pdmgen: Add core parsing logic

Add logic to parse each yaml file in three stages.
  1 - Invoke factory methods for config file directives, generating
      more factory methods.
  2 - Invoke factory methods from 1 for the full set of renderable
      items.
  3 - Run 'setup' on all renderable items to resolve item cross
      references.

Change-Id: I428a9ae1c41cf65e1efc05f3ec7177375822d772
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>

2 files changed, 205 insertions, 14 deletions

diff --git a/src/pdmgen.py b/src/pdmgen.py
index 6476a95..711df52 100755
--- a/src/pdmgen.py
+++ b/src/pdmgen.py
@@ -21,6 +21,66 @@ import yaml
 import mako.lookup
 from argparse import ArgumentParser
 from sdbusplus.renderer import Renderer
+from sdbusplus.namedelement import NamedElement
+
+
+class InvalidConfigError(BaseException):
+    '''General purpose config file parsing error.'''
+
+    def __init__(self, path, msg):
+        '''Display configuration file with the syntax
+        error and the error message.'''
+
+        self.config = path
+        self.msg = msg
+
+
+class NotUniqueError(InvalidConfigError):
+    '''Within a config file names must be unique.
+    Display the config file with the duplicate and
+    the duplicate itself.'''
+
+    def __init__(self, path, cls, *names):
+        fmt = 'Duplicate {0}: "{1}"'
+        super(NotUniqueError, self).__init__(
+            path, fmt.format(cls, ' '.join(names)))
+
+
+def get_index(objs, cls, name, config=None):
+    '''Items are usually rendered as C++ arrays and as
+    such are stored in python lists.  Given an item name
+    its class, and an optional config file filter, find
+    the item index.'''
+
+    for i, x in enumerate(objs.get(cls, [])):
+        if config and x.configfile != config:
+            continue
+        if x.name != name:
+            continue
+
+        return i
+    raise InvalidConfigError(config, 'Could not find name: "{0}"'.format(name))
+
+
+def exists(objs, cls, name, config=None):
+    '''Check to see if an item already exists in a list given
+    the item name.'''
+
+    try:
+        get_index(objs, cls, name, config)
+    except:
+        return False
+
+    return True
+
+
+def add_unique(obj, *a, **kw):
+    '''Add an item to one or more lists unless already present,
+    with an option to constrain the search to a specific config file.'''
+
+    for container in a:
+        if not exists(container, obj.cls, obj.name, config=kw.get('config')):
+            container.setdefault(obj.cls, []).append(obj)
 
 
 class Indent(object):
@@ -37,24 +97,148 @@ class Indent(object):
         return 4*' '*(depth + self.depth)
 
 
+class ConfigEntry(NamedElement):
+    '''Base interface for rendered items.'''
+
+    def __init__(self, *a, **kw):
+        '''Pop the configfile/class/subclass keywords.'''
+
+        self.configfile = kw.pop('configfile')
+        self.cls = kw.pop('class')
+        self.subclass = kw.pop(self.cls)
+        super(ConfigEntry, self).__init__(**kw)
+
+    def factory(self, objs):
+        ''' Optional factory interface for subclasses to add
+        additional items to be rendered.'''
+
+        pass
+
+    def setup(self, objs):
+        ''' Optional setup interface for subclasses, invoked
+        after all factory methods have been run.'''
+
+        pass
+
+
+class Group(ConfigEntry):
+    '''Pop the members keyword for groups.'''
+
+    def __init__(self, *a, **kw):
+        self.members = kw.pop('members')
+        super(Group, self).__init__(**kw)
+
+
+class ImplicitGroup(Group):
+    '''Provide a factory method for groups whose members are
+    not explicitly declared in the config files.'''
+
+    def __init__(self, *a, **kw):
+        super(ImplicitGroup, self).__init__(**kw)
+
+    def factory(self, objs):
+        '''Create group members.'''
+
+        factory = Everything.classmap(self.subclass, 'element')
+        for m in self.members:
+            args = {
+                'class': self.subclass,
+                self.subclass: 'element',
+                'name': m
+            }
+
+            obj = factory(configfile=self.configfile, **args)
+            add_unique(obj, objs)
+            obj.factory(objs)
+
+        super(ImplicitGroup, self).factory(objs)
+
+
 class Everything(Renderer):
     '''Parse/render entry point.'''
 
     @staticmethod
+    def classmap(cls, sub=None):
+        '''Map render item class and subclass entries to the appropriate
+        handler methods.'''
+
+        class_map = {
+        }
+
+        if cls not in class_map:
+            raise NotImplementedError('Unknown class: "{0}"'.format(cls))
+        if sub not in class_map[cls]:
+            raise NotImplementedError('Unknown {0} type: "{1}"'.format(
+                cls, sub))
+
+        return class_map[cls][sub]
+
+    @staticmethod
+    def load_one_yaml(path, fd, objs):
+        '''Parse a single YAML file.  Parsing occurs in three phases.
+        In the first phase a factory method associated with each
+        configuration file directive is invoked.  These factory
+        methods generate more factory methods.  In the second
+        phase the factory methods created in the first phase
+        are invoked.  In the last phase a callback is invoked on
+        each object created in phase two.  Typically the callback
+        resolves references to other configuration file directives.'''
+
+        factory_objs = {}
+        for x in yaml.safe_load(fd.read()) or {}:
+
+            # Create factory object for this config file directive.
+            cls = x['class']
+            sub = x.get(cls)
+            if cls == 'group':
+                cls = '{0}group'.format(sub)
+
+            factory = Everything.classmap(cls, sub)
+            obj = factory(configfile=path, **x)
+
+            # For a given class of directive, validate the file
+            # doesn't have any duplicate names (duplicates are
+            # ok across config files).
+            if exists(factory_objs, obj.cls, obj.name, config=path):
+                raise NotUniqueError(path, cls, obj.name)
+
+            factory_objs.setdefault(cls, []).append(obj)
+            objs.setdefault(cls, []).append(obj)
+
+        for cls, items in factory_objs.items():
+            for obj in items:
+                # Add objects for template consumption.
+                obj.factory(objs)
+
+    @staticmethod
     def load(args):
         '''Aggregate all the YAML in the input directory
         into a single aggregate.'''
 
-        if os.path.exists(args.inputdir):
-            yaml_files = filter(
-                lambda x: x.endswith('.yaml'),
-                os.listdir(args.inputdir))
+        objs = {}
+        yaml_files = filter(
+            lambda x: x.endswith('.yaml'),
+            os.listdir(args.inputdir))
 
-            for x in yaml_files:
-                with open(os.path.join(args.inputdir, x), 'r') as fd:
-                    yaml.safe_load(fd.read())
+        yaml_files.sort()
 
-        return Everything()
+        for x in yaml_files:
+            path = os.path.join(args.inputdir, x)
+            with open(path, 'r') as fd:
+                Everything.load_one_yaml(path, fd, objs)
+
+        # Configuration file directives reference each other via
+        # the name attribute; however, when rendered the reference
+        # is just an array index.
+        #
+        # At this point all objects have been created but references
+        # have not been resolved to array indicies.  Instruct objects
+        # to do that now.
+        for cls, items in objs.items():
+            for obj in items:
+                obj.setup(objs)
+
+        return Everything(**objs)
 
     def __init__(self, *a, **kw):
         super(Everything, self).__init__(**kw)
@@ -66,7 +250,6 @@ class Everything(Renderer):
                 self.render(
                     loader,
                     args.template,
-                    events={},
                     indent=Indent()))
 
 if __name__ == '__main__':
@@ -109,8 +292,11 @@ if __name__ == '__main__':
     else:
         lookup = mako.lookup.TemplateLookup(
             directories=args.template_search.split())
-
-    function = getattr(
-        Everything.load(args),
-        valid_commands[args.command])
-    function(lookup)
+    try:
+        function = getattr(
+            Everything.load(args),
+            valid_commands[args.command])
+        function(lookup)
+    except InvalidConfigError as e:
+        sys.stdout.write('{0}: {1}\n\n'.format(e.config, e.msg))
+        raise
diff --git a/src/templates/generated.mako.hpp b/src/templates/generated.mako.hpp
index a2e1adf..2a9c2d1 100644
--- a/src/templates/generated.mako.hpp
+++ b/src/templates/generated.mako.hpp
@@ -2,6 +2,11 @@
 /* This is an auto generated file. Do not edit. */
 #pragma once
 
+#include <array>
+#include <string>
+
+using namespace std::string_literals;
+
 namespace phosphor
 {
 namespace dbus