init nfvparser code

Change-Id: I8e264c87777e36c4a42f0aa42ab4ae66a1d59a0b
Signed-off-by: Zhaoxing <meng.zhaoxing1@zte.com.cn>

1 files changed, 826 insertions, 0 deletions

diff --git a/nfvparser/src/main/python/toscaparser/functions.py b/nfvparser/src/main/python/toscaparser/functions.py
new file mode 100644
index 0000000..d498229
--- /dev/null
+++ b/nfvparser/src/main/python/toscaparser/functions.py
@@ -0,0 +1,826 @@
+#
+#    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.
+
+
+import abc
+import six
+import toscaparser.elements.interfaces
+
+from toscaparser.common.exception import ExceptionCollector
+from toscaparser.common.exception import UnknownInputError
+from toscaparser.dataentity import DataEntity
+from toscaparser.elements.constraints import Schema
+from toscaparser.elements.datatype import DataType
+from toscaparser.elements.entity_type import EntityType
+from toscaparser.elements.relationshiptype import RelationshipType
+from toscaparser.elements.statefulentitytype import StatefulEntityType
+from toscaparser.utils.gettextutils import _
+
+
+GET_PROPERTY = 'get_property'
+GET_ATTRIBUTE = 'get_attribute'
+GET_INPUT = 'get_input'
+GET_OPERATION_OUTPUT = 'get_operation_output'
+CONCAT = 'concat'
+TOKEN = 'token'
+
+SELF = 'SELF'
+HOST = 'HOST'
+TARGET = 'TARGET'
+SOURCE = 'SOURCE'
+
+HOSTED_ON = 'tosca.relationships.HostedOn'
+
+
+@six.add_metaclass(abc.ABCMeta)
+class Function(object):
+    """An abstract type for representing a Tosca template function."""
+
+    def __init__(self, tosca_tpl, context, name, args):
+        self.tosca_tpl = tosca_tpl
+        self.context = context
+        self.name = name
+        self.args = args
+        self.validate()
+
+    @abc.abstractmethod
+    def result(self):
+        """Invokes the function and returns its result
+
+        Some methods invocation may only be relevant on runtime (for example,
+        getting runtime properties) and therefore its the responsibility of
+        the orchestrator/translator to take care of such functions invocation.
+
+        :return: Function invocation result.
+        """
+        return {self.name: self.args}
+
+    @abc.abstractmethod
+    def validate(self):
+        """Validates function arguments."""
+        pass
+
+
+class GetInput(Function):
+    """Get a property value declared within the input of the service template.
+
+    Arguments:
+
+    * Input name.
+
+    Example:
+
+    * get_input: port
+    """
+
+    def validate(self):
+        if len(self.args) != 1:
+            ExceptionCollector.appendException(
+                ValueError(_(
+                    'Expected one argument for function "get_input" but '
+                    'received "%s".') % self.args))
+        inputs = [input.name for input in self.tosca_tpl.inputs]
+        if self.args[0] not in inputs:
+            ExceptionCollector.appendException(
+                UnknownInputError(input_name=self.args[0]))
+
+    def result(self):
+        if self.tosca_tpl.parsed_params and \
+           self.input_name in self.tosca_tpl.parsed_params:
+            return DataEntity.validate_datatype(
+                self.tosca_tpl.tpl['inputs'][self.input_name]['type'],
+                self.tosca_tpl.parsed_params[self.input_name])
+
+        input = [input_def for input_def in self.tosca_tpl.inputs
+                 if self.input_name == input_def.name][0]
+        return input.default
+
+    @property
+    def input_name(self):
+        return self.args[0]
+
+
+class GetAttribute(Function):
+    """Get an attribute value of an entity defined in the service template
+
+    Node template attributes values are set in runtime and therefore its the
+    responsibility of the Tosca engine to implement the evaluation of
+    get_attribute functions.
+
+    Arguments:
+
+    * Node template name | HOST.
+    * Attribute name.
+
+    If the HOST keyword is passed as the node template name argument the
+    function will search each node template along the HostedOn relationship
+    chain until a node which contains the attribute is found.
+
+    Examples:
+
+    * { get_attribute: [ server, private_address ] }
+    * { get_attribute: [ HOST, private_address ] }
+    * { get_attribute: [ HOST, private_address, 0 ] }
+    * { get_attribute: [ HOST, private_address, 0, some_prop] }
+    """
+
+    def validate(self):
+        if len(self.args) < 2:
+            ExceptionCollector.appendException(
+                ValueError(_('Illegal arguments for function "{0}". Expected '
+                             'arguments: "node-template-name", "req-or-cap"'
+                             '(optional), "property name"'
+                             ).format(GET_ATTRIBUTE)))
+            return
+        elif len(self.args) == 2:
+            self._find_node_template_containing_attribute()
+        else:
+            node_tpl = self._find_node_template(self.args[0])
+            if node_tpl is None:
+                return
+            index = 2
+            attrs = node_tpl.type_definition.get_attributes_def()
+            found = [attrs[self.args[1]]] if self.args[1] in attrs else []
+            if found:
+                attr = found[0]
+            else:
+                index = 3
+                # then check the req or caps
+                attr = self._find_req_or_cap_attribute(self.args[1],
+                                                       self.args[2])
+
+            value_type = attr.schema['type']
+            if len(self.args) > index:
+                for elem in self.args[index:]:
+                    if value_type == "list":
+                        if not isinstance(elem, int):
+                            ExceptionCollector.appendException(
+                                ValueError(_('Illegal arguments for function'
+                                             ' "{0}". "{1}" Expected positive'
+                                             ' integer argument'
+                                             ).format(GET_ATTRIBUTE, elem)))
+                        value_type = attr.schema['entry_schema']['type']
+                    elif value_type == "map":
+                        value_type = attr.schema['entry_schema']['type']
+                    elif value_type in Schema.PROPERTY_TYPES:
+                        ExceptionCollector.appendException(
+                            ValueError(_('Illegal arguments for function'
+                                         ' "{0}". Unexpected attribute/'
+                                         'index value "{1}"'
+                                         ).format(GET_ATTRIBUTE, elem)))
+                        return
+                    else:  # It is a complex type
+                        data_type = DataType(value_type)
+                        props = data_type.get_all_properties()
+                        found = [props[elem]] if elem in props else []
+                        if found:
+                            prop = found[0]
+                            value_type = prop.schema['type']
+                        else:
+                            ExceptionCollector.appendException(
+                                KeyError(_('Illegal arguments for function'
+                                           ' "{0}". Attribute name "{1}" not'
+                                           ' found in "{2}"'
+                                           ).format(GET_ATTRIBUTE,
+                                                    elem,
+                                                    value_type)))
+
+    def result(self):
+        return self
+
+    def get_referenced_node_template(self):
+        """Gets the NodeTemplate instance the get_attribute function refers to.
+
+        If HOST keyword was used as the node template argument, the node
+        template which contains the attribute along the HostedOn relationship
+        chain will be returned.
+        """
+        return self._find_node_template_containing_attribute()
+
+    # Attributes can be explicitly created as part of the type definition
+    # or a property name can be implicitly used as an attribute name
+    def _find_node_template_containing_attribute(self):
+        node_tpl = self._find_node_template(self.args[0])
+        if node_tpl and \
+                not self._attribute_exists_in_type(node_tpl.type_definition) \
+                and self.attribute_name not in node_tpl.get_properties():
+            ExceptionCollector.appendException(
+                KeyError(_('Attribute "%(att)s" was not found in node '
+                           'template "%(ntpl)s".') %
+                         {'att': self.attribute_name,
+                          'ntpl': node_tpl.name}))
+        return node_tpl
+
+    def _attribute_exists_in_type(self, type_definition):
+        attrs_def = type_definition.get_attributes_def()
+        found = [attrs_def[self.attribute_name]] \
+            if self.attribute_name in attrs_def else []
+        return len(found) == 1
+
+    def _find_host_containing_attribute(self, node_template_name=SELF):
+        node_template = self._find_node_template(node_template_name)
+        if node_template:
+            hosted_on_rel = EntityType.TOSCA_DEF[HOSTED_ON]
+            for r in node_template.requirements:
+                for requirement, target_name in r.items():
+                    target_node = self._find_node_template(target_name)
+                    target_type = target_node.type_definition
+                    for capability in target_type.get_capabilities_objects():
+                        if capability.type in \
+                                hosted_on_rel['valid_target_types']:
+                            if self._attribute_exists_in_type(target_type):
+                                return target_node
+                            return self._find_host_containing_attribute(
+                                target_name)
+
+    def _find_node_template(self, node_template_name):
+        if node_template_name == HOST:
+            # Currently this is the only way to tell whether the function
+            # is used within the outputs section of the TOSCA template.
+            if isinstance(self.context, list):
+                ExceptionCollector.appendException(
+                    ValueError(_(
+                        '"get_attribute: [ HOST, ... ]" is not allowed in '
+                        '"outputs" section of the TOSCA template.')))
+                return
+            node_tpl = self._find_host_containing_attribute()
+            if not node_tpl:
+                ExceptionCollector.appendException(
+                    ValueError(_(
+                        '"get_attribute: [ HOST, ... ]" was used in node '
+                        'template "{0}" but "{1}" was not found in '
+                        'the relationship chain.').format(self.context.name,
+                                                          HOSTED_ON)))
+                return
+            return node_tpl
+        if node_template_name == TARGET:
+            if not isinstance(self.context.type_definition, RelationshipType):
+                ExceptionCollector.appendException(
+                    KeyError(_('"TARGET" keyword can only be used in context'
+                               ' to "Relationships" target node')))
+                return
+            return self.context.target
+        if node_template_name == SOURCE:
+            if not isinstance(self.context.type_definition, RelationshipType):
+                ExceptionCollector.appendException(
+                    KeyError(_('"SOURCE" keyword can only be used in context'
+                               ' to "Relationships" source node')))
+                return
+            return self.context.source
+        name = self.context.name \
+            if node_template_name == SELF and \
+            not isinstance(self.context, list) \
+            else node_template_name
+        for node_template in self.tosca_tpl.nodetemplates:
+            if node_template.name == name:
+                return node_template
+        ExceptionCollector.appendException(
+            KeyError(_(
+                'Node template "{0}" was not found.'
+                ).format(node_template_name)))
+
+    def _find_req_or_cap_attribute(self, req_or_cap, attr_name):
+        node_tpl = self._find_node_template(self.args[0])
+        # Find attribute in node template's requirements
+        for r in node_tpl.requirements:
+            for req, node_name in r.items():
+                if req == req_or_cap:
+                    node_template = self._find_node_template(node_name)
+                    return self._get_capability_attribute(
+                        node_template,
+                        req,
+                        attr_name)
+        # If requirement was not found, look in node template's capabilities
+        return self._get_capability_attribute(node_tpl,
+                                              req_or_cap,
+                                              attr_name)
+
+    def _get_capability_attribute(self,
+                                  node_template,
+                                  capability_name,
+                                  attr_name):
+        """Gets a node template capability attribute."""
+        caps = node_template.get_capabilities()
+        if caps and capability_name in caps.keys():
+            cap = caps[capability_name]
+            attribute = None
+            attrs = cap.definition.get_attributes_def()
+            if attrs and attr_name in attrs.keys():
+                attribute = attrs[attr_name]
+            if not attribute:
+                ExceptionCollector.appendException(
+                    KeyError(_('Attribute "%(attr)s" was not found in '
+                               'capability "%(cap)s" of node template '
+                               '"%(ntpl1)s" referenced from node template '
+                               '"%(ntpl2)s".') % {'attr': attr_name,
+                                                  'cap': capability_name,
+                                                  'ntpl1': node_template.name,
+                                                  'ntpl2': self.context.name}))
+            return attribute
+        msg = _('Requirement/Capability "{0}" referenced from node template '
+                '"{1}" was not found in node template "{2}".').format(
+                    capability_name,
+                    self.context.name,
+                    node_template.name)
+        ExceptionCollector.appendException(KeyError(msg))
+
+    @property
+    def node_template_name(self):
+        return self.args[0]
+
+    @property
+    def attribute_name(self):
+        return self.args[1]
+
+
+class GetProperty(Function):
+    """Get a property value of an entity defined in the same service template.
+
+    Arguments:
+
+    * Node template name | SELF | HOST | SOURCE | TARGET.
+    * Requirement or capability name (optional).
+    * Property name.
+
+    If requirement or capability name is specified, the behavior is as follows:
+    The req or cap name is first looked up in the specified node template's
+    requirements.
+    If found, it would search for a matching capability
+    of an other node template and get its property as specified in function
+    arguments.
+    Otherwise, the req or cap name would be looked up in the specified
+    node template's capabilities and if found, it would return  the property of
+    the capability as specified in function arguments.
+
+    Examples:
+
+    * { get_property: [ mysql_server, port ] }
+    * { get_property: [ SELF, db_port ] }
+    * { get_property: [ SELF, database_endpoint, port ] }
+    * { get_property: [ SELF, database_endpoint, port, 1 ] }
+    """
+
+    def validate(self):
+        if len(self.args) < 2:
+            ExceptionCollector.appendException(
+                ValueError(_(
+                    'Expected arguments: "node-template-name", "req-or-cap" '
+                    '(optional), "property name".')))
+            return
+        if len(self.args) == 2:
+            found_prop = self._find_property(self.args[1])
+            if not found_prop:
+                return
+            prop = found_prop.value
+            if not isinstance(prop, Function):
+                get_function(self.tosca_tpl, self.context, prop)
+        elif len(self.args) >= 3:
+            # do not use _find_property to avoid raise KeyError
+            # if the prop is not found
+            # First check if there is property with this name
+            node_tpl = self._find_node_template(self.args[0])
+            props = node_tpl.get_properties() if node_tpl else []
+            index = 2
+            found = [props[self.args[1]]] if self.args[1] in props else []
+            if found:
+                property_value = found[0].value
+            else:
+                index = 3
+                # then check the req or caps
+                property_value = self._find_req_or_cap_property(self.args[1],
+                                                                self.args[2])
+            if len(self.args) > index:
+                for elem in self.args[index:]:
+                    if isinstance(property_value, list):
+                        int_elem = int(elem)
+                        property_value = self._get_index_value(property_value,
+                                                               int_elem)
+                    else:
+                        property_value = self._get_attribute_value(
+                            property_value,
+                            elem)
+
+    def _find_req_or_cap_property(self, req_or_cap, property_name):
+        node_tpl = self._find_node_template(self.args[0])
+        # Find property in node template's requirements
+        for r in node_tpl.requirements:
+            for req, node_name in r.items():
+                if req == req_or_cap:
+                    node_template = self._find_node_template(node_name)
+                    return self._get_capability_property(
+                        node_template,
+                        req,
+                        property_name)
+        # If requirement was not found, look in node template's capabilities
+        return self._get_capability_property(node_tpl,
+                                             req_or_cap,
+                                             property_name)
+
+    def _get_capability_property(self,
+                                 node_template,
+                                 capability_name,
+                                 property_name):
+        """Gets a node template capability property."""
+        caps = node_template.get_capabilities()
+        if caps and capability_name in caps.keys():
+            cap = caps[capability_name]
+            property = None
+            props = cap.get_properties()
+            if props and property_name in props.keys():
+                property = props[property_name].value
+            if not property:
+                ExceptionCollector.appendException(
+                    KeyError(_('Property "%(prop)s" was not found in '
+                               'capability "%(cap)s" of node template '
+                               '"%(ntpl1)s" referenced from node template '
+                               '"%(ntpl2)s".') % {'prop': property_name,
+                                                  'cap': capability_name,
+                                                  'ntpl1': node_template.name,
+                                                  'ntpl2': self.context.name}))
+            return property
+        msg = _('Requirement/Capability "{0}" referenced from node template '
+                '"{1}" was not found in node template "{2}".').format(
+                    capability_name,
+                    self.context.name,
+                    node_template.name)
+        ExceptionCollector.appendException(KeyError(msg))
+
+    def _find_property(self, property_name):
+        node_tpl = self._find_node_template(self.args[0])
+        if not node_tpl:
+            return
+        props = node_tpl.get_properties()
+        found = [props[property_name]] if property_name in props else []
+        if len(found) == 0:
+            ExceptionCollector.appendException(
+                KeyError(_('Property "%(prop)s" was not found in node '
+                           'template "%(ntpl)s".') %
+                         {'prop': property_name,
+                          'ntpl': node_tpl.name}))
+            return None
+        return found[0]
+
+    def _find_node_template(self, node_template_name):
+        if node_template_name == SELF:
+            return self.context
+        # enable the HOST value in the function
+        if node_template_name == HOST:
+            return self._find_host_containing_property()
+        if node_template_name == TARGET:
+            if not isinstance(self.context.type_definition, RelationshipType):
+                ExceptionCollector.appendException(
+                    KeyError(_('"TARGET" keyword can only be used in context'
+                               ' to "Relationships" target node')))
+                return
+            return self.context.target
+        if node_template_name == SOURCE:
+            if not isinstance(self.context.type_definition, RelationshipType):
+                ExceptionCollector.appendException(
+                    KeyError(_('"SOURCE" keyword can only be used in context'
+                               ' to "Relationships" source node')))
+                return
+            return self.context.source
+        if not hasattr(self.tosca_tpl, 'nodetemplates'):
+            return
+        for node_template in self.tosca_tpl.nodetemplates:
+            if node_template.name == node_template_name:
+                return node_template
+        ExceptionCollector.appendException(
+            KeyError(_(
+                'Node template "{0}" was not found.'
+                ).format(node_template_name)))
+
+    def _get_index_value(self, value, index):
+        if isinstance(value, list):
+            if index < len(value):
+                return value[index]
+            else:
+                ExceptionCollector.appendException(
+                    KeyError(_(
+                        "Property '{0}' found in capability '{1}'"
+                        " referenced from node template {2}"
+                        " must have an element with index {3}.").
+                        format(self.args[2],
+                               self.args[1],
+                               self.context.name,
+                               index)))
+        else:
+            ExceptionCollector.appendException(
+                KeyError(_(
+                    "Property '{0}' found in capability '{1}'"
+                    " referenced from node template {2}"
+                    " must be a list.").format(self.args[2],
+                                               self.args[1],
+                                               self.context.name)))
+
+    def _get_attribute_value(self, value, attibute):
+        if isinstance(value, dict):
+            if attibute in value:
+                return value[attibute]
+            else:
+                ExceptionCollector.appendException(
+                    KeyError(_(
+                        "Property '{0}' found in capability '{1}'"
+                        " referenced from node template {2}"
+                        " must have an attribute named {3}.").
+                        format(self.args[2],
+                               self.args[1],
+                               self.context.name,
+                               attibute)))
+        else:
+            ExceptionCollector.appendException(
+                KeyError(_(
+                    "Property '{0}' found in capability '{1}'"
+                    " referenced from node template {2}"
+                    " must be a dict.").format(self.args[2],
+                                               self.args[1],
+                                               self.context.name)))
+
+    # Add this functions similar to get_attribute case
+    def _find_host_containing_property(self, node_template_name=SELF):
+        node_template = self._find_node_template(node_template_name)
+        hosted_on_rel = EntityType.TOSCA_DEF[HOSTED_ON]
+        for r in node_template.requirements:
+            for requirement, target_name in r.items():
+                target_node = self._find_node_template(target_name)
+                target_type = target_node.type_definition
+                for capability in target_type.get_capabilities_objects():
+                    if capability.type in hosted_on_rel['valid_target_types']:
+                        if self._property_exists_in_type(target_type):
+                            return target_node
+                        return self._find_host_containing_property(
+                            target_name)
+        return None
+
+    def _property_exists_in_type(self, type_definition):
+        props_def = type_definition.get_properties_def()
+        found = [props_def[self.args[1]]] \
+            if self.args[1] in props_def else []
+        return len(found) == 1
+
+    def result(self):
+        if len(self.args) >= 3:
+            # First check if there is property with this name
+            node_tpl = self._find_node_template(self.args[0])
+            props = node_tpl.get_properties() if node_tpl else []
+            index = 2
+            found = [props[self.args[1]]] if self.args[1] in props else []
+            if found:
+                property_value = found[0].value
+            else:
+                index = 3
+                # then check the req or caps
+                property_value = self._find_req_or_cap_property(self.args[1],
+                                                                self.args[2])
+            if len(self.args) > index:
+                for elem in self.args[index:]:
+                    if isinstance(property_value, list):
+                        int_elem = int(elem)
+                        property_value = self._get_index_value(property_value,
+                                                               int_elem)
+                    else:
+                        property_value = self._get_attribute_value(
+                            property_value,
+                            elem)
+        else:
+            property_value = self._find_property(self.args[1]).value
+        if isinstance(property_value, Function):
+            return property_value.result()
+        return get_function(self.tosca_tpl,
+                            self.context,
+                            property_value)
+
+    @property
+    def node_template_name(self):
+        return self.args[0]
+
+    @property
+    def property_name(self):
+        if len(self.args) > 2:
+            return self.args[2]
+        return self.args[1]
+
+    @property
+    def req_or_cap(self):
+        if len(self.args) > 2:
+            return self.args[1]
+        return None
+
+
+class GetOperationOutput(Function):
+    def validate(self):
+        if len(self.args) == 4:
+            self._find_node_template(self.args[0])
+            interface_name = self._find_interface_name(self.args[1])
+            self._find_operation_name(interface_name, self.args[2])
+        else:
+            ExceptionCollector.appendException(
+                ValueError(_('Illegal arguments for function "{0}". Expected '
+                             'arguments: "template_name","interface_name",'
+                             '"operation_name","output_variable_name"'
+                             ).format(GET_OPERATION_OUTPUT)))
+            return
+
+    def _find_interface_name(self, interface_name):
+        if interface_name in toscaparser.elements.interfaces.SECTIONS:
+            return interface_name
+        else:
+            ExceptionCollector.appendException(
+                ValueError(_('Enter a valid interface name'
+                             ).format(GET_OPERATION_OUTPUT)))
+            return
+
+    def _find_operation_name(self, interface_name, operation_name):
+        if(interface_name == 'Configure' or
+           interface_name == 'tosca.interfaces.node.relationship.Configure'):
+            if(operation_name in
+               StatefulEntityType.
+               interfaces_relationship_configure_operations):
+                return operation_name
+            else:
+                ExceptionCollector.appendException(
+                    ValueError(_('Enter an operation of Configure interface'
+                                 ).format(GET_OPERATION_OUTPUT)))
+                return
+        elif(interface_name == 'Standard' or
+             interface_name == 'tosca.interfaces.node.lifecycle.Standard'):
+            if(operation_name in
+               StatefulEntityType.interfaces_node_lifecycle_operations):
+                return operation_name
+            else:
+                ExceptionCollector.appendException(
+                    ValueError(_('Enter an operation of Standard interface'
+                                 ).format(GET_OPERATION_OUTPUT)))
+                return
+        else:
+            ExceptionCollector.appendException(
+                ValueError(_('Enter a valid operation name'
+                             ).format(GET_OPERATION_OUTPUT)))
+            return
+
+    def _find_node_template(self, node_template_name):
+        if node_template_name == TARGET:
+            if not isinstance(self.context.type_definition, RelationshipType):
+                ExceptionCollector.appendException(
+                    KeyError(_('"TARGET" keyword can only be used in context'
+                               ' to "Relationships" target node')))
+                return
+            return self.context.target
+        if node_template_name == SOURCE:
+            if not isinstance(self.context.type_definition, RelationshipType):
+                ExceptionCollector.appendException(
+                    KeyError(_('"SOURCE" keyword can only be used in context'
+                               ' to "Relationships" source node')))
+                return
+            return self.context.source
+        name = self.context.name \
+            if node_template_name == SELF and \
+            not isinstance(self.context, list) \
+            else node_template_name
+        for node_template in self.tosca_tpl.nodetemplates:
+            if node_template.name == name:
+                return node_template
+        ExceptionCollector.appendException(
+            KeyError(_(
+                'Node template "{0}" was not found.'
+                ).format(node_template_name)))
+
+    def result(self):
+        return self
+
+
+class Concat(Function):
+    """Validate the function and provide an instance of the function
+
+    Concatenation of values are supposed to be produced at runtime and
+    therefore its the responsibility of the TOSCA engine to implement the
+    evaluation of Concat functions.
+
+    Arguments:
+
+    * List of strings that needs to be concatenated
+
+    Example:
+
+      [ 'http://',
+        get_attribute: [ server, public_address ],
+        ':' ,
+        get_attribute: [ server, port ] ]
+    """
+
+    def validate(self):
+        if len(self.args) < 1:
+            ExceptionCollector.appendException(
+                ValueError(_('Invalid arguments for function "{0}". Expected '
+                             'at least one arguments.').format(CONCAT)))
+
+    def result(self):
+        return self
+
+
+class Token(Function):
+    """Validate the function and provide an instance of the function
+
+    The token function is used within a TOSCA service template on a string to
+    parse out (tokenize) substrings separated by one or more token characters
+    within a larger string.
+
+
+    Arguments:
+
+    * The composite string that contains one or more substrings separated by
+      token characters.
+    * The string that contains one or more token characters that separate
+      substrings within the composite string.
+    * The integer indicates the index of the substring to return from the
+      composite string.  Note that the first substring is denoted by using
+      the '0' (zero) integer value.
+
+    Example:
+
+     [ get_attribute: [ my_server, data_endpoint, ip_address ], ':', 1 ]
+
+    """
+
+    def validate(self):
+        if len(self.args) < 3:
+            ExceptionCollector.appendException(
+                ValueError(_('Invalid arguments for function "{0}". Expected '
+                             'at least three arguments.').format(TOKEN)))
+        else:
+            if not isinstance(self.args[1], str) or len(self.args[1]) != 1:
+                ExceptionCollector.appendException(
+                    ValueError(_('Invalid arguments for function "{0}". '
+                                 'Expected single char value as second '
+                                 'argument.').format(TOKEN)))
+
+            if not isinstance(self.args[2], int):
+                ExceptionCollector.appendException(
+                    ValueError(_('Invalid arguments for function "{0}". '
+                                 'Expected integer value as third '
+                                 'argument.').format(TOKEN)))
+
+    def result(self):
+        return self
+
+function_mappings = {
+    GET_PROPERTY: GetProperty,
+    GET_INPUT: GetInput,
+    GET_ATTRIBUTE: GetAttribute,
+    GET_OPERATION_OUTPUT: GetOperationOutput,
+    CONCAT: Concat,
+    TOKEN: Token
+}
+
+
+def is_function(function):
+    """Returns True if the provided function is a Tosca intrinsic function.
+
+    Examples:
+
+    * "{ get_property: { SELF, port } }"
+    * "{ get_input: db_name }"
+    * Function instance
+
+    :param function: Function as string or a Function instance.
+    :return: True if function is a Tosca intrinsic function, otherwise False.
+    """
+    if isinstance(function, dict) and len(function) == 1:
+        func_name = list(function.keys())[0]
+        return func_name in function_mappings
+    return isinstance(function, Function)
+
+
+def get_function(tosca_tpl, node_template, raw_function):
+    """Gets a Function instance representing the provided template function.
+
+    If the format provided raw_function format is not relevant for template
+    functions or if the function name doesn't exist in function mapping the
+    method returns the provided raw_function.
+
+    :param tosca_tpl: The tosca template.
+    :param node_template: The node template the function is specified for.
+    :param raw_function: The raw function as dict.
+    :return: Template function as Function instance or the raw_function if
+     parsing was unsuccessful.
+    """
+    if is_function(raw_function):
+        if isinstance(raw_function, dict):
+            func_name = list(raw_function.keys())[0]
+            if func_name in function_mappings:
+                func = function_mappings[func_name]
+                func_args = list(raw_function.values())[0]
+                if not isinstance(func_args, list):
+                    func_args = [func_args]
+                return func(tosca_tpl, node_template, func_name, func_args)
+    return raw_function