Add literals source (with true, false, and nil)

Fixes #34.

project.clj

@@ -1,4 +1,4 @@
-(defproject compliment "0.2.5"
+(defproject compliment "0.2.6-SNAPSHOT"
   :description "The Clojure completion library you deserve"
   :url "https://github.com/alexander-yakushev/compliment"
   :license {:name "Eclipse Public License"

src/compliment/sources/special_forms.clj

@@ -34,3 +34,14 @@
   :candidates #'candidates
   :doc doc
   :tag-fn (fn [m _] (assoc m :type :special-form)))
+
+(defn literal-candidates
+  "We define `true`, `false`, and `nil` in a separate source because they are
+  not context-dependent (don't have to be first items in the list)."
+  [prefix _ __]
+  (filter #(.startsWith ^String % prefix) ["true" "false" "nil"]))
+
+(defsource ::literals
+  :candidates #'literal-candidates
+  :doc (constantly nil)
+  :tag-fn (fn [m _] (assoc m :type :special-form)))

test/compliment/sources/t_special_forms.clj

@@ -20,6 +20,11 @@
     (src/candidates "" *ns* (ctx/parse-context '[__prefix__ 42]))
     => nil)
 
+  (fact "literals are completed"
+    (src/literal-candidates "tr" *ns* nil) => ["true"]
+    (src/literal-candidates "f" *ns* nil) => ["false"]
+    (src/literal-candidates "n"  *ns* nil) => ["nil"])
+
   (fact "there are docs for special forms too"
     (src/doc "try" *ns*) => string?
     (src/doc "not-a-form" *ns*) => nil))

test/compliment/t_core.clj

@@ -120,6 +120,9 @@
     (core/completions "recu" {:tag-candidates true}) =>
     (contains [{:candidate "recur", :type :special-form}])
 
+    (core/completions "tru" {:tag-candidates true}) =>
+    (contains [{:candidate "true", :type :special-form}])
+
     (core/completions "ba" {:context "(defn foo [bar baz] (+ 1 __prefix__))"
                             :tag-candidates true}) =>
                             (contains #{{:candidate "bar", :type :local} {:candidate "baz", :type :local}})