Merge pull request #51 from Artiavis/zipper-toc
Use Zippers to Build TOC Data Structure and add unit tests Fixes cryogen-project/cryogen#62
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Carmen La
commit
6d50af6a7a
2 changed files with 174 additions and 35 deletions
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(ns cryogen-core.toc
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(:require [crouton.html :as html]
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(:require [clojure.zip :as z]
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[crouton.html :as html]
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[hiccup.core :as hiccup]))
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(def _h [:h1 :h2 :h3 :h4 :h5 :h6])
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(defn- compare_index [i1 i2] (- (.indexOf ^clojure.lang.APersistentVector _h i2) (.indexOf ^clojure.lang.APersistentVector _h i1)))
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(defn- compare-index [i1 i2] (- (.indexOf ^clojure.lang.APersistentVector _h i2) (.indexOf ^clojure.lang.APersistentVector _h i1)))
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(defn- get-headings
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"Turn a body of html content into a vector of elements whose tags are
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@ -19,33 +20,77 @@
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headings)))
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[] content))
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(defn make-links
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"Create a table of contents from the given headings. This function will look
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for either:
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(1) headings with a child anchor with a non-nil name attribute, e.g.
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<h1><a name=\"reference\">Reference Title</a></h1>
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or
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(2) headings with an id attribute, e.g. <h1 id=\"reference\">Reference Title</h1>
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In both cases above, the anchor reference becomes \"#reference\" and the
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anchor text is \"Reference Title\"."
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[headings li-tags]
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(let [[li-open li-close] li-tags]
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(loop [items headings acc nil _last nil]
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(defn- zip-toc-tree-to-insertion-point
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"Given a toc-tree zipper and a header level, navigate
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the zipper to the appropriate parent of the level for that header
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to be inserted and return the zipper."
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[toctree h-tag]
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(if-let [current-tag (-> toctree first :value :tag)]
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(let [direction (compare-index h-tag current-tag)]
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(cond (zero? direction) (z/up toctree) ; Tag belongs at current level
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(neg? direction) toctree ; Tag belongs below this level
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(pos? direction) (recur (z/up toctree) h-tag))) ; Keep looking up
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; This level is the root list, return it
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toctree))
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(defn- insert-toc-tree-entry
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"Inserts a toc-tree (zipper) entry for the given entry at the appropriate place.
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Obeys the invariant that the toc-tree (zipper) is always moved to the inserted loc."
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[tree entry]
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(let [{htag :tag} entry
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tree (zip-toc-tree-to-insertion-point tree htag)]
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(-> tree (z/append-child {:children [] :value entry}) z/down z/rightmost)))
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(defn- build-toc-tree
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"Given a sequence of header nodes, build a toc tree using zippers
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and return it."
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[headings]
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(loop [zp (z/zipper
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map?
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:children
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(fn [node children] (assoc node :children (apply vector children)))
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{:value :root :children []})
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items headings]
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(if-let [{tag :tag {id :id} :attrs [{{name :name} :attrs} title :as htext] :content} (first items)]
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(let [anchor (or id name)]
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(if (nil? anchor)
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(recur (rest items) acc nil)
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(let [entry [:li [:a {:href (str "#" anchor)} (or title (first htext))]]
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jump (compare_index _last tag)]
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(cond (> jump 0) (recur (rest items) (str acc li-open (hiccup/html entry)) tag)
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(= jump 0) (recur (rest items) (str acc (hiccup/html entry)) tag)
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(< jump 0) (recur (rest items) (str acc (apply str (repeat (* -1 jump) li-close))
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(hiccup/html entry)) tag)))))
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(str acc li-close)))))
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(recur zp (rest items))
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(recur (insert-toc-tree-entry
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zp {:tag tag :anchor anchor :text (or title (first htext))})
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(rest items))))
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(z/root zp))))
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(def _list-types {true ["<ol>" "</ol>"] :ol ["<ol>" "</ol>"] :ul ["<ul>" "</ul>"]})
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(defn generate-toc [^String html & {list-type :list-type :or {list-type true}}]
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(defn- make-toc-entry
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"Given an anchor link and some text, construct a toc entry
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consisting of link to the anchor using the given text, wrapped
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in an <li> tag."
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[anchor text]
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(when (and anchor text)
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[:li [:a {:href (str "#" anchor)} text]]))
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(defn- build-toc
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"Given the root of a toc tree and either :ol or :ul,
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generate the table of contents and return it as a hiccup tree."
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[toc-tree list-open & {:keys [outer-list?] :or {outer-list? true}}]
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(let [{:keys [children], {:keys [anchor text]} :value} toc-tree
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li (make-toc-entry anchor text)
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first-list-open (if outer-list?
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(keyword (str (name list-open) ".content"))
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list-open)]
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; Create hiccup sequence of :ol/:ul tag and sequence of :li tags
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(if (seq children)
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(let [sublist [first-list-open (map build-toc children
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(repeat list-open)
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(repeat :outer-list?)
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(repeat false))]]
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(if-let [li li] ; The root element has nothing so ignore it
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(seq [li sublist]) ; Use seq to lazily concat the li with the sublists
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sublist))
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li))) ; Or just return the naked :li tag
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(defn generate-toc
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"Reads an HTML string and parses it for headers, then returns a list of links
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to them.
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:ol and true will result in an ordered list being generated for the table of
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contents, while :ul will result in an unordered list. The default is an
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ordered list."
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(let [li-tags (_list-types list-type)
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top-tag (-> li-tags first (subs 1 3))]
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[^String html & {:keys [list-type] :or {list-type :ol}}]
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(-> html
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(.getBytes "UTF-8")
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(java.io.ByteArrayInputStream.)
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(html/parse)
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:content
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(get-headings)
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(make-links li-tags)
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(clojure.string/replace-first
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(re-pattern top-tag) (str top-tag " class=\"contents\"")))))
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(build-toc-tree)
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(build-toc list-type)
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(hiccup/html)))
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95
test/cryogen_core/toc_test.clj
Normal file
95
test/cryogen_core/toc_test.clj
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(ns cryogen-core.toc-test
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(:require [clojure.test :refer :all]
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[clojure.string :refer [join]]
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[clojure.zip :as z]
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[crouton.html :as html]
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[hiccup.core :as hiccup]
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[cryogen-core.toc :refer :all]))
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; Reimport private functions
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(def get-headings #'cryogen-core.toc/get-headings)
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(def make-toc-entry #'cryogen-core.toc/make-toc-entry)
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(def zip-toc-tree-to-insertion-point #'cryogen-core.toc/zip-toc-tree-to-insertion-point)
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(def insert-toc-tree-entry #'cryogen-core.toc/insert-toc-tree-entry)
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(def build-toc-tree #'cryogen-core.toc/build-toc-tree)
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(def build-toc #'cryogen-core.toc/build-toc)
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(defn parse-to-headings
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[hiccup-seq]
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(-> hiccup-seq hiccup/html html/parse-string :content get-headings))
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; Test that the get-headings function properly filters non-headers
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(deftest test-get-headings
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(let [noisy-headers [:div [:h1 "First H1"]
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[:p "Ignore..."]
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[:h2 "First H2"]]]
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(is (= (parse-to-headings noisy-headers)
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[{:tag :h1 :attrs nil :content ["First H1"]}
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{:tag :h2 :attrs nil :content ["First H2"]}]))))
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; Test that the make-toc-entry ignores invalid input
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(deftest test-make-toc-entry
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(is (nil?
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(make-toc-entry nil "Text")))
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(is (nil?
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(make-toc-entry "anchor" nil)))
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(is (= [:li [:a {:href "#anchor"} "Text"]]
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(make-toc-entry "anchor" "Text"))))
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; Test that the built table of contents always treats later
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; headers as being at the same level as earlier headers, even
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; if the later headers are strictly greater in value.
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; E.G.
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; * h2
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; * h3
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; * h1
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(deftest test-build-toc
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(let [simplest-header [:div [:h2 [:a {:name "test"}] "Test"]]
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no-headers [:div [:p "This is not a header"]]
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closing-header-larger-than-opening-1
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[:div [:h2 [:a {:name "starting_low"}]
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"Starting Low"]
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[:h1 [:a {:name "finishing_high"}]
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"Finishing High"]]
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closing-header-larger-than-opening-2
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[:div [:h2 [:a {:name "starting_low"}]
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"Starting Low"]
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[:h4 [:a {:name "jumping_in"}]
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"Jumping Right In"]
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[:h3 [:a {:name "pulling_back"}]
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"But then pull back"]
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[:h2 [:a {:name "to_the_top"}]
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"To the top"]]]
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(is (= [:ol.content (seq [[:li [:a {:href "#test"} "Test"]]])]
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(-> simplest-header parse-to-headings build-toc-tree
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(build-toc :ol))))
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(is (nil?
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(-> no-headers parse-to-headings build-toc-tree
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(build-toc :ol))))
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(is (= [:ol.content (seq [[:li [:a {:href "#starting_low"} "Starting Low"]]
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[:li [:a {:href "#finishing_high"} "Finishing High"]]])]
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(-> closing-header-larger-than-opening-1
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parse-to-headings
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build-toc-tree
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(build-toc :ol)))
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"No outer header should be less indented than the first header tag.")
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(is (= [:ul.content
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(seq [
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(seq [
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[:li [:a {:href "#starting_low"} "Starting Low"]]
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[:ul
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(seq [
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[:li [:a {:href "#jumping_in"} "Jumping Right In"]]
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[:li [:a {:href "#pulling_back"} "But then pull back"]]
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])
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] ])
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[:li [:a {:href "#to_the_top"} "To the top"]]
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])]
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(-> closing-header-larger-than-opening-2
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parse-to-headings
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build-toc-tree
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(build-toc :ul)))
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(join "" ["Inner headers can be more indented, "
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"but outer headers cannot be less indented "
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"than the original header."]))
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))
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