/usr/share/pyshared/ometa/builder.py is in python-parsley 1.2-1.
This file is owned by root:root, with mode 0o644.
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import ast
from StringIO import StringIO
from types import ModuleType as module
import linecache, sys
from terml.nodes import Term, Tag, coerceToTerm
class TextWriter(object):
stepSize = 4
def __init__(self, f, indentSteps=0):
self.file = f
self.indentSteps = indentSteps
def writeln(self, data):
if data:
self.file.write(" " * (self.indentSteps * self.stepSize))
self.file.write(data)
self.file.write("\n")
def indent(self):
return TextWriter(self.file, self.indentSteps + 1)
class PythonWriter(object):
"""
Converts an OMeta syntax tree into Python source.
"""
def __init__(self, tree, grammarText):
self.tree = tree
self.grammarText = grammarText
self.gensymCounter = 0
self.compiledExprCache = None
def _generate(self, out, expr, retrn=False, debugname=None):
result = self._generateNode(out, expr, debugname=debugname)
if retrn:
out.writeln("return (%s, self.currentError)" % (result,))
elif result:
out.writeln(result)
def output(self, out):
self._generate(out, self.tree)
def _generateNode(self, out, node, debugname=None):
name = node.tag.name
args = node.args
if name == 'null':
return 'None'
if node.span:
out.writeln("self._trace(%r, %r, self.input.position)"
% (self.grammarText[slice(*node.span)], node.span))
return getattr(self, "generate_"+name)(out, *args, debugname=debugname)
def _gensym(self, name):
"""
Produce a unique name for a variable in generated code.
"""
self.gensymCounter += 1
return "_G_%s_%s" % (name, self.gensymCounter)
def _newThunkFor(self, out, name, expr):
"""
Define a new function of no arguments.
@param name: The name of the rule generating this thunk.
@param expr: A list of lines of Python code.
"""
fname = self._gensym(name)
self._writeFunction(out, fname, (), expr)
return fname
def _expr(self, out, typ, e, debugname=None):
"""
Generate the code needed to execute the expression, and return the
variable name bound to its value.
"""
name = self._gensym(typ)
out.writeln("%s, lastError = %s" % (name, e))
out.writeln("self.considerError(lastError, %r)" % (debugname and debugname.data,))
return name
def _writeFunction(self, out, fname, arglist, expr):
"""
Generate a function.
@param out: the TextWriter used for output.
@param fname: The name of the function generated.
@param arglist: A list of parameter names.
@param expr: The term tree to generate the function body from.
"""
out.writeln("def %s(%s):" % (fname, ", ".join(arglist)))
self._generate(out.indent(), expr, retrn=True)
return fname
def compilePythonExpr(self, out, expr, debugname=None):
"""
Generate code for running embedded Python expressions.
"""
try:
ast.literal_eval(expr)
return self._expr(out, 'python', '(' + expr + '), None', debugname)
except ValueError:
if self.compiledExprCache is None:
return self._expr(out, 'python',
'eval(%r, self.globals, _locals), None' % (expr,),
debugname)
else:
if expr in self.compiledExprCache:
sym = self.compiledExprCache[expr]
else:
sym = self.compiledExprCache[expr] = self._gensym('expr')
return self._expr(out, 'python',
'eval(self.%s, self.globals, _locals), None' % (sym,),
debugname)
def _convertArgs(self, out, rawArgs, debugname):
return [self._generateNode(out, x, debugname) for x in rawArgs]
def generate_Apply(self, out, ruleName, codeName, rawArgs, debugname=None):
"""
Create a call to self.apply(ruleName, *args).
"""
ruleName = ruleName.data
args = self._convertArgs(out, rawArgs.args, debugname)
if ruleName == 'super':
return self._expr(out, 'apply', 'self.superApply("%s", %s)'
% (codeName.data, ', '.join(args)),
debugname)
return self._expr(out, 'apply', 'self._apply(self.rule_%s, "%s", [%s])'
% (ruleName, ruleName, ', '.join(args)),
debugname)
def generate_ForeignApply(self, out, grammarName, ruleName, codeName,
rawArgs, debugname=None):
"""
Create a call to self.foreignApply(ruleName, *args)
"""
grammarName = grammarName.data
ruleName = ruleName.data
args = self._convertArgs(out, rawArgs.args, debugname)
call = ('self.foreignApply("%s", "%s", self.globals, _locals, %s)'
% (grammarName, ruleName, ', '.join(args)))
return self._expr(out, 'apply', call, debugname)
def generate_Exactly(self, out, literal, debugname=None):
"""
Create a call to self.exactly(expr).
"""
return self._expr(out, 'exactly', 'self.exactly(%r)' % (literal.data,), debugname)
def generate_Token(self, out, literal, debugname=None):
if self.takesTreeInput:
return self.generate_Exactly(out, literal, debugname)
else:
return self._expr(out, 'apply',
'self._apply(self.rule_token, "token", ["%s"])'
% (literal.data,),
debugname)
def generate_Many(self, out, expr, debugname=None):
"""
Create a call to self.many(lambda: expr).
"""
fname = self._newThunkFor(out, "many", expr)
return self._expr(out, 'many', 'self.many(%s)' % (fname,), debugname)
def generate_Many1(self, out, expr, debugname=None):
"""
Create a call to self.many(lambda: expr).
"""
fname = self._newThunkFor(out, "many1", expr)
return self._expr(out, 'many1', 'self.many(%s, %s())' % (fname, fname), debugname)
def generate_Repeat(self, out, min, max, expr, debugname=None):
"""
Create a call to self.repeat(min, max, lambda: expr).
"""
fname = self._newThunkFor(out, "repeat", expr)
if min.tag.name == '.int.':
min = min.data
else:
min = '_locals["%s"]' % min.data
if max.tag.name == '.int.':
max = max.data
else:
max = '_locals["%s"]' % max.data
if min == max == 0:
return "''"
return self._expr(out, 'repeat', 'self.repeat(%s, %s, %s)'
% (min, max, fname))
def generate_Optional(self, out, expr, debugname=None):
"""
Try to parse an expr and continue if it fails.
"""
realf = self._newThunkFor(out, "optional", expr)
passf = self._gensym("optional")
out.writeln("def %s():" % (passf,))
out.indent().writeln("return (None, self.input.nullError())")
return self._expr(out, 'or', 'self._or([%s])'
% (', '.join([realf, passf])),
debugname)
def generate_Or(self, out, exprs, debugname=None):
"""
Create a call to
self._or([lambda: expr1, lambda: expr2, ... , lambda: exprN]).
"""
if len(exprs.args) > 1:
fnames = [self._newThunkFor(out, "or", expr) for expr in exprs.args]
return self._expr(out, 'or', 'self._or([%s])' % (', '.join(fnames)), debugname)
else:
return self._generateNode(out, exprs.args[0], debugname)
def generate_Not(self, out, expr, debugname=None):
"""
Create a call to self._not(lambda: expr).
"""
fname = self._newThunkFor(out, "not", expr)
return self._expr(out, "not", "self._not(%s)" % (fname,), debugname)
def generate_Lookahead(self, out, expr, debugname=None):
"""
Create a call to self.lookahead(lambda: expr).
"""
fname = self._newThunkFor(out, "lookahead", expr)
return self._expr(out, "lookahead", "self.lookahead(%s)" %(fname,), debugname)
def generate_And(self, out, exprs, debugname=None):
"""
Generate code for each statement in order.
"""
v = None
for ex in exprs.args:
v = self._generateNode(out, ex, debugname)
return v
def generate_Bind(self, out, name, expr, debugname=None):
"""
Bind the value of 'expr' to a name in the _locals dict.
"""
v = self._generateNode(out, expr, debugname)
if name.data:
ref = "_locals['%s']" % (name.data,)
out.writeln("%s = %s" % (ref, v))
else:
for i, n in enumerate(name.args):
ref = "_locals['%s']" % (n.data,)
out.writeln("%s = %s[%i]" %(ref, v, i))
return v
def generate_Predicate(self, out, expr, debugname=None):
"""
Generate a call to self.pred(lambda: expr).
"""
fname = self._newThunkFor(out, "pred", expr)
return self._expr(out, "pred", "self.pred(%s)" %(fname,), debugname)
def generate_Action(self, out, expr, debugname=None):
"""
Generate this embedded Python expression on its own line.
"""
return self.compilePythonExpr(out, expr.data, debugname)
def generate_Python(self, out, expr, debugname=None):
"""
Generate this embedded Python expression on its own line.
"""
return self.compilePythonExpr(out, expr.data, debugname)
def generate_List(self, out, expr, debugname=None):
"""
Generate a call to self.listpattern(lambda: expr).
"""
fname = self._newThunkFor(out, "listpattern", expr)
return self._expr(out, "listpattern", "self.listpattern(%s)" %(fname,),
debugname)
def generate_Label(self, out, expr, label, debugname=None):
"""
Generate code for expr, and create label.
"""
fname = self._newThunkFor(out, "label", expr)
return self._expr(out, 'label', 'self.label(%s, "%s")' % (fname, label.data, ), debugname)
def generate_TermPattern(self, out, name, expr, debugname=None):
fname = self._newThunkFor(out, "termpattern", expr)
return self._expr(out, 'termpattern', 'self.termpattern(%r, %s)' % (name.data, fname),
debugname)
def generate_StringTemplate(self, out, template, debugname=None):
out.writeln("from terml.parser import parseTerm as term")
return self._expr(out, 'stringtemplate', 'self.stringtemplate(%s, _locals)' % (template,))
def generate_ConsumedBy(self, out, expr, debugname=None):
"""
Generate a call to self.consumedBy(lambda: expr).
"""
fname = self._newThunkFor(out, "consumedby", expr)
return self._expr(out, "consumedby", "self.consumedby(%s)" %(fname,),
debugname)
def generate_Rule(self, prevOut, name, expr, debugname=None):
prevOut.writeln("def rule_%s(self):" % (name.data,))
out = prevOut.indent()
out.writeln("_locals = {'self': self}")
out.writeln("self.locals[%r] = _locals" % (name.data,))
self._generate(prevOut.indent(), expr, retrn=True, debugname=name)
def generate_Grammar(self, out, name, takesTreeInput, rules,
debugname=None):
self.compiledExprCache = {}
self.takesTreeInput = takesTreeInput.tag.name == 'true'
out.writeln("def createParserClass(GrammarBase, ruleGlobals):")
funcOut = out.indent()
funcOut.writeln("if ruleGlobals is None:")
funcOut.indent().writeln("ruleGlobals = {}")
funcOut.writeln("class %s(GrammarBase):" % (name.data,))
out = funcOut.indent()
for rule in rules.args:
self._generateNode(out, rule, debugname)
out.writeln("")
out.writeln("")
if self.takesTreeInput:
out.writeln("tree = %s" % self.takesTreeInput)
for expr, sym in self.compiledExprCache.items():
out.writeln("%s = compile(%r, '<string>', 'eval')" % (sym, expr))
funcOut.writeln(
"if %s.globals is not None:" % (name.data,))
out.writeln("%s.globals = %s.globals.copy()" % (name.data,
name.data))
out.writeln("%s.globals.update(ruleGlobals)" % (name.data,))
funcOut.writeln(
"else:")
out.writeln("%s.globals = ruleGlobals" % (name.data,))
funcOut.writeln("return " + name.data)
self.compiledExprCache = None
class _Term2PythonAction(object):
def leafData(bldr, data, span):
return repr(data)
def leafTag(bldr, tag, span):
return tag.name
def term(bldr, tag, args):
if tag == '.tuple.':
return "[%s]" % (', '.join(args),)
elif tag == '.attr.':
return "(%s)" % (', '.join(args),)
elif tag == '.bag.':
return "dict(%s)" % (', '.join(args),)
if not args:
return tag
return "%s(%s)" % (tag, ', '.join(args))
class TermActionPythonWriter(PythonWriter):
builder = _Term2PythonAction
def _convertArgs(self, out, termArgs, debugname):
return [self._termAsPython(out, a, debugname) for a in termArgs]
def generate_Predicate(self, out, term, debugname=None):
"""
Generate a call to self.pred(lambda: expr).
"""
fname = self._newThunkFor(out, "pred", Term(Tag("Action"), None,
[term], None))
return self._expr(out, "pred", "self.pred(%s)" %(fname,), debugname)
def generate_Action(self, out, term, debugname=None):
return self._termAsPython(out, term, debugname)
generate_Python = generate_Action
def _termAsPython(self, out, term, debugname):
if not term.args:
if term.data is None:
return self.compilePythonExpr(out, term.tag.name, debugname)
else:
name = self._gensym("literal")
out.writeln("%s = %r" % (name, term.data))
return name
else:
return self.compilePythonExpr(out, term.build(self.builder()), debugname)
def writePython(tree, txt):
f = StringIO()
out = TextWriter(f)
pw = PythonWriter(tree, txt)
pw.output(out)
return f.getvalue().strip()
class GeneratedCodeLoader(object):
"""
Object for use as a module's __loader__, to display generated
source.
"""
def __init__(self, source):
self.source = source
def get_source(self, name):
return self.source
def moduleFromGrammar(source, className, modname, filename):
mod = module(modname)
mod.__name__ = modname
mod.__loader__ = GeneratedCodeLoader(source)
code = compile(source, filename, "exec")
eval(code, mod.__dict__)
sys.modules[modname] = mod
linecache.getlines(filename, mod.__dict__)
return mod
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