Add parse.navigation module

With tests

3 files changed, 115 insertions, 0 deletions

diff --git a/lib/parse/index.js b/lib/parse/index.js
index 2caf6a4..f6593ef 100644
--- a/lib/parse/index.js
+++ b/lib/parse/index.js
@@ -1,4 +1,6 @@
 module.exports = {
     summary: require('./summary'),
     page: require('./page'),
+
+    navigation: require('./navigation'),
 };
diff --git a/lib/parse/navigation.js b/lib/parse/navigation.js
new file mode 100644
index 0000000..8d39a4e
--- /dev/null
+++ b/lib/parse/navigation.js
@@ -0,0 +1,67 @@
+var _ = require('lodash');
+
+// Cleans up an article/chapter object
+// remove 'articles' and '_path' attributes
+function clean(obj) {
+    return _.omit(obj, ['articles', '_path']);
+}
+
+// Returns a map of
+/*
+    {
+        "file/path.html": {
+            prev: ...,
+            next: ...,
+        },
+        ...
+    }
+*/
+function navigation(summary, files) {
+    // Support single files as well as list
+    files = _.isArray(files) ? files : (_.isString(files) ? [files] : null);
+
+    // Mapping of prev/next for a give path
+    var mapping = {};
+
+    // Walk the chapter/article tree and create navigation entires
+    _.each(summary.chapters, function(chapter, idx, chapters) {
+        var currentChapter = clean(chapter);
+        var prevChapter = (idx-1 < 0) ? null : clean(chapters[idx-1]);
+        var nextChapter = (idx+1 >= chapters.length) ? null : clean(chapters[idx+1]);
+
+        // Add chapter mapping
+        mapping[chapter.path] = {
+            prev: prevChapter,
+            next: nextChapter,
+        };
+
+        // Check a chapter's articles
+        _.each(chapter.articles, function(article, _idx, articles) {
+
+            var prev = (_idx-1 < 0) ? currentChapter : clean(articles[_idx-1]);
+            var next = (_idx+1 >= articles.length) ? nextChapter : clean(articles[_idx+1]);
+
+            mapping[article.path] = {
+                prev: prev,
+                next: next,
+            };
+        });
+    });
+
+    // Hack for README.html
+    mapping['README.html'] = {
+        prev: null,
+        next: clean(summary.chapters[0]),
+    };
+
+    // Filter for only files we want
+    if(files) {
+        return _.pick(mapping, files);
+    }
+
+    return mapping;
+}
+
+
+// Exports
+module.exports = navigation;
diff --git a/test/navigation.js b/test/navigation.js
new file mode 100644
index 0000000..d34c12a
--- /dev/null
+++ b/test/navigation.js
@@ -0,0 +1,46 @@
+var fs = require('fs');
+var path = require('path');
+var assert = require('assert');
+
+var summary = require('../').parse.summary;
+var navigation = require('../').parse.navigation;
+
+
+var CONTENT = fs.readFileSync(path.join(__dirname, './fixtures/SUMMARY.md'), 'utf8');
+var LEXED = summary(CONTENT);
+
+
+describe('Summary navigation', function() {
+    it('should provide next & prev entries for a file', function() {
+        var nav = navigation(LEXED, [
+            'README.html',
+            'chapter-1/ARTICLE1.html',
+            'chapter-1/ARTICLE2.html'
+        ]);
+
+        // Make sure it found the files we gave it
+        assert(nav['README.html']);
+        assert(nav['chapter-1/ARTICLE1.html']);
+        assert(nav['chapter-1/ARTICLE2.html']);
+
+        assert.equal(nav['README.html'].prev, null);
+        assert.equal(nav['README.html'].next.path, 'chapter-1/README.html');
+
+        assert.equal(nav['chapter-1/ARTICLE1.html'].prev.path, 'chapter-1/README.html');
+        assert.equal(nav['chapter-1/ARTICLE1.html'].next.path, 'chapter-1/ARTICLE2.html');
+
+        assert.equal(nav['chapter-1/ARTICLE2.html'].prev.path, 'chapter-1/ARTICLE1.html');
+        assert.equal(nav['chapter-1/ARTICLE2.html'].next.path, 'chapter-2/README.html');
+    });
+
+    it('should give full tree, when not limited', function() {
+        var nav = navigation(LEXED);
+
+        assert(nav['README.html']);
+        assert(nav['chapter-1/README.html']);
+        assert(nav['chapter-1/ARTICLE1.html']);
+        assert(nav['chapter-1/ARTICLE2.html']);
+        assert(nav['chapter-2/README.html']);
+        assert(nav['chapter-3/README.html']);
+    });
+});