Add infrastructure for debug pretty printers

1 files changed, 59 insertions, 0 deletions

diff --git a/src/main-gdb-head.py b/src/main-gdb-head.py
new file mode 100644
index 0000000..cfdce2b
--- /dev/null
+++ b/src/main-gdb-head.py
@@ -0,0 +1,59 @@
+# Work around awkwardness in gdb's python printers:
+# 1. In src/main-gdb-head.py, define the printer mechanism.
+# 2. In src/*/*.py, define all the printer classes.
+# 3. In src/main-gdb-tail.py, reflect to actually add the printers.
+
+# gdb sticks everything in one scope.
+# This lets us enumerate what *we* added.
+initial_globals = set(globals())
+
+def finish():
+    diff = set(globals()) - initial_globals
+    fp = FastPrinters()
+    # After this, don't access any more globals in this function.
+    global finish, initial_globals, FastPrinters
+    del finish, initial_globals, FastPrinters
+
+    for k in diff:
+        v = globals()[k]
+        if hasattr(v, 'children') or hasattr(v, 'to_string'):
+            fp.add_printer(v)
+
+    gdb.current_objfile().pretty_printers.append(fp)
+
+class FastPrinters(object):
+    ''' printer dispatch the way gdb *should* have done it
+    '''
+    __slots__ = ('name', 'enabled', 'printers')
+
+    def __init__(self):
+        self.name = 'tmwa'
+        self.enabled = True
+        self.printers = {}
+
+    def add_printer(self, cls):
+        assert hasattr(cls, 'enabled')
+        self.printers[cls.name] = cls
+
+    @property
+    def subprinters(self):
+        return self.printers.values()
+
+    def strip_templates(self, name, __pattern=re.compile('<[^<>]>')):
+        # TODO what about '<' and '>' as non-type template parameters?
+        changed = 1
+        while changed:
+            name, changed = __pattern.subn('', name)
+        return name
+
+    def __call__(self, value):
+        stype = gdb.types.get_basic_type(value.type).tag
+        #dtype = gdb.types.get_basic_type(value.dynamic_type).tag
+        if stype is None:
+            return
+
+        stype = self.strip_templates(stype)
+        p = self.printers.get(stype)
+        if p is not None and p.enabled:
+            return p(value)
+        return None