Extract common helper functions. Fix docstrings to reflect operator b…

…ehavior.

graphql_compiler/compiler/compiler_frontend.py

@@ -71,8 +71,8 @@
                                 validate_vertex_field_directive_interactions)
 from .filters import process_filter_directive
 from .helpers import (FoldScopeLocation, Location, get_ast_field_name, get_field_type_from_schema,
-                      get_uniquely_named_objects_by_name, strip_non_null_from_type,
-                      validate_safe_string)
+                      get_uniquely_named_objects_by_name, is_vertex_field_name,
+                      strip_non_null_from_type, validate_safe_string)
 
 
 # The OutputMetadata will have the following types for its members:
@@ -91,11 +91,6 @@ def __ne__(self, other):
         return not self.__eq__(other)
 
 
-def _is_vertex_field_name(field_name):
-    """Return True if the field name denotes a vertex field, or False if it's a property field."""
-    return field_name.startswith('out_') or field_name.startswith('in_')
-
-
 def _get_fields(ast):
     """Return a list of property fields, and a list of vertex fields, for the given AST node.
 
@@ -132,7 +127,7 @@ def _get_fields(ast):
         seen_field_names.add(name)
 
         # Vertex fields start with 'out_' or 'in_', denoting the edge direction to that vertex.
-        if _is_vertex_field_name(name):
+        if is_vertex_field_name(name):
             switched_to_vertices = True
             vertex_fields.append(field_ast)
         else:

graphql_compiler/compiler/filters.py

@@ -81,6 +81,16 @@ def wrapper(schema, current_schema_type, ast, context,
     return decorator
 
 
+def _is_variable_argument(argument_name):
+    """Return True if the argument is a runtime variable, and False otherwise."""
+    return argument_name.startswith('$')
+
+
+def _is_tag_argument(argument_name):
+    """Return True if the argument is a tagged value, and False otherwise."""
+    return argument_name.startswith('%')
+
+
 def _represent_argument(schema, ast, context, argument, inferred_type):
     """Return a two-element tuple that represents the argument to the directive being processed.
 
@@ -106,7 +116,7 @@ def _represent_argument(schema, ast, context, argument, inferred_type):
     argument_name = argument[1:]
     validate_safe_string(argument_name)
 
-    if argument.startswith('$'):
+    if _is_variable_argument(argument):
         existing_type = context['inputs'].get(argument_name, inferred_type)
         if not inferred_type.is_same_type(existing_type):
             raise GraphQLCompilationError(u'Incompatible types inferred for argument {}. '
@@ -116,7 +126,7 @@ def _represent_argument(schema, ast, context, argument, inferred_type):
         context['inputs'][argument_name] = inferred_type
 
         return (expressions.Variable(argument, inferred_type), None)
-    elif argument.startswith('%'):
+    elif _is_tag_argument(argument):
         argument_context = context['tags'].get(argument_name, None)
         if argument_context is None:
             raise GraphQLCompilationError(u'Undeclared argument used: {}'.format(argument))
@@ -164,7 +174,7 @@ def _process_comparison_filter_directive(schema, current_schema_type, ast,
                  is optional, etc.). May be mutated in-place in this function!
         directive: GraphQL directive object, obtained from the AST node
         parameters: list of 1 element, containing the value to perform the comparison against;
-                    if the parameter is optional and missing, the check is performed against 'null'
+                    if the parameter is optional and missing, the check will return True
         operator: unicode, a comparison operator, like '=', '!=', '>=' etc.
                   This is a kwarg only to preserve the same positional arguments in the
                   function signature, to ease validation.
@@ -211,7 +221,7 @@ def _process_name_or_alias_filter_directive(schema, current_schema_type, ast,
                  is optional, etc.). May be mutated in-place in this function!
         directive: GraphQL directive object, obtained from the AST node
         parameters: list of 1 element, containing the value to check the name or alias against;
-                    if the parameter is optional and missing, the check is performed against 'null'
+                    if the parameter is optional and missing, the check will return True
 
     Returns:
         a Filter basic block that performs the check against the name or alias
@@ -326,7 +336,7 @@ def _process_in_collection_filter_directive(schema, current_schema_type, ast,
                  is optional, etc.). May be mutated in-place in this function!
         directive: GraphQL directive object, obtained from the AST node
         parameters: list of 1 element, specifying the collection in which the value must exist;
-                    if the collection is optional and missing, the check is assumed to be False
+                    if the collection is optional and missing, the check will return True
 
     Returns:
         a Filter basic block that performs the collection existence check
@@ -362,7 +372,7 @@ def _process_has_substring_filter_directive(schema, current_schema_type, ast,
                  is optional, etc.). May be mutated in-place in this function!
         directive: GraphQL directive object, obtained from the AST node
         parameters: list of 1 element, specifying the collection in which the value must exist;
-                    if the collection is optional and missing, the check is assumed to be False
+                    if the collection is optional and missing, the check will return True
 
     Returns:
         a Filter basic block that performs the substring check
@@ -401,7 +411,7 @@ def _process_contains_filter_directive(schema, current_schema_type, ast,
                  is optional, etc.). May be mutated in-place in this function!
         directive: GraphQL directive object, obtained from the AST node
         parameters: list of 1 element, specifying the collection in which the value must exist;
-                    if the collection is optional and missing, the check is assumed to be False
+                    if the collection is optional and missing, the check will return True
 
     Returns:
         a Filter basic block that performs the substring check

graphql_compiler/compiler/helpers.py

@@ -48,6 +48,17 @@ def strip_non_null_from_type(graphql_type):
     return graphql_type
 
 
+def is_vertex_field_name(field_name):
+    """Return True if the field's name indicates it is a non-root vertex field."""
+    return field_name.startswith('out_') or field_name.startswith('in_')
+
+
+def is_non_root_vertex_field(ast, graphql_type):
+    """Return True if the AST belongs to a vertex field that is not the root vertex."""
+    field_name = get_ast_field_name(ast)
+    return is_vertex_field_name(field_name) and is_vertex_field_type(graphql_type)
+
+
 def is_vertex_field_type(graphql_type):
     """Return True if the argument is a vertex field type, and False otherwise."""
     # This will need to change if we ever support complex embedded types or edge field types.