#!/usr/bin/env python # -*- coding: utf-8 -*- # java2python.compiler.template -> Base classes for writing Python source. # # This module defines templates -- chunks of Python source code -- # that can be easily manipulated and written. Each class provides # string methods (__str__, dump, dumps) for serializing instances as a # source code string. # # The Factory class is used to to provide runtime lookup of concrete # classes; this was necessary to accommodate splitting the behavior of # the compiler subpackage into multiple modules. So-called patterns # are usually a sign of a bad design and/or language limitations, and # this case is no exception. from cStringIO import StringIO from functools import partial from itertools import chain, ifilter, imap from java2python.lang import tokens from java2python.lib import FS, colors class Factory(object): """ Factory -> creates pre-configured callables for new block instances. Both templates and visitors use an instance of this class as a simple interface to create new blocks like this: stat = self.factory.statement() The `__getattr__` method does the work of looking up and returning the appropriate block class. The lookup depends on the types registry, which is populated by the FactoryTypeDetector metaclass below. One important thing to realize regarding this factory is this: when an attribute is requested (`self.factory.expr` for example), the factory locates the type and returns a constructor for it with the config object pre-applied. """ types = {} def __init__(self, config): self.config = config def __getattr__(self, name): try: return partial(self.types[name], self.config) except (KeyError, ): raise AttributeError('Factory missing "{0}" type.'.format(name)) class FactoryTypeDetector(type): """ FactoryTypeDetector -> detects factory-creatable types as they are defined. As subclasses are created they are checked for an attribute called `factoryName`. If present, that key is used to populate the type registry in the Factory class. Note that the actual subclasses are not created here (templates and visitors do not specify a `factoryName`). Actual factory types are created in `java2python.compiler.block`. This is because we're after not templates or visitors, but rather visitors combined with templates (aka blocks). Refer to the `blocks` module for the specific factory type names. """ def __init__(cls, name, bases, namespace): try: Factory.types[cls.factoryName] = cls except (AttributeError, ): pass class Base(object): """ Base -> base class for formatting Python output. This class defines a large set of attributes and methods for the other concrete templates defined below. The items defined here can be grouped as follows: * References This class defines `bases`, `children`, `decorators`, etc. for tracking the relationship between this instance and other blocks. * Type Information This class defines many is-A properties, such as isClass, isModule, isVoid, etc. Subclasses typically override one or more of these with an attribute or property. * Configuration This class provides utility methods for retrieving values from the runtime configuration. See the definition of `configHandler` and `configHandlers` for details. * Serialization This class provides a default implementation for subclasses to serialize their instances as Python source code strings. Notably, the `__str__` method is provided, which in turn defers most of its work to the `dumps` method. Subclasses provide different implementations of these methods where needed. Also, the `__repr__` method is defined by this class for printing a the template as tree for debugging. """ __metaclass__ = FactoryTypeDetector isAnnotation = isClass = isComment = isEnum = isExpression = \ isInterface = isMethod = isModule = isStatement = False def __init__(self, config, name=None, type=None, parent=None): self.bases = [] self.children = [] self.config = config self.decorators = [] self.factory = Factory(config) self.modifiers = [] self.name = name self.parameters = [] self.parent = parent self.type = type self.variables = [] if parent: parent.children.append(self) def __repr__(self): """ Returns the debug string representation of this template. """ name = colors.white('name:') + colors.cyan(self.name) if self.name else '' parts = [colors.green(self.typeName), name] if self.type: parts.append(colors.white('type:') + colors.cyan(self.type)) if self.modifiers: parts.append(colors.white('modifiers:') + colors.cyan(','.join(self.modifiers))) return ' '.join(parts) def __str__(self): """ Returns the Python source code representation of this template. """ handlers = self.configHandlers('Output') return reduce(lambda v, func:func(self, v), handlers, self.dumps(-1)) def adopt(self, child, index=-1): """ Adds child to this objecs children and sets the childs parent. """ self.children.insert(index, child) child.parent = self def altIdent(self, name): """ Returns an alternate identifier for the one given. """ for klass in self.parents(lambda v:v.isClass): if name in klass.variables: try: method = self.parents(lambda v:v.isMethod).next() except (StopIteration, ): return name if name in [p['name'] for p in method.parameters]: return name if name in method.variables: return name return ('cls' if method.isStatic else 'self') + '.' + name return name def configHandler(self, part, suffix='Handler', default=None): """ Returns the config handler for this type of template. """ name = '{0}{1}{2}'.format(self.typeName, part, suffix) return self.config.last(name, default) def configHandlers(self, part, suffix='Handlers'): """ Returns config handlers for this type of template """ name = '{0}{1}{2}'.format(self.typeName, part, suffix) return imap(self.toIter, self.config.last(name, ())) def dump(self, fd, level=0): """ Writes the Python source code for this template to the given file. """ indent, isNotNone = level * self.indent, lambda x:x is not None lineFormat = '{0}{1}\n'.format for line in ifilter(isNotNone, self.iterPrologue()): line = lineFormat(indent, line) fd.write(line if line.strip() else '\n') for item in ifilter(isNotNone, self.iterHead()): item.dump(fd, level+1) for item in self.iterBody(): item.dump(fd, level+1) for line in ifilter(isNotNone, self.iterEpilogue()): line = lineFormat(indent, line) fd.write(line if line.strip() else '\n') def dumps(self, level=0): """ Dumps this template to a string. """ fd = StringIO() self.dump(fd, level) return fd.getvalue() def dumpRepr(self, fd, level=0): """ Writes a debug string for this template to the given file. """ indent, default = self.indent, lambda x, y:None fd.write('{0}{1!r}\n'.format(indent*level, self)) for child in ifilter(None, self.children): getattr(child, 'dumpRepr', default)(fd, level+1) @property def indent(self): """ Returns the indent string for this item. """ return self.config.last('indentPrefix', ' ') @property def isPublic(self): """ True if this item is static. """ return 'public' in self.modifiers @property def isStatic(self): """ True if this item is static. """ return 'static' in self.modifiers @property def isVoid(self): """ True if this item is void. """ return 'void' == self.type def iterPrologue(self): """ Yields the items in the prologue of this template. """ return chain(*(h(self) for h in self.configHandlers('Prologue'))) def iterHead(self): """ Yields the items in the head of this template. """ items = chain(*(h(self) for h in self.configHandlers('Head'))) return imap(self.toExpr, items) def iterBody(self): """ Yields the items in the body of this template. """ return iter(self.children) def iterEpilogue(self): """ Yields the items in the epilogue of this template. """ return chain(*(h(self) for h in self.configHandlers('Epilogue'))) def makeParam(self, name, type, **kwds): """ Creates a parameter as a mapping. """ param = dict(name=name, type=type) if 'default' in kwds: param['default'] = kwds['default'] return param def parents(self, pred=lambda v:True): """ Yield each parent in the family tree. """ while self: if pred(self): yield self self = self.parent def find(self, pred=lambda v:True): """ Yield each child in the family tree. """ for child in self.children: if pred(child): yield child if hasattr(child, 'find'): for value in child.find(pred): yield value @property def className(self): """ Returns the name of the class of this item. """ return self.__class__.__name__ @property def typeName(self): """ Returns the name of this template type. """ return self.className.lower() def toExpr(self, value): """ Returns an expression for the given value if it is a string. """ try: return self.factory.expr(left=value+'') except (TypeError, ): return value def toIter(self, value): """ Returns an iterator for the given value if it is a string. """ try: value + '' except (TypeError, ): return value else: def wrapper(*a, **b): yield value return wrapper class Expression(Base): """ Expression -> formatting for Python expressions. """ isExpression = True def __init__(self, config, left='', right='', fs=FS.lr, parent=None, tail=''): super(Expression, self).__init__(config, parent=parent) self.left, self.right, self.fs, self.tail = left, right, fs, tail def __repr__(self): """ Returns the debug string representation of this template. """ parts, parent, showfs = [colors.blue(self.typeName)], self.parent, True if isinstance(self.left, (basestring, )) and self.left: parts.append(colors.white('left:') + colors.yellow(self.left)) showfs = False if isinstance(self.right, (basestring, )) and self.right: parts.append(colors.white('right:') + colors.yellow(self.right)) showfs = False if self.modifiers: parts.append(colors.white('modifiers:') + colors.cyan(','.join(self.modifiers))) if self.type: parts.append(colors.white('type:') + colors.cyan(self.type)) if showfs: parts.append(colors.white('format:') + colors.yellow(self.fs)) if self.tail: parts.append(colors.white('tail:') + colors.black(self.tail)) return ' '.join(parts) def __str__(self): """ Returns the Python source code representation of this template. """ return self.fs.format(left=self.left, right=self.right) + self.tail def dump(self, fd, level=0): """ Writes the Python source code for this template to the given file. """ line = '{0}{1}\n'.format(self.indent*level, self) fd.write(line if line.strip() else '\n') def dumpRepr(self, fd, level=0): """ Writes a debug string for this template to the given file. """ fd.write('{0}{1!r}\n'.format(self.indent*level, self)) for obj in (self.left, self.right): dumper = getattr(obj, 'dumpRepr', lambda x, y:None) dumper(fd, level+1) @property def isComment(self): """ True if this expression is a comment. """ try: return self.left.strip().startswith('#') except (AttributeError, ): return False class Comment(Expression): """ Comment -> formatting for Python comments. """ isComment = True def __repr__(self): """ Returns the debug string representation of this comment. """ parts = [colors.white(self.typeName+':'), colors.black(self.left) + colors.black(self.right) + colors.black(self.tail), ] return ' '.join(parts) class Statement(Base): """ Statement -> formatting for Python statements. """ isStatement = True def __init__(self, config, keyword, fs=FS.lr, parent=None): super(Statement, self).__init__(config, parent=parent) self.keyword = keyword self.expr = self.factory.expr(left=keyword, fs=fs) self.expr.parent = self def __repr__(self): """ Returns the debug string representation of this statement. """ parts = [colors.green(self.typeName), colors.white('keyword:')+colors.cyan(self.keyword)] return ' '.join(parts) def iterPrologue(self): """ Yields the keyword (and clause, if any) for this statement . """ yield self.expr class Module(Base): """ Module -> formatting for Python modules. """ isModule = True def iterBody(self): """ Yields the items in the body of this template. """ blank, prev = self.factory.expr(), None for child in super(Module, self).iterBody(): if prev and not prev.isComment: yield blank if prev and prev.isClass and child and child.isClass: yield blank yield child prev = child class ClassMethodSharedMixin(object): """ ClassMethodSharedMixin -> shared methods for Class and Method types. """ def iterPrologue(self): """ Yields the items in the prologue of this template. """ prologue = super(ClassMethodSharedMixin, self).iterPrologue() return chain(prologue, self.decorators, self.iterDecl()) class Class(ClassMethodSharedMixin, Base): """ Class -> formatting for Python classes. """ isClass = True def iterBases(self): """ Yields the base classes for this type. """ return chain(*(h(self) for h in self.configHandlers('Base'))) def iterDecl(self): """ Yields the declaration for this type. """ bases = ', '.join(self.iterBases()) bases = '({0})'.format(bases) if bases else '' yield 'class {0}{1}:'.format(self.name, bases) def iterBody(self): """ Yields the items in the body of this template. """ def sprinkleBlanks(body): blank, prev = self.factory.expr(), None for item in body: if prev: if type(prev) != type(item) and not prev.isComment: yield blank elif item.isMethod and prev.isMethod: yield blank elif prev.isClass: yield blank yield item prev = item for handler in self.configHandlers('PostWalk'): handler(self) head = any(self.iterHead()) body = list(super(Class, self).iterBody()) tail = () if (body or head) else [self.factory.expr(left='pass')] body = () if tail else sprinkleBlanks(body) return chain(body, tail) class Annotation(Class): """ Annotation -> formatting for annotations converted to Python classes. """ isAnnotation = True def __init__(self, config, name=None, type=None, parent=None): super(Annotation, self).__init__(config, name, type, parent) class Enum(Class): """ Enum -> formatting for enums converted to Python classes. """ isEnum = True class Interface(Class): """ Interface -> formatting for interfaces converted to Python classes. """ isInterface = True class MethodContent(Base): """ MethodContent -> formatting for content within Python methods. """ class Method(ClassMethodSharedMixin, Base): """ Method -> formatting for Python methods. """ isMethod = True def __init__(self, config, name=None, type=None, parent=None): super(Method, self).__init__(config, name, type, parent) self.parameters.append(self.makeParam('self', 'object')) def iterParams(self): """ Yields the parameters of this method template. """ return chain(*(h(self) for h in self.configHandlers('Param'))) def iterDecl(self): """ Yields the declaration for this method template. """ def formatParam(p): if 'default' in p: return '{0}={1}'.format(p['name'], p['default']) return p['name'] params = ', '.join(formatParam(param) for param in self.iterParams()) yield 'def {0}({1}):'.format(self.name, params) def iterBody(self): """ Yields the items in the body of this method template. """ head = any(self.iterHead()) body = list(super(Method, self).iterBody()) tail = () if (body or head) else [self.factory.expr(left='pass')] return chain(body, tail)