Merge pull request #1291 from GitbookIO/summary-modifiers

Summary modifiers

1 files changed, 60 insertions, 0 deletions

diff --git a/lib/modifiers/summary/moveArticleAfter.js b/lib/modifiers/summary/moveArticleAfter.js
new file mode 100644
index 0000000..e268f73
--- /dev/null
+++ b/lib/modifiers/summary/moveArticleAfter.js
@@ -0,0 +1,60 @@
+var is = require('is');
+var removeArticle = require('./removeArticle');
+var insertArticle = require('./insertArticle');
+
+/**
+    Returns a new summary, with the an article moved after another
+    article. Unlike `moveArticle`, does not ensure that the article
+    will be found at the target's level plus one.
+
+    @param {Summary} summary
+    @param {String|SummaryArticle} origin
+    @param {String|SummaryArticle} afterTarget
+    @return {Summary}
+*/
+function moveArticleAfter(summary, origin, afterTarget) {
+    // Coerce to level
+    var originLevel = is.string(origin)? origin : origin.getLevel();
+    var afterTargetLevel = is.string(afterTarget)? afterTarget : afterTarget.getLevel();
+    var article = summary.getByLevel(originLevel);
+
+    var targetLevel = increment(afterTargetLevel);
+
+    if (targetLevel < origin) {
+        // Remove first
+        var removed = removeArticle(summary, originLevel);
+        // Insert then
+        return insertArticle(removed, article, targetLevel);
+    } else {
+        // Insert right after first
+        var inserted = insertArticle(summary, article, targetLevel);
+        // Remove old one
+        return removeArticle(inserted, originLevel);
+    }
+}
+
+/**
+    @param {String}
+    @return {Array<Number>}
+ */
+function levelToArray(l) {
+    return l.split('.').map(function (char) {
+        return parseInt(char, 10);
+    });
+}
+
+/**
+    @param {Array<Number>}
+    @return {String}
+ */
+function arrayToLevel(a) {
+    return a.join('.');
+}
+
+function increment(level) {
+    level = levelToArray(level);
+    level[level.length - 1]++;
+    return arrayToLevel(level);
+}
+
+module.exports = moveArticleAfter;