# Embedded file name: lib\web\template.py
"""
simple, elegant templating
(part of web.py)

Template design:

Template string is split into tokens and the tokens are combined into nodes. 
Parse tree is a nodelist. TextNode and ExpressionNode are simple nodes and 
for-loop, if-loop etc are block nodes, which contain multiple child nodes. 

Each node can emit some python string. python string emitted by the 
root node is validated for safeeval and executed using python in the given environment.

Enough care is taken to make sure the generated code and the template has line to line match, 
so that the error messages can point to exact line number in template. (It doesn't work in some cases still.)

Grammar:

    template -> defwith sections 
    defwith -> '$def with (' arguments ')' | ''
    sections -> section*
    section -> block | assignment | line

    assignment -> '$ ' <assignment expression>
    line -> (text|expr)*
    text -> <any characters other than $>
    expr -> '$' pyexpr | '$(' pyexpr ')' | '${' pyexpr '}'
    pyexpr -> <python expression>
"""
from __future__ import print_function
from io import open
__all__ = ['Template',
 'Render',
 'render',
 'frender',
 'ParseError',
 'SecurityError',
 'test']
import tokenize
import os
import sys
import glob
import re
import warnings
import ast
from .utils import storage, safeunicode, safestr, re_compile
from .webapi import config
from .net import websafe
from .py3helpers import PY2, iteritems
if PY2:
    from UserDict import DictMixin

    class MutableMapping(object, DictMixin):
        pass


else:
    from collections import MutableMapping

def splitline(text):
    r"""
    Splits the given text at newline.
    
        >>> splitline('foo\nbar')
        ('foo\n', 'bar')
        >>> splitline('foo')
        ('foo', '')
        >>> splitline('')
        ('', '')
    """
    index = text.find('\n') + 1
    if index:
        return (text[:index], text[index:])
    else:
        return (text, '')


class Parser():
    """Parser Base.
    """

    def __init__(self):
        self.statement_nodes = STATEMENT_NODES
        self.keywords = KEYWORDS

    def parse(self, text, name = '<template>'):
        self.text = text
        self.name = name
        defwith, text = self.read_defwith(text)
        suite = self.read_suite(text)
        return DefwithNode(defwith, suite)

    def read_defwith(self, text):
        if text.startswith('$def with'):
            defwith, text = splitline(text)
            defwith = defwith[1:].strip()
            return (defwith, text)
        else:
            return ('', text)

    def read_section(self, text):
        r"""Reads one section from the given text.
        
        section -> block | assignment | line
        
            >>> read_section = Parser().read_section
            >>> read_section('foo\nbar\n')
            (<line: [t'foo\n']>, 'bar\n')
            >>> read_section('$ a = b + 1\nfoo\n')
            (<assignment: 'a = b + 1'>, 'foo\n')
            
        read_section('$for in range(10):\n    hello $i\nfoo)
        """
        if text.lstrip(' ').startswith('$'):
            index = text.index('$')
            begin_indent, text2 = text[:index], text[index + 1:]
            ahead = self.python_lookahead(text2)
            if ahead == 'var':
                return self.read_var(text2)
            if ahead in self.statement_nodes:
                return self.read_block_section(text2, begin_indent)
            if ahead in self.keywords:
                return self.read_keyword(text2)
            if ahead.strip() == '':
                return self.read_assignment(text2)
        return self.readline(text)

    def read_var(self, text):
        r"""Reads a var statement.
        
            >>> read_var = Parser().read_var
            >>> read_var('var x=10\nfoo')
            (<var: x = 10>, 'foo')
            >>> read_var('var x: hello $name\nfoo')
            (<var: x = join_(u'hello ', escape_(name, True))>, 'foo')
        """
        line, text = splitline(text)
        tokens = self.python_tokens(line)
        if len(tokens) < 4:
            raise SyntaxError('Invalid var statement')
        name = tokens[1]
        sep = tokens[2]
        value = line.split(sep, 1)[1].strip()
        if sep == '=':
            pass
        elif sep == ':':
            if tokens[3] == '\n':
                block, text = self.read_indented_block(text, '    ')
                lines = [ self.readline(x)[0] for x in block.splitlines() ]
                nodes = []
                for x in lines:
                    nodes.extend(x.nodes)
                    nodes.append(TextNode('\n'))

            else:
                linenode, _ = self.readline(value)
                nodes = linenode.nodes
            parts = [ node.emit('') for node in nodes ]
            value = 'join_(%s)' % ', '.join(parts)
        else:
            raise SyntaxError('Invalid var statement')
        return (VarNode(name, value), text)

    def read_suite(self, text):
        r"""Reads section by section till end of text.
        
            >>> read_suite = Parser().read_suite
            >>> read_suite('hello $name\nfoo\n')
            [<line: [t'hello ', $name, t'\n']>, <line: [t'foo\n']>]
        """
        sections = []
        while text:
            section, text = self.read_section(text)
            sections.append(section)

        return SuiteNode(sections)

    def readline(self, text):
        r"""Reads one line from the text. Newline is supressed if the line ends with \.
        
            >>> readline = Parser().readline
            >>> readline('hello $name!\nbye!')
            (<line: [t'hello ', $name, t'!\n']>, 'bye!')
            >>> readline('hello $name!\\\nbye!')
            (<line: [t'hello ', $name, t'!']>, 'bye!')
            >>> readline('$f()\n\n')
            (<line: [$f(), t'\n']>, '\n')
        """
        line, text = splitline(text)
        if line.endswith('\\\n'):
            line = line[:-2]
        nodes = []
        while line:
            node, line = self.read_node(line)
            nodes.append(node)

        return (LineNode(nodes), text)

    def read_node(self, text):
        """Reads a node from the given text and returns the node and remaining text.
        
            >>> read_node = Parser().read_node
            >>> read_node('hello $name')
            (t'hello ', '$name')
            >>> read_node('$name')
            ($name, '')
        """
        if text.startswith('$$'):
            return (TextNode('$'), text[2:])
        elif text.startswith('$#'):
            line, text = splitline(text)
            return (TextNode('\n'), text)
        elif text.startswith('$'):
            text = text[1:]
            if text.startswith(':'):
                escape = False
                text = text[1:]
            else:
                escape = True
            return self.read_expr(text, escape=escape)
        else:
            return self.read_text(text)

    def read_text(self, text):
        """Reads a text node from the given text.
        
            >>> read_text = Parser().read_text
            >>> read_text('hello $name')
            (t'hello ', '$name')
        """
        index = text.find('$')
        if index < 0:
            return (TextNode(text), '')
        else:
            return (TextNode(text[:index]), text[index:])

    def read_keyword(self, text):
        line, text = splitline(text)
        return (StatementNode(line.strip() + '\n'), text)

    def read_expr(self, text, escape = True):
        """Reads a python expression from the text and returns the expression and remaining text.
        
        expr -> simple_expr | paren_expr
        simple_expr -> id extended_expr
        extended_expr -> attr_access | paren_expr extended_expr | ''
        attr_access -> dot id extended_expr
        paren_expr -> [ tokens ] | ( tokens ) | { tokens }
        
            >>> read_expr = Parser().read_expr
            >>> read_expr("name")
            ($name, '')
            >>> read_expr("a.b and c")
            ($a.b, ' and c')
            >>> read_expr("a. b")
            ($a, '. b')
            >>> read_expr("name</h1>")
            ($name, '</h1>')
            >>> read_expr("(limit)ing")
            ($(limit), 'ing')
            >>> read_expr('a[1, 2][:3].f(1+2, "weird string[).", 3 + 4) done.')
            ($a[1, 2][:3].f(1+2, "weird string[).", 3 + 4), ' done.')
        """

        def simple_expr():
            identifier()
            extended_expr()

        def identifier():
            next(tokens)

        def extended_expr():
            lookahead = tokens.lookahead()
            if lookahead is None:
                return
            else:
                if lookahead.value == '.':
                    attr_access()
                elif lookahead.value in parens:
                    paren_expr()
                    extended_expr()
                else:
                    return
                return

        def attr_access():
            from token import NAME
            dot = tokens.lookahead()
            if tokens.lookahead2().type == NAME:
                next(tokens)
                identifier()
                extended_expr()

        def paren_expr():
            begin = next(tokens).value
            end = parens[begin]
            while True:
                if tokens.lookahead().value in parens:
                    paren_expr()
                else:
                    t = next(tokens)
                    if t.value == end:
                        break

        parens = {'(': ')',
         '[': ']',
         '{': '}'}

        def get_tokens(text):
            """tokenize text using python tokenizer.
            Python tokenizer ignores spaces, but they might be important in some cases. 
            This function introduces dummy space tokens when it identifies any ignored space.
            Each token is a storage object containing type, value, begin and end.
            """
            i = iter([text])
            readline = lambda : next(i)
            end = None
            for t in tokenize.generate_tokens(readline):
                t = storage(type=t[0], value=t[1], begin=t[2], end=t[3])
                if end is not None and end != t.begin:
                    _, x1 = end
                    _, x2 = t.begin
                    yield storage(type=-1, value=text[x1:x2], begin=end, end=t.begin)
                end = t.end
                yield t

            return

        class BetterIter:
            """Iterator like object with 2 support for 2 look aheads."""

            def __init__(self, items):
                self.iteritems = iter(items)
                self.items = []
                self.position = 0
                self.current_item = None
                return

            def lookahead(self):
                if len(self.items) <= self.position:
                    self.items.append(self._next())
                return self.items[self.position]

            def _next(self):
                try:
                    return next(self.iteritems)
                except StopIteration:
                    return None

                return None

            def lookahead2(self):
                if len(self.items) <= self.position + 1:
                    self.items.append(self._next())
                return self.items[self.position + 1]

            def __next__(self):
                self.current_item = self.lookahead()
                self.position += 1
                return self.current_item

            next = __next__

        tokens = BetterIter(get_tokens(text))
        if tokens.lookahead().value in parens:
            paren_expr()
        else:
            simple_expr()
        row, col = tokens.current_item.end
        return (ExpressionNode(text[:col], escape=escape), text[col:])

    def read_assignment(self, text):
        r"""Reads assignment statement from text.
        
            >>> read_assignment = Parser().read_assignment
            >>> read_assignment('a = b + 1\nfoo')
            (<assignment: 'a = b + 1'>, 'foo')
        """
        line, text = splitline(text)
        return (AssignmentNode(line.strip()), text)

    def python_lookahead(self, text):
        """Returns the first python token from the given text.
        
            >>> python_lookahead = Parser().python_lookahead
            >>> python_lookahead('for i in range(10):')
            'for'
            >>> python_lookahead('else:')
            'else'
            >>> python_lookahead(' x = 1')
            ' '
        """
        i = iter([text])
        readline = lambda : next(i)
        tokens = tokenize.generate_tokens(readline)
        return next(tokens)[1]

    def python_tokens(self, text):
        i = iter([text])
        readline = lambda : next(i)
        tokens = tokenize.generate_tokens(readline)
        return [ t[1] for t in tokens ]

    def read_indented_block(self, text, indent):
        r"""Read a block of text. A block is what typically follows a for or it statement.
        It can be in the same line as that of the statement or an indented block.
        
            >>> read_indented_block = Parser().read_indented_block
            >>> read_indented_block('  a\n  b\nc', '  ')
            ('a\nb\n', 'c')
            >>> read_indented_block('  a\n    b\n  c\nd', '  ')
            ('a\n  b\nc\n', 'd')
            >>> read_indented_block('  a\n\n    b\nc', '  ')
            ('a\n\n  b\n', 'c')
        """
        if indent == '':
            return ('', text)
        block = ''
        while text:
            line, text2 = splitline(text)
            if line.strip() == '':
                block += '\n'
            elif line.startswith(indent):
                block += line[len(indent):]
            else:
                break
            text = text2

        return (block, text)

    def read_statement(self, text):
        """Reads a python statement.
        
            >>> read_statement = Parser().read_statement
            >>> read_statement('for i in range(10): hello $name')
            ('for i in range(10):', ' hello $name')
        """
        tok = PythonTokenizer(text)
        tok.consume_till(':')
        return (text[:tok.index], text[tok.index:])

    def read_block_section(self, text, begin_indent = ''):
        r"""
            >>> read_block_section = Parser().read_block_section
            >>> read_block_section('for i in range(10): hello $i\nfoo')
            (<block: 'for i in range(10):', [<line: [t'hello ', $i, t'\n']>]>, 'foo')
            >>> read_block_section('for i in range(10):\n        hello $i\n    foo', begin_indent='    ')
            (<block: 'for i in range(10):', [<line: [t'hello ', $i, t'\n']>]>, '    foo')
            >>> read_block_section('for i in range(10):\n  hello $i\nfoo')
            (<block: 'for i in range(10):', [<line: [t'hello ', $i, t'\n']>]>, 'foo')
        """
        line, text = splitline(text)
        stmt, line = self.read_statement(line)
        keyword = self.python_lookahead(stmt)
        if line.strip():
            block = line.lstrip()
        else:

            def find_indent(text):
                rx = re_compile('  +')
                match = rx.match(text)
                first_indent = match and match.group(0)
                return first_indent or ''

            first_indent = find_indent(text)[len(begin_indent):]
            if keyword == 'code':
                indent = begin_indent + first_indent
            else:
                indent = begin_indent + min(first_indent, INDENT)
            block, text = self.read_indented_block(text, indent)
        return (self.create_block_node(keyword, stmt, block, begin_indent), text)

    def create_block_node(self, keyword, stmt, block, begin_indent):
        if keyword in self.statement_nodes:
            return self.statement_nodes[keyword](stmt, block, begin_indent)
        raise ParseError('Unknown statement: %s' % repr(keyword))


class PythonTokenizer():
    """Utility wrapper over python tokenizer."""

    def __init__(self, text):
        self.text = text
        i = iter([text])
        readline = lambda : next(i)
        self.tokens = tokenize.generate_tokens(readline)
        self.index = 0

    def consume_till(self, delim):
        """Consumes tokens till colon.
        
            >>> tok = PythonTokenizer('for i in range(10): hello $i')
            >>> tok.consume_till(':')
            >>> tok.text[:tok.index]
            'for i in range(10):'
            >>> tok.text[tok.index:]
            ' hello $i'
        """
        try:
            while True:
                t = next(self)
                if t.value == delim:
                    break
                elif t.value == '(':
                    self.consume_till(')')
                elif t.value == '[':
                    self.consume_till(']')
                elif t.value == '{':
                    self.consume_till('}')
                if t.value == '\n':
                    break

        except:
            return

    def __next__(self):
        type, t, begin, end, line = next(self.tokens)
        row, col = end
        self.index = col
        return storage(type=type, value=t, begin=begin, end=end)

    next = __next__


class DefwithNode():

    def __init__(self, defwith, suite):
        if defwith:
            self.defwith = defwith.replace('with', '__template__') + ':'
            self.defwith += '\n    __lineoffset__ = -4'
        else:
            self.defwith = 'def __template__():'
            self.defwith += '\n    __lineoffset__ = -5'
        self.defwith += '\n    loop = ForLoop()'
        self.defwith += '\n    self = TemplateResult(); extend_ = self.extend'
        self.suite = suite
        self.end = '\n    return self'

    def emit(self, indent):
        encoding = '# coding: utf-8\n'
        return encoding + self.defwith + self.suite.emit(indent + INDENT) + self.end

    def __repr__(self):
        return '<defwith: %s, %s>' % (self.defwith, self.suite)


class TextNode():

    def __init__(self, value):
        self.value = value

    def emit(self, indent, begin_indent = ''):
        return repr(safeunicode(self.value))

    def __repr__(self):
        return 't' + repr(self.value)


class ExpressionNode():

    def __init__(self, value, escape = True):
        self.value = value.strip()
        if value.startswith('{') and value.endswith('}'):
            self.value = '(' + self.value[1:-1] + ')'
        self.escape = escape

    def emit(self, indent, begin_indent = ''):
        return 'escape_(%s, %s)' % (self.value, bool(self.escape))

    def __repr__(self):
        if self.escape:
            escape = ''
        else:
            escape = ':'
        return '$%s%s' % (escape, self.value)


class AssignmentNode():

    def __init__(self, code):
        self.code = code

    def emit(self, indent, begin_indent = ''):
        return indent + self.code + '\n'

    def __repr__(self):
        return '<assignment: %s>' % repr(self.code)


class LineNode():

    def __init__(self, nodes):
        self.nodes = nodes

    def emit(self, indent, text_indent = '', name = ''):
        text = [ node.emit('') for node in self.nodes ]
        if text_indent:
            text = [repr(text_indent)] + text
        return indent + 'extend_([%s])\n' % ', '.join(text)

    def __repr__(self):
        return '<line: %s>' % repr(self.nodes)


INDENT = '    '

class BlockNode():

    def __init__(self, stmt, block, begin_indent = ''):
        self.stmt = stmt
        self.suite = Parser().read_suite(block)
        self.begin_indent = begin_indent

    def emit(self, indent, text_indent = ''):
        text_indent = self.begin_indent + text_indent
        out = indent + self.stmt + self.suite.emit(indent + INDENT, text_indent)
        return out

    def __repr__(self):
        return '<block: %s, %s>' % (repr(self.stmt), repr(self.suite))


class ForNode(BlockNode):

    def __init__(self, stmt, block, begin_indent = ''):
        self.original_stmt = stmt
        tok = PythonTokenizer(stmt)
        tok.consume_till('in')
        a = stmt[:tok.index]
        b = stmt[tok.index:-1]
        stmt = a + ' loop.setup(' + b.strip() + '):'
        BlockNode.__init__(self, stmt, block, begin_indent)

    def __repr__(self):
        return '<block: %s, %s>' % (repr(self.original_stmt), repr(self.suite))


class CodeNode():

    def __init__(self, stmt, block, begin_indent = ''):
        self.code = '\n' + block

    def emit(self, indent, text_indent = ''):
        import re
        rx = re.compile('^', re.M)
        return rx.sub(indent, self.code).rstrip(' ')

    def __repr__(self):
        return '<code: %s>' % repr(self.code)


class StatementNode():

    def __init__(self, stmt):
        self.stmt = stmt

    def emit(self, indent, begin_indent = ''):
        return indent + self.stmt

    def __repr__(self):
        return '<stmt: %s>' % repr(self.stmt)


class IfNode(BlockNode):
    pass


class ElseNode(BlockNode):
    pass


class ElifNode(BlockNode):
    pass


class DefNode(BlockNode):

    def __init__(self, *a, **kw):
        BlockNode.__init__(self, *a, **kw)
        code = CodeNode('', '')
        code.code = 'self = TemplateResult(); extend_ = self.extend\n'
        self.suite.sections.insert(0, code)
        code = CodeNode('', '')
        code.code = 'return self\n'
        self.suite.sections.append(code)

    def emit(self, indent, text_indent = ''):
        text_indent = self.begin_indent + text_indent
        out = indent + self.stmt + self.suite.emit(indent + INDENT, text_indent)
        return indent + '__lineoffset__ -= 3\n' + out


class VarNode():

    def __init__(self, name, value):
        self.name = name
        self.value = value

    def emit(self, indent, text_indent):
        return indent + 'self[%s] = %s\n' % (repr(self.name), self.value)

    def __repr__(self):
        return '<var: %s = %s>' % (self.name, self.value)


class SuiteNode():
    """Suite is a list of sections."""

    def __init__(self, sections):
        self.sections = sections

    def emit(self, indent, text_indent = ''):
        return '\n' + ''.join([ s.emit(indent, text_indent) for s in self.sections ])

    def __repr__(self):
        return repr(self.sections)


STATEMENT_NODES = {'for': ForNode,
 'while': BlockNode,
 'if': IfNode,
 'elif': ElifNode,
 'else': ElseNode,
 'def': DefNode,
 'code': CodeNode}
KEYWORDS = ['pass',
 'break',
 'continue',
 'return']
TEMPLATE_BUILTIN_NAMES = ['dict',
 'enumerate',
 'float',
 'int',
 'bool',
 'list',
 'long',
 'reversed',
 'set',
 'slice',
 'tuple',
 'xrange',
 'abs',
 'all',
 'any',
 'callable',
 'chr',
 'cmp',
 'divmod',
 'filter',
 'hex',
 'id',
 'isinstance',
 'iter',
 'len',
 'max',
 'min',
 'oct',
 'ord',
 'pow',
 'range',
 'True',
 'False',
 'None',
 '__import__']
if PY2:
    import __builtin__ as builtins
else:
    import builtins
TEMPLATE_BUILTINS = dict([ (name, getattr(builtins, name)) for name in TEMPLATE_BUILTIN_NAMES if name in builtins.__dict__ ])

class ForLoop():
    """
    Wrapper for expression in for stament to support loop.xxx helpers.
    
        >>> loop = ForLoop()
        >>> for x in loop.setup(['a', 'b', 'c']):
        ...     print(loop.index, loop.revindex, loop.parity, x)
        ...
        1 3 odd a
        2 2 even b
        3 1 odd c
        >>> loop.index
        Traceback (most recent call last):
            ...
        AttributeError: index
    """

    def __init__(self):
        self._ctx = None
        return

    def __getattr__(self, name):
        if self._ctx is None:
            raise AttributeError(name)
        else:
            return getattr(self._ctx, name)
        return

    def setup(self, seq):
        self._push()
        return self._ctx.setup(seq)

    def _push(self):
        self._ctx = ForLoopContext(self, self._ctx)

    def _pop(self):
        self._ctx = self._ctx.parent


class ForLoopContext():
    """Stackable context for ForLoop to support nested for loops.
    """

    def __init__(self, forloop, parent):
        self._forloop = forloop
        self.parent = parent

    def setup(self, seq):
        try:
            self.length = len(seq)
        except:
            self.length = 0

        self.index = 0
        for a in seq:
            self.index += 1
            yield a

        self._forloop._pop()

    index0 = property(lambda self: self.index - 1)
    first = property(lambda self: self.index == 1)
    last = property(lambda self: self.index == self.length)
    odd = property(lambda self: self.index % 2 == 1)
    even = property(lambda self: self.index % 2 == 0)
    parity = property(lambda self: ['odd', 'even'][self.even])
    revindex0 = property(lambda self: self.length - self.index)
    revindex = property(lambda self: self.length - self.index + 1)


class BaseTemplate():

    def __init__(self, code, filename, filter, globals, builtins):
        self.filename = filename
        self.filter = filter
        self._globals = globals
        self._builtins = builtins
        if code:
            self.t = self._compile(code)
        else:
            self.t = lambda : ''

    def _compile(self, code):
        env = self.make_env(self._globals or {}, self._builtins)
        exec code in env
        return env['__template__']

    def __call__(self, *a, **kw):
        __hidetraceback__ = True
        return self.t(*a, **kw)

    def make_env(self, globals, builtins):
        return dict(globals, __builtins__=builtins, ForLoop=ForLoop, TemplateResult=TemplateResult, escape_=self._escape, join_=self._join)

    def _join(self, *items):
        return u''.join(items)

    def _escape(self, value, escape = False):
        if value is None:
            value = ''
        value = safeunicode(value)
        if escape and self.filter:
            value = self.filter(value)
        return value


class Template(BaseTemplate):
    CONTENT_TYPES = {'.html': 'text/html; charset=utf-8',
     '.xhtml': 'application/xhtml+xml; charset=utf-8',
     '.txt': 'text/plain'}
    FILTERS = {'.html': websafe,
     '.xhtml': websafe,
     '.xml': websafe}
    globals = {}

    def __init__(self, text, filename = '<template>', filter = None, globals = None, builtins = None, extensions = None):
        self.extensions = extensions or []
        text = Template.normalize_text(text)
        code = self.compile_template(text, filename)
        _, ext = os.path.splitext(filename)
        filter = filter or self.FILTERS.get(ext, None)
        self.content_type = self.CONTENT_TYPES.get(ext, None)
        if globals is None:
            globals = self.globals
        if builtins is None:
            builtins = TEMPLATE_BUILTINS
        BaseTemplate.__init__(self, code=code, filename=filename, filter=filter, globals=globals, builtins=builtins)
        return

    def normalize_text(text):
        """Normalizes template text by correcting 
        , tabs and BOM chars."""
        text = text.replace('\r\n', '\n').replace('\r', '\n').expandtabs()
        if not text.endswith('\n'):
            text += '\n'
        BOM = '\xef\xbb\xbf'
        if isinstance(text, str) and text.startswith(BOM):
            text = text[len(BOM):]
        text = text.replace('\\$', '$$')
        return text

    normalize_text = staticmethod(normalize_text)

    def __call__(self, *a, **kw):
        __hidetraceback__ = True
        from . import webapi as web
        if 'headers' in web.ctx and self.content_type:
            web.header('Content-Type', self.content_type, unique=True)
        return BaseTemplate.__call__(self, *a, **kw)

    def generate_code(text, filename, parser = None):
        parser = parser or Parser()
        rootnode = parser.parse(text, filename)
        code = rootnode.emit(indent='').strip()
        return safestr(code)

    generate_code = staticmethod(generate_code)

    def create_parser(self):
        p = Parser()
        for ext in self.extensions:
            p = ext(p)

        return p

    def compile_template(self, template_string, filename):
        code = Template.generate_code(template_string, filename, parser=self.create_parser())

        def get_source_line(filename, lineno):
            try:
                lines = open(filename, encoding='utf-8').read().splitlines()
                return lines[lineno]
            except:
                return None

            return None

        try:
            compiled_code = compile(code, filename, 'exec')
        except SyntaxError as err:
            err.msg += '\n\nTemplate traceback:\n    File %s, line %s\n        %s' % (repr(err.filename), err.lineno, get_source_line(err.filename, err.lineno - 1))
            raise

        ast_node = ast.parse(code, filename)
        SafeVisitor().walk(ast_node, filename)
        return compiled_code


class CompiledTemplate(Template):

    def __init__(self, f, filename):
        Template.__init__(self, '', filename)
        self.t = f

    def compile_template(self, *a):
        return None

    def _compile(self, *a):
        return None


class Render():
    """The most preferred way of using templates.
    
        render = web.template.render('templates')
        print render.foo()
        
    Optional parameter can be `base` can be used to pass output of 
    every template through the base template.
    
        render = web.template.render('templates', base='layout')
    """

    def __init__(self, loc = 'templates', cache = None, base = None, **keywords):
        self._loc = loc
        self._keywords = keywords
        if cache is None:
            cache = not config.get('debug', False)
        if cache:
            self._cache = {}
        else:
            self._cache = None
        if base and not hasattr(base, '__call__'):
            self._base = lambda page: self._template(base)(page)
        else:
            self._base = base
        return

    def _add_global(self, obj, name = None):
        """Add a global to this rendering instance."""
        if 'globals' not in self._keywords:
            self._keywords['globals'] = {}
        if not name:
            name = obj.__name__
        self._keywords['globals'][name] = obj

    def _lookup(self, name):
        path = os.path.join(self._loc, name)
        if os.path.isdir(path):
            return ('dir', path)
        else:
            path = self._findfile(path)
            if path:
                return ('file', path)
            return ('none', None)
            return None

    def _load_template(self, name):
        kind, path = self._lookup(name)
        if kind == 'dir':
            return Render(path, cache=(self._cache is not None), base=self._base, **self._keywords)
        elif kind == 'file':
            return Template(open(path, encoding='utf-8').read(), filename=path, **self._keywords)
        else:
            raise AttributeError('No template named ' + name)
            return None

    def _findfile(self, path_prefix):
        p = [ f for f in glob.glob(path_prefix + '.*') if not f.endswith('~') ]
        p.sort()
        if not p and os.path.exists(path_prefix):
            p = [path_prefix]
        return p and p[0]

    def _template(self, name):
        if self._cache is not None:
            if name not in self._cache:
                self._cache[name] = self._load_template(name)
            return self._cache[name]
        else:
            return self._load_template(name)
            return

    def __getattr__(self, name):
        t = self._template(name)
        if self._base and isinstance(t, Template):

            def template(*a, **kw):
                return self._base(t(*a, **kw))

            return template
        else:
            return self._template(name)


class GAE_Render(Render):
    super = Render

    def __init__(self, loc, *a, **kw):
        GAE_Render.super.__init__(self, loc, *a, **kw)
        import types
        if isinstance(loc, types.ModuleType):
            self.mod = loc
        else:
            name = loc.rstrip('/').replace('/', '.')
            self.mod = __import__(name, None, None, ['x'])
        self.mod.__dict__.update(kw.get('builtins', TEMPLATE_BUILTINS))
        self.mod.__dict__.update(Template.globals)
        self.mod.__dict__.update(kw.get('globals', {}))
        return

    def _load_template(self, name):
        t = getattr(self.mod, name)
        import types
        if isinstance(t, types.ModuleType):
            return GAE_Render(t, cache=(self._cache is not None), base=self._base, **self._keywords)
        else:
            return t
            return


render = Render
try:
    from google import appengine
    render = Render = GAE_Render
except ImportError:
    pass

def frender(path, **keywords):
    """Creates a template from the given file path.
    """
    return Template(open(path, encoding='utf-8').read(), filename=path, **keywords)


def compile_templates(root):
    """Compiles templates to python code."""
    re_start = re_compile('^', re.M)
    for dirpath, dirnames, filenames in os.walk(root):
        filenames = [ f for f in filenames if not f.startswith('.') and not f.endswith('~') and not f.startswith('__init__.py') ]
        for d in dirnames[:]:
            if d.startswith('.'):
                dirnames.remove(d)

        out = open(os.path.join(dirpath, '__init__.py'), 'w', encoding='utf-8')
        out.write('from web.template import CompiledTemplate, ForLoop, TemplateResult\n\n')
        if dirnames:
            out.write('import ' + ', '.join(dirnames))
        out.write('\n')
        for f in filenames:
            path = os.path.join(dirpath, f)
            if '.' in f:
                name, _ = f.split('.', 1)
            else:
                name = f
            text = open(path, encoding='utf-8').read()
            text = Template.normalize_text(text)
            code = Template.generate_code(text, path)
            code = code.replace('__template__', name, 1)
            out.write(code)
            out.write('\n\n')
            out.write('%s = CompiledTemplate(%s, %s)\n' % (name, name, repr(path)))
            out.write('join_ = %s._join; escape_ = %s._escape\n\n' % (name, name))
            t = Template(open(path, encoding='utf-8').read(), path)

        out.close()


class ParseError(Exception):
    pass


class SecurityError(Exception):
    """The template seems to be trying to do something naughty."""
    pass


ALLOWED_AST_NODES = ['Interactive',
 'Expression',
 'Suite',
 'FunctionDef',
 'ClassDef',
 'Return',
 'Delete',
 'Assign',
 'AugAssign',
 'alias',
 'For',
 'While',
 'If',
 'With',
 'comprehension',
 'NameConstant',
 'arg',
 'Expr',
 'Pass',
 'Break',
 'Continue',
 'BoolOp',
 'BinOp',
 'UnaryOp',
 'Lambda',
 'IfExp',
 'Dict',
 'Module',
 'arguments',
 'keyword',
 'Set',
 'ListComp',
 'SetComp',
 'DictComp',
 'GeneratorExp',
 'Yield',
 'Compare',
 'Call',
 'Num',
 'Str',
 'Attribute',
 'Subscript',
 'Name',
 'List',
 'Tuple',
 'Load',
 'Store',
 'Del',
 'AugLoad',
 'AugStore',
 'Param',
 'Ellipsis',
 'Slice',
 'ExtSlice',
 'Index',
 'And',
 'Or',
 'Add',
 'Sub',
 'Mult',
 'Div',
 'Mod',
 'Pow',
 'LShift',
 'RShift',
 'BitOr',
 'BitXor',
 'BitAnd',
 'FloorDiv',
 'Invert',
 'Not',
 'UAdd',
 'USub',
 'Eq',
 'NotEq',
 'Lt',
 'LtE',
 'Gt',
 'GtE',
 'Is',
 'IsNot',
 'In',
 'NotIn',
 'ExceptHandler']

class SafeVisitor(ast.NodeVisitor):
    """
    Make sure code is safe by walking through the AST.
    
    Code considered unsafe if:
        * it has restricted AST nodes (only nodes defined in ALLOWED_AST_NODES are allowed)
        * it is trying to assign to attributes
        * it is trying to access resricted attributes   
        
    Adopted from http://www.zafar.se/bkz/uploads/safe.txt (public domain, Babar K. Zafar)
        * Using ast rather than compiler tree, for jython and Py3 support since Py2.6
        * Simplified with ast.NodeVisitor class
    """

    def __init__(self, *args, **kwargs):
        """Initialize visitor by generating callbacks for all AST node types."""
        super(SafeVisitor, self).__init__(*args, **kwargs)
        self.errors = []

    def walk(self, tree, filename):
        """Validate each node in AST and raise SecurityError if the code is not safe."""
        self.filename = filename
        self.visit(tree)
        if self.errors:
            raise SecurityError('\n'.join([ str(err) for err in self.errors ]))

    def generic_visit(self, node):
        nodename = type(node).__name__
        if nodename not in ALLOWED_AST_NODES:
            self.fail_name(node, nodename)
        super(SafeVisitor, self).generic_visit(node)

    def visit_Attribute(self, node):
        attrname = self.get_node_attr(node)
        if self.is_unallowed_attr(attrname):
            self.fail_attribute(node, attrname)
        super(SafeVisitor, self).generic_visit(node)

    def visit_Assign(self, node):
        self.check_assign_targets(node)

    def visit_AugAssign(self, node):
        self.check_assign_target(node)

    def check_assign_targets(self, node):
        for target in node.targets:
            self.check_assign_target(target)

        super(SafeVisitor, self).generic_visit(node)

    def check_assign_target(self, targetnode):
        targetname = type(targetnode).__name__
        if targetname == 'Attribute':
            attrname = self.get_node_attr(targetnode)
            self.fail_attribute(targetnode, attrname)

    def fail_name(self, node, nodename):
        lineno = self.get_node_lineno(node)
        e = SecurityError("%s:%d - execution of '%s' statements is denied" % (self.filename, lineno, nodename))
        self.errors.append(e)

    def fail_attribute(self, node, attrname):
        lineno = self.get_node_lineno(node)
        e = SecurityError("%s:%d - access to attribute '%s' is denied" % (self.filename, lineno, attrname))
        self.errors.append(e)

    def is_unallowed_attr(self, name):
        return name.startswith('_') or name.startswith('func_') or name.startswith('im_')

    def get_node_attr(self, node):
        return 'attr' in node._fields and node.attr or None

    def get_node_lineno(self, node):
        return node.lineno and node.lineno or 0


class TemplateResult(MutableMapping):
    """Dictionary like object for storing template output.
    
    The result of a template execution is usally a string, but sometimes it
    contains attributes set using $var. This class provides a simple
    dictionary like interface for storing the output of the template and the
    attributes. The output is stored with a special key __body__. Convering
    the the TemplateResult to string or unicode returns the value of __body__.
    
    When the template is in execution, the output is generated part by part
    and those parts are combined at the end. Parts are added to the
    TemplateResult by calling the `extend` method and the parts are combined
    seemlessly when __body__ is accessed.
    
        >>> d = TemplateResult(__body__='hello, world', x='foo')
        >>> print(d)
        hello, world
        >>> d.x
        'foo'
        >>> d = TemplateResult()
        >>> d.extend([u'hello', u'world'])
        >>> d
        <TemplateResult: {'__body__': u'helloworld'}>
    """

    def __init__(self, *a, **kw):
        self.__dict__['_d'] = dict(*a, **kw)
        self._d.setdefault('__body__', u'')
        self.__dict__['_parts'] = []
        self.__dict__['extend'] = self._parts.extend
        self._d.setdefault('__body__', None)
        return

    def keys(self):
        return self._d.keys()

    def _prepare_body(self):
        """Prepare value of __body__ by joining parts.
        """
        if self._parts:
            value = u''.join(self._parts)
            self._parts[:] = []
            body = self._d.get('__body__')
            if body:
                self._d['__body__'] = body + value
            else:
                self._d['__body__'] = value

    def __getitem__(self, name):
        if name == '__body__':
            self._prepare_body()
        return self._d[name]

    def __setitem__(self, name, value):
        if name == '__body__':
            self._prepare_body()
        return self._d.__setitem__(name, value)

    def __delitem__(self, name):
        if name == '__body__':
            self._prepare_body()
        return self._d.__delitem__(name)

    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError as k:
            raise AttributeError(k)

    def __setattr__(self, key, value):
        self[key] = value

    def __delattr__(self, key):
        try:
            del self[key]
        except KeyError as k:
            raise AttributeError(k)

    def __unicode__(self):
        self._prepare_body()
        return self['__body__']

    def __str__(self):
        self._prepare_body()
        if PY2:
            return self['__body__'].encode('utf-8')
        else:
            return self['__body__']

    def __repr__(self):
        self._prepare_body()
        return '<TemplateResult: %s>' % self._d

    def __len__(self):
        return self._d.__len__()

    def __iter__(self):
        for i in self._d.__iter__():
            if i == '__body__':
                self._prepare_body()
            yield i


def test():
    r"""Doctest for testing template module.
    
    Define a utility function to run template test.
    
        >>> class TestResult:
        ...     def __init__(self, t): self.t = t
        ...     def __getattr__(self, name): return getattr(self.t, name)
        ...     def __repr__(self): return repr(unicode(self.t) if PY2 else str(self.t))
        ...
        >>> def t(code, **keywords):
        ...     tmpl = Template(code, **keywords)
        ...     return lambda *a, **kw: TestResult(tmpl(*a, **kw))
        ...
    
    Simple tests.
    
        >>> t('1')()
        u'1\n'
        >>> t('$def with ()\n1')()
        u'1\n'
        >>> t('$def with (a)\n$a')(1)
        u'1\n'
        >>> t('$def with (a=0)\n$a')(1)
        u'1\n'
        >>> t('$def with (a=0)\n$a')(a=1)
        u'1\n'
    
    Test complicated expressions.
        
        >>> t('$def with (x)\n$x.upper()')('hello')
        u'HELLO\n'
        >>> t('$(2 * 3 + 4 * 5)')()
        u'26\n'
        >>> t('${2 * 3 + 4 * 5}')()
        u'26\n'
        >>> t('$def with (limit)\nkeep $(limit)ing.')('go')
        u'keep going.\n'
        >>> t('$def with (a)\n$a.b[0]')(storage(b=[1]))
        u'1\n'
        
    Test html escaping.
    
        >>> t('$def with (x)\n$x', filename='a.html')('<html>')
        u'&lt;html&gt;\n'
        >>> t('$def with (x)\n$x', filename='a.txt')('<html>')
        u'<html>\n'
                
    Test if, for and while.
    
        >>> t('$if 1: 1')()
        u'1\n'
        >>> t('$if 1:\n    1')()
        u'1\n'
        >>> t('$if 1:\n    1\\')()
        u'1'
        >>> t('$if 0: 0\n$elif 1: 1')()
        u'1\n'
        >>> t('$if 0: 0\n$elif None: 0\n$else: 1')()
        u'1\n'
        >>> t('$if 0 < 1 and 1 < 2: 1')()
        u'1\n'
        >>> t('$for x in [1, 2, 3]: $x')()
        u'1\n2\n3\n'
        >>> t('$def with (d)\n$for k, v in d.items(): $k')({1: 1})
        u'1\n'
        >>> t('$for x in [1, 2, 3]:\n\t$x')()
        u'    1\n    2\n    3\n'
        >>> t('$def with (a)\n$while a and a.pop():1')([1, 2, 3])
        u'1\n1\n1\n'
    
    The space after : must be ignored.
    
        >>> t('$if True: foo')()
        u'foo\n'
    
    Test loop.xxx.
    
        >>> t("$for i in range(5):$loop.index, $loop.parity")()
        u'1, odd\n2, even\n3, odd\n4, even\n5, odd\n'
        >>> t("$for i in range(2):\n    $for j in range(2):$loop.parent.parity $loop.parity")()
        u'odd odd\nodd even\neven odd\neven even\n'
        
    Test assignment.
    
        >>> t('$ a = 1\n$a')()
        u'1\n'
        >>> t('$ a = [1]\n$a[0]')()
        u'1\n'
        >>> t('$ a = {1: 1}\n$list(a.keys())[0]')()
        u'1\n'
        >>> t('$ a = []\n$if not a: 1')()
        u'1\n'
        >>> t('$ a = {}\n$if not a: 1')()
        u'1\n'
        >>> t('$ a = -1\n$a')()
        u'-1\n'
        >>> t('$ a = "1"\n$a')()
        u'1\n'
    
    Test comments.
    
        >>> t('$# 0')()
        u'\n'
        >>> t('hello$#comment1\nhello$#comment2')()
        u'hello\nhello\n'
        >>> t('$#comment0\nhello$#comment1\nhello$#comment2')()
        u'\nhello\nhello\n'
        
    Test unicode.
    
        >>> t('$def with (a)\n$a')(u'\u203d')
        u'\u203d\n'
        >>> t(u'$def with (a)\n$a $:a')(u'\u203d')
        u'\u203d \u203d\n'
        >>> t(u'$def with ()\nfoo')()
        u'foo\n'
        >>> def f(x): return x
        ...
        >>> t(u'$def with (f)\n$:f("x")')(f)
        u'x\n'
        >>> t('$def with (f)\n$:f("x")')(f)
        u'x\n'
    
    Test dollar escaping.
    
        >>> t("Stop, $$money isn't evaluated.")()
        u"Stop, $money isn't evaluated.\n"
        >>> t("Stop, \$money isn't evaluated.")()
        u"Stop, $money isn't evaluated.\n"
        
    Test space sensitivity.
    
        >>> t('$def with (x)\n$x')(1)
        u'1\n'
        >>> t('$def with(x ,y)\n$x')(1, 1)
        u'1\n'
        >>> t('$(1 + 2*3 + 4)')()
        u'11\n'
        
    Make sure globals are working.
            
        >>> t('$x')()
        Traceback (most recent call last):
            ...
        NameError: global name 'x' is not defined
        >>> t('$x', globals={'x': 1})()
        u'1\n'
        
    Can't change globals.
    
        >>> t('$ x = 2\n$x', globals={'x': 1})()
        u'2\n'
        >>> t('$ x = x + 1\n$x', globals={'x': 1})()
        Traceback (most recent call last):
            ...
        UnboundLocalError: local variable 'x' referenced before assignment
    
    Make sure builtins are customizable.
    
        >>> t('$min(1, 2)')()
        u'1\n'
        >>> t('$min(1, 2)', builtins={})()
        Traceback (most recent call last):
            ...
        NameError: global name 'min' is not defined
        
    Test vars.
    
        >>> x = t('$var x: 1')()
        >>> x.x
        u'1'
        >>> x = t('$var x = 1')()
        >>> x.x
        1
        >>> x = t('$var x:  \n    foo\n    bar')()
        >>> x.x
        u'foo\nbar\n'
    
    Test BOM chars.
    
        >>> t('\xef\xbb\xbf$def with(x)\n$x')('foo')
        u'foo\n'
    
    Test for with weird cases.
    
        >>> t('$for i in range(10)[1:5]:\n    $i')()
        u'1\n2\n3\n4\n'
        >>> t("$for k, v in sorted({'a': 1, 'b': 2}.items()):\n    $k $v", globals={'sorted':sorted})()
        u'a 1\nb 2\n'
    
    Test for syntax error.
    
        >>> try:
        ...     t("$for k, v in ({'a': 1, 'b': 2}.items():\n    $k $v")()
        ... except SyntaxError:
        ...     print("OK")
        ... else:
        ...     print("Expected SyntaxError")
        ...
        OK
    
    Test datetime.
    
        >>> import datetime
        >>> t("$def with (date)\n$date.strftime('%m %Y')")(datetime.datetime(2009, 1, 1))
        u'01 2009\n'
    
    """
    pass


if __name__ == '__main__':
    import sys
    if '--compile' in sys.argv:
        compile_templates(sys.argv[2])
    else:
        import doctest
        doctest.testmod()