From 5979697fb5dd9b95bf834811f8b77e5ccbe33d8e Mon Sep 17 00:00:00 2001
From: "sirui.csr" <sirui.csr@alibaba-inc.com>
Date: Fri, 7 Aug 2020 20:56:37 +0800
Subject: [PATCH 1/2] fix: substracted css-variable from zero

---
 src/__tests__/index.js |  7 +++++++
 src/lib/reducer.js     | 13 ++++++++++++-
 src/lib/transform.js   |  2 +-
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/__tests__/index.js b/src/__tests__/index.js
index b656c61..d40e636 100644
--- a/src/__tests__/index.js
+++ b/src/__tests__/index.js
@@ -396,6 +396,13 @@ test(
   'calc(-100vw + -10px)',
 );
 
+test(
+  'should reduce substracted expression from zero (css-variable)',
+  testValue,
+  'calc( 0px - (var(--foo, 4px) / 2))',
+  'calc(0px - var(--foo, 4px)/2)',
+);
+
 test(
   'should reduce nested expression',
   testValue,
diff --git a/src/lib/reducer.js b/src/lib/reducer.js
index dc50560..a2ae69d 100644
--- a/src/lib/reducer.js
+++ b/src/lib/reducer.js
@@ -62,7 +62,7 @@ function reduceAddSubExpression(node, precision) {
     isValueType(node.left.type) &&
     node.left.value === 0 &&
     node.operator === "-" &&
-    node.right.type !== "Function"
+    !containCSSFunction(node.right)
   ) {
     return flipValue(node.right);
   }
@@ -330,3 +330,14 @@ function reduce(node, precision) {
 }
 
 export default reduce;
+
+
+function containCSSFunction(node) {
+  if (node.type === "Function") {
+    return true;
+  }
+  if (node.type === "MathExpression") {
+    return containCSSFunction(node.left) || containCSSFunction(node.right);
+  }
+  return false;
+}
diff --git a/src/lib/transform.js b/src/lib/transform.js
index 73fc545..2436ed4 100644
--- a/src/lib/transform.js
+++ b/src/lib/transform.js
@@ -1,5 +1,5 @@
 import selectorParser from 'postcss-selector-parser';
-import valueParser from 'postcss-value-parser'; 
+import valueParser from 'postcss-value-parser';
 
 // eslint-disable-next-line import/no-unresolved
 import { parser } from '../parser';

From f91f34d91974f001e9d9c09c663722b5bc746d0a Mon Sep 17 00:00:00 2001
From: "sirui.csr" <sirui.csr@alibaba-inc.com>
Date: Fri, 7 Aug 2020 21:13:20 +0800
Subject: [PATCH 2/2] rename containCSSFunction to isCSSFunction

---
 src/lib/reducer.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/lib/reducer.js b/src/lib/reducer.js
index a2ae69d..277a394 100644
--- a/src/lib/reducer.js
+++ b/src/lib/reducer.js
@@ -62,7 +62,7 @@ function reduceAddSubExpression(node, precision) {
     isValueType(node.left.type) &&
     node.left.value === 0 &&
     node.operator === "-" &&
-    !containCSSFunction(node.right)
+    !isCSSFunction(node.right)
   ) {
     return flipValue(node.right);
   }
@@ -332,12 +332,12 @@ function reduce(node, precision) {
 export default reduce;
 
 
-function containCSSFunction(node) {
+function isCSSFunction(node) {
   if (node.type === "Function") {
     return true;
   }
   if (node.type === "MathExpression") {
-    return containCSSFunction(node.left) || containCSSFunction(node.right);
+    return isCSSFunction(node.left) || isCSSFunction(node.right);
   }
   return false;
 }