Add cli/summarize

Default options summary generation function. More minimal than
cli/banner-for, and also does not handle any other text besides the
options summary.

src/main/clojure/clojure/tools/cli.clj

@@ -347,3 +347,26 @@
             [m (conj errors error)]))
         [m (conj errors (str "Unknown option: " (pr-str opt)))]))
     [(default-option-map specs) []] tokens))
+
+(defn- summarize
+  "Reduce options specs into a options summary for printing at a terminal."
+  [specs]
+  (let [all-boolean? (every? (comp not :required) specs)
+        parts (map (fn [{:keys [short-opt long-opt required default default-desc desc]}]
+                     (let [opt (cond (and short-opt long-opt) (str short-opt ", " long-opt)
+                                     long-opt (str "    " long-opt)
+                                     short-opt short-opt)
+                           [opt dd] (if required
+                                      [(str opt \space required) (or default-desc (if default (str default) ""))]
+                                      [opt ""])]
+                       (if all-boolean?
+                         [opt (or desc "")]
+                         [opt dd (or desc "")])))
+                   specs)
+        cl-fmt (if all-boolean?
+                 "~{  ~vA  ~vA~}"
+                 "~{  ~vA  ~vA  ~vA~}")
+        lens (apply map (fn [& cols] (apply max (map count cols))) parts)
+        lines (map #(s/trimr (cl-format nil cl-fmt (interleave lens %)))
+                   parts)]
+    (s/join \newline lines)))

src/test/clojure/clojure/tools/cli_test.clj

@@ -1,5 +1,5 @@
 (ns clojure.tools.cli-test
-  (:use [clojure.string :only [split]]
+  (:use [clojure.string :only [join split]]
         [clojure.test :only [deftest is testing]]
         [clojure.tools.cli :as cli :only [cli]]))
 
@@ -273,3 +273,31 @@
                                          [:short-opt "-v"]
                                          [:long-opt "--verbose"]])
              [{:alpha true :verbose 3} []])))))
+
+(def summarize
+  #'cli/summarize)
+
+(deftest test-summarize
+  (testing "summarizes options"
+    (is (= (summarize (compile-option-specs
+                        [["-s" "--server HOST" "Upstream server"
+                          :default :some-object-whose-string-representation-is-awful
+                          :default-desc "example.com"]
+                         ["-p" "--port=PORT" "Upstream port number"
+                          :default 80]
+                         ["-o" nil "Output file"
+                          :id :output
+                          :required "PATH"]
+                         ["-v" nil "Verbosity level; may be specified more than once"
+                          :id :verbose
+                          :default 0]
+                         [nil "--help"]]))
+           (join \newline
+                 ["  -s, --server HOST  example.com  Upstream server"
+                  "  -p, --port PORT    80           Upstream port number"
+                  "  -o PATH                         Output file"
+                  "  -v                              Verbosity level; may be specified more than once"
+                  "      --help"]))))
+  (testing "does not print :default column when all options are boolean"
+    (is (= (summarize (compile-option-specs [["-m" "--minimal" "A minimal option summary"]]))
+           "  -m, --minimal  A minimal option summary"))))