[nongnu] elpa/dart-mode ecf3191 091/192: Add a command to show hover information

[ELPA Syncer]

branch: elpa/dart-mode
commit ecf319136713578a62683ecfdf0474376d18cb14
Author: Natalie Weizenbaum <nex342@gmail.com>
Commit: Natalie Weizenbaum <nex342@gmail.com>

    Add a command to show hover information
---
 CHANGELOG.md |  3 +++
 README.md    |  8 +++++++
 dart-mode.el | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09dc7a6..dd5321e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,7 @@
 ## 1.0.0
 
+* Added a `dart-show-hover` command bound to `C-c ?` which displays information
+  about the Dart API under the cursor.
+
 * `dart-executable-path`'s default value is now set correctly even if the
   executable named `dart` on the user's path is a symlink or a wrapper script.
diff --git a/README.md b/README.md
index 52ce774..42d4e79 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,7 @@
 * [Installation](#installation)
 * [Dart Analyzer](#dart-analyzer)
   * [Error Checking](#error-checking)
+  * [Seeing Information](#seeing-information)
 
 ## Installation
 
@@ -33,3 +34,10 @@ your Dart code. To enable this, just add `(add-hook 
'dart-mode-hook
 Flycheck—if you have `dart-mode`, you automatically have it as well!
 
 [Flycheck]: http://www.flycheck.org/en/latest/
+
+### Seeing Information
+
+To see all the information the analyzer knows about a particular identifier,
+move your cursor onto it and press `C-c ?`. This will show the identifier's 
type
+and documentation in the echo area at the bottom of the editor, as well as some
+extra information if it's available.
diff --git a/dart-mode.el b/dart-mode.el
index 009debe..731d4cc 100644
--- a/dart-mode.el
+++ b/dart-mode.el
@@ -161,6 +161,29 @@ function."
          (delete-region (progn (forward-visible-line 0) (point))
                         (progn (forward-visible-line arg) (point))))))
 
+(defmacro dart--json-let (json fields &rest body)
+  "Assigns variables named FIELDS to the corresponding fields in JSON.
+FIELDS may be either identifiers or (ELISP-IDENTIFIER JSON-IDENTIFIER) pairs."
+  (declare (indent 2))
+  (let ((json-variable (make-symbol "json")))
+    `(let ((,json-variable ,json))
+       (let ,(mapcar (lambda (name)
+                       (let ((elisp-name (if (symbolp name) name (car name)))
+                             (json-name (if (symbolp name) name (cadr name))))
+                         `(,elisp-name (cdr (assoc ',json-name 
,json-variable)))))
+                     fields)
+         ,@body))))
+
+(defun dart--property-string (text prop value)
+  "Returns a copy of TEXT with PROP set to VALUE."
+  (let ((copy (substring text 0)))
+    (put-text-property 0 (length copy) prop value copy)
+    copy))
+
+(defun dart--face-string (text face)
+  "Returns a copy of TEXT with its font face set to FACE."
+  (dart--property-string text 'face face))
+
 (defun dart--read-file (filename)
   "Returns the contents of FILENAME."
   (with-temp-buffer
@@ -368,6 +391,7 @@ Any stderr is logged using dart-log. Returns nil if the 
exit code is non-0."
 
 (defvar dart-mode-map (c-make-inherited-keymap)
   "Keymap used in dart-mode buffers.")
+(define-key dart-mode-map (kbd "C-c ?") 'dart-show-hover)
 
 ;;; CC indentation support
 
@@ -893,6 +917,8 @@ the callback for that request is given the json decoded 
response."
           (dart--analysis-server-on-error-callback msg)
         (dart-info (format "No callback was associated with id %s" raw-id))))))
 
+;;;; Flycheck Error Reporting
+
 (defun dart--flycheck-start (_ callback)
   "Run the CHECKER and report the errors to the CALLBACK."
   (dart-info (format "Checking syntax for %s" (current-buffer)))
@@ -946,6 +972,50 @@ reported to CALLBACK."
    ((string= severity "WARNING") 'warning)
    ((string= severity "ERROR") 'error)))
 
+;;;; Hover
+
+(defun dart-show-hover ()
+  "Displays hover information for the current point."
+  (interactive)
+  (-when-let (filename (buffer-file-name))
+    (lexical-let ((buffer (current-buffer)))
+      (dart--analysis-server-send
+       "analysis.getHover"
+       `(("file" . ,filename) ("offset" . ,(point)))
+       (lambda (response)
+         (-when-let* ((result (cdr (assoc 'result response)))
+                      (hovers (cdr (assoc 'hovers result)))
+                      (hover (if (eq (length hovers) 0) nil (elt hovers 0))))
+           (dart--json-let hover
+               (offset
+                length
+                dartdoc
+                (element-description elementDescription)
+                (element-kind elementKind)
+                (is-deprecated isDeprecated)
+                parameter)
+
+             ;; Briefly highlight the region that's being shown.
+             (with-current-buffer buffer
+               (lexical-let ((overlay (make-overlay (+ 1 offset) (+ 1 offset 
length))))
+                 (overlay-put overlay 'face 'highlight)
+                 (run-at-time "1 sec" nil (lambda () (delete-overlay 
overlay)))))
+
+             (with-temp-buffer
+               (when element-description
+                 (insert element-description
+                         (dart--face-string (concat " (" element-kind ")") 
'italic))
+                 (when (or dartdoc parameter) (insert ?\n)))
+               (when parameter
+                 (insert
+                  parameter
+                  (dart--face-string " (parameter type)" 'italic))
+                 (when dartdoc) (insert ?\n))
+               (when dartdoc
+                 (when (or element-description parameter) (insert ?\n))
+                 (insert dartdoc))
+               (message "%s" (buffer-string))))))))))
+
 
 ;;; Formatting