Expectation refactoring 5/7: Refactor "buildMesage"

Mostly just extract few functions, increasing readability.

lib/compiler/passes/generate-js.js

@@ -1111,34 +1111,38 @@ function generateJS(ast, options) {
       '        return DESCRIBE_EXPECTATION_FNS[expectation.type](expectation);',
       '      }',
       '',
-      '      var expectedDescs = new Array(expected.length),',
-      '          expectedDesc, foundDesc, i, j;',
+      '      function describeExpected(expected) {',
+      '        var descriptions = new Array(expected.length),',
+      '            i, j;',
       '',
-      '      for (i = 0; i < expected.length; i++) {',
-      '        expectedDescs[i] = describeExpectation(expected[i]);',
-      '      }',
+      '        for (i = 0; i < expected.length; i++) {',
+      '          descriptions[i] = describeExpectation(expected[i]);',
+      '        }',
       '',
-      '      expectedDescs.sort();',
+      '        descriptions.sort();',
       '',
-      '      if (expectedDescs.length > 0) {',
-      '        for (i = 1, j = 1; i < expectedDescs.length; i++) {',
-      '          if (expectedDescs[i - 1] !== expectedDescs[i]) {',
-      '            expectedDescs[j] = expectedDescs[i];',
-      '            j++;',
+      '        if (descriptions.length > 0) {',
+      '          for (i = 1, j = 1; i < descriptions.length; i++) {',
+      '            if (descriptions[i - 1] !== descriptions[i]) {',
+      '              descriptions[j] = descriptions[i];',
+      '              j++;',
+      '            }',
       '          }',
+      '          descriptions.length = j;',
       '        }',
-      '        expectedDescs.length = j;',
-      '      }',
       '',
-      '      expectedDesc = expectedDescs.length > 1',
-      '        ? expectedDescs.slice(0, -1).join(", ")',
-      '            + " or "',
-      '            + expectedDescs[expectedDescs.length - 1]',
-      '        : expectedDescs[0];',
+      '        return descriptions.length > 1',
+      '          ? descriptions.slice(0, -1).join(", ")',
+      '              + " or "',
+      '              + descriptions[descriptions.length - 1]',
+      '          : descriptions[0];',
+      '      }',
       '',
-      '      foundDesc = found ? "\\"" + literalEscape(found) + "\\"" : "end of input";',
+      '      function describeFound(found) {',
+      '        return found ? "\\"" + literalEscape(found) + "\\"" : "end of input";',
+      '      }',
       '',
-      '      return "Expected " + expectedDesc + " but " + foundDesc + " found.";',
+      '      return "Expected " + describeExpected(expected) + " but " + describeFound(found) + " found.";',
       '    }',
       '',
       '    return new peg$SyntaxError(',