[PATCH] D48512: [gdb] Add pretty printer for Expected

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added a reviewer: dblaikie.
Herald added a subscriber: llvm-commits.

Repository:
  rL LLVM

https://reviews.llvm.org/D48512

Files:
  utils/gdb-scripts/prettyprinters.py


Index: utils/gdb-scripts/prettyprinters.py
===================================================================
--- utils/gdb-scripts/prettyprinters.py
+++ utils/gdb-scripts/prettyprinters.py
@@ -1,4 +1,17 @@
 import gdb.printing
+
+class Iterator:
+  def __iter__(self):
+    return self
+
+  # Python 2 compatibility
+  def next(self):
+    return self.__next__()
+
+  def children(self):
+    return self
+
+
 class SmallStringPrinter:
   """Print an llvm::SmallString object."""
 
@@ -103,6 +116,26 @@
   def display_hint (self):
     return 'array'
 
+class ExpectedPrinter(Iterator):
+  """Print an llvm::Expected object."""
+
+  def __init__(self, val):
+    self.val = val
+
+  def __next__(self):
+    val = self.val
+    if val is None:
+      raise StopIteration
+    self.val = None
+    if val['HasError']:
+      return ('error', val['ErrorStorage'].address.cast(
+          gdb.lookup_type('llvm::ErrorInfoBase').pointer()).dereference())
+    return ('value', val['TStorage'].address.cast(
+        val.type.template_argument(0).pointer()).dereference())
+
+  def to_string(self):
+    return 'llvm::Expected<{}>'.format(str(self.val.type.template_argument(0)))
+
 class OptionalPrinter:
   """Print an llvm::Optional object."""
 
@@ -315,6 +348,7 @@
 pp.add_printer('llvm::StringRef', '^llvm::StringRef$', StringRefPrinter)
 pp.add_printer('llvm::SmallVectorImpl', '^llvm::SmallVector(Impl)?<.*>$', SmallVectorPrinter)
 pp.add_printer('llvm::ArrayRef', '^llvm::(Const)?ArrayRef<.*>$', ArrayRefPrinter)
+pp.add_printer('llvm::Expected', '^llvm::Expected<.*>$', ExpectedPrinter)
 pp.add_printer('llvm::Optional', '^llvm::Optional<.*>$', OptionalPrinter)
 pp.add_printer('llvm::DenseMap', '^llvm::DenseMap<.*>$', DenseMapPrinter)
 pp.add_printer('llvm::Twine', '^llvm::Twine$', TwinePrinter)


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