This patch adds a RESTful HTTP interface to Asterisk.

The API itself is documented using Swagger, a lightweight mechanism for
documenting RESTful API's using JSON. This allows us to use swagger-ui
to provide executable documentation for the API, generate client
bindings in different languages, and generate a lot of the boilerplate
code for implementing the RESTful bindings. The API docs live in the
rest-api/ directory.

The RESTful bindings are generated from the Swagger API docs using a set
of Mustache templates.  The code generator is written in Python, and
uses Pystache. Pystache has no dependencies, and be installed easily
using pip. Code generation code lives in rest-api-templates/.

The generated code reduces a lot of boilerplate when it comes to
handling HTTP requests. It also helps us have greater consistency in the
REST API.

(closes issue ASTERISK-20891)
Review: https://reviewboard.asterisk.org/r/2376/

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@386232 65c4cc65-6c06-0410-ace0-fbb531ad65f3

rest-api-templates/asterisk_processor.py

@@ -0,0 +1,179 @@
+#
+# Asterisk -- An open source telephony toolkit.
+#
+# Copyright (C) 2013, Digium, Inc.
+#
+# David M. Lee, II <dlee@digium.com>
+#
+# See http://www.asterisk.org for more information about
+# the Asterisk project. Please do not directly contact
+# any of the maintainers of this project for assistance;
+# the project provides a web site, mailing lists and IRC
+# channels for your use.
+#
+# This program is free software, distributed under the terms of
+# the GNU General Public License Version 2. See the LICENSE file
+# at the top of the source tree.
+#
+
+"""Implementation of SwaggerPostProcessor which adds fields needed to generate
+Asterisk RESTful HTTP binding code.
+"""
+
+import re
+
+from swagger_model import *
+
+
+def simple_name(name):
+    """Removes the {markers} from a path segement.
+
+    @param name: Swagger path segement, with {pathVar} markers.
+    """
+    if name.startswith('{') and name.endswith('}'):
+        return name[1:-1]
+    return name
+
+
+def snakify(name):
+    """Helper to take a camelCase or dash-seperated name and make it
+    snake_case.
+    """
+    r = ''
+    prior_lower = False
+    for c in name:
+        if c.isupper() and prior_lower:
+            r += "_"
+        if c is '-':
+            c = '_'
+        prior_lower = c.islower()
+        r += c.lower()
+    return r
+
+
+class PathSegment(Stringify):
+    """Tree representation of a Swagger API declaration.
+    """
+    def __init__(self, name, parent):
+        """Ctor.
+
+        @param name: Name of this path segment. May have {pathVar} markers.
+        @param parent: Parent PathSegment.
+        """
+        #: Segment name, with {pathVar} markers removed
+        self.name = simple_name(name)
+        #: True if segment is a {pathVar}, else None.
+        self.is_wildcard = None
+        #: Underscore seperated name all ancestor segments
+        self.full_name = None
+        #: Dictionary of child PathSegements
+        self.__children = OrderedDict()
+        #: List of operations on this segement
+        self.operations = []
+
+        if self.name != name:
+            self.is_wildcard = True
+
+        if not self.name:
+            assert(not parent)
+            self.full_name = ''
+        if not parent or not parent.name:
+            self.full_name = name
+        else:
+            self.full_name = "%s_%s" % (parent.full_name, self.name)
+
+    def get_child(self, path):
+        """Walks decendents to get path, creating it if necessary.
+
+        @param path: List of path names.
+        @return: PageSegment corresponding to path.
+        """
+        assert simple_name(path[0]) == self.name
+        if (len(path) == 1):
+            return self
+        child = self.__children.get(path[1])
+        if not child:
+            child = PathSegment(path[1], self)
+            self.__children[path[1]] = child
+        return child.get_child(path[1:])
+
+    def children(self):
+        """Gets list of children.
+        """
+        return self.__children.values()
+
+    def num_children(self):
+        """Gets count of children.
+        """
+        return len(self.__children)
+
+
+class AsteriskProcessor(SwaggerPostProcessor):
+    """A SwaggerPostProcessor which adds fields needed to generate Asterisk
+    RESTful HTTP binding code.
+    """
+
+    #: How Swagger types map to C.
+    type_mapping = {
+        'string': 'const char *',
+        'boolean': 'int',
+        'number': 'int',
+        'int': 'int',
+        'long': 'long',
+        'double': 'double',
+        'float': 'float',
+    }
+
+    #: String conversion functions for string to C type.
+    convert_mapping = {
+        'const char *': '',
+        'int': 'atoi',
+        'long': 'atol',
+        'double': 'atof',
+    }
+
+    def process_api(self, resource_api, context):
+        # Derive a resource name from the API declaration's filename
+        resource_api.name = re.sub('\..*', '',
+                                   os.path.basename(resource_api.path))
+        # Now in all caps, from include guard
+        resource_api.name_caps = resource_api.name.upper()
+        # Construct the PathSegement tree for the API.
+        if resource_api.api_declaration:
+            resource_api.root_path = PathSegment('', None)
+            for api in resource_api.api_declaration.apis:
+                segment = resource_api.root_path.get_child(api.path.split('/'))
+                for operation in api.operations:
+                    segment.operations.append(operation)
+            # Since every API path should start with /[resource], root should
+            # have exactly one child.
+            if resource_api.root_path.num_children() != 1:
+                raise SwaggerError(
+                    "Should not mix resources in one API declaration", context)
+            # root_path isn't needed any more
+            resource_api.root_path = resource_api.root_path.children()[0]
+            if resource_api.name != resource_api.root_path.name:
+                raise SwaggerError(
+                    "API declaration name should match", context)
+            resource_api.root_full_name = resource_api.root_path.full_name
+
+    def process_operation(self, operation, context):
+        # Nicknames are camelcase, Asterisk coding is snake case
+        operation.c_nickname = snakify(operation.nickname)
+        operation.c_http_method = 'AST_HTTP_' + operation.http_method
+        if not operation.summary.endswith("."):
+            raise SwaggerError("Summary should end with .", context)
+
+    def process_parameter(self, parameter, context):
+        if not parameter.data_type in self.type_mapping:
+            raise SwaggerError(
+                "Invalid parameter type %s" % paramter.data_type, context)
+        # Parameter names are camelcase, Asterisk convention is snake case
+        parameter.c_name = snakify(parameter.name)
+        parameter.c_data_type = self.type_mapping[parameter.data_type]
+        parameter.c_convert = self.convert_mapping[parameter.c_data_type]
+        # You shouldn't put a space between 'char *' and the variable
+        if parameter.c_data_type.endswith('*'):
+            parameter.c_space = ''
+        else:
+            parameter.c_space = ' '