tools/apilint/apilint.py

#!/usr/bin/env python

# Copyright (C) 2014 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the 'License');
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an 'AS IS' BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""
Enforces common Android public API design patterns.  It ignores lint messages from
a previous API level, if provided.

Usage: apilint.py current.txt
Usage: apilint.py current.txt previous.txt

You can also splice in blame details like this:
$ git blame api/current.txt -t -e > /tmp/currentblame.txt
$ apilint.py /tmp/currentblame.txt previous.txt --no-color
"""

import re, sys, collections, traceback, argparse


BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)

ALLOW_GOOGLE = False
USE_COLOR = True

def format(fg=None, bg=None, bright=False, bold=False, dim=False, reset=False):
    # manually derived from http://en.wikipedia.org/wiki/ANSI_escape_code#Codes
    if not USE_COLOR: return ""
    codes = []
    if reset: codes.append("0")
    else:
        if not fg is None: codes.append("3%d" % (fg))
        if not bg is None:
            if not bright: codes.append("4%d" % (bg))
            else: codes.append("10%d" % (bg))
        if bold: codes.append("1")
        elif dim: codes.append("2")
        else: codes.append("22")
    return "\033[%sm" % (";".join(codes))


class Field():
    def __init__(self, clazz, line, raw, blame):
        self.clazz = clazz
        self.line = line
        self.raw = raw.strip(" {;")
        self.blame = blame

        raw = raw.split()
        self.split = list(raw)

        for r in ["field", "volatile", "transient", "public", "protected", "static", "final", "deprecated"]:
            while r in raw: raw.remove(r)

        self.typ = raw[0]
        self.name = raw[1].strip(";")
        if len(raw) >= 4 and raw[2] == "=":
            self.value = raw[3].strip(';"')
        else:
            self.value = None

        self.ident = self.raw.replace(" deprecated ", " ")

    def __hash__(self):
        return hash(self.raw)

    def __repr__(self):
        return self.raw


class Method():
    def __init__(self, clazz, line, raw, blame):
        self.clazz = clazz
        self.line = line
        self.raw = raw.strip(" {;")
        self.blame = blame

        # drop generics for now
        raw = re.sub("<.+?>", "", raw)

        raw = re.split("[\s(),;]+", raw)
        for r in ["", ";"]:
            while r in raw: raw.remove(r)
        self.split = list(raw)

        for r in ["method", "public", "protected", "static", "final", "deprecated", "abstract", "default"]:
            while r in raw: raw.remove(r)

        self.typ = raw[0]
        self.name = raw[1]
        self.args = []
        for r in raw[2:]:
            if r == "throws": break
            self.args.append(r)

        # identity for compat purposes
        ident = self.raw
        ident = ident.replace(" deprecated ", " ")
        ident = ident.replace(" synchronized ", " ")
        ident = re.sub("<.+?>", "", ident)
        if " throws " in ident:
            ident = ident[:ident.index(" throws ")]
        self.ident = ident

    def __hash__(self):
        return hash(self.raw)

    def __repr__(self):
        return self.raw


class Class():
    def __init__(self, pkg, line, raw, blame):
        self.pkg = pkg
        self.line = line
        self.raw = raw.strip(" {;")
        self.blame = blame
        self.ctors = []
        self.fields = []
        self.methods = []

        raw = raw.split()
        self.split = list(raw)
        if "class" in raw:
            self.fullname = raw[raw.index("class")+1]
        elif "interface" in raw:
            self.fullname = raw[raw.index("interface")+1]
        else:
            raise ValueError("Funky class type %s" % (self.raw))

        if "extends" in raw:
            self.extends = raw[raw.index("extends")+1]
            self.extends_path = self.extends.split(".")
        else:
            self.extends = None
            self.extends_path = []

        self.fullname = self.pkg.name + "." + self.fullname
        self.fullname_path = self.fullname.split(".")

        self.name = self.fullname[self.fullname.rindex(".")+1:]

    def __hash__(self):
        return hash((self.raw, tuple(self.ctors), tuple(self.fields), tuple(self.methods)))

    def __repr__(self):
        return self.raw


class Package():
    def __init__(self, line, raw, blame):
        self.line = line
        self.raw = raw.strip(" {;")
        self.blame = blame

        raw = raw.split()
        self.name = raw[raw.index("package")+1]
        self.name_path = self.name.split(".")

    def __repr__(self):
        return self.raw


def _parse_stream(f, clazz_cb=None):
    line = 0
    api = {}
    pkg = None
    clazz = None
    blame = None

    re_blame = re.compile("^([a-z0-9]{7,}) \(<([^>]+)>.+?\) (.+?)$")
    for raw in f:
        line += 1
        raw = raw.rstrip()
        match = re_blame.match(raw)
        if match is not None:
            blame = match.groups()[0:2]
            raw = match.groups()[2]
        else:
            blame = None

        if raw.startswith("package"):
            pkg = Package(line, raw, blame)
        elif raw.startswith("  ") and raw.endswith("{"):
            # When provided with class callback, we treat as incremental
            # parse and don't build up entire API
            if clazz and clazz_cb:
                clazz_cb(clazz)
            clazz = Class(pkg, line, raw, blame)
            if not clazz_cb:
                api[clazz.fullname] = clazz
        elif raw.startswith("    ctor"):
            clazz.ctors.append(Method(clazz, line, raw, blame))
        elif raw.startswith("    method"):
            clazz.methods.append(Method(clazz, line, raw, blame))
        elif raw.startswith("    field"):
            clazz.fields.append(Field(clazz, line, raw, blame))

    # Handle last trailing class
    if clazz and clazz_cb:
        clazz_cb(clazz)

    return api


class Failure():
    def __init__(self, sig, clazz, detail, error, rule, msg):
        self.sig = sig
        self.error = error
        self.rule = rule
        self.msg = msg

        if error:
            self.head = "Error %s" % (rule) if rule else "Error"
            dump = "%s%s:%s %s" % (format(fg=RED, bg=BLACK, bold=True), self.head, format(reset=True), msg)
        else:
            self.head = "Warning %s" % (rule) if rule else "Warning"
            dump = "%s%s:%s %s" % (format(fg=YELLOW, bg=BLACK, bold=True), self.head, format(reset=True), msg)

        self.line = clazz.line
        blame = clazz.blame
        if detail is not None:
            dump += "\n    in " + repr(detail)
            self.line = detail.line
            blame = detail.blame
        dump += "\n    in " + repr(clazz)
        dump += "\n    in " + repr(clazz.pkg)
        dump += "\n    at line " + repr(self.line)
        if blame is not None:
            dump += "\n    last modified by %s in %s" % (blame[1], blame[0])

        self.dump = dump

    def __repr__(self):
        return self.dump


failures = {}

def _fail(clazz, detail, error, rule, msg):
    """Records an API failure to be processed later."""
    global failures

    sig = "%s-%s-%s" % (clazz.fullname, repr(detail), msg)
    sig = sig.replace(" deprecated ", " ")

    failures[sig] = Failure(sig, clazz, detail, error, rule, msg)


def warn(clazz, detail, rule, msg):
    _fail(clazz, detail, False, rule, msg)

def error(clazz, detail, rule, msg):
    _fail(clazz, detail, True, rule, msg)


noticed = {}

def notice(clazz):
    global noticed

    noticed[clazz.fullname] = hash(clazz)


def verify_constants(clazz):
    """All static final constants must be FOO_NAME style."""
    if re.match("android\.R\.[a-z]+", clazz.fullname): return
    if clazz.fullname.startswith("android.os.Build"): return
    if clazz.fullname == "android.system.OsConstants": return

    req = ["java.lang.String","byte","short","int","long","float","double","boolean","char"]
    for f in clazz.fields:
        if "static" in f.split and "final" in f.split:
            if re.match("[A-Z0-9_]+", f.name) is None:
                error(clazz, f, "C2", "Constant field names must be FOO_NAME")
            if f.typ != "java.lang.String":
                if f.name.startswith("MIN_") or f.name.startswith("MAX_"):
                    warn(clazz, f, "C8", "If min/max could change in future, make them dynamic methods")
            if f.typ in req and f.value is None:
                error(clazz, f, None, "All constants must be defined at compile time")


def verify_enums(clazz):
    """Enums are bad, mmkay?"""
    if "extends java.lang.Enum" in clazz.raw:
        error(clazz, None, "F5", "Enums are not allowed")


def verify_class_names(clazz):
    """Try catching malformed class names like myMtp or MTPUser."""
    if clazz.fullname.startswith("android.opengl"): return
    if clazz.fullname.startswith("android.renderscript"): return
    if re.match("android\.R\.[a-z]+", clazz.fullname): return

    if re.search("[A-Z]{2,}", clazz.name) is not None:
        warn(clazz, None, "S1", "Class names with acronyms should be Mtp not MTP")
    if re.match("[^A-Z]", clazz.name):
        error(clazz, None, "S1", "Class must start with uppercase char")


def verify_method_names(clazz):
    """Try catching malformed method names, like Foo() or getMTU()."""
    if clazz.fullname.startswith("android.opengl"): return
    if clazz.fullname.startswith("android.renderscript"): return
    if clazz.fullname == "android.system.OsConstants": return

    for m in clazz.methods:
        if re.search("[A-Z]{2,}", m.name) is not None:
            warn(clazz, m, "S1", "Method names with acronyms should be getMtu() instead of getMTU()")
        if re.match("[^a-z]", m.name):
            error(clazz, m, "S1", "Method name must start with lowercase char")


def verify_callbacks(clazz):
    """Verify Callback classes.
    All callback classes must be abstract.
    All methods must follow onFoo() naming style."""
    if clazz.fullname == "android.speech.tts.SynthesisCallback": return

    if clazz.name.endswith("Callbacks"):
        error(clazz, None, "L1", "Callback class names should be singular")
    if clazz.name.endswith("Observer"):
        warn(clazz, None, "L1", "Class should be named FooCallback")

    if clazz.name.endswith("Callback"):
        if "interface" in clazz.split:
            error(clazz, None, "CL3", "Callbacks must be abstract class to enable extension in future API levels")

        for m in clazz.methods:
            if not re.match("on[A-Z][a-z]*", m.name):
                error(clazz, m, "L1", "Callback method names must be onFoo() style")


def verify_listeners(clazz):
    """Verify Listener classes.
    All Listener classes must be interface.
    All methods must follow onFoo() naming style.
    If only a single method, it must match class name:
        interface OnFooListener { void onFoo() }"""

    if clazz.name.endswith("Listener"):
        if " abstract class " in clazz.raw:
            error(clazz, None, "L1", "Listeners should be an interface, or otherwise renamed Callback")

        for m in clazz.methods:
            if not re.match("on[A-Z][a-z]*", m.name):
                error(clazz, m, "L1", "Listener method names must be onFoo() style")

        if len(clazz.methods) == 1 and clazz.name.startswith("On"):
            m = clazz.methods[0]
            if (m.name + "Listener").lower() != clazz.name.lower():
                error(clazz, m, "L1", "Single listener method name must match class name")


def verify_actions(clazz):
    """Verify intent actions.
    All action names must be named ACTION_FOO.
    All action values must be scoped by package and match name:
        package android.foo {
            String ACTION_BAR = "android.foo.action.BAR";
        }"""
    for f in clazz.fields:
        if f.value is None: continue
        if f.name.startswith("EXTRA_"): continue
        if f.name == "SERVICE_INTERFACE" or f.name == "PROVIDER_INTERFACE": continue
        if "INTERACTION" in f.name: continue

        if "static" in f.split and "final" in f.split and f.typ == "java.lang.String":
            if "_ACTION" in f.name or "ACTION_" in f.name or ".action." in f.value.lower():
                if not f.name.startswith("ACTION_"):
                    error(clazz, f, "C3", "Intent action constant name must be ACTION_FOO")
                else:
                    if clazz.fullname == "android.content.Intent":
                        prefix = "android.intent.action"
                    elif clazz.fullname == "android.provider.Settings":
                        prefix = "android.settings"
                    elif clazz.fullname == "android.app.admin.DevicePolicyManager" or clazz.fullname == "android.app.admin.DeviceAdminReceiver":
                        prefix = "android.app.action"
                    else:
                        prefix = clazz.pkg.name + ".action"
                    expected = prefix + "." + f.name[7:]
                    if f.value != expected:
                        error(clazz, f, "C4", "Inconsistent action value; expected %s" % (expected))


def verify_extras(clazz):
    """Verify intent extras.
    All extra names must be named EXTRA_FOO.
    All extra values must be scoped by package and match name:
        package android.foo {
            String EXTRA_BAR = "android.foo.extra.BAR";
        }"""
    if clazz.fullname == "android.app.Notification": return
    if clazz.fullname == "android.appwidget.AppWidgetManager": return

    for f in clazz.fields:
        if f.value is None: continue
        if f.name.startswith("ACTION_"): continue

        if "static" in f.split and "final" in f.split and f.typ == "java.lang.String":
            if "_EXTRA" in f.name or "EXTRA_" in f.name or ".extra" in f.value.lower():
                if not f.name.startswith("EXTRA_"):
                    error(clazz, f, "C3", "Intent extra must be EXTRA_FOO")
                else:
                    if clazz.pkg.name == "android.content" and clazz.name == "Intent":
                        prefix = "android.intent.extra"
                    elif clazz.pkg.name == "android.app.admin":
                        prefix = "android.app.extra"
                    else:
                        prefix = clazz.pkg.name + ".extra"
                    expected = prefix + "." + f.name[6:]
                    if f.value != expected:
                        error(clazz, f, "C4", "Inconsistent extra value; expected %s" % (expected))


def verify_equals(clazz):
    """Verify that equals() and hashCode() must be overridden together."""
    eq = False
    hc = False
    for m in clazz.methods:
        if " static " in m.raw: continue
        if "boolean equals(java.lang.Object)" in m.raw: eq = True
        if "int hashCode()" in m.raw: hc = True
    if eq != hc:
        error(clazz, None, "M8", "Must override both equals and hashCode; missing one")


def verify_parcelable(clazz):
    """Verify that Parcelable objects aren't hiding required bits."""
    if "implements android.os.Parcelable" in clazz.raw:
        creator = [ i for i in clazz.fields if i.name == "CREATOR" ]
        write = [ i for i in clazz.methods if i.name == "writeToParcel" ]
        describe = [ i for i in clazz.methods if i.name == "describeContents" ]

        if len(creator) == 0 or len(write) == 0 or len(describe) == 0:
            error(clazz, None, "FW3", "Parcelable requires CREATOR, writeToParcel, and describeContents; missing one")

        if ((" final class " not in clazz.raw) and
            (" final deprecated class " not in clazz.raw)):
            error(clazz, None, "FW8", "Parcelable classes must be final")


def verify_protected(clazz):
    """Verify that no protected methods or fields are allowed."""
    for m in clazz.methods:
        if "protected" in m.split:
            error(clazz, m, "M7", "Protected methods not allowed; must be public")
    for f in clazz.fields:
        if "protected" in f.split:
            error(clazz, f, "M7", "Protected fields not allowed; must be public")


def verify_fields(clazz):
    """Verify that all exposed fields are final.
    Exposed fields must follow myName style.
    Catch internal mFoo objects being exposed."""

    IGNORE_BARE_FIELDS = [
        "android.app.ActivityManager.RecentTaskInfo",
        "android.app.Notification",
        "android.content.pm.ActivityInfo",
        "android.content.pm.ApplicationInfo",
        "android.content.pm.ComponentInfo",
        "android.content.pm.ResolveInfo",
        "android.content.pm.FeatureGroupInfo",
        "android.content.pm.InstrumentationInfo",
        "android.content.pm.PackageInfo",
        "android.content.pm.PackageItemInfo",
        "android.content.res.Configuration",
        "android.graphics.BitmapFactory.Options",
        "android.os.Message",
        "android.system.StructPollfd",
    ]

    for f in clazz.fields:
        if not "final" in f.split:
            if clazz.fullname in IGNORE_BARE_FIELDS:
                pass
            elif clazz.fullname.endswith("LayoutParams"):
                pass
            elif clazz.fullname.startswith("android.util.Mutable"):
                pass
            else:
                error(clazz, f, "F2", "Bare fields must be marked final, or add accessors if mutable")

        if not "static" in f.split:
            if not re.match("[a-z]([a-zA-Z]+)?", f.name):
                error(clazz, f, "S1", "Non-static fields must be named using myField style")

        if re.match("[ms][A-Z]", f.name):
            error(clazz, f, "F1", "Internal objects must not be exposed")

        if re.match("[A-Z_]+", f.name):
            if "static" not in f.split or "final" not in f.split:
                error(clazz, f, "C2", "Constants must be marked static final")


def verify_register(clazz):
    """Verify parity of registration methods.
    Callback objects use register/unregister methods.
    Listener objects use add/remove methods."""
    methods = [ m.name for m in clazz.methods ]
    for m in clazz.methods:
        if "Callback" in m.raw:
            if m.name.startswith("register"):
                other = "unregister" + m.name[8:]
                if other not in methods:
                    error(clazz, m, "L2", "Missing unregister method")
            if m.name.startswith("unregister"):
                other = "register" + m.name[10:]
                if other not in methods:
                    error(clazz, m, "L2", "Missing register method")

            if m.name.startswith("add") or m.name.startswith("remove"):
                error(clazz, m, "L3", "Callback methods should be named register/unregister")

        if "Listener" in m.raw:
            if m.name.startswith("add"):
                other = "remove" + m.name[3:]
                if other not in methods:
                    error(clazz, m, "L2", "Missing remove method")
            if m.name.startswith("remove") and not m.name.startswith("removeAll"):
                other = "add" + m.name[6:]
                if other not in methods:
                    error(clazz, m, "L2", "Missing add method")

            if m.name.startswith("register") or m.name.startswith("unregister"):
                error(clazz, m, "L3", "Listener methods should be named add/remove")


def verify_sync(clazz):
    """Verify synchronized methods aren't exposed."""
    for m in clazz.methods:
        if "synchronized" in m.split:
            error(clazz, m, "M5", "Internal locks must not be exposed")


def verify_intent_builder(clazz):
    """Verify that Intent builders are createFooIntent() style."""
    if clazz.name == "Intent": return

    for m in clazz.methods:
        if m.typ == "android.content.Intent":
            if m.name.startswith("create") and m.name.endswith("Intent"):
                pass
            else:
                warn(clazz, m, "FW1", "Methods creating an Intent should be named createFooIntent()")


def verify_helper_classes(clazz):
    """Verify that helper classes are named consistently with what they extend.
    All developer extendable methods should be named onFoo()."""
    test_methods = False
    if "extends android.app.Service" in clazz.raw:
        test_methods = True
        if not clazz.name.endswith("Service"):
            error(clazz, None, "CL4", "Inconsistent class name; should be FooService")

        found = False
        for f in clazz.fields:
            if f.name == "SERVICE_INTERFACE":
                found = True
                if f.value != clazz.fullname:
                    error(clazz, f, "C4", "Inconsistent interface constant; expected %s" % (clazz.fullname))

    if "extends android.content.ContentProvider" in clazz.raw:
        test_methods = True
        if not clazz.name.endswith("Provider"):
            error(clazz, None, "CL4", "Inconsistent class name; should be FooProvider")

        found = False
        for f in clazz.fields:
            if f.name == "PROVIDER_INTERFACE":
                found = True
                if f.value != clazz.fullname:
                    error(clazz, f, "C4", "Inconsistent interface constant; expected %s" % (clazz.fullname))

    if "extends android.content.BroadcastReceiver" in clazz.raw:
        test_methods = True
        if not clazz.name.endswith("Receiver"):
            error(clazz, None, "CL4", "Inconsistent class name; should be FooReceiver")

    if "extends android.app.Activity" in clazz.raw:
        test_methods = True
        if not clazz.name.endswith("Activity"):
            error(clazz, None, "CL4", "Inconsistent class name; should be FooActivity")

    if test_methods:
        for m in clazz.methods:
            if "final" in m.split: continue
            if not re.match("on[A-Z]", m.name):
                if "abstract" in m.split:
                    warn(clazz, m, None, "Methods implemented by developers should be named onFoo()")
                else:
                    warn(clazz, m, None, "If implemented by developer, should be named onFoo(); otherwise consider marking final")


def verify_builder(clazz):
    """Verify builder classes.
    Methods should return the builder to enable chaining."""
    if " extends " in clazz.raw: return
    if not clazz.name.endswith("Builder"): return

    if clazz.name != "Builder":
        warn(clazz, None, None, "Builder should be defined as inner class")

    has_build = False
    for m in clazz.methods:
        if m.name == "build":
            has_build = True
            continue

        if m.name.startswith("get"): continue
        if m.name.startswith("clear"): continue

        if m.name.startswith("with"):
            warn(clazz, m, None, "Builder methods names should use setFoo() style")

        if m.name.startswith("set"):
            if not m.typ.endswith(clazz.fullname):
                warn(clazz, m, "M4", "Methods must return the builder object")

    if not has_build:
        warn(clazz, None, None, "Missing build() method")


def verify_aidl(clazz):
    """Catch people exposing raw AIDL."""
    if "extends android.os.Binder" in clazz.raw or "implements android.os.IInterface" in clazz.raw:
        error(clazz, None, None, "Raw AIDL interfaces must not be exposed")


def verify_internal(clazz):
    """Catch people exposing internal classes."""
    if clazz.pkg.name.startswith("com.android"):
        error(clazz, None, None, "Internal classes must not be exposed")


def verify_layering(clazz):
    """Catch package layering violations.
    For example, something in android.os depending on android.app."""
    ranking = [
        ["android.service","android.accessibilityservice","android.inputmethodservice","android.printservice","android.appwidget","android.webkit","android.preference","android.gesture","android.print"],
        "android.app",
        "android.widget",
        "android.view",
        "android.animation",
        "android.provider",
        ["android.content","android.graphics.drawable"],
        "android.database",
        "android.graphics",
        "android.text",
        "android.os",
        "android.util"
    ]

    def rank(p):
        for i in range(len(ranking)):
            if isinstance(ranking[i], list):
                for j in ranking[i]:
                    if p.startswith(j): return i
            else:
                if p.startswith(ranking[i]): return i

    cr = rank(clazz.pkg.name)
    if cr is None: return

    for f in clazz.fields:
        ir = rank(f.typ)
        if ir and ir < cr:
            warn(clazz, f, "FW6", "Field type violates package layering")

    for m in clazz.methods:
        ir = rank(m.typ)
        if ir and ir < cr:
            warn(clazz, m, "FW6", "Method return type violates package layering")
        for arg in m.args:
            ir = rank(arg)
            if ir and ir < cr:
                warn(clazz, m, "FW6", "Method argument type violates package layering")


def verify_boolean(clazz):
    """Verifies that boolean accessors are named correctly.
    For example, hasFoo() and setHasFoo()."""

    def is_get(m): return len(m.args) == 0 and m.typ == "boolean"
    def is_set(m): return len(m.args) == 1 and m.args[0] == "boolean"

    gets = [ m for m in clazz.methods if is_get(m) ]
    sets = [ m for m in clazz.methods if is_set(m) ]

    def error_if_exists(methods, trigger, expected, actual):
        for m in methods:
            if m.name == actual:
                error(clazz, m, "M6", "Symmetric method for %s must be named %s" % (trigger, expected))

    for m in clazz.methods:
        if is_get(m):
            if re.match("is[A-Z]", m.name):
                target = m.name[2:]
                expected = "setIs" + target
                error_if_exists(sets, m.name, expected, "setHas" + target)
            elif re.match("has[A-Z]", m.name):
                target = m.name[3:]
                expected = "setHas" + target
                error_if_exists(sets, m.name, expected, "setIs" + target)
                error_if_exists(sets, m.name, expected, "set" + target)
            elif re.match("get[A-Z]", m.name):
                target = m.name[3:]
                expected = "set" + target
                error_if_exists(sets, m.name, expected, "setIs" + target)
                error_if_exists(sets, m.name, expected, "setHas" + target)

        if is_set(m):
            if re.match("set[A-Z]", m.name):
                target = m.name[3:]
                expected = "get" + target
                error_if_exists(sets, m.name, expected, "is" + target)
                error_if_exists(sets, m.name, expected, "has" + target)


def verify_collections(clazz):
    """Verifies that collection types are interfaces."""
    if clazz.fullname == "android.os.Bundle": return

    bad = ["java.util.Vector", "java.util.LinkedList", "java.util.ArrayList", "java.util.Stack",
           "java.util.HashMap", "java.util.HashSet", "android.util.ArraySet", "android.util.ArrayMap"]
    for m in clazz.methods:
        if m.typ in bad:
            error(clazz, m, "CL2", "Return type is concrete collection; must be higher-level interface")
        for arg in m.args:
            if arg in bad:
                error(clazz, m, "CL2", "Argument is concrete collection; must be higher-level interface")


def verify_flags(clazz):
    """Verifies that flags are non-overlapping."""
    known = collections.defaultdict(int)
    for f in clazz.fields:
        if "FLAG_" in f.name:
            try:
                val = int(f.value)
            except:
                continue

            scope = f.name[0:f.name.index("FLAG_")]
            if val & known[scope]:
                warn(clazz, f, "C1", "Found overlapping flag constant value")
            known[scope] |= val


def verify_exception(clazz):
    """Verifies that methods don't throw generic exceptions."""
    for m in clazz.methods:
        if "throws java.lang.Exception" in m.raw or "throws java.lang.Throwable" in m.raw or "throws java.lang.Error" in m.raw:
            error(clazz, m, "S1", "Methods must not throw generic exceptions")

        if "throws android.os.RemoteException" in m.raw:
            if clazz.name == "android.content.ContentProviderClient": continue
            if clazz.name == "android.os.Binder": continue
            if clazz.name == "android.os.IBinder": continue

            error(clazz, m, "FW9", "Methods calling into system server should rethrow RemoteException as RuntimeException")


def verify_google(clazz):
    """Verifies that APIs never reference Google."""

    if re.search("google", clazz.raw, re.IGNORECASE):
        error(clazz, None, None, "Must never reference Google")

    test = []
    test.extend(clazz.ctors)
    test.extend(clazz.fields)
    test.extend(clazz.methods)

    for t in test:
        if re.search("google", t.raw, re.IGNORECASE):
            error(clazz, t, None, "Must never reference Google")


def verify_bitset(clazz):
    """Verifies that we avoid using heavy BitSet."""

    for f in clazz.fields:
        if f.typ == "java.util.BitSet":
            error(clazz, f, None, "Field type must not be heavy BitSet")

    for m in clazz.methods:
        if m.typ == "java.util.BitSet":
            error(clazz, m, None, "Return type must not be heavy BitSet")
        for arg in m.args:
            if arg == "java.util.BitSet":
                error(clazz, m, None, "Argument type must not be heavy BitSet")


def verify_manager(clazz):
    """Verifies that FooManager is only obtained from Context."""

    if not clazz.name.endswith("Manager"): return

    for c in clazz.ctors:
        error(clazz, c, None, "Managers must always be obtained from Context; no direct constructors")

    for m in clazz.methods:
        if m.typ == clazz.fullname:
            error(clazz, m, None, "Managers must always be obtained from Context")


def verify_boxed(clazz):
    """Verifies that methods avoid boxed primitives."""

    boxed = ["java.lang.Number","java.lang.Byte","java.lang.Double","java.lang.Float","java.lang.Integer","java.lang.Long","java.lang.Short"]

    for c in clazz.ctors:
        for arg in c.args:
            if arg in boxed:
                error(clazz, c, "M11", "Must avoid boxed primitives")

    for f in clazz.fields:
        if f.typ in boxed:
            error(clazz, f, "M11", "Must avoid boxed primitives")

    for m in clazz.methods:
        if m.typ in boxed:
            error(clazz, m, "M11", "Must avoid boxed primitives")
        for arg in m.args:
            if arg in boxed:
                error(clazz, m, "M11", "Must avoid boxed primitives")


def verify_static_utils(clazz):
    """Verifies that helper classes can't be constructed."""
    if clazz.fullname.startswith("android.opengl"): return
    if clazz.fullname.startswith("android.R"): return

    # Only care about classes with default constructors
    if len(clazz.ctors) == 1 and len(clazz.ctors[0].args) == 0:
        test = []
        test.extend(clazz.fields)
        test.extend(clazz.methods)

        if len(test) == 0: return
        for t in test:
            if "static" not in t.split:
                return

        error(clazz, None, None, "Fully-static utility classes must not have constructor")


def verify_overload_args(clazz):
    """Verifies that method overloads add new arguments at the end."""
    if clazz.fullname.startswith("android.opengl"): return

    overloads = collections.defaultdict(list)
    for m in clazz.methods:
        if "deprecated" in m.split: continue
        overloads[m.name].append(m)

    for name, methods in overloads.items():
        if len(methods) <= 1: continue

        # Look for arguments common across all overloads
        def cluster(args):
            count = collections.defaultdict(int)
            res = set()
            for i in range(len(args)):
                a = args[i]
                res.add("%s#%d" % (a, count[a]))
                count[a] += 1
            return res

        common_args = cluster(methods[0].args)
        for m in methods:
            common_args = common_args & cluster(m.args)

        if len(common_args) == 0: continue

        # Require that all common arguments are present at start of signature
        locked_sig = None
        for m in methods:
            sig = m.args[0:len(common_args)]
            if not common_args.issubset(cluster(sig)):
                warn(clazz, m, "M2", "Expected common arguments [%s] at beginning of overloaded method" % (", ".join(common_args)))
            elif not locked_sig:
                locked_sig = sig
            elif locked_sig != sig:
                error(clazz, m, "M2", "Expected consistent argument ordering between overloads: %s..." % (", ".join(locked_sig)))


def verify_callback_handlers(clazz):
    """Verifies that methods adding listener/callback have overload
    for specifying delivery thread."""

    # Ignore UI packages which assume main thread
    skip = [
        "animation",
        "view",
        "graphics",
        "transition",
        "widget",
        "webkit",
    ]
    for s in skip:
        if s in clazz.pkg.name_path: return
        if s in clazz.extends_path: return

    # Ignore UI classes which assume main thread
    if "app" in clazz.pkg.name_path or "app" in clazz.extends_path:
        for s in ["ActionBar","Dialog","Application","Activity","Fragment","Loader"]:
            if s in clazz.fullname: return
    if "content" in clazz.pkg.name_path or "content" in clazz.extends_path:
        for s in ["Loader"]:
            if s in clazz.fullname: return

    found = {}
    by_name = collections.defaultdict(list)
    for m in clazz.methods:
        if m.name.startswith("unregister"): continue
        if m.name.startswith("remove"): continue
        if re.match("on[A-Z]+", m.name): continue

        by_name[m.name].append(m)

        for a in m.args:
            if a.endswith("Listener") or a.endswith("Callback") or a.endswith("Callbacks"):
                found[m.name] = m

    for f in found.values():
        takes_handler = False
        takes_exec = False
        for m in by_name[f.name]:
            if "android.os.Handler" in m.args:
                takes_handler = True
            if "java.util.concurrent.Executor" in m.args:
                takes_exec = True
        if not takes_exec:
            warn(clazz, f, "L1", "Registration methods should have overload that accepts delivery Executor")


def verify_context_first(clazz):
    """Verifies that methods accepting a Context keep it the first argument."""
    examine = clazz.ctors + clazz.methods
    for m in examine:
        if len(m.args) > 1 and m.args[0] != "android.content.Context":
            if "android.content.Context" in m.args[1:]:
                error(clazz, m, "M3", "Context is distinct, so it must be the first argument")
        if len(m.args) > 1 and m.args[0] != "android.content.ContentResolver":
            if "android.content.ContentResolver" in m.args[1:]:
                error(clazz, m, "M3", "ContentResolver is distinct, so it must be the first argument")


def verify_listener_last(clazz):
    """Verifies that methods accepting a Listener or Callback keep them as last arguments."""
    examine = clazz.ctors + clazz.methods
    for m in examine:
        if "Listener" in m.name or "Callback" in m.name: continue
        found = False
        for a in m.args:
            if a.endswith("Callback") or a.endswith("Callbacks") or a.endswith("Listener"):
                found = True
            elif found and a != "android.os.Handler" and a != "java.util.concurrent.Executor":
                warn(clazz, m, "M3", "Listeners should always be at end of argument list")


def verify_resource_names(clazz):
    """Verifies that resource names have consistent case."""
    if not re.match("android\.R\.[a-z]+", clazz.fullname): return

    # Resources defined by files are foo_bar_baz
    if clazz.name in ["anim","animator","color","dimen","drawable","interpolator","layout","transition","menu","mipmap","string","plurals","raw","xml"]:
        for f in clazz.fields:
            if re.match("[a-z1-9_]+$", f.name): continue
            error(clazz, f, None, "Expected resource name in this class to be foo_bar_baz style")

    # Resources defined inside files are fooBarBaz
    if clazz.name in ["array","attr","id","bool","fraction","integer"]:
        for f in clazz.fields:
            if re.match("config_[a-z][a-zA-Z1-9]*$", f.name): continue
            if re.match("layout_[a-z][a-zA-Z1-9]*$", f.name): continue
            if re.match("state_[a-z_]*$", f.name): continue

            if re.match("[a-z][a-zA-Z1-9]*$", f.name): continue
            error(clazz, f, "C7", "Expected resource name in this class to be fooBarBaz style")

    # Styles are FooBar_Baz
    if clazz.name in ["style"]:
        for f in clazz.fields:
            if re.match("[A-Z][A-Za-z1-9]+(_[A-Z][A-Za-z1-9]+?)*$", f.name): continue
            error(clazz, f, "C7", "Expected resource name in this class to be FooBar_Baz style")


def verify_files(clazz):
    """Verifies that methods accepting File also accept streams."""

    has_file = set()
    has_stream = set()

    test = []
    test.extend(clazz.ctors)
    test.extend(clazz.methods)

    for m in test:
        if "java.io.File" in m.args:
            has_file.add(m)
        if "java.io.FileDescriptor" in m.args or "android.os.ParcelFileDescriptor" in m.args or "java.io.InputStream" in m.args or "java.io.OutputStream" in m.args:
            has_stream.add(m.name)

    for m in has_file:
        if m.name not in has_stream:
            warn(clazz, m, "M10", "Methods accepting File should also accept FileDescriptor or streams")


def verify_manager_list(clazz):
    """Verifies that managers return List<? extends Parcelable> instead of arrays."""

    if not clazz.name.endswith("Manager"): return

    for m in clazz.methods:
        if m.typ.startswith("android.") and m.typ.endswith("[]"):
            warn(clazz, m, None, "Methods should return List<? extends Parcelable> instead of Parcelable[] to support ParceledListSlice under the hood")


def verify_abstract_inner(clazz):
    """Verifies that abstract inner classes are static."""

    if re.match(".+?\.[A-Z][^\.]+\.[A-Z]", clazz.fullname):
        if " abstract " in clazz.raw and " static " not in clazz.raw:
            warn(clazz, None, None, "Abstract inner classes should be static to improve testability")


def verify_runtime_exceptions(clazz):
    """Verifies that runtime exceptions aren't listed in throws."""

    banned = [
        "java.lang.NullPointerException",
        "java.lang.ClassCastException",
        "java.lang.IndexOutOfBoundsException",
        "java.lang.reflect.UndeclaredThrowableException",
        "java.lang.reflect.MalformedParametersException",
        "java.lang.reflect.MalformedParameterizedTypeException",
        "java.lang.invoke.WrongMethodTypeException",
        "java.lang.EnumConstantNotPresentException",
        "java.lang.IllegalMonitorStateException",
        "java.lang.SecurityException",
        "java.lang.UnsupportedOperationException",
        "java.lang.annotation.AnnotationTypeMismatchException",
        "java.lang.annotation.IncompleteAnnotationException",
        "java.lang.TypeNotPresentException",
        "java.lang.IllegalStateException",
        "java.lang.ArithmeticException",
        "java.lang.IllegalArgumentException",
        "java.lang.ArrayStoreException",
        "java.lang.NegativeArraySizeException",
        "java.util.MissingResourceException",
        "java.util.EmptyStackException",
        "java.util.concurrent.CompletionException",
        "java.util.concurrent.RejectedExecutionException",
        "java.util.IllformedLocaleException",
        "java.util.ConcurrentModificationException",
        "java.util.NoSuchElementException",
        "java.io.UncheckedIOException",
        "java.time.DateTimeException",
        "java.security.ProviderException",
        "java.nio.BufferUnderflowException",
        "java.nio.BufferOverflowException",
    ]

    test = []
    test.extend(clazz.ctors)
    test.extend(clazz.methods)

    for t in test:
        if " throws " not in t.raw: continue
        throws = t.raw[t.raw.index(" throws "):]
        for b in banned:
            if b in throws:
                error(clazz, t, None, "Methods must not mention RuntimeException subclasses in throws clauses")


def verify_error(clazz):
    """Verifies that we always use Exception instead of Error."""
    if not clazz.extends: return
    if clazz.extends.endswith("Error"):
        error(clazz, None, None, "Trouble must be reported through an Exception, not Error")
    if clazz.extends.endswith("Exception") and not clazz.name.endswith("Exception"):
        error(clazz, None, None, "Exceptions must be named FooException")


def verify_units(clazz):
    """Verifies that we use consistent naming for units."""

    # If we find K, recommend replacing with V
    bad = {
        "Ns": "Nanos",
        "Ms": "Millis or Micros",
        "Sec": "Seconds", "Secs": "Seconds",
        "Hr": "Hours", "Hrs": "Hours",
        "Mo": "Months", "Mos": "Months",
        "Yr": "Years", "Yrs": "Years",
        "Byte": "Bytes", "Space": "Bytes",
    }

    for m in clazz.methods:
        if m.typ not in ["short","int","long"]: continue
        for k, v in bad.iteritems():
            if m.name.endswith(k):
                error(clazz, m, None, "Expected method name units to be " + v)
        if m.name.endswith("Nanos") or m.name.endswith("Micros"):
            warn(clazz, m, None, "Returned time values are strongly encouraged to be in milliseconds unless you need the extra precision")
        if m.name.endswith("Seconds"):
            error(clazz, m, None, "Returned time values must be in milliseconds")

    for m in clazz.methods:
        typ = m.typ
        if typ == "void":
            if len(m.args) != 1: continue
            typ = m.args[0]

        if m.name.endswith("Fraction") and typ != "float":
            error(clazz, m, None, "Fractions must use floats")
        if m.name.endswith("Percentage") and typ != "int":
            error(clazz, m, None, "Percentage must use ints")


def verify_closable(clazz):
    """Verifies that classes are AutoClosable."""
    if "implements java.lang.AutoCloseable" in clazz.raw: return
    if "implements java.io.Closeable" in clazz.raw: return

    for m in clazz.methods:
        if len(m.args) > 0: continue
        if m.name in ["close","release","destroy","finish","finalize","disconnect","shutdown","stop","free","quit"]:
            warn(clazz, m, None, "Classes that release resources should implement AutoClosable and CloseGuard")
            return


def verify_member_name_not_kotlin_keyword(clazz):
    """Prevent method names which are keywords in Kotlin."""

    # https://kotlinlang.org/docs/reference/keyword-reference.html#hard-keywords
    # This list does not include Java keywords as those are already impossible to use.
    keywords = [
        'as',
        'fun',
        'in',
        'is',
        'object',
        'typealias',
        'val',
        'var',
        'when',
    ]

    for m in clazz.methods:
        if m.name in keywords:
            error(clazz, m, None, "Method name must not be a Kotlin keyword")
    for f in clazz.fields:
        if f.name in keywords:
            error(clazz, f, None, "Field name must not be a Kotlin keyword")


def verify_method_name_not_kotlin_operator(clazz):
    """Warn about method names which become operators in Kotlin."""

    binary = set()

    def unique_binary_op(m, op):
        if op in binary:
            error(clazz, m, None, "Only one of '{0}' and '{0}Assign' methods should be present for Kotlin".format(op))
        binary.add(op)

    for m in clazz.methods:
        if 'static' in m.split:
            continue

        # https://kotlinlang.org/docs/reference/operator-overloading.html#unary-prefix-operators
        if m.name in ['unaryPlus', 'unaryMinus', 'not'] and len(m.args) == 0:
            warn(clazz, m, None, "Method can be invoked as a unary operator from Kotlin")

        # https://kotlinlang.org/docs/reference/operator-overloading.html#increments-and-decrements
        if m.name in ['inc', 'dec'] and len(m.args) == 0 and m.typ != 'void':
            # This only applies if the return type is the same or a subtype of the enclosing class, but we have no
            # practical way of checking that relationship here.
            warn(clazz, m, None, "Method can be invoked as a pre/postfix inc/decrement operator from Kotlin")

        # https://kotlinlang.org/docs/reference/operator-overloading.html#arithmetic
        if m.name in ['plus', 'minus', 'times', 'div', 'rem', 'mod', 'rangeTo'] and len(m.args) == 1:
            warn(clazz, m, None, "Method can be invoked as a binary operator from Kotlin")
            unique_binary_op(m, m.name)

        # https://kotlinlang.org/docs/reference/operator-overloading.html#in
        if m.name == 'contains' and len(m.args) == 1 and m.typ == 'boolean':
            warn(clazz, m, None, "Method can be invoked as a 'in' operator from Kotlin")

        # https://kotlinlang.org/docs/reference/operator-overloading.html#indexed
        if (m.name == 'get' and len(m.args) > 0) or (m.name == 'set' and len(m.args) > 1):
            warn(clazz, m, None, "Method can be invoked with an indexing operator from Kotlin")

        # https://kotlinlang.org/docs/reference/operator-overloading.html#invoke
        if m.name == 'invoke':
            warn(clazz, m, None, "Method can be invoked with function call syntax from Kotlin")

        # https://kotlinlang.org/docs/reference/operator-overloading.html#assignments
        if m.name in ['plusAssign', 'minusAssign', 'timesAssign', 'divAssign', 'remAssign', 'modAssign'] \
                and len(m.args) == 1 \
                and m.typ == 'void':
            warn(clazz, m, None, "Method can be invoked as a compound assignment operator from Kotlin")
            unique_binary_op(m, m.name[:-6])  # Remove 'Assign' suffix


def verify_collections_over_arrays(clazz):
    """Warn that [] should be Collections."""

    safe = ["java.lang.String[]","byte[]","short[]","int[]","long[]","float[]","double[]","boolean[]","char[]"]
    for m in clazz.methods:
        if m.typ.endswith("[]") and m.typ not in safe:
            warn(clazz, m, None, "Method should return Collection<> (or subclass) instead of raw array")
        for arg in m.args:
            if arg.endswith("[]") and arg not in safe:
                warn(clazz, m, None, "Method argument should be Collection<> (or subclass) instead of raw array")


def examine_clazz(clazz):
    """Find all style issues in the given class."""

    notice(clazz)

    if clazz.pkg.name.startswith("java"): return
    if clazz.pkg.name.startswith("junit"): return
    if clazz.pkg.name.startswith("org.apache"): return
    if clazz.pkg.name.startswith("org.xml"): return
    if clazz.pkg.name.startswith("org.json"): return
    if clazz.pkg.name.startswith("org.w3c"): return
    if clazz.pkg.name.startswith("android.icu."): return

    verify_constants(clazz)
    verify_enums(clazz)
    verify_class_names(clazz)
    verify_method_names(clazz)
    verify_callbacks(clazz)
    verify_listeners(clazz)
    verify_actions(clazz)
    verify_extras(clazz)
    verify_equals(clazz)
    verify_parcelable(clazz)
    verify_protected(clazz)
    verify_fields(clazz)
    verify_register(clazz)
    verify_sync(clazz)
    verify_intent_builder(clazz)
    verify_helper_classes(clazz)
    verify_builder(clazz)
    verify_aidl(clazz)
    verify_internal(clazz)
    verify_layering(clazz)
    verify_boolean(clazz)
    verify_collections(clazz)
    verify_flags(clazz)
    verify_exception(clazz)
    if not ALLOW_GOOGLE: verify_google(clazz)
    verify_bitset(clazz)
    verify_manager(clazz)
    verify_boxed(clazz)
    verify_static_utils(clazz)
    # verify_overload_args(clazz)
    verify_callback_handlers(clazz)
    verify_context_first(clazz)
    verify_listener_last(clazz)
    verify_resource_names(clazz)
    verify_files(clazz)
    verify_manager_list(clazz)
    verify_abstract_inner(clazz)
    verify_runtime_exceptions(clazz)
    verify_error(clazz)
    verify_units(clazz)
    verify_closable(clazz)
    verify_member_name_not_kotlin_keyword(clazz)
    verify_method_name_not_kotlin_operator(clazz)
    verify_collections_over_arrays(clazz)


def examine_stream(stream):
    """Find all style issues in the given API stream."""
    global failures, noticed
    failures = {}
    noticed = {}
    _parse_stream(stream, examine_clazz)
    return (failures, noticed)


def examine_api(api):
    """Find all style issues in the given parsed API."""
    global failures
    failures = {}
    for key in sorted(api.keys()):
        examine_clazz(api[key])
    return failures


def verify_compat(cur, prev):
    """Find any incompatible API changes between two levels."""
    global failures

    def class_exists(api, test):
        return test.fullname in api

    def ctor_exists(api, clazz, test):
        for m in clazz.ctors:
            if m.ident == test.ident: return True
        return False

    def all_methods(api, clazz):
        methods = list(clazz.methods)
        if clazz.extends is not None:
            methods.extend(all_methods(api, api[clazz.extends]))
        return methods

    def method_exists(api, clazz, test):
        methods = all_methods(api, clazz)
        for m in methods:
            if m.ident == test.ident: return True
        return False

    def field_exists(api, clazz, test):
        for f in clazz.fields:
            if f.ident == test.ident: return True
        return False

    failures = {}
    for key in sorted(prev.keys()):
        prev_clazz = prev[key]

        if not class_exists(cur, prev_clazz):
            error(prev_clazz, None, None, "Class removed or incompatible change")
            continue

        cur_clazz = cur[key]

        for test in prev_clazz.ctors:
            if not ctor_exists(cur, cur_clazz, test):
                error(prev_clazz, prev_ctor, None, "Constructor removed or incompatible change")

        methods = all_methods(prev, prev_clazz)
        for test in methods:
            if not method_exists(cur, cur_clazz, test):
                error(prev_clazz, test, None, "Method removed or incompatible change")

        for test in prev_clazz.fields:
            if not field_exists(cur, cur_clazz, test):
                error(prev_clazz, test, None, "Field removed or incompatible change")

    return failures


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Enforces common Android public API design \
            patterns. It ignores lint messages from a previous API level, if provided.")
    parser.add_argument("current.txt", type=argparse.FileType('r'), help="current.txt")
    parser.add_argument("previous.txt", nargs='?', type=argparse.FileType('r'), default=None,
            help="previous.txt")
    parser.add_argument("--no-color", action='store_const', const=True,
            help="Disable terminal colors")
    parser.add_argument("--allow-google", action='store_const', const=True,
            help="Allow references to Google")
    parser.add_argument("--show-noticed", action='store_const', const=True,
            help="Show API changes noticed")
    args = vars(parser.parse_args())

    if args['no_color']:
        USE_COLOR = False

    if args['allow_google']:
        ALLOW_GOOGLE = True

    current_file = args['current.txt']
    previous_file = args['previous.txt']

    with current_file as f:
        cur_fail, cur_noticed = examine_stream(f)
    if not previous_file is None:
        with previous_file as f:
            prev_fail, prev_noticed = examine_stream(f)

        # ignore errors from previous API level
        for p in prev_fail:
            if p in cur_fail:
                del cur_fail[p]

        # ignore classes unchanged from previous API level
        for k, v in prev_noticed.iteritems():
            if k in cur_noticed and v == cur_noticed[k]:
                del cur_noticed[k]

        """
        # NOTE: disabled because of memory pressure
        # look for compatibility issues
        compat_fail = verify_compat(cur, prev)

        print "%s API compatibility issues %s\n" % ((format(fg=WHITE, bg=BLUE, bold=True), format(reset=True)))
        for f in sorted(compat_fail):
            print compat_fail[f]
            print
        """

    if args['show_noticed'] and len(cur_noticed) != 0:
        print "%s API changes noticed %s\n" % ((format(fg=WHITE, bg=BLUE, bold=True), format(reset=True)))
        for f in sorted(cur_noticed.keys()):
            print f
        print

    if len(cur_fail) != 0:
        print "%s API style issues %s\n" % ((format(fg=WHITE, bg=BLUE, bold=True), format(reset=True)))
        for f in sorted(cur_fail):
            print cur_fail[f]
            print
        sys.exit(77)