Separate source map generation into a mixin

Author: andreypopp

index.js

@@ -22,6 +22,11 @@ module.exports = function(node, options){
     ? new Compressed(options)
     : new Identity(options);
 
+  if (options.sourceMap) {
+    var addSourceMaps = require('./lib/source-map-support');
+    addSourceMaps(compiler);
+  }
+
   var code = compiler.compile(node);
   if (options.sourceMap)
     return {code: code, map: compiler.map.toJSON()}

lib/compiler.js

@@ -1,63 +1,17 @@
-var SourceMapGenerator = require('source-map').SourceMapGenerator;
 
 module.exports = Compiler;
 
 function Compiler(options) {
-  options = options || {};
-  this.map = new SourceMapGenerator({file: options.filename || 'generated.css'});
-  this.position = {line: 1, column: 1};
+  this.options = options || {};
 }
 
 /**
- * Update current position according to `str` being emitted
+ * Emit `str`
  */
-Compiler.prototype.updatePosition = function(str) {
-  var lines = str.match(/\n/g);
-  if (lines) this.position.line += lines.length;
-  var i = str.lastIndexOf('\n');
-  this.position.column = ~i ? str.length - i : this.position.column + str.length;
-}
-
-/**
- * Emit `str` and update current position, use original source `pos` to
- * construct source mapping.
- */
-
 Compiler.prototype.emit = function(str, pos, startOnly) {
-  if (pos && pos.start) {
-    this.map.addMapping({
-      generated: {
-        line: this.position.line,
-        column: Math.max(this.position.column - 1, 0)
-      },
-      source: pos.source || 'source.css',
-      original: {
-        line: pos.start.line,
-        column: pos.start.column - 1
-      }
-    });
-  }
-
-  this.updatePosition(str);
-
-  if (!startOnly && pos && pos.end) {
-    this.map.addMapping({
-      generated: {
-        line: this.position.line,
-        column: Math.max(this.position.column - 1, 0)
-      },
-      source: pos.source || 'source.css',
-      original: {
-        line: pos.end.line,
-        column: pos.end.column - 1
-      }
-    });
-  }
-
   return str;
 }
 
-
 /**
  * Visit `node`.
  */

lib/source-map-support.js

@@ -0,0 +1,61 @@
+var SourceMapGenerator = require('source-map').SourceMapGenerator;
+
+module.exports = mixin;
+
+/**
+ * Mixin source map support into the `compiler`
+ */
+function mixin(compiler) {
+  compiler.map = new SourceMapGenerator({file: compiler.options.filename || 'generated.css'});
+  compiler.position = {line: 1, column: 1};
+
+  for (var k in SourceMapSupport) {
+    compiler[k] = SourceMapSupport[k];
+  }
+}
+
+/**
+ * Compiler mixin which adds source map support
+ */
+var SourceMapSupport = {
+  updatePosition: function(str) {
+    var lines = str.match(/\n/g);
+    if (lines) this.position.line += lines.length;
+    var i = str.lastIndexOf('\n');
+    this.position.column = ~i ? str.length - i : this.position.column + str.length;
+  },
+
+  emit: function(str, pos, startOnly) {
+    if (pos && pos.start) {
+      this.map.addMapping({
+        generated: {
+          line: this.position.line,
+          column: Math.max(this.position.column - 1, 0)
+        },
+        source: pos.source || 'source.css',
+        original: {
+          line: pos.start.line,
+          column: pos.start.column - 1
+        }
+      });
+    }
+
+    this.updatePosition(str);
+
+    if (!startOnly && pos && pos.end) {
+      this.map.addMapping({
+        generated: {
+          line: this.position.line,
+          column: Math.max(this.position.column - 1, 0)
+        },
+        source: pos.source || 'source.css',
+        original: {
+          line: pos.end.line,
+          column: pos.end.column - 1
+        }
+      });
+    }
+
+    return str;
+  }
+};