Limit textual representation of arrays in debugger

runtime/bin/dbg_message.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/dbg_connection.h"
 #include "bin/dbg_message.h"
 #include "bin/dartutils.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
 
@@ skipping 87 matching lines @@
     return NULL;
   }
   intptr_t buflen = pr.ValueLen() + 1;
   char* param_chars = reinterpret_cast<char*>(malloc(buflen));
   pr.GetValueChars(param_chars, buflen);
   // TODO(hausner): Decode escape sequences.
   return param_chars;
 }
 
 
-static void FormatEncodedString(dart::TextBuffer* buf, Dart_Handle str) {
+static void FormatEncodedChars(dart::TextBuffer* buf, Dart_Handle str) {
   intptr_t str_len = 0;
   Dart_Handle res = Dart_StringLength(str, &str_len);
   ASSERT_NOT_ERROR(res);
   uint16_t* codepoints =
       reinterpret_cast<uint16_t*>(malloc(str_len * sizeof(uint16_t)));
   ASSERT(codepoints != NULL);
   intptr_t actual_len = str_len;
   res = Dart_StringToUTF16(str, codepoints, &actual_len);
   ASSERT_NOT_ERROR(res);
   ASSERT(str_len == actual_len);
-  buf->AddChar('\"');
   for (int i = 0; i < str_len; i++) {
     buf->AddEscapedChar(codepoints[i]);
   }
-  buf->AddChar('\"');
   free(codepoints);
 }
 
 
-static void FormatErrorMsg(dart::TextBuffer* buf, Dart_Handle err) {
-  ASSERT(Dart_IsError(err));
-  const char* msg = Dart_GetError(err);
-  Dart_Handle str = Dart_NewStringFromCString(msg);
-  FormatEncodedString(buf, str);
+static void FormatEncodedString(dart::TextBuffer* buf, Dart_Handle str) {
+  buf->AddChar('\"');
+  FormatEncodedChars(buf, str);
+  buf->AddChar('\"');
 }
 
 
-static void FormatTextualValue(dart::TextBuffer* buf, Dart_Handle object) {
-  Dart_Handle text;
-  if (Dart_IsNull(object)) {
-    text = Dart_Null();
+static void FormatTextualListElement(dart::TextBuffer* buf,
+                                     Dart_Handle object) {
+  if (Dart_IsList(object)) {
+    buf->Printf("[...]");
+  } else if (Dart_IsNull(object)) {
+    buf->Printf("null");
+  } else if (Dart_IsError(object)) {
+    buf->Printf("#ERROR");
   } else {
-    Dart_ExceptionPauseInfo savedState = Dart_GetExceptionPauseInfo();
-
-    // TODO(hausner): Check whether recursive/reentrant pauses on exceptions
-    // should be prevented in Debugger::SignalExceptionThrown() instead.
-    if (savedState != kNoPauseOnExceptions) {
-      Dart_Handle res = Dart_SetExceptionPauseInfo(kNoPauseOnExceptions);
-      ASSERT_NOT_ERROR(res);
+    const bool need_quotes = Dart_IsString(object);
+    Dart_Handle text = Dart_ToString(object);
+    if (need_quotes) buf->Printf("\\\"");
+    if (Dart_IsNull(text)) {
+      buf->Printf("null");
+    } else if (Dart_IsError(text)) {
+      buf->Printf("#ERROR");
+    } else {
+      FormatEncodedChars(buf, text);
     }
-
-    text = Dart_ToString(object);
-
-    if (savedState != kNoPauseOnExceptions) {
-      Dart_Handle res = Dart_SetExceptionPauseInfo(savedState);
-      ASSERT_NOT_ERROR(res);
-    }
-  }
-  buf->Printf("\"text\":");
-  if (Dart_IsNull(text)) {
-    buf->Printf("null");
-  } else if (Dart_IsError(text)) {
-    FormatErrorMsg(buf, text);
-  } else {
-    FormatEncodedString(buf, text);
+    if (need_quotes) buf->Printf("\\\"");
   }
 }
 
+
+static void FormatTextualListValue(dart::TextBuffer* buf, Dart_Handle list) {

[srdjan, 2013/01/23 18:35:45]

Do you want to do the same for very long Strings and Maps as well?

+  intptr_t len = 0;
+  Dart_Handle res = Dart_ListLength(list, &len);
+  ASSERT_NOT_ERROR(res);
+  const intptr_t initial_buffer_length = buf->length();
+  // Maximum number of characters we print for array elements.
+  const intptr_t max_chars = 256;
+  const intptr_t max_buffer_length = initial_buffer_length + max_chars;
+  buf->Printf("[");
+  for (int i = 0; i < len; i++) {
+    if (i > 0) {
+      buf->Printf(", ");
+    }
+    Dart_Handle elem = Dart_ListGetAt(list, i);

[srdjan, 2013/01/23 18:35:45]

Instead of adding and checking if buffer exceeded, you could compute the length
first and then add the element on condition that it does not exceed the max
length, otherwise you still could end up with a huge buffer.

+    FormatTextualListElement(buf, elem);
+    if (buf->length() > max_buffer_length) {
+      buf->Printf(", ...");
+      break;
+    }
+  }
+  buf->Printf("]");
+}
+
+
+static void FormatTextualValue(dart::TextBuffer* buf,
+                               Dart_Handle object) {
+  if (Dart_IsList(object)) {
+    FormatTextualListValue(buf, object);
+  } else if (Dart_IsNull(object)) {
+    buf->Printf("null");
+  } else {
+    Dart_Handle text = Dart_ToString(object);
+    if (Dart_IsNull(text)) {
+      buf->Printf("null");
+    } else if (Dart_IsError(text)) {
+      buf->Printf("#ERROR");
+    } else {
+      FormatEncodedChars(buf, text);
+    }
+  }
+}
+
 
 static void FormatValue(dart::TextBuffer* buf, Dart_Handle object) {
   if (Dart_IsInteger(object)) {
     buf->Printf("\"kind\":\"integer\",");
   } else if (Dart_IsString(object)) {
     buf->Printf("\"kind\":\"string\",");
   } else if (Dart_IsBoolean(object)) {
     buf->Printf("\"kind\":\"boolean\",");
   } else if (Dart_IsList(object)) {
     intptr_t len = 0;
     Dart_Handle res = Dart_ListLength(object, &len);
     ASSERT_NOT_ERROR(res);
     buf->Printf("\"kind\":\"list\",\"length\":%"Pd",", len);
   } else {
     buf->Printf("\"kind\":\"object\",");
   }
+  buf->Printf("\"text\":\"");
   FormatTextualValue(buf, object);
+  buf->Printf("\"");
 }
 
 
 static void FormatValueObj(dart::TextBuffer* buf, Dart_Handle object) {
   buf->Printf("{");
   FormatValue(buf, object);
   buf->Printf("}");
 }
 
 
@@ skipping 897 matching lines @@
     msg_queue->SendIsolateEvent(isolate_id, kind);
     if (kind == kInterrupted) {
       msg_queue->HandleMessages();
     } else {
       ASSERT(kind == kShutdown);
       RemoveIsolateMsgQueue(isolate_id);
     }
   }
   Dart_ExitScope();
 }