Better logging small bug in wv-dialog, conversion to stdio.

racket-webview-qt.rkt

@@ -448,18 +448,58 @@
                 (dispatch-protocol-message message)
                 (loop)))))))))
 
+(define (log-backend-message level message [elapsed #f])
+  (define formatted
+    (if (number? elapsed)
+        (format "~a: ~a" elapsed message)
+        message))
+  (case level
+    ((error err)
+     (err-webview-backend "~a" formatted))
+    ((warning warn)
+     (warn-webview-backend "~a" formatted))
+    ((info)
+     (info-webview-backend "~a" formatted))
+    (else
+     (dbg-webview-backend "~a" formatted))))
+
+(define (log-structured-backend-line line)
+  (with-handlers
+      ((exn:fail?
+        (lambda (exception)
+          (warn-webview-backend
+           "Invalid structured backend log: ~a; line: ~a"
+           (exn-message exception)
+           line))))
+    (define entry (string->jsexpr (substring line 5)))
+    (unless (hash? entry)
+      (error 'log-structured-backend-line "JSON object expected"))
+    (define level-value (hash-ref entry 'level "debug"))
+    (define level
+      (cond
+        ((symbol? level-value) level-value)
+        ((string? level-value) (string->symbol (string-downcase level-value)))
+        (else 'debug)))
+    (define message (hash-ref entry 'message ""))
+    (define elapsed (hash-ref entry 'elapsed #f))
+    (log-backend-message level (format "~a" message) elapsed)))
+
 (define (log-backend-line line)
   (cond
+    ((string-prefix? line "json:")
+     (log-structured-backend-line line))
     ((regexp-match? #rx"^ERROR[ ]*:" line)
-     (err-webview "qt: ~a" line))
+     (err-webview-backend "~a" line))
     ((regexp-match? #rx"^WARNING[ ]*:" line)
-     (warn-webview "qt: ~a" line))
+     (warn-webview-backend "~a" line))
     ((regexp-match? #rx"^INFO[ ]*:" line)
-     (info-webview "qt: ~a" line))
+     (info-webview-backend "~a" line))
     ((regexp-match? #rx"^DEBUG[ ]*:" line)
-     (dbg-webview "qt: ~a" line))
+     (dbg-webview-backend "~a" line))
     (else
-     (dbg-webview "qt: ~a" line))))
+     ;; Libraries used by Qt may occasionally write unstructured text to
+     ;; stderr. Keep it visible without confusing it with protocol output.
+     (dbg-webview-backend "~a" line))))
 
 (define (start-error-forwarder!)
   (set!