Edit File: visitors.cpython-37.pyc
B ��4] ( � @ s� d Z ddlmZ ddlZddlmZ ddlmZ ddd d d d d dddddg ZG dd� de�Z dd� Z G dd� de� e e ��Z G dd � d e �ZG dd � d e�ZG dd � d e�Zdd � Zdd � Zd d� Zd d� Zd d� Zd d� Zd d� ZdS )!aO Visitor/traversal interface and library functions. SQLAlchemy schema and expression constructs rely on a Python-centric version of the classic "visitor" pattern as the primary way in which they apply functionality. The most common use of this pattern is statement compilation, where individual expression classes match up to rendering methods that produce a string result. Beyond this, the visitor system is also used to inspect expressions for various information and patterns, as well as for usage in some kinds of expression transformation. Other kinds of transformation use a non-visitor traversal system. For many examples of how the visit system is used, see the sqlalchemy.sql.util and the sqlalchemy.sql.compiler modules. For an introduction to clause adaption, see http://techspot.zzzeek.org/2008/01/23/expression-transformations/ � )�dequeN� )�exc)�util� VisitableType� Visitable� ClauseVisitor�CloningVisitor�ReplacingCloningVisitor�iterate�iterate_depthfirst�traverse_using�traverse�traverse_depthfirst�cloned_traverse�replacement_traversec s e Zd ZdZ� fdd�Z� ZS )r ae Metaclass which assigns a `_compiler_dispatch` method to classes having a `__visit_name__` attribute. The _compiler_dispatch attribute becomes an instance method which looks approximately like the following:: def _compiler_dispatch (self, visitor, **kw): '''Look for an attribute named "visit_" + self.__visit_name__ on the visitor, and call it with the same kw params.''' visit_attr = 'visit_%s' % self.__visit_name__ return getattr(visitor, visit_attr)(self, **kw) Classes having no __visit_name__ attribute will remain unaffected. c s2 |dkrt | d�rt| � tt| ��|||� d S )Nr �__visit_name__)�hasattr�_generate_dispatch�superr �__init__)�clsZclsname�basesZclsdict)� __class__� �J/opt/alt/python37/lib64/python3.7/site-packages/sqlalchemy/sql/visitors.pyr B s zVisitableType.__init__)�__name__� __module__� __qualname__�__doc__r � __classcell__r r )r r r 2 s c sT d� j krP� j}t|t�r8t�d| ��� �fdd�}n � fdd�}d|_|� _dS )zYReturn an optimized visit dispatch function for the cls for use by the compiler. r zvisit_%sc s> y �|�}W n t k r, t�|� ��Y nX || f|�S d S )N)�AttributeErrorr �UnsupportedCompilationError)�self�visitor�kw�meth)r �getterr r �_compiler_dispatchU s z._generate_dispatch.<locals>._compiler_dispatchc sJ d| j }yt||�}W n tk r8 t�|� ��Y nX || f|�S d S )Nzvisit_%s)r �getattrr! r r" )r# r$ r% Z visit_attrr& )r r r r( a s z�Look for an attribute named "visit_" + self.__visit_name__ on the visitor, and call it with the same kw params. N)�__dict__r � isinstance�str�operator� attrgetterr r( )r Z visit_namer( r )r r' r r I s r c @ s e Zd ZdZdS )r zTBase class for visitable objects, applies the ``VisitableType`` metaclass. N)r r r r r r r r r p s c @ sN e Zd ZdZi Zdd� Zdd� Zdd� Zej dd � �Z e d d � �Z d d � Z dS )r zZBase class for visitor objects which can traverse using the traverse() function. c K s6 x0| j D ]&}t|d|j d �}|r||f|�S qW d S )Nzvisit_%s)�visitor_iteratorr) r )r# �objr% �vr& r r r �traverse_single s z ClauseVisitor.traverse_singlec C s t || j�S )zatraverse the given expression structure, returning an iterator of all elements. )r �__traverse_options__)r# r0 r r r r � s zClauseVisitor.iteratec C s t || j| j�S )z2traverse and visit the given expression structure.)r r3 � _visitor_dict)r# r0 r r r r � s zClauseVisitor.traversec C s: i }x0t | �D ]$}|�d�rt| |�||dd � < qW |S )N�visit_� )�dir� startswithr) )r# �visitors�namer r r r4 � s zClauseVisitor._visitor_dictc c s$ | }x|r |V t |dd�}qW dS )z8iterate through this visitor and each 'chained' visitor.�_nextN)r) )r# r1 r r r r/ � s z ClauseVisitor.visitor_iteratorc C s t | j�d }||_| S )z�'chain' an additional ClauseVisitor onto this ClauseVisitor. the chained visitor will receive all visit events after this one. ���)�listr/ r; )r# r$ �tailr r r �chain� s zClauseVisitor.chainN)r r r r r3 r2 r r r Zmemoized_propertyr4 �propertyr/ r? r r r r r w s c @ s e Zd ZdZdd� Zdd� ZdS )r zaBase class for visitor objects which can traverse using the cloned_traverse() function. c s � fdd�|D �S )z`Apply cloned traversal to the given list of elements, and return the new list. c s g | ]}� � |��qS r )r )�.0�x)r# r r � <listcomp>� s z3CloningVisitor.copy_and_process.<locals>.<listcomp>r )r# Zlist_r )r# r �copy_and_process� s z CloningVisitor.copy_and_processc C s t || j| j�S )z2traverse and visit the given expression structure.)r r3 r4 )r# r0 r r r r � s zCloningVisitor.traverseN)r r r r rD r r r r r r � s c @ s e Zd ZdZdd� Zdd� ZdS )r zfBase class for visitor objects which can traverse using the replacement_traverse() function. c C s dS )a receive pre-copied elements during a cloning traversal. If the method returns a new element, the element is used instead of creating a simple copy of the element. Traversal will halt on the newly returned element if it is re-encountered. Nr )r# �elemr r r �replace� s z ReplacingCloningVisitor.replacec s � fdd�}t |� j|�S )z2traverse and visit the given expression structure.c s* x$� j D ]}|�| �}|d k r|S qW d S )N)r/ rF )rE r1 �e)r# r r rF � s z1ReplacingCloningVisitor.traverse.<locals>.replace)r r3 )r# r0 rF r )r# r r � s z ReplacingCloningVisitor.traverseN)r r r r rF r r r r r r � s c C sj | j f |�}|s| gS t� }t| g�}x:|r`|�� }|�|� x |j f |�D ]}|�|� qLW q(W t|�S )zwtraverse the given expression structure, returning an iterator. traversal is configured to be breadth-first. )� get_childrenr �popleft�append�iter)r0 �opts�children� traversal�stack�t�cr r r r � s c C sj | j f |�}|s| gS t| g�}t� }x:|r`|�� }|�|� x |j f |�D ]}|�|� qLW q(W t|�S )zutraverse the given expression structure, returning an iterator. traversal is configured to be depth-first. )rH r �pop� appendleftrJ rK )r0 rL rM rO rN rP rQ r r r r � s c C s, x&| D ] }|� |jd�}|r||� qW |S )zSvisit the given expression structure using the given iterator of objects. N)�getr )�iteratorr0 r9 �targetr& r r r r s c C s t t| |�| |�S )zXtraverse and visit the given expression structure using the default iterator. )r r )r0 rL r9 r r r r s c C s t t| |�| |�S )z[traverse and visit the given expression structure using the depth-first iterator. )r r )r0 rL r9 r r r r s c s: i �t |�dg ���� ���fdd�� | dk r6� | �} | S )zMclone the given expression structure, allowing modifications by visitors.�stop_onc sb | �kr | S t | ��krR| �� �t | �< }|j� d� ��|jd �}|rR||� �t | � S d S )N)�clone)�id�_clone�_copy_internalsrT r )rE �newelemr& )rX �clonedrW r9 r r rX + s z cloned_traverse.<locals>.cloneN)�setrT )r0 rL r9 r )rX r] rW r9 r r $ s c sD i �dd� |� dg �D ��� ���fdd�� | dk r@� | f|�} | S )zgclone the given expression structure, allowing element replacement by a given replacement function.c S s h | ] }t |��qS r )rY )rA rB r r r � <setcomp>A s z'replacement_traverse.<locals>.<setcomp>rW c st t | ��ksd| jkr| S �| �}|d k r<��t |�� |S | �krh| �� �| < }|jf d� i|�� �| S d S )NZno_replacement_traverserX )rY Z _annotations�addrZ r[ )rE r% r\ )rX r] rF rW r r rX C s z#replacement_traverse.<locals>.cloneN)rT )r0 rL rF r )rX r] rF rW r r < s )r � collectionsr r- � r r �__all__�typer r �with_metaclass�objectr r r r r r r r r r r r r r r �<module> s: '7