Support tab completion of line:col in the debugger.

runtime/observatory/lib/src/debugger/debugger_location.dart

Index: runtime/observatory/lib/src/debugger/debugger_location.dart
diff --git a/runtime/observatory/lib/src/debugger/debugger_location.dart b/runtime/observatory/lib/src/debugger/debugger_location.dart
index a517cd28ab3fada3c2508bc650be83517ad6461e..05645a39456f21a298f9842e0c32e52b2a338163 100644
--- a/runtime/observatory/lib/src/debugger/debugger_location.dart
+++ b/runtime/observatory/lib/src/debugger/debugger_location.dart
@@ -42,23 +42,29 @@ class DebuggerLocation {
         "Invalid source location '${locDesc}'"));
   }
 
-  static Future<DebuggerLocation> _currentLocation(Debugger debugger) {
+  static Future<ServiceMap> _currentFrame(Debugger debugger) async {
     ServiceMap stack = debugger.stack;
     if (stack == null || stack['frames'].length == 0) {
-      return new Future.value(new DebuggerLocation.error(
-          'A script must be provided when the stack is empty'));
+      return null;
+    }
+    return stack['frames'][debugger.currentFrame];
+  }
+
+  static Future<DebuggerLocation> _currentLocation(Debugger debugger) async {
+    var frame = await _currentFrame(debugger);
+    if (frame == null) {
+      return new DebuggerLocation.error(
+          'A script must be provided when the stack is empty');
     }
-    var frame = stack['frames'][debugger.currentFrame];
     Script script = frame.location.script;
-    return script.load().then((_) {
-      var line = script.tokenToLine(frame.location.tokenPos);
-      var col = script.tokenToCol(frame.location.tokenPos);
-      return new Future.value(new DebuggerLocation.file(script, line, col));
-    });
+    await script.load();
+    var line = script.tokenToLine(frame.location.tokenPos);
+    var col = script.tokenToCol(frame.location.tokenPos);
+    return new DebuggerLocation.file(script, line, col);
   }
 
   static Future<DebuggerLocation> _parseScriptLine(Debugger debugger,
-                                                   Match match) {
+                                                   Match match) async {
     var scriptName = match.group(1);
     if (scriptName != null) {
       scriptName = scriptName.substring(0, scriptName.length - 1);
@@ -84,28 +90,25 @@ class DebuggerLocation {
 
     if (scriptName != null) {
       // Resolve the script.
-      return _lookupScript(debugger.isolate, scriptName).then((scripts) {
-        if (scripts.length == 0) {
-          return new DebuggerLocation.error("Script '${scriptName}' not found");
-        } else if (scripts.length == 1) {
-          return new DebuggerLocation.file(scripts[0], line, col);
-        } else {
-          // TODO(turnidge): Allow the user to disambiguate.
-          return new DebuggerLocation.error("Script '${scriptName}' is ambigous");
-        }
-      });
+      var scripts = await _lookupScript(debugger.isolate, scriptName);
+      if (scripts.length == 0) {
+        return new DebuggerLocation.error("Script '${scriptName}' not found");
+      } else if (scripts.length == 1) {
+        return new DebuggerLocation.file(scripts[0], line, col);
+      } else {
+        // TODO(turnidge): Allow the user to disambiguate.
+        return new DebuggerLocation.error("Script '${scriptName}' is ambigous");
+      }
     } else {
       // No script provided.  Default to top of stack for now.
-      ServiceMap stack = debugger.stack;
-      if (stack == null || stack['frames'].length == 0) {
+      var frame = await _currentFrame(debugger);
+      if (frame == null) {
         return new Future.value(new DebuggerLocation.error(
             'A script must be provided when the stack is empty'));
       }
-      var frame = stack['frames'][debugger.currentFrame];
       Script script = frame.location.script;
-      return script.load().then((_) {
-        return new Future.value(new DebuggerLocation.file(script, line, col));
-      });
+      await script.load();
+      return new DebuggerLocation.file(script, line, col);
     }
   }
 
@@ -161,6 +164,9 @@ class DebuggerLocation {
   static Future<List<Class>> _lookupClass(Isolate isolate,
                                           String name,
                                           { bool allowPrefix: false }) {
+    if (isolate == null) {
+      return [];
+    }
     var pending = [];
     for (var lib in isolate.libraries) {
       assert(lib.loaded);
@@ -255,7 +261,7 @@ class DebuggerLocation {
   }
 
   static RegExp partialSourceLocMatcher =
-      new RegExp(r'^([^\d:]?[^:]+[:]?)?(\d+)?([:]\d+)?');
+      new RegExp(r'^([^\d:]?[^:]+[:]?)?(\d+)?([:]\d*)?');
   static RegExp partialFunctionMatcher = new RegExp(r'^([^.]*)([.][^.]*)?');
 
   /// Completes a partial source location description.
@@ -326,25 +332,105 @@ class DebuggerLocation {
     }
   }
 
-  static Future<List<String>> _completeFile(Debugger debugger, Match match) {
-    var scriptName = match.group(1);
-    var lineStr = match.group(2);
-    var colStr = match.group(3);
-    if (lineStr != null || colStr != null) {
-      // TODO(turnidge): Complete valid line and column numbers.
-      return new Future.value([]);
+  static bool _startsWithDigit(String s) {
+    return '0'.compareTo(s[0]) <= 0 && '9'.compareTo(s[0]) >= 0;
+  }
+
+  static Future<List<String>> _completeFile(
+      Debugger debugger, Match match) async {
+    var scriptName;
+    var scriptNameComplete = false;
+    var lineStr;
+    var lineStrComplete = false;
+    var colStr;
+    if (_startsWithDigit(match.group(1))) {
+      // CASE 1: We have matched a prefix of (lineStr:)(colStr)
+      var frame = await _currentFrame(debugger);
+      if (frame == null) {
+        return [];
+      }
+      scriptName = frame.location.script.name;
+      scriptNameComplete = true;
+      lineStr = match.group(1);
+      lineStr = (lineStr == null ? '' : lineStr);

[Cutch, 2015/10/06 18:08:16]

lineStr ?= '';

[turnidge, 2015/10/06 18:33:37]

Done.

+      if (lineStr.endsWith(':')) {
+        lineStr = lineStr.substring(0, lineStr.length - 1);
+        lineStrComplete = true;
+      }
+      colStr = match.group(2);
+      colStr = (colStr == null ? '' : colStr);

[Cutch, 2015/10/06 18:08:16]

colStr ?= '';

[turnidge, 2015/10/06 18:33:37]

Done.

+    } else {
+      // CASE 2: We have matched a prefix of (scriptName:)(lineStr)(:colStr)
+      scriptName = match.group(1);
+      scriptName = (scriptName == null ? '' : scriptName);
+      if (scriptName.endsWith(':')) {

[Cutch, 2015/10/06 18:08:16]

Not necessarily an issue for the current CL but couldn't ':' appear in a script
uri (drive letter, protocol specification), etc.

[turnidge, 2015/10/06 18:33:37]

True.  Currently the script name that we use is just the last part of the path
'whatever.dart', so this doesn't come up.  If we allow completion to full uris
then this will be an issue.

+        scriptName = scriptName.substring(0, scriptName.length - 1);
+        scriptNameComplete = true;
+      }
+      lineStr = match.group(2);
+      lineStr = (lineStr == null ? '' : lineStr);
+      colStr = match.group(3);
+      colStr = (colStr == null ? '' : colStr);
+      if (colStr.startsWith(':')) {
+        lineStrComplete = true;
+        colStr = colStr.substring(1);
+      }
     }
-    scriptName = (scriptName == null ? '' : scriptName);
 
-    return _lookupScript(debugger.isolate, scriptName, allowPrefix:true)
-      .then((scripts) {
+    if (!scriptNameComplete) {
+      // The script name is incomplete.  Complete it.
+      var scripts =
+          await _lookupScript(debugger.isolate, scriptName, allowPrefix:true);
+      List completions = [];
+      for (var script in scripts) {
+        completions.add(script.name + ':');
+      }
+      completions.sort();
+      return completions;
+
+    } else {
+      // The script name is complete.  Look it up.
+      var scripts =
+          await _lookupScript(debugger.isolate, scriptName, allowPrefix:false);
+      if (scripts.isEmpty) {
+        return [];
+      }
+      var script = scripts[0];
+      await script.load();
+      if (!lineStrComplete) {
+        // Complete the line.
+        var sharedPrefix = '${script.name}:';
         List completions = [];
-        for (var script in scripts) {
-          completions.add(script.name + ':');
+        for (var line in script.lines) {
+          if (line.possibleBpt) {
+            var currentLineStr = line.line.toString();
+            if (currentLineStr.startsWith(lineStr)) {
+              completions.add('${sharedPrefix}${currentLineStr} ');
+              completions.add('${sharedPrefix}${currentLineStr}:');
+            }
+          }
         }
-        completions.sort();
         return completions;
-      });
+
+      } else {
+        // Complete the column.
+        int lineNum = int.parse(lineStr);
+        var scriptLine = script.getLine(lineNum);
+        if (!scriptLine.possibleBpt) {
+          return [];
+        }
+        var sharedPrefix = '${script.name}:${lineStr}:';
+        List completions = [];
+        int maxCol = scriptLine.text.runes.length;
+        for (int i = 1; i <= maxCol; i++) {
+          var currentColStr = i.toString();
+          if (currentColStr.startsWith(colStr)) {
+            completions.add('${sharedPrefix}${currentColStr} ');
+          }
+        }
+        return completions;
+      }
+    }
   }
 
   String toString() {