gnab#105: Trim equal amount of leading whitespace from all lines to a…

…llow for indenting entire presentation.

src/remark/parser.js

@@ -32,7 +32,7 @@ function Parser () { }
  */
 Parser.prototype.parse = function (src) {
   var lexer = new Lexer(),
-      tokens = lexer.lex(src),
+      tokens = lexer.lex(cleanInput(src)),
       slides = [],
 
       // The last item on the stack contains the current slide or
@@ -142,3 +142,17 @@ function extractProperties (source, properties) {
 
   return source;
 }
+
+function cleanInput(source) {
+  // If all lines are indented, we should trim them all to the same point so that code doesn't
+  // need to start at column 0 in the source (see GitHub Issue #105)
+
+  // Calculate the minimum leading whitespace
+  var leadingWhitespacePattern = /^(\s*)/gm;
+  var whitespace = source.match(leadingWhitespacePattern).map(function (s) { return s.length; });
+  var minWhitespace = Math.min.apply(Math, whitespace);
+
+  // Trim off the exact amount of whitespace
+  var trimWhitespacePattern = new RegExp('^\\s{' + minWhitespace + '}', 'gm');
+  return source.replace(trimWhitespacePattern, '');
+}

test/remark/parser_test.js

@@ -173,14 +173,14 @@ describe('Parser', function () {
       var slides = parser.parse('      1\n      ---\n          2\n      ---\n      3');
 
       slides[0].content.should.eql(['1']);
-      slides[1].content.should.eql(['    2']);
+      slides[1].content.should.eql(['    2\n']); // Note: lexer includes trailing newines in code blocks
       slides[2].content.should.eql(['3']);
     });
 
     it('should preserve leading whitespace that goes beyond the minimum whitespace on the first line', function () {
       var slides = parser.parse('          1\n      ---\n      2\n      ---\n      3');
 
-      slides[0].content.should.eql(['    1']);
+      slides[0].content.should.eql(['    1\n']); // Note: lexer includes trailing newines in code blocks
       slides[1].content.should.eql(['2']);
       slides[2].content.should.eql(['3']);
     });