listSlice->addChild(transformExpression(*ctx.oC_Expression(1)));
+            // Parsing [left:] syntax.
         } else {
-            return listExtract;
+            listSlice->addChild(transformExpression(*ctx.oC_Expression(0)));
+            listSlice->addChild(getZeroLiteral());
         }
     }
-}
+    return listSlice;
+};
+
+unique_ptr<ParsedExpression> Transformer::transformListExtractOperatorExpression(
+    CypherParser::KU_ListExtractOperatorExpressionContext& ctx,
+    unique_ptr<ParsedExpression> propertyExpression) {
+    auto rawExpression = propertyExpression->getRawName() + " " + ctx.getText();
+    auto listExtract =
+        make_unique<ParsedFunctionExpression>(LIST_EXTRACT_FUNC_NAME, move(rawExpression));
+    listExtract->addChild(move(propertyExpression));
+    listExtract->addChild(transformExpression(*ctx.oC_Expression()));
+    return listExtract;
+};
 
 unique_ptr<ParsedExpression> Transformer::transformNullOperatorExpression(
     CypherParser::OC_NullOperatorExpressionContext& ctx,