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Diffstat (limited to 'websdk/jinja2/meta.py')
| -rw-r--r-- | websdk/jinja2/meta.py | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/websdk/jinja2/meta.py b/websdk/jinja2/meta.py new file mode 100644 index 0000000..3a779a5 --- /dev/null +++ b/websdk/jinja2/meta.py @@ -0,0 +1,102 @@ +# -*- coding: utf-8 -*- +""" + jinja2.meta + ~~~~~~~~~~~ + + This module implements various functions that exposes information about + templates that might be interesting for various kinds of applications. + + :copyright: (c) 2010 by the Jinja Team, see AUTHORS for more details. + :license: BSD, see LICENSE for more details. +""" +from jinja2 import nodes +from jinja2.compiler import CodeGenerator + + +class TrackingCodeGenerator(CodeGenerator): + """We abuse the code generator for introspection.""" + + def __init__(self, environment): + CodeGenerator.__init__(self, environment, '<introspection>', + '<introspection>') + self.undeclared_identifiers = set() + + def write(self, x): + """Don't write.""" + + def pull_locals(self, frame): + """Remember all undeclared identifiers.""" + self.undeclared_identifiers.update(frame.identifiers.undeclared) + + +def find_undeclared_variables(ast): + """Returns a set of all variables in the AST that will be looked up from + the context at runtime. Because at compile time it's not known which + variables will be used depending on the path the execution takes at + runtime, all variables are returned. + + >>> from jinja2 import Environment, meta + >>> env = Environment() + >>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}') + >>> meta.find_undeclared_variables(ast) + set(['bar']) + + .. admonition:: Implementation + + Internally the code generator is used for finding undeclared variables. + This is good to know because the code generator might raise a + :exc:`TemplateAssertionError` during compilation and as a matter of + fact this function can currently raise that exception as well. + """ + codegen = TrackingCodeGenerator(ast.environment) + codegen.visit(ast) + return codegen.undeclared_identifiers + + +def find_referenced_templates(ast): + """Finds all the referenced templates from the AST. This will return an + iterator over all the hardcoded template extensions, inclusions and + imports. If dynamic inheritance or inclusion is used, `None` will be + yielded. + + >>> from jinja2 import Environment, meta + >>> env = Environment() + >>> ast = env.parse('{% extends "layout.html" %}{% include helper %}') + >>> list(meta.find_referenced_templates(ast)) + ['layout.html', None] + + This function is useful for dependency tracking. For example if you want + to rebuild parts of the website after a layout template has changed. + """ + for node in ast.find_all((nodes.Extends, nodes.FromImport, nodes.Import, + nodes.Include)): + if not isinstance(node.template, nodes.Const): + # a tuple with some non consts in there + if isinstance(node.template, (nodes.Tuple, nodes.List)): + for template_name in node.template.items: + # something const, only yield the strings and ignore + # non-string consts that really just make no sense + if isinstance(template_name, nodes.Const): + if isinstance(template_name.value, basestring): + yield template_name.value + # something dynamic in there + else: + yield None + # something dynamic we don't know about here + else: + yield None + continue + # constant is a basestring, direct template name + if isinstance(node.template.value, basestring): + yield node.template.value + # a tuple or list (latter *should* not happen) made of consts, + # yield the consts that are strings. We could warn here for + # non string values + elif isinstance(node, nodes.Include) and \ + isinstance(node.template.value, (tuple, list)): + for template_name in node.template.value: + if isinstance(template_name, basestring): + yield template_name + # something else we don't care about, we could warn here + else: + yield None |