Merge pull request #52 from UmamiAppearance/v0.5.0

V0.5.0

Author: UmamiAppearance

README.md

@@ -2,15 +2,15 @@
 [![License](https://img.shields.io/github/license/UmamiAppearance/rollup-plugin-your-function?color=009911&style=for-the-badge)](./LICENSE)
 [![npm](https://img.shields.io/npm/v/rollup-plugin-your-function?color=009911&style=for-the-badge)](https://www.npmjs.com/package/rollup-plugin-your-function)
 
-A very simple rollup-plugin, which gives you the opportunity to manipulate your build files as you like. Dead simple. The last plugin you need (for simple tasks).
+A very simple rollup-plugin, which gives you the opportunity to manipulate your build files as you like. Dead simple. The last plugin you need (for small tasks).
 
 
 ## Idea
-There are many plugins for rollup available. And many times the only thing you would like to perform is a little change. Now the big research begins: _which plugin fits the best?_  
+There are many plugins for rollup available. And many times the only thing you would like to perform is a little change, just some regex magic, only a small string replacement, etc. Now the big research begins: _which plugin fits the best?_  
 
 Eventually you will find what you need, but now you'll have to figure out the particularities of the plugin. And you find yourself thinking: _"Why was that so complicated? I could have done this to a regular file in seconds!"_.  
 
-This is where **rollup-plugin-your-function** comes into play. The _only!_ thing it does, is to take a function, that you create by yourself. Your function needs to take one argument, that is the source file, it must return the output code as the first parameter, optionally a sourcemap as a second. And that's it.
+This is where **rollup-plugin-your-function** comes into play. The _only!_ thing it does, is to take a function, that you create by yourself. Your function needs to take one argument, that is the source file, it must return the output code as the first parameter, optionally a sourcemap as a second (otherwise it gets generated automatically and includes the performed changes). And that's it.  
 
 
 ## Install

cjs/your-function.cjs

@@ -1,8 +1,8 @@
 'use strict';
 
 var pluginutils = require('@rollup/pluginutils');
-var MagicString = require('magic-string');
 var diff = require('diff');
+var MagicString = require('magic-string');
 var colorette = require('colorette');
 
 /**
@@ -129,7 +129,7 @@ const showDiff = (filename, source, code, diffOption, pluginName) => {
 /**
  * [rollup-plugin-your-function]{@link https://github.com/UmamiAppearance/rollup-plugin-your-function}
  *
- * @version 0.4.12
+ * @version 0.5.0
  * @author UmamiAppearance [[email protected]]
  * @license MIT
  */
@@ -166,7 +166,26 @@ const yourFunction = (settings={}) => {
 
         if (settings.sourceMap !== false && settings.sourcemap !== false) {
             if (!map) {
-                const ms = new MagicString(code);
+
+                // If no Source Map was provided generate one, by
+                // comparing character by character with the help
+                // of diff and using the output to apply the changes
+                // to the source with the help of magic string. 
+
+                const ms = new MagicString(source);
+                let i = 0;
+                
+                for (const diff$1 of diff.diffChars(source, code)) {
+
+                    if (diff$1.added) {
+                        ms.appendRight(i, diff$1.value);
+                    } else if (diff$1.removed) {
+                        ms.remove(i, i+=diff$1.count);
+                    } else {
+                        i += diff$1.count;
+                    }
+                }
+
                 map = ms.generateMap({ hires: true });
             }
         } else {

cjs/your-function.cjs.map

@@ -1,6 +1,6 @@
 {
   "name": "rollup-plugin-your-function",
-  "version": "0.4.12",
+  "version": "0.5.0",
   "description": "Provide a custom function as a rollup plugin.",
   "main": "./cjs/your-function.cjs",
   "module": "./src/your-function.js",

package-lock.json

@@ -1,16 +1,16 @@
 /**
  * [rollup-plugin-your-function]{@link https://github.com/UmamiAppearance/rollup-plugin-your-function}
  *
- * @version 0.4.12
+ * @version 0.5.0
  * @author UmamiAppearance [[email protected]]
  * @license MIT
  */
 
 import { createFilter } from "@rollup/pluginutils";
+import { diffChars } from "diff";
 import MagicString from "magic-string";
 import showDiff from "./diff.js";
 
-
 const yourFunction = (settings={}) => {
 
     if (!settings.fn) {
@@ -25,7 +25,7 @@ const yourFunction = (settings={}) => {
             : "your-function"
     };
 
-    const fnWrap = async (source, options) => {
+    const fnWrap = async (source, options, context) => {
 
         if (!filter(options.id)) return null;
 
@@ -42,7 +42,56 @@ const yourFunction = (settings={}) => {
 
         if (settings.sourceMap !== false && settings.sourcemap !== false) {
             if (!map) {
-                const ms = new MagicString(code);
+
+                // If no Source Map was provided generate one, by
+                // comparing character by character with the help
+                // of diff and using the output to apply the changes
+                // to the source with the help of magic string. 
+
+                let error = false;
+                const errorCase = (e) => {
+                    error = true;
+                    let msg = "Automatic source map generation failed, or produced an inaccurate result. If you need a proper source map, you should provide it manually, otherwise you can ignore this message.";
+                    if (e) {
+                        msg = `${msg}\n___\n${e}`;
+                    }
+                    context.warn(msg);
+                };
+
+                const ms = new MagicString(source);
+                let i = 0;
+                
+                for (const diff of diffChars(source, code)) {
+
+                    if (diff.added) {
+                        try {
+                            ms.appendRight(i, diff.value);
+                        } catch(e) {
+                            errorCase(e);
+                            break;
+                        }
+                    }
+                    
+                    else if (diff.removed) {
+                        try {
+                            ms.remove(i, i+=diff.count);
+                        } catch(e) {
+                            errorCase(e);
+                            break;
+                        }
+                    }
+                    
+                    else {
+                        i += diff.count;
+                    }
+                }
+
+                // Test if the code output of the magic string instance
+                // matches the output provided by the user 
+                if (!error && ms.toString() !== code) {
+                    errorCase();
+                }
+
                 map = ms.generateMap({ hires: true });
             }
         } else {
@@ -54,29 +103,32 @@ const yourFunction = (settings={}) => {
 
 
     if (settings.output) { 
-        plugin.renderChunk = async (source, chunk, outputOptions, meta) => {
+        plugin.renderChunk = async function(source, chunk, outputOptions, meta) {
             return await fnWrap(
                 source,
                 {
                     id: chunk.fileName,
                     chunk,
                     outputOptions,
                     meta
-                }
+                },
+                this
             );
         };
     }
 
     else {
-        plugin.transform = async (source, id) => {
+        plugin.transform = async function(source, id) {
             return await fnWrap(
                 source,
-                { id }
+                { id },
+                this
             );
         };
     }
 
     return plugin;    
 };
 
+
 export { yourFunction };