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pystache_custom
Commit 854b84c9 by Chris Jerdonek
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Created a parser module.

parent 19ac543d
Showing with 199 additions and 183 deletions
pystache/parser.py 0 → 100644
# coding: utf-8
"""
Provides a class for parsing template strings.
This module is only meant for internal use by the renderengine module.
"""
import re
DEFAULT_DELIMITERS = ('{{', '}}')
END_OF_LINE_CHARACTERS = ['\r', '\n']
def _compile_template_re(delimiters):
# The possible tag type characters following the opening tag,
# excluding "=" and "{".
tag_types = "!>&/#^"
# TODO: are we following this in the spec?
#
# The tag's content MUST be a non-whitespace character sequence
# NOT containing the current closing delimiter.
#
tag = r"""
(?P<whitespace>[\ \t]*)
%(otag)s \s*
(?:
(?P<change>=) \s* (?P<delims>.+?) \s* = |
(?P<raw>{) \s* (?P<raw_name>.+?) \s* } |
(?P<tag>[%(tag_types)s]?) \s* (?P<name>[\s\S]+?)
)
\s* %(ctag)s
""" % {'tag_types': tag_types, 'otag': re.escape(delimiters[0]), 'ctag': re.escape(delimiters[1])}
return re.compile(tag, re.VERBOSE)
class EndOfSection(Exception):
def __init__(self, parse_tree, template, position):
self.parse_tree = parse_tree
self.template = template
self.position = position
class Parser(object):
_delimiters = None
_template_re = None
def __init__(self, engine, delimiters=None):
"""
Construct an instance.
Arguments:
engine: a RenderEngine instance.
"""
if delimiters is None:
delimiters = DEFAULT_DELIMITERS
self._delimiters = delimiters
self.engine = engine
def compile_template_re(self):
self._template_re = _compile_template_re(self._delimiters)
def _change_delimiters(self, delimiters):
self._delimiters = delimiters
self.compile_template_re()
def parse(self, template, index=0):
"""
Parse a template string into a syntax tree using current attributes.
This method uses the current RenderEngine instance's attributes,
including the current tag delimiter, etc.
"""
parse_tree = []
start_index = index
while True:
match = self._template_re.search(template, index)
if match is None:
break
match_index = match.start()
end_index = match.end()
before_tag = template[index : match_index]
parse_tree.append(before_tag)
matches = match.groupdict()
index = self._handle_match(template, parse_tree, matches, start_index, match_index, end_index)
# Save the rest of the template.
parse_tree.append(template[index:])
return parse_tree
def _handle_match(self, template, parse_tree, matches, start_index, match_index, end_index):
engine = self.engine
# Normalize the matches dictionary.
if matches['change'] is not None:
matches.update(tag='=', name=matches['delims'])
elif matches['raw'] is not None:
matches.update(tag='&', name=matches['raw_name'])
tag_type = matches['tag']
# Standalone (non-interpolation) tags consume the entire line,
# both leading whitespace and trailing newline.
did_tag_begin_line = match_index == 0 or template[match_index - 1] in END_OF_LINE_CHARACTERS
did_tag_end_line = end_index == len(template) or template[end_index] in END_OF_LINE_CHARACTERS
is_tag_interpolating = tag_type in ['', '&']
if did_tag_begin_line and did_tag_end_line and not is_tag_interpolating:
if end_index < len(template):
end_index += template[end_index] == '\r' and 1 or 0
if end_index < len(template):
end_index += template[end_index] == '\n' and 1 or 0
elif matches['whitespace']:
parse_tree.append(matches['whitespace'])
match_index += len(matches['whitespace'])
matches['whitespace'] = ''
name = matches['name']
if tag_type == '!':
return end_index
if tag_type == '=':
delimiters = name.split()
self._change_delimiters(delimiters)
return end_index
if tag_type == '>':
func = engine._make_get_partial(name, matches['whitespace'])
elif tag_type in ['#', '^']:
try:
self.parse(template=template, index=end_index)
except EndOfSection as e:
bufr = e.parse_tree
tmpl = e.template
end_index = e.position
if tag_type == '#':
func = engine._make_get_section(name, bufr, tmpl, self._delimiters)
else:
func = engine._make_get_inverse(name, bufr)
elif tag_type == '&':
func = engine._make_get_literal(name)
elif tag_type == '':
func = engine._make_get_escaped(name)
elif tag_type == '/':
# TODO: don't use exceptions for flow control.
raise EndOfSection(parse_tree, template[start_index:match_index], end_index)
else:
raise Exception("Unrecognized tag type: %s" % repr(tag_type))
parse_tree.append(func)
return end_index
pystache/renderengine.py
......@@ -7,34 +7,10 @@ Defines a class responsible for rendering logic.
import re
from parser import Parser
DEFAULT_DELIMITERS = ('{{', '}}')
END_OF_LINE_CHARACTERS = ['\r', '\n']
def _compile_template_re(delimiters):
# The possible tag type characters following the opening tag,
# excluding "=" and "{".
tag_types = "!>&/#^"
# TODO: are we following this in the spec?
#
# The tag's content MUST be a non-whitespace character sequence
# NOT containing the current closing delimiter.
#
tag = r"""
(?P<whitespace>[\ \t]*)
%(otag)s \s*
(?:
(?P<change>=) \s* (?P<delims>.+?) \s* = |
(?P<raw>{) \s* (?P<raw_name>.+?) \s* } |
(?P<tag>[%(tag_types)s]?) \s* (?P<name>[\s\S]+?)
)
\s* %(ctag)s
""" % {'tag_types': tag_types, 'otag': re.escape(delimiters[0]), 'ctag': re.escape(delimiters[1])}
return re.compile(tag, re.VERBOSE)
NON_BLANK_RE = re.compile(r'^(.)', re.M)
def render_parse_tree(parse_tree, context):
......@@ -70,27 +46,6 @@ def render_parse_tree(parse_tree, context):
return unicode(s)
def _make_get_inverse(name, parsed):
def get_inverse(context):
"""
Returns a string with type unicode.
"""
data = context.get(name)
if data:
return u''
return render_parse_tree(parsed, context)
return get_inverse
class EndOfSection(Exception):
def __init__(self, parse_tree, template, position):
self.parse_tree = parse_tree
self.template = template
self.position = position
class RenderEngine(object):
"""
......@@ -110,8 +65,6 @@ class RenderEngine(object):
"""
nonblank_re = re.compile(r'^(.)', re.M)
def __init__(self, load_partial=None, literal=None, escape=None):
"""
Arguments:
......@@ -217,11 +170,24 @@ class RenderEngine(object):
"""
template = self.load_partial(name)
# Indent before rendering.
template = re.sub(self.nonblank_re, indentation + r'\1', template)
template = re.sub(NON_BLANK_RE, indentation + r'\1', template)
return self._render(template, context)
return get_partial
def _make_get_inverse(self, name, parsed):
def get_inverse(context):
"""
Returns a string with type unicode.
"""
data = context.get(name)
if data:
return u''
return render_parse_tree(parsed, context)
return get_inverse
def _make_get_section(self, name, parse_tree_, template_, delims):
def get_section(context):
"""
......@@ -256,7 +222,7 @@ class RenderEngine(object):
Parse the given template into a parse tree using a new parser.
"""
parser = _Parser(self, delimiters=delimiters)
parser = Parser(self, delimiters=delimiters)
parser.compile_template_re()
return parser.parse(template=template_string)
......@@ -296,135 +262,3 @@ class RenderEngine(object):
template = unicode(template)
return self._render(template, context)
class _Parser(object):
_delimiters = None
_template_re = None
def __init__(self, engine, delimiters=None):
"""
Construct an instance.
"""
if delimiters is None:
delimiters = DEFAULT_DELIMITERS
self._delimiters = delimiters
self.engine = engine
def compile_template_re(self):
self._template_re = _compile_template_re(self._delimiters)
def _change_delimiters(self, delimiters):
self._delimiters = delimiters
self.compile_template_re()
def parse(self, template, index=0):
"""
Parse a template string into a syntax tree using current attributes.
This method uses the current RenderEngine instance's attributes,
including the current tag delimiter, etc.
"""
parse_tree = []
start_index = index
while True:
match = self._template_re.search(template, index)
if match is None:
break
match_index = match.start()
end_index = match.end()
before_tag = template[index : match_index]
parse_tree.append(before_tag)
matches = match.groupdict()
index = self._handle_match(template, parse_tree, matches, start_index, match_index, end_index)
# Save the rest of the template.
parse_tree.append(template[index:])
return parse_tree
def _handle_match(self, template, parse_tree, matches, start_index, match_index, end_index):
engine = self.engine
# Normalize the matches dictionary.
if matches['change'] is not None:
matches.update(tag='=', name=matches['delims'])
elif matches['raw'] is not None:
matches.update(tag='&', name=matches['raw_name'])
tag_type = matches['tag']
# Standalone (non-interpolation) tags consume the entire line,
# both leading whitespace and trailing newline.
did_tag_begin_line = match_index == 0 or template[match_index - 1] in END_OF_LINE_CHARACTERS
did_tag_end_line = end_index == len(template) or template[end_index] in END_OF_LINE_CHARACTERS
is_tag_interpolating = tag_type in ['', '&']
if did_tag_begin_line and did_tag_end_line and not is_tag_interpolating:
if end_index < len(template):
end_index += template[end_index] == '\r' and 1 or 0
if end_index < len(template):
end_index += template[end_index] == '\n' and 1 or 0
elif matches['whitespace']:
parse_tree.append(matches['whitespace'])
match_index += len(matches['whitespace'])
matches['whitespace'] = ''
name = matches['name']
if tag_type == '!':
return end_index
if tag_type == '=':
delimiters = name.split()
self._change_delimiters(delimiters)
return end_index
if tag_type == '>':
func = engine._make_get_partial(name, matches['whitespace'])
elif tag_type in ['#', '^']:
try:
self.parse(template=template, index=end_index)
except EndOfSection as e:
bufr = e.parse_tree
tmpl = e.template
end_index = e.position
if tag_type == '#':
func = engine._make_get_section(name, bufr, tmpl, self._delimiters)
else:
func = _make_get_inverse(name, bufr)
elif tag_type == '&':
func = engine._make_get_literal(name)
elif tag_type == '':
func = engine._make_get_escaped(name)
elif tag_type == '/':
# TODO: don't use exceptions for flow control.
raise EndOfSection(parse_tree, template[start_index:match_index], end_index)
else:
raise Exception("Unrecognized tag type: %s" % repr(tag_type))
parse_tree.append(func)
return end_index
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