Remove overall indentation

Author: ThomasWeinert

README.md

@@ -104,6 +104,29 @@ The line numbers specified in `data-sample-mark` are relative to the snippet
 itself, not to the file from which the snippet was extracted. Also, line
 ranges are supported, just like for extracting snippets from a file.
 
+### Remove indentation
+If all lines of the sample have an overall indentation you can remove it using the 
+attribute `data-sample-indent`.
+
+```html
+<pre><code data-sample='path/to/source#sample-name' data-sample-indent="remove"></code></pre>
+<pre><code data-sample='path/to/source#sample-name' data-sample-indent="keep"></code></pre>
+```
+
+You can change the default behaviour (snippets without the attribute) using
+an the option `sampler.removeIndentation`.
+
+```js
+{ 
+    sampler : {
+        removeIndentation: true
+    } 
+}
+```
+
+
+
+
 ### Example
 
 It's that simple! To get started, you can find an example of using the plugin

example/index.html

@@ -94,6 +94,11 @@ <h2>Skip some lines in the file</h2>
                     <h2>Skip some lines in the file, with line selection</h2>
                     <pre><code data-sample='skip-sample.cpp#3-9'></code></pre>
                 </section>
+
+                <section>
+                    <h2>Remove indent</h2>
+                    <pre><code data-sample='sample.c#6' data-sample-indent="remove"></code></pre>
+                </section>
             </div>
         </div>
 

sampler.js

@@ -141,6 +141,33 @@
         return function(code) { return postProcess(extractor(code)); };
     };
 
+    // To remove the indentation find the shortest leading whitespace sequence
+    // and remove it from all lines.
+    var removeIndentationFromLines = function(code) {
+        var indent, indentPattern;
+        var indentMatch = code.match(/^[ \t]+/mg);
+        if (indentMatch) {
+            indent = indentMatch.reduce(
+                function(previousValue, currentValue) {
+                    if (previousValue.length < currentValue.length) {
+                        return previousValue;
+                    }
+                    return currentValue;
+                }
+            );
+            indentPattern = new RegExp('^' + indent + '', 'mg');
+            return code.replace(indentPattern, '');
+        }
+        return code;
+    };
+
+    // Read configuration options
+    var config = Reveal.getConfig() || {};
+    config.sampler = config.sampler || {};
+    var options = {
+        removeIndentation: !!config.sampler.removeIndentation
+    };
+
     var elements = document.querySelectorAll('[data-sample]');
     elements.forEach(function(element) {
         var slug = element.getAttribute('data-sample').match(/([^#]+)(?:#(.+))?/);
@@ -155,6 +182,22 @@
                 throw "Could not find sample '" + selector + "' in file '" + file + "'.";
             }
 
+            // Read indentation behaviour defined by attribute or global option
+            var removeIndentation;
+            switch (element.getAttribute('data-sample-indent')) {
+                case 'keep' :
+                    removeIndentation = false;
+                    break;
+                case 'remove':
+                    removeIndentation = true;
+                    break;
+                default :
+                    removeIndentation = options.removeIndentation;
+            }
+            if (removeIndentation) {
+              sample = removeIndentationFromLines(sample);
+            }
+
             // Mark lines in the sample, if requested.
             var marked = expandRangesToLinesIndex(
                 parseRanges(element.getAttribute('data-sample-mark') || '')