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# Copyright (C) 2012 Tim Radvan
# This file is part of Kurt.
# Kurt is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
# Kurt is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
# You should have received a copy of the GNU Lesser General Public License along
# with Kurt. If not, see <>.
"""Experimental text parser for scripts.
The original parser used block plugin syntax, the same as the ``scratchblocks``
tag used on the Scratch Forums and Wiki. See:
This parser supports most of the block plugin syntax. Most notably, using < >
for boolean shaped blocks is not supported.
import re
from collections import OrderedDict
import kurt
#-- Tokens --#
class Token(object):
def __init__(self, value):
self.value = value
def __repr__(self):
return "%s(%r)" % (self.__class__.__name__, self.value)
class symbol(Token):
lbp = 0
class literal(Token):
def nud(self):
return self.value
class number(Token):
def __init__(self, value):
value = float(value)
if int(value) == value:
value = int(value)
self.value = value
def nud(self):
return self
class string(Token):
lbp = 0
def nud(self):
return self
class color(Token):
def nud(self):
self.value = kurt.Color(self.value)
return self
class lparen(Token):
lbp = 0
def nud(self):
global token
contents = expression()
if isinstance(contents, rparen): # empty brackets
if not isinstance(token, rparen):
raise SyntaxError("Expected bracket to match %s" % self.value)
token = next()
return contents
class rparen(Token):
lbp = 0
def nud(self):
return self
class newline(symbol):
name = "EOL"
lbp = 3
def nud(self):
return []
def led(self, left):
if isinstance(left, kurt.Block):
left = [left]
return left
class end_token(Token):
name = "EOF"
lbp = 0
def __init__(self):
self.value = None
def __repr__(self):
return "%s()" % self.__class__.__name__
#-- Identity Token --#
# block kinds:
# - infix
# - postfix ("_ sensor value")
# - insert transformations ("var", "list", "param", "{}")
def inline_blocks():
for block in kurt.plugin.Kurt.blocks:
if len(block.inserts) == 1 and block.inserts[0].shape == "inline":
yield block
def all_the_blocks():
for block in kurt.plugin.Kurt.blocks:
done_text = set()
for block in block.conversions:
if block.text in done_text:
yield block
def match_part(part, block_part):
if isinstance(block_part, kurt.Insert):
return (isinstance(part, (Token, kurt.Block, list)))
return (block_part.strip() == part)
def blocks_starting_with(parts):
suppress_blocks = set(suppress_block_names())
for block in all_the_blocks():
if len(parts) > len(
if (isinstance([0], basestring)
and[0].strip() in suppress_blocks):
for (p, bp) in zip(parts,
if not match_part(p, bp):
yield block
def next_block_part(parts):
for block in blocks_starting_with(parts):
next_part = ([len(parts)]
if len( > len(parts)
else None)
if isinstance(next_part, basestring):
next_part = next_part.strip()
yield next_part
def blocks_by_parts(parts):
for block in all_the_blocks():
if len(parts) != len(
for (p, bp) in zip(parts,
if not match_part(p, bp):
yield block
def block_from_parts(parts):
args = []
for part in parts:
if isinstance(part, (Token, kurt.Block, list)):
failure = ""
for block in blocks_by_parts(parts):
block_args = []
for (arg, insert) in zip(args, block.inserts):
if isinstance(arg, Token):
if (isinstance(arg, iden) and
not insert.shape in ("number-menu", "readonly-menu")):
arg = kurt.Block(arg.value)
elif (isinstance(arg, iden) and
insert.shape in ("number-menu", "readonly-menu") and
arg not in insert.options()):
arg = kurt.Block(arg.value)
except kurt.UnknownBlock:
arg = arg.value
arg = arg.value
elif (isinstance(arg, kurt.Block) and
arg.type.text in insert.options(context)):
arg = arg.type.text
ok = False
if insert.shape == "string" or insert.kind == "broadcast":
if isinstance(arg, (int, long, float, complex, str)):
arg = unicode(arg)
ok = isinstance(arg, (unicode, kurt.Block))
elif insert.shape == "color":
ok = isinstance(arg, kurt.Color)
elif insert.shape == "boolean":
ok = arg is None or (isinstance(arg, kurt.Block)
and arg.type.shape == "boolean")
elif insert.shape == "stack":
ok = isinstance(arg, list)
elif insert.shape in ("number", "number-menu", "readonly-menu"):
if insert.shape in ("number", "number-menu"):
if isinstance(arg, basestring):
arg = float(arg)
arg = int(arg) if int(arg) == arg else arg
except ValueError:
if isinstance(arg, (int, long, float, complex,
ok = True
if insert.shape in ("readonly-menu", "number-menu"):
if (str(arg) in insert.options(context)
or isinstance(arg, kurt.Block)):
ok = True
if not ok:
failure = "%r doesn't fit %s" % (arg, insert.shape)
if insert.kind:
failure += " " + insert.kind
return kurt.Block(block, *block_args)
throw("Wrong type of arguments to block: %s" % failure, repr(parts))
class iden(Token):
def lbp(self):
return PRECEDENCE.get(self.value, 100)
def nud(self):
return self.parse_block([self.value])
except SyntaxError:
for block in inline_blocks():
if self.value in block.inserts[0].options(context):
return kurt.Block(block, self.value)
if len( == 1 and self.value in set(make_menu_tokens()):
return iden(self.value)
def led(self, left):
if isinstance(left, list):
return left + [self.parse_block([self.value])]
return self.parse_block([left, self.value])
def parse_block(self, parts):
global token = parts
while 1:
part = self.parse_one_part(parts)
if part is not None:
if isinstance(part, rparen):
part = False
block = block_from_parts(parts)
if isinstance(token, end_token):
return block
if block.type.has_insert("stack"):
if not token.value == "end":
throw("Expected 'end' after C mouth")
token = next()
return block
def parse_one_part(self, parts):
global token, next
expect = set(next_block_part(parts))
if not expect: = parts
throw("Can't find block %r" % parts)
if expect == set(['']):
return ''
all_inserts = filter(lambda p: isinstance(p, kurt.Insert), expect)
if isinstance(token, iden):
text_segments = filter(lambda p: isinstance(p, basestring), expect)
menu_inserts = filter(lambda i: i.options(context), all_inserts)
if token.value in text_segments:
part = token.value
token = next()
return part
for insert in menu_inserts:
if token.value in insert.options(context):
part = token
token = next()
return part
if None in expect:
return None
stack_inserts = filter(lambda i: i.shape == 'stack', all_inserts)
if stack_inserts:
if isinstance(token, end_token):
part = []
part = expression(1)
assert isinstance(part, list)
return part
if isinstance(token, (newline, end_token)):
throw("Unexpected EOL", expected=expect)
if all_inserts:
return expression(self.lbp)
throw("Wrong argument", expected=expect)
#-- Tokenizer --#
"*": 130,
"/": 130,
"+": 120,
"-": 120,
"<": 110,
"=": 110,
">": 110,
"else": 0,
TOKENS = [(re.compile(r), cls) for (r, cls) in [
(r'end', symbol),
(r'(-?[0-9]+(\.[0-9]+)?)', number),
(r'\[(#[A-Fa-f0-9]{3,6})\]', color),
(r'\[([^\]]+?)( v)?\]', string),
(r'\"([^"]+)\"', string),
(r"\'([^']+)\'", string),
(r'\(', lparen),
(r'\)', rparen),
# (r'\<', lparen),
# (r'\>', rparen),
(r'\n|\r|\r\n', newline),
NEWLINE_PAT = re.compile(r'\n|\r|\r\n')
SEPARATOR_PAT = re.compile(r'[^A-Za-z:#%+*-,=<?>]')
WHITESPACE_PAT = re.compile(r'[ \t]+')
"when green flag clicked": "when @greenFlag clicked",
"when gf clicked": "when @greenFlag clicked",
"turn left": "turn @turnLeft",
"turn right": "turn @turnRight",
"turn ccw": "turn @turnRight",
"turn cw": "turn @turnRight",
def make_block_tokens():
for block in kurt.plugin.Kurt.blocks:
for part in
if isinstance(part, basestring):
yield part.strip()
for alias in SEGMENT_ALIASES:
yield alias
def make_menu_tokens():
global context
for kind in kurt.Insert.KIND_OPTIONS:
if kind == "broadcast": continue
for o in kurt.Insert(None, kind).options(context):
yield str(o)
def suppress_block_names():
for block in kurt.plugin.Kurt.blocks:
if isinstance([0], kurt.Insert):
for o in[0].options(context):
yield o
def tokenize(program):
block_tokens = sorted(set(make_block_tokens()) | set(make_menu_tokens()))
block_tokens.sort(key=len, reverse=True)
block_tokens = filter(lambda x: not x.isdigit(), block_tokens)
block_tokens = filter(None, block_tokens)
global remain, lineno
remain = program
lineno = 1
while remain:
m = WHITESPACE_PAT.match(remain)
if m:
remain = remain[m.end():]
if not remain:
for (pat, cls) in TOKENS:
m = pat.match(remain)
if m:
if m.groups():
contents =
contents =
yield cls(contents)
remain = remain[m.end():]
if cls == newline:
lineno += 1
for value in block_tokens:
if remain.startswith(value):
after_value = remain[len(value):]
if not after_value or SEPARATOR_PAT.match(after_value[0]):
value = SEGMENT_ALIASES.get(value, value)
yield iden(value)
remain = after_value
throw("Unknown token at %r" % remain.split("\n")[0])
yield end_token()
#-- Parser --#
p_input = ""
def expression(rbp=0):
global token
t = token
token = next()
left = t.nud()
if not hasattr(token, "lbp"):
throw("Not an operator: %r" % token)
while rbp < token.lbp:
t = token
token = next()
left = t.led(left)
if not hasattr(token, "lbp"):
throw("Not an operator: %r" % token)
return left
def parse(program, scriptable):
global token, next, context, p_input
# for errors
p_input = program
context = scriptable
next = tokenize(program).next
token = next()
result = expression()
if not isinstance(token, end_token):
throw("Expected end of input")
if isinstance(result, kurt.Block):
result = [result]
if not isinstance(result, list):
throw("Result does not evaluate to a block")
return kurt.Script(result)
def throw(msg, hint=None, expected=None):
global remain
if expected:
repr_expected = map(repr, expected)
hint = "Expected %s" % (repr_expected[0] if len(repr_expected) == 1
else "one of " + ", ".join(repr_expected))
if hint:
msg += ". " + hint
line = NEWLINE_PAT.split(p_input)[lineno - 1]
offset = len(p_input) - len(remain) #- len(token.value)
err = SyntaxError(msg, ('<string>', lineno, offset, line))
err.expected = expected
raise err
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