Added initial code completion support for the `expr` command

Summary:
This patch adds initial code completion support for the `expr` command.

We now have a completion handler in the expression CommandObject that
essentially just attempts to parse the given user expression with Clang with
an attached code completion consumer. We filter and prepare the
code completions provided by Clang and send them back to the completion
API.

The current completion is limited to variables that are in the current scope.
This includes local variables and all types used by local variables. We however
don't do any completion of symbols that are not used in the local scope (or
in some other way already in the ASTContext).

This is partly because there is not yet any code that manually searches for additiona
information in the debug information. Another cause is that for some reason the existing
code for loading these additional symbols when requested by Clang doesn't seem to work.
This will be fixed in a future patch.

Reviewers: jingham, teemperor

Reviewed By: teemperor

Subscribers: labath, aprantl, JDevlieghere, friss, lldb-commits

Differential Revision: https://reviews.llvm.org/D48465

llvm-svn: 341086

1 files changed, 40 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/lldbtest.py b/lldb/packages/Python/lldbsuite/test/lldbtest.py
index e7316af9e89..cee4d34101a 100644
--- a/lldb/packages/Python/lldbsuite/test/lldbtest.py
+++ b/lldb/packages/Python/lldbsuite/test/lldbtest.py
@@ -2145,6 +2145,46 @@ class TestBase(Base):
 
         return match_object
 
+
+    def complete_exactly(self, str_input, patterns):
+        self.complete_from_to(str_input, patterns, True)
+
+    def complete_from_to(self, str_input, patterns, turn_off_re_match=False):
+        """Test that the completion mechanism completes str_input to patterns,
+        where patterns could be a pattern-string or a list of pattern-strings"""
+        # Patterns should not be None in order to proceed.
+        self.assertFalse(patterns is None)
+        # And should be either a string or list of strings.  Check for list type
+        # below, if not, make a list out of the singleton string.  If patterns
+        # is not a string or not a list of strings, there'll be runtime errors
+        # later on.
+        if not isinstance(patterns, list):
+            patterns = [patterns]
+
+        interp = self.dbg.GetCommandInterpreter()
+        match_strings = lldb.SBStringList()
+        num_matches = interp.HandleCompletion(str_input, len(str_input), 0, -1, match_strings)
+        common_match = match_strings.GetStringAtIndex(0)
+        if num_matches == 0:
+            compare_string = str_input
+        else:
+            if common_match != None and len(common_match) > 0:
+                compare_string = str_input + common_match
+            else:
+                compare_string = ""
+                for idx in range(1, num_matches+1):
+                    compare_string += match_strings.GetStringAtIndex(idx) + "\n"
+
+        for p in patterns:
+            if turn_off_re_match:
+                self.expect(
+                    compare_string, msg=COMPLETION_MSG(
+                        str_input, p, match_strings), exe=False, substrs=[p])
+            else:
+                self.expect(
+                    compare_string, msg=COMPLETION_MSG(
+                        str_input, p, match_strings), exe=False, patterns=[p])
+
     def expect(
             self,
             str,