Revert "inspector: find magic comment using V8 scanner"

This reverts commit 1b3b808a.

Reason for revert: crbug/879988

TBR=kozy@chromium.org

Original change's description:
> inspector: find magic comment using V8 scanner
>
> Inspector tries to provide sourceURL and sourceMappingURL for scripts
> with parser errors. Without this CL we convert source of each script
> to inspector string and search for magic comment there. Some web sites
> use pattern when they get some data from network and constantly try to
> parse this data as JSON, in this case we do a lot of useless work.
>
> So we can parse magic comments on V8 side only for compilation errors
> (excluding parse JSON errors), to do it we can reuse scanner by running
> it on each potential comment.
>
> R=​alph@chromium.org,verwaest@chromium.org,yangguo@chromium.org
>
> Bug: chromium:873865,v8:7731
> Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
> Change-Id: I77c270fd0e95cd7b2c9ee4b7f72ef344bc1fa104
> Reviewed-on: https://chromium-review.googlesource.com/1182446
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Alexei Filippov <alph@chromium.org>
> Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55280}

TBR=alph@chromium.org,yangguo@chromium.org,kozyatinskiy@chromium.org,verwaest@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:873865, v8:7731, chromium:879988
Change-Id: Ia7ac766e19f9b58562d9430811f10b25c4556a46
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/1202583
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55594}

src/debug/debug.cc

@@ -32,8 +32,6 @@
 #include "src/objects/debug-objects-inl.h"
 #include "src/objects/js-generator-inl.h"
 #include "src/objects/js-promise-inl.h"
-#include "src/parsing/scanner-character-streams.h"
-#include "src/parsing/scanner.h"
 #include "src/snapshot/natives.h"
 #include "src/snapshot/snapshot.h"
 #include "src/wasm/wasm-objects-inl.h"
@@ -1844,60 +1842,15 @@ bool Debug::SetScriptSource(Handle<Script> script, Handle<String> source,
   return result->status == debug::LiveEditResult::OK;
 }
 
-void Debug::OnParseJSONError(Handle<Script> script) {
-  ProcessCompileEvent(CompileStatus::JSON_PARSE_ERROR, script);
-}
-
 void Debug::OnCompileError(Handle<Script> script) {
-  ProcessCompileEvent(CompileStatus::COMPILE_ERROR, script);
+  ProcessCompileEvent(true, script);
 }
 
 void Debug::OnAfterCompile(Handle<Script> script) {
-  ProcessCompileEvent(CompileStatus::OK, script);
-}
-
-namespace {
-void EnsureMagicComments(Isolate* isolate, Handle<Script> script) {
-  Handle<Object> source_value(script->source(), isolate);
-  DCHECK(source_value->IsString());
-  Handle<String> comment_start =
-      isolate->factory()->NewStringFromStaticChars("//");
-  Handle<String> source(Handle<String>::cast(source_value));
-  std::unique_ptr<Utf16CharacterStream> scanner_stream(
-      ScannerStream::For(isolate, source));
-  Scanner scanner(isolate->unicode_cache(), scanner_stream.get(), false);
-  scanner.Initialize();
-
-  bool has_source_url = script->source_url()->IsString();
-  bool has_source_mapping_url = script->source_mapping_url()->IsString();
-
-  int prev_start = source->length();
-  while (prev_start > 0 && (!has_source_mapping_url || !has_source_url)) {
-    int start = Smi::ToInt(
-        String::LastIndexOf(isolate, source, comment_start,
-                            handle(Smi::FromInt(prev_start), isolate)));
-    if (start == -1) return;
-
-    scanner_stream->Seek(start);
-    scanner_stream->Advance();
-    scanner.Next();
-
-    Handle<String> source_url = scanner.SourceUrl(isolate);
-    if (!has_source_url && !source_url.is_null()) {
-      script->set_source_url(*source_url);
-      has_source_url = true;
-    }
-    Handle<String> source_mapping_url = scanner.SourceMappingUrl(isolate);
-    if (!has_source_mapping_url && !source_mapping_url.is_null()) {
-      script->set_source_mapping_url(*source_mapping_url);
-      has_source_mapping_url = true;
-    }
-    prev_start = start - 1;
-  }
+  ProcessCompileEvent(false, script);
 }
-}  // namespace
 
-void Debug::ProcessCompileEvent(CompileStatus status, Handle<Script> script) {
+void Debug::ProcessCompileEvent(bool has_compile_error, Handle<Script> script) {
   // TODO(kozyatinskiy): teach devtools to work with liveedit scripts better
   // first and then remove this fast return.
   if (running_live_edit_) return;
@@ -1909,19 +1862,13 @@ void Debug::ProcessCompileEvent(CompileStatus status, Handle<Script> script) {
     return;
   }
   if (!debug_delegate_) return;
-
-  if (status == CompileStatus::COMPILE_ERROR) {
-    EnsureMagicComments(isolate_, script);
-  }
-
   SuppressDebug while_processing(this);
   DebugScope debug_scope(this);
   HandleScope scope(isolate_);
   DisableBreak no_recursive_break(this);
   AllowJavascriptExecution allow_script(isolate_);
   debug_delegate_->ScriptCompiled(ToApiHandle<debug::Script>(script),
-                                  running_live_edit_,
-                                  status != CompileStatus::OK);
+                                  running_live_edit_, has_compile_error);
 }
 
 int Debug::CurrentFrameCount() {

src/debug/debug.h

@@ -222,7 +222,6 @@ class Debug {
   void OnThrow(Handle<Object> exception);
   void OnPromiseReject(Handle<Object> promise, Handle<Object> value);
   void OnCompileError(Handle<Script> script);
-  void OnParseJSONError(Handle<Script> script);
   void OnAfterCompile(Handle<Script> script);
 
   void HandleDebugBreak(IgnoreBreakMode ignore_break_mode);
@@ -409,8 +408,7 @@ class Debug {
 
   void OnException(Handle<Object> exception, Handle<Object> promise);
 
-  enum CompileStatus { OK, COMPILE_ERROR, JSON_PARSE_ERROR };
-  void ProcessCompileEvent(CompileStatus status, Handle<Script> script);
+  void ProcessCompileEvent(bool has_compile_error, Handle<Script> script);
 
   // Find the closest source position for a break point for a given position.
   int FindBreakablePosition(Handle<DebugInfo> debug_info, int source_position);

src/inspector/search-util.cc

@@ -13,6 +13,57 @@ namespace v8_inspector {
 
 namespace {
 
+String16 findMagicComment(const String16& content, const String16& name,
+                          bool multiline) {
+  DCHECK_EQ(String16::kNotFound, name.find("="));
+  size_t length = content.length();
+  size_t nameLength = name.length();
+
+  size_t pos = length;
+  size_t equalSignPos = 0;
+  size_t closingCommentPos = 0;
+  while (true) {
+    pos = content.reverseFind(name, pos);
+    if (pos == String16::kNotFound) return String16();
+
+    // Check for a /\/[\/*][@#][ \t]/ regexp (length of 4) before found name.
+    if (pos < 4) return String16();
+    pos -= 4;
+    if (content[pos] != '/') continue;
+    if ((content[pos + 1] != '/' || multiline) &&
+        (content[pos + 1] != '*' || !multiline))
+      continue;
+    if (content[pos + 2] != '#' && content[pos + 2] != '@') continue;
+    if (content[pos + 3] != ' ' && content[pos + 3] != '\t') continue;
+    equalSignPos = pos + 4 + nameLength;
+    if (equalSignPos < length && content[equalSignPos] != '=') continue;
+    if (multiline) {
+      closingCommentPos = content.find("*/", equalSignPos + 1);
+      if (closingCommentPos == String16::kNotFound) return String16();
+    }
+
+    break;
+  }
+
+  DCHECK(equalSignPos);
+  DCHECK(!multiline || closingCommentPos);
+  size_t urlPos = equalSignPos + 1;
+  String16 match = multiline
+                       ? content.substring(urlPos, closingCommentPos - urlPos)
+                       : content.substring(urlPos);
+
+  size_t newLine = match.find("\n");
+  if (newLine != String16::kNotFound) match = match.substring(0, newLine);
+  match = match.stripWhiteSpace();
+
+  for (size_t i = 0; i < match.length(); ++i) {
+    UChar c = match[i];
+    if (c == '"' || c == '\'' || c == ' ' || c == '\t') return "";
+  }
+
+  return match;
+}
+
 String16 createSearchRegexSource(const String16& text) {
   String16Builder result;
 
@@ -102,4 +153,13 @@ searchInTextByLinesImpl(V8InspectorSession* session, const String16& text,
     result.push_back(buildObjectForSearchMatch(match.first, match.second));
   return result;
 }
+
+String16 findSourceURL(const String16& content, bool multiline) {
+  return findMagicComment(content, "sourceURL", multiline);
+}
+
+String16 findSourceMapURL(const String16& content, bool multiline) {
+  return findMagicComment(content, "sourceMappingURL", multiline);
+}
+
 }  // namespace v8_inspector

src/inspector/search-util.h

@@ -12,6 +12,8 @@ namespace v8_inspector {
 
 class V8InspectorSession;
 
+String16 findSourceURL(const String16& content, bool multiline);
+String16 findSourceMapURL(const String16& content, bool multiline);
 std::vector<std::unique_ptr<protocol::Debugger::SearchMatch>>
 searchInTextByLinesImpl(V8InspectorSession*, const String16& text,
                         const String16& query, bool caseSensitive,

src/inspector/v8-debugger-agent-impl.cc

@@ -1377,6 +1377,12 @@ bool V8DebuggerAgentImpl::isPaused() const {
 void V8DebuggerAgentImpl::didParseSource(
     std::unique_ptr<V8DebuggerScript> script, bool success) {
   v8::HandleScope handles(m_isolate);
+  if (!success) {
+    DCHECK(!script->isSourceLoadedLazily());
+    String16 scriptSource = script->source(0);
+    script->setSourceURL(findSourceURL(scriptSource, false));
+    script->setSourceMappingURL(findSourceMapURL(scriptSource, false));
+  }
 
   int contextId = script->executionContextId();
   int contextGroupId = m_inspector->contextGroupId(contextId);

src/json-parser.cc

@@ -201,7 +201,7 @@ MaybeHandle<Object> JsonParser<seq_one_byte>::ParseJson() {
     }
     // We should sent compile error event because we compile JSON object in
     // separated source file.
-    isolate()->debug()->OnParseJSONError(script);
+    isolate()->debug()->OnCompileError(script);
     MessageLocation location(script, position_, position_ + 1);
     Handle<Object> error = factory->NewSyntaxError(message, arg1, arg2);
     return isolate()->template Throw<Object>(error, &location);

test/inspector/debugger/script-on-after-compile-expected.txt

@@ -692,24 +692,6 @@ scriptFailedToParse
     startLine : 0
     url : failed.js
 }
-scriptFailedToParse
-{
-    scriptSource : {a:2://# sourceURL=failed.js<nl>//# sourceMappingURL=failed-map
-}
-{
-    endColumn : 31
-    endLine : 1
-    executionContextId : <executionContextId>
-    hasSourceURL : true
-    hash : 370d368557b75a8e281e4a84625a9e0263647da6
-    isModule : false
-    length : 60
-    scriptId : <scriptId>
-    sourceMapURL : failed-map
-    startColumn : 0
-    startLine : 0
-    url : failed.js
-}
 scriptParsed
 {
     scriptSource : function foo16(){}<nl>

test/inspector/debugger/script-on-after-compile.js

@@ -37,7 +37,6 @@ function addScripts() {
     .then(() => addScript("{a:2:\n//# sourceURL=http://a.js"))
   // sourceURL and sourceMappingURL works even for script with syntax error
     .then(() => addScript("}//# sourceURL=failed.js\n//# sourceMappingURL=failed-map"))
-    .then(() => addScript("{a:2://# sourceURL=failed.js\n//# sourceMappingURL=failed-map"))
   // empty lines at end
     .then(() => addScript("function foo16(){}\n"))
     .then(() => addScript("function foo17(){}\n\n"))