Add tools/find-add-class to tools/lint-all.

The find-add-class tool, when in lint mode, verifies that we can
understand all calls to addClass from our JS code.

When in non-lint mode, i.e. verbose mode, the tool prints out a
list of tuples of (fn, class) that we can use as we wish in other
tools.

tools/lib/find_add_class.py

@@ -0,0 +1,98 @@
+from __future__ import absolute_import
+from __future__ import print_function
+
+from typing import Set, Tuple
+
+import os
+import re
+
+GENERIC_KEYWORDS = [
+    'active',
+    'alert',
+    'danger',
+    'condensed',
+    'disabled',
+    'error',
+    'expanded',
+    'hide',
+    'notdisplayed',
+    'popover',
+    'success',
+    'text-error',
+    'warning',
+]
+
+def raise_error(fn, i, line):
+    # type: (str, int, str) -> None
+    error = '''
+        In %s line %d there is the following line of code:
+
+        %s
+
+        Our tools want to be able to identify which modules
+        add which HTML/CSS classes, and we need two things to
+        happen:
+
+            - The code must explicitly name the class.
+            - Only one module can refer to that class (unless
+              it is something generic like an alert class).
+
+        If you get this error, you can usually address it by
+        refactoring your code to be more explicit, or you can
+        move the common code that sets the class to a library
+        module.  If neither of those applies, you need to
+        modify %s
+        ''' % (fn, i, line, __file__)
+    raise Exception(error)
+
+def generic(html_class):
+    # type: (str) -> bool
+    for kw in GENERIC_KEYWORDS:
+        if kw in html_class:
+            return True
+
+def display(fns):
+    # type: (List[str]) -> None
+    for tup in find(fns):
+        # this format is for code generation purposes
+        print(' ' * 8 + repr(tup) + ',')
+
+def find(fns):
+    # type: (List[str]) -> List[Tuple[str, str]]
+    encountered = set() # type: Set[str]
+    tups = [] # type: List[Tuple[str, str]]
+    for fn in fns:
+        lines = list(open(fn))
+        fn = os.path.basename(fn)
+        module_classes = set() # type: Set[str]
+        for i, line in enumerate(lines):
+            if 'addClass' in line:
+                html_classes = [] # type: List[str]
+                m = re.search('addClass\([\'"](.*?)[\'"]', line)
+                if m:
+                    html_classes = [m.group(1)]
+                if not html_classes:
+                    if 'bar-success' in line:
+                        html_classes = ['bar-success', 'bar-danger']
+                    elif 'color_class' in line:
+                        continue
+                    elif 'stream_dark' in line:
+                        continue
+                    elif fn == 'signup.js' and 'class_to_add' in line:
+                        html_classes = ['error', 'success']
+                    elif fn == 'ui.js' and 'status_classes' in line:
+                        html_classes = ['alert']
+
+                if not html_classes:
+                    raise_error(fn, i, line)
+                for html_class in html_classes:
+                    if generic(html_class):
+                        continue
+                    if html_class in module_classes:
+                        continue
+                    if html_class in encountered:
+                        raise_error(fn, i, line)
+                    tups.append((fn, html_class))
+                    module_classes.add(html_class)
+                    encountered.add(html_class)
+    return tups