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transformers.cljc
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transformers.cljc
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(ns markdown.transformers
(:require [clojure.string :as string]
[clojure.edn :as edn]
[markdown.links
:refer [link
image
reference-link
image-reference-link
implicit-reference-link
footnote-link]]
[markdown.lists :refer [li]]
[markdown.tables :refer [table]]
[markdown.common
:refer
[escape-code
escaped-chars
freeze-string
thaw-strings
strong
bold
bold-italic
em
italics
strikethrough
inline-code
escape-inhibit-separator
inhibit
make-heading
dashes]]
#?(:clj [clj-yaml.core :as yaml])))
(def ^:dynamic *formatter*)
(defn heading? [text type]
(when-not (every? #{\space} (take 4 text))
(let [trimmed (some-> text string/trim)]
(and (not-empty trimmed) (every? #{type} trimmed)))))
(defn h1? [text]
(heading? text \=))
(defn h2? [text]
(heading? text \-))
(defn empty-line [text {:keys [code codeblock] :as state}]
(if (or code codeblock)
[text state]
[(if (or (h1? text) (h2? text)) "" text)
(if (string/blank? text) (dissoc state :hr :heading) state)]))
(defn superscript [text state]
(if (:code state)
[text state]
(let [tokens (partition-by (partial contains? #{\^ \space}) text)]
(loop [buf []
remaining tokens]
(cond
(empty? remaining)
[(string/join buf) state]
(= (first remaining) [\^])
(recur (into buf (concat (seq "<sup>") (second remaining) (seq "</sup>")))
(drop 2 remaining))
:default
(recur (into buf (first remaining)) (rest remaining)))))))
(defn heading [text {:keys [buf next-line code codeblock heading-anchors] :as state}]
(cond
(or codeblock code)
[text state]
(h1? (or buf next-line))
[(str "<h1>" text "</h1>") (assoc state :heading true)]
(h2? (or buf next-line))
[(str "<h2>" text "</h2>") (assoc state :heading true)]
:else
(if-let [heading (make-heading text heading-anchors)]
[heading (assoc state :inline-heading true)]
[text state])))
(defn br [text {:keys [code lists] :as state}]
[(if (and (= [\space \space] (take-last 2 text))
(not (or code lists)))
(str (apply str (drop-last 2 text)) "<br />")
text)
state])
(defn autourl-transformer [text {:keys [code frozen-strings] :as state}]
(if code
[text state]
(let [currently-frozen (volatile! {:frozen-strings frozen-strings})]
[(string/replace
text
#"<https?://[-A-Za-z0-9+&@#/%?=~_()|!:,.;]*[-A-Za-z0-9+&@#/%=~_()|]>"
#(let [[url frozen-strings] (freeze-string (subs % 1 (dec (count %))) @currently-frozen)]
(vreset! currently-frozen frozen-strings)
(str "<a href=\"" url "\">" url "</a>")))
(merge state @currently-frozen)])))
(defn autoemail-transformer [text state]
(let [left-pad (fn [s]
(cond->> s
(= 1 (count s)) (str "0")))
encoder (if (:clojurescript state)
(fn [c] (str "&#x" (-> c (.charCodeAt 0) (.toString 16) left-pad) ";"))
(fn [c] (*formatter* "&#x%02x;" (int c))))]
[(if (or (:code state) (:codeblock state))
text
(string/replace
text
#"<[\w._%+-]+@[\w.-]+\.[\w]{2,4}>"
#(let [encoded (->> (subs % 1 (dec (count %)))
(map encoder)
(apply str))]
(str "<a href=\"mailto:" encoded "\">" encoded "</a>"))))
state]))
(defn set-line-state [text {:keys [inline-heading] :as state}]
[text
(-> state
(dissoc :inline-heading)
(assoc-in [:temp :inline-heading] inline-heading))])
(defn clear-line-state [text state]
[text (dissoc state :temp)])
(defn paragraph-text [last-line-empty? text]
(if (and (not last-line-empty?) (not-empty text))
(str " " text)
text))
(defn open-paragraph
[text {:keys [eof heading inline-heading temp hr code lists blockquote paragraph last-line-empty?] :as state}]
(cond
(and paragraph lists)
[(str "</p>" text) (dissoc state :paragraph)]
(or heading inline-heading hr code lists blockquote)
[text state]
paragraph
(if (or eof (empty? (string/trim text)))
[(str (paragraph-text last-line-empty? text) "</p>") (dissoc state :paragraph)]
[(paragraph-text last-line-empty? text) state])
(and (not eof) (not (string/blank? text)) (or (:inline-heading temp) last-line-empty?))
[(str "<p>" text) (assoc state :paragraph true :last-line-empty? false)]
:default
[text state]))
(defn close-paragraph [text {:keys [next-line paragraph] :as state}]
(if (and paragraph (some-> next-line string/trim (string/ends-with? "```")))
[(str text "</p>") (dissoc state :paragraph)]
[text state]))
(defn paragraph [text state]
(apply close-paragraph (open-paragraph text state)))
(defn code [text {:keys [eof indent-code-end next-line lists code codeblock paragraph] :as state}]
(let [should-close? (or eof
(not (or (string/blank? next-line)
(string/starts-with? next-line " "))))]
(cond
(or lists codeblock)
[text state]
indent-code-end
[text (-> state
(dissoc :code :indent-code-end :indented-code)
(assoc :last-line-empty? true))]
code
[(str (escape-code (string/replace-first text #" " "\n"))
(when should-close? "</code></pre>"))
(cond-> state
should-close? (assoc :indent-code-end true))]
paragraph
[text state]
(empty? (string/trim text))
[text state]
:default
(let [num-spaces (count (take-while (partial = \space) text))]
(if (>= num-spaces 4)
[(str "<pre><code>"
(escape-code (string/replace-first text #" " ""))
(when should-close? "</code></pre>"))
(cond-> (assoc state :code true :indented-code true)
should-close? (assoc :indent-code-end true))]
[text state])))))
(defn codeblock [text {:keys [codeblock-no-escape? codeblock-buf codeblock-lang codeblock-callback codeblock codeblock-end indented-code next-line lists] :as state}]
(let [trimmed (string/trim text)
next-line-closes? (some-> next-line string/trim (string/ends-with? "```"))]
(cond
(and lists codeblock-end)
["" (dissoc state :code :codeblock :codeblock-end :codeblock-lang :codeblock-buf)]
codeblock-end
[text (-> state
(assoc :last-line-empty? true)
(dissoc :code :codeblock :codeblock-end :codeblock-lang :codeblock-buf))]
(and next-line-closes? codeblock)
(let [buffered-code (str codeblock-buf text \newline (apply str (first (string/split next-line #"```"))))
code (if codeblock-callback (codeblock-callback buffered-code codeblock-lang) buffered-code)]
[(str
(if codeblock-no-escape?
code
(escape-code code))
"</code></pre>")
(assoc state :skip-next-line? (not lists)
:codeblock-end true
:last-line-empty? (not lists))])
(and
(not indented-code)
(string/starts-with? trimmed "```"))
(let [[lang code] (split-with (partial not= \newline) (drop 3 trimmed))
lang (string/trim (string/join lang))
s (apply str (rest code))
code-formatter (:code-style state)
pre-formatter (:pre-style state)]
[(str "<pre"
(when (seq lang)
(if pre-formatter
(str " " (pre-formatter lang))
""))
"><code"
(when (seq lang)
(str " "
(if code-formatter
(code-formatter lang)
(str "class=\"" (string/join lang) "\"")))) ">"
(escape-code (if (empty? s) s (str s "\n")))
(when next-line-closes? "</code></pre>"))
(if next-line-closes?
(assoc state :codeblock-end true :skip-next-line? true)
(assoc state :code true
:codeblock true
:codeblock-lang lang
:codeblock-buf ""))])
codeblock
["" (assoc state :codeblock-buf (str codeblock-buf text \newline))]
:default
[text state])))
(defn hr [text state]
(if (:code state)
[text state]
(if (and
(or (empty? (drop-while #{\* \space} text))
(empty? (drop-while #{\- \space} text))
(empty? (drop-while #{\_ \space} text)))
(> (count (remove #{\space} text)) 2))
[(str "<hr/>") (assoc state :hr true)]
[text state])))
(defn blockquote-1
"Check for blockquotes and signal to blockquote-2 function with
states blockquote-start and blockquote-end so that tags can be added.
This approach enables lists to be included in blockquotes."
[text {:keys [eof code codeblock] :as state}]
(let [trimmed (string/trim text)]
(cond
(or code codeblock)
[text state]
(:blockquote state)
(cond (or eof (empty? trimmed))
[text (assoc state :blockquote-end true :blockquote false)]
(= ">" trimmed)
[(str (when (:blockquote-paragraph state) "</p>") "<p>") (assoc state :blockquote-paragraph true)]
(and (>= (count trimmed) 2) (= ">-" (subs trimmed 0 2)))
[(str (when (:blockquote-paragraph state) "</p>") "<footer>" (subs text 2) "</footer>") (assoc state :blockquote-paragraph false)]
(= ">" (subs trimmed 0 1))
[(str (when-not (:blockquote-paragraph state) "<p>") (subs text 1) " ") (assoc state :blockquote-paragraph true)]
:default
[(str (when-not (:blockquote-paragraph state) "<p>") text " ") (assoc state :blockquote-paragraph true)])
:default
(if (= \> (first text))
[(str (string/join (rest text)) " ")
(assoc state :blockquote-start true :blockquote true :blockquote-paragraph true)]
[text state]))))
(defn blockquote-2
"Check for change in blockquote states and add start or end tags.
Closing a blockquote with a list in it is a bit more complex,
as the list is not closed until the following blank line."
[text {:keys [blockquote-start blockquote-end blockquote-paragraph lists] :as state}]
(let [not-in-list (or (not lists) (empty? lists))]
(cond blockquote-start
[(str "<blockquote><p>" text)
(dissoc state :blockquote-start)]
(and blockquote-end not-in-list)
[(str text (when blockquote-paragraph "</p>") "</blockquote>")
(dissoc state :blockquote :blockquote-paragraph :blockquote-end)]
:default
[text state])))
(defn footer [footnotes]
(if (empty? (:processed footnotes))
""
(->> (:processed footnotes)
(into (sorted-map))
(reduce
(fn [footnotes [id label]]
(str footnotes
"<li id='fn-" id "'>"
(apply str (interpose " " label))
"<a href='#fnref" id "'>↩</a></li>"))
"")
(#(str "<ol class='footnotes'>" % "</ol>")))))
(defn parse-metadata-line
"Given a line of metadata header text return either a list containing a parsed
and normalizd key and the original text of the value, or if no header is found
(this is a continuation or new value from a pervious header key) simply
return the text. If a blank or invalid line is found return nil."
[line]
(when line
(let [[_ key val] (re-matches #"^([0-9A-Za-z_-]*):(.*)$" line)
[_ next-val] (re-matches #"^ (.*)$" line)]
(when (not= (string/trim line) "")
(cond
key [(keyword (string/lower-case key)) val]
next-val line)))))
(defn flatten-metadata
"Given a list of maps which contain a single key/value, flatten them all into
a single map with all the leading spaces removed. If an empty list is provided
then return nil."
[metadata]
(when (pos? (count metadata))
(loop [acc {}
remain metadata
prev-key nil]
(if (seq remain)
(let [data (first remain)
[key val] (if (sequential? data) data [prev-key data])
prev-val (get acc key [])
postfix (if (= [\space \space] (take-last 2 val)) "\n" "")
norm-val (str (string/trim val) postfix)
new-val (if-not (empty? norm-val)
(conj prev-val norm-val)
prev-val)]
(recur (merge acc {key new-val}) (rest remain) key))
acc))))
(defn parse-wiki-metadata-headers
[lines-seq]
(reduce
(fn [acc line]
(if-let [parsed (parse-metadata-line line)]
(conj acc parsed)
(reduced [(flatten-metadata acc) (count acc)])))
[] lines-seq))
(defn parse-yaml-metadata-headers
[lines-seq]
#?(:clj
(let [yaml-lines (->> lines-seq
;; leave off opening ---
(drop 1)
;; take lines until we see the closing ---
(take-while (comp not (partial re-matches #"---\s*"))))]
[(->> yaml-lines
;; join together and parse
(string/join "\n")
yaml/parse-string)
;; number of lines consumed must consider opening and closing ---
(+ (count yaml-lines) 2)])
:cljs
(throw (js/Error. "YAML is unsupported in ClojureScript mode"))))
(defn parse-edn-metadata-headers
[lines-seq]
;; take sequences until you hit an empty line
(let [meta-lines (take-while (comp not (partial re-matches #"\s*"))
lines-seq)]
[(->> meta-lines
;; join together and parse
(string/join "\n")
edn/read-string)
;; count the trailing empty line
(inc (count meta-lines))]))
(defn parse-metadata-headers
"Given a sequence of lines from a markdown document, attempt to parse a
metadata header if it exists. Accepts wiki, yaml, and edn formats.
Returns the parsed headers number of lines the metadata spans"
[lines-seq]
{:pre [(sequential? lines-seq)
(every? string? lines-seq)]}
(cond
;; Treat as yaml
(re-matches #"---\s*" (first lines-seq))
(parse-yaml-metadata-headers lines-seq)
;; Treat as wiki
(re-matches #"\w+: .*" (first lines-seq))
(parse-wiki-metadata-headers lines-seq)
;; Treat as edn
(re-matches #"\{.*" (first lines-seq))
(parse-edn-metadata-headers lines-seq)))
(def transformer-vector
[set-line-state
empty-line
inhibit
escape-inhibit-separator
code
codeblock
escaped-chars
inline-code
autoemail-transformer
autourl-transformer
image
image-reference-link
link
implicit-reference-link
reference-link
footnote-link
hr
blockquote-1
li
heading
blockquote-2
italics
bold-italic
em
strong
bold
strikethrough
superscript
table
paragraph
br
thaw-strings
dashes
clear-line-state])