From 8492df556cbba0c1110fb21ba89aa04b808b7281 Mon Sep 17 00:00:00 2001
From: nilianzhu <nilianzhu@bytedance.com>
Date: Thu, 30 Jan 2020 14:04:08 +0800
Subject: [PATCH] feat: change rootValue to support both number and function

---
 README.md            |  4 ++--
 index.js             |  4 +++-
 package.json         |  2 +-
 spec/pxtorem-spec.js | 18 ++++++++++++++++++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 9ce3feb..b2f4b03 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,7 @@ Default:
 }
 ```
 
-- `rootValue` (Number) The root element font size.
+- `rootValue` (Number | Function) Represents the root element font size or returns the root element font size based on the [`input`](https://api.postcss.org/Input.html) parameter
 - `unitPrecision` (Number) The decimal numbers to allow the REM units to grow to.
 - `propList` (Array) The properties that can change from px to rem.
     - Values need to be exact matches.
@@ -84,7 +84,7 @@ Default:
         - `['body']` will match `.body-class`
     - If value is regexp, it checks to see if the selector matches the regexp.
         - `[/^body$/]` will match `body` but not `.body`
-- `replace` (Boolean) replaces rules containing rems instead of adding fallbacks.
+- `replace` (Boolean) Replaces rules containing rems instead of adding fallbacks.
 - `mediaQuery` (Boolean) Allow px to be converted in media queries.
 - `minPixelValue` (Number) Set the minimum pixel value to replace.
 
diff --git a/index.js b/index.js
index fbc1919..fccb557 100644
--- a/index.js
+++ b/index.js
@@ -29,12 +29,14 @@ module.exports = postcss.plugin('postcss-pxtorem', function (options) {
     convertLegacyOptions(options);
 
     var opts = objectAssign({}, defaults, options);
-    var pxReplace = createPxReplace(opts.rootValue, opts.unitPrecision, opts.minPixelValue);
 
     var satisfyPropList = createPropListMatcher(opts.propList);
 
     return function (css) {
 
+        var rootValue = typeof opts.rootValue === 'function' ? opts.rootValue(css.source.input) : opts.rootValue;
+        var pxReplace = createPxReplace(rootValue, opts.unitPrecision, opts.minPixelValue);
+
         css.walkDecls(function (decl, i) {
             // This should be the fastest test and will remove most declarations
             if (decl.value.indexOf('px') === -1) return;
diff --git a/package.json b/package.json
index cf31e7d..c6279da 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "postcss-pxtorem",
   "description": "A CSS post-processor that converts px to rem.",
-  "version": "4.0.1",
+  "version": "4.1.0",
   "author": "cuth",
   "license": "MIT",
   "repository": {
diff --git a/spec/pxtorem-spec.js b/spec/pxtorem-spec.js
index d3563cb..1f0ce34 100644
--- a/spec/pxtorem-spec.js
+++ b/spec/pxtorem-spec.js
@@ -149,6 +149,24 @@ describe('rootValue', function () {
 
         expect(processed).toBe(expected);
     });
+
+    it('should replace using different root values with different files', function () {
+        var css2 = '.rule { font-size: 20px }';
+        var expected = '.rule { font-size: 1rem }';
+        var options = {
+            rootValue: function (input) {
+                if (input.from.indexOf('basic.css') !== -1) {
+                    return 15;
+                }
+                return 20;
+            }
+        };
+        var processed1 = postcss(pxtorem(options)).process(basicCSS, { from: '/tmp/basic.css' }).css;
+        var processed2 = postcss(pxtorem(options)).process(css2, { from: '/tmp/whatever.css' }).css;
+
+        expect(processed1).toBe(expected);
+        expect(processed2).toBe(expected);
+    });
 });
 
 describe('unitPrecision', function () {