1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/js/src/gdb/mozilla/Root.py Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,90 @@
1.4 +# Pretty-printers and utilities for SpiderMonkey rooting templates:
1.5 +# Rooted, Handle, MutableHandle, etc.
1.6 +
1.7 +import mozilla.prettyprinters
1.8 +from mozilla.prettyprinters import pretty_printer, template_pretty_printer
1.9 +
1.10 +# Forget any printers from previous loads of this module.
1.11 +mozilla.prettyprinters.clear_module_printers(__name__)
1.12 +
1.13 +# Common base class for all the rooting template pretty-printers. All these
1.14 +# templates have one member holding the referent (or a pointer to it), so
1.15 +# there's not much to it.
1.16 +class Common(object):
1.17 + # The name of the template member holding the referent.
1.18 + member = 'ptr'
1.19 +
1.20 + # If True, this is a handle type, and should be dereferenced. If False,
1.21 + # the template member holds the referent directly.
1.22 + handle = False
1.23 +
1.24 + # Initialize a pretty-printer for |value|, using |cache|.
1.25 + #
1.26 + # If given, |content_printer| is a pretty-printer constructor to use for
1.27 + # this handle/root/etc.'s referent. Usually, we can just omit this argument
1.28 + # and let GDB choose a pretty-printer for the referent given its type, but
1.29 + # when the referent is a typedef of an integral type (say, |jsid| in a
1.30 + # non-|DEBUG| build), the GNU toolchain (at least) loses the typedef name,
1.31 + # and all we know about the referent is its fundamental integer type ---
1.32 + # |JS::Rooted<jsid>|, for example, appears in GDB as |JS::Rooted<long>| ---
1.33 + # and we are left with no way to choose a meaningful pretty-printer based on
1.34 + # the type of the referent alone. However, because we know that the only
1.35 + # integer type for which |JS::Rooted| is likely to be instantiated is
1.36 + # |jsid|, we *can* register a pretty-printer constructor for the full
1.37 + # instantiation |JS::Rooted<long>|. That constructor creates a |JS::Rooted|
1.38 + # pretty-printer, and explicitly specifies the constructor for the referent,
1.39 + # using this initializer's |content_printer| argument.
1.40 + def __init__(self, value, cache, content_printer=None):
1.41 + self.value = value
1.42 + self.cache = cache
1.43 + self.content_printer = content_printer
1.44 + def to_string(self):
1.45 + ptr = self.value[self.member]
1.46 + if self.handle:
1.47 + ptr = ptr.dereference()
1.48 + if self.content_printer:
1.49 + return self.content_printer(ptr, self.cache).to_string()
1.50 + else:
1.51 + # As of 2012-11, GDB suppresses printing pointers in replacement
1.52 + # values; see http://sourceware.org/ml/gdb/2012-11/msg00055.html
1.53 + # That means that simply returning the 'ptr' member won't work.
1.54 + # Instead, just invoke GDB's formatter ourselves.
1.55 + return str(ptr)
1.56 +
1.57 +@template_pretty_printer("JS::Rooted")
1.58 +class Rooted(Common):
1.59 + pass
1.60 +
1.61 +@template_pretty_printer("JS::Handle")
1.62 +class Handle(Common):
1.63 + handle = True
1.64 +
1.65 +@template_pretty_printer("JS::MutableHandle")
1.66 +class MutableHandle(Common):
1.67 + handle = True
1.68 +
1.69 +@template_pretty_printer("js::EncapsulatedPtr")
1.70 +class EncapsulatedPtr(Common):
1.71 + member = 'value'
1.72 +
1.73 +@pretty_printer("js::EncapsulatedValue")
1.74 +class EncapsulatedValue(Common):
1.75 + member = 'value'
1.76 +
1.77 +@pretty_printer("js::BarrieredValue")
1.78 +class BarrieredValue(Common):
1.79 + member = 'value'
1.80 +
1.81 +# Return the referent of a HeapPtr, Rooted, or Handle.
1.82 +def deref(root):
1.83 + tag = root.type.strip_typedefs().tag
1.84 + if not tag:
1.85 + raise TypeError("Can't dereference type with no structure tag: %s" % (root.type,))
1.86 + elif tag.startswith('js::HeapPtr<'):
1.87 + return root['value']
1.88 + elif tag.startswith('JS::Rooted<'):
1.89 + return root['ptr']
1.90 + elif tag.startswith('JS::Handle<'):
1.91 + return root['ptr']
1.92 + else:
1.93 + raise NotImplementedError
