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Python Open Source » Development » Pyrex 
Pyrex » Pyrex 0.9.9 » Pyrex » Compiler » Parsing.py
#
#   Pyrex Parser
#

import os, re
from string import join,replace
from types import ListType,TupleType
from Scanning import PyrexScanner
import Nodes
import ExprNodes
from ModuleNode import ModuleNode
from Errors import warning,error,InternalError


class Ctx(object):
    #  Parsing context
    level = 'other'
    visibility = 'private'
    extern_from = False
    cdef_flag = 0
    cplus_flag = 0
    typedef_flag = 0
    api = 0
    nogil = 0
    
    def __init__(self, **kwds):
        self.__dict__.update(kwds)
    
    def __call__(self, **kwds):
        ctx = Ctx()
        d = ctx.__dict__
        d.update(self.__dict__)
        d.update(kwds)
        return ctx

    def cplus_check(self, pos):
        #if self.visibility <> 'extern':
        #  error(pos, "C++ declarations must be 'extern'")
        if self.cplus_flag and not self.extern_from:
            error(pos, "C++ declarations must be in an 'extern from' block")


def p_ident(s, message = "Expected an identifier"):
    if s.sy == 'IDENT':
        name = s.systring
        s.next()
        return name
    else:
        s.error(message)

def p_ident_list(s):
    names = []
    while s.sy == 'IDENT':
        names.append(s.systring)
        s.next()
        if s.sy <> ',':
            break
        s.next()
    return names

#------------------------------------------
#
#   Expressions
#
#------------------------------------------

def p_binop_expr(s, ops, p_sub_expr):
    n1 = p_sub_expr(s)
    while s.sy in ops:
        op = s.sy
        pos = s.position()
        s.next()
        n2 = p_sub_expr(s)
        n1 = ExprNodes.binop_node(pos, op, n1, n2)
    return n1

#test: and_test ('or' and_test)* | lambdef

def p_simple_expr(s):
    return p_rassoc_binop_expr(s, ('or',), p_and_test)

def p_rassoc_binop_expr(s, ops, p_subexpr):
    n1 = p_subexpr(s)
    if s.sy in ops:
        pos = s.position()
        op = s.sy
        s.next()
        n2 = p_rassoc_binop_expr(s, ops, p_subexpr)
        n1 = ExprNodes.binop_node(pos, op, n1, n2)
    return n1

#and_test: not_test ('and' not_test)*

def p_and_test(s):
    #return p_binop_expr(s, ('and',), p_not_test)
    return p_rassoc_binop_expr(s, ('and',), p_not_test)

#not_test: 'not' not_test | comparison

def p_not_test(s):
    if s.sy == 'not':
        pos = s.position()
        s.next()
        return ExprNodes.NotNode(pos, operand = p_not_test(s))
    else:
        return p_comparison(s)

#comparison: expr (comp_op expr)*
#comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'

def p_comparison(s):
    n1 = p_bit_expr(s)
    if s.sy in comparison_ops:
        pos = s.position()
        op = p_cmp_op(s)
        n2 = p_bit_expr(s)
        n1 = ExprNodes.PrimaryCmpNode(pos, 
            operator = op, operand1 = n1, operand2 = n2)
        if s.sy in comparison_ops:
            n1.cascade = p_cascaded_cmp(s)
    return n1

def p_cascaded_cmp(s):
    pos = s.position()
    op = p_cmp_op(s)
    n2 = p_bit_expr(s)
    result = ExprNodes.CascadedCmpNode(pos, 
        operator = op, operand2 = n2)
    if s.sy in comparison_ops:
        result.cascade = p_cascaded_cmp(s)
    return result

def p_cmp_op(s):
    if s.sy == 'not':
        s.next()
        s.expect('in')
        op = 'not_in'
    elif s.sy == 'is':
        s.next()
        if s.sy == 'not':
            s.next()
            op = 'is_not'
        else:
            op = 'is'
    else:
        op = s.sy
        s.next()
    if op == '<>':
        op = '!='
    return op
    
comparison_ops = (
    '<', '>', '==', '>=', '<=', '<>', '!=', 
    'in', 'is', 'not'
)

#expr: xor_expr ('|' xor_expr)*

def p_bit_expr(s):
    return p_binop_expr(s, ('|',), p_xor_expr)

#xor_expr: and_expr ('^' and_expr)*

def p_xor_expr(s):
    return p_binop_expr(s, ('^',), p_and_expr)

#and_expr: shift_expr ('&' shift_expr)*

def p_and_expr(s):
    return p_binop_expr(s, ('&',), p_shift_expr)

#shift_expr: arith_expr (('<<'|'>>') arith_expr)*

def p_shift_expr(s):
    return p_binop_expr(s, ('<<', '>>'), p_arith_expr)

#arith_expr: term (('+'|'-') term)*

def p_arith_expr(s):
    return p_binop_expr(s, ('+', '-'), p_term)

#term: factor (('*'|'/'|'%') factor)*

def p_term(s):
    return p_binop_expr(s, ('*', '/', '%'), p_factor)

#factor: ('+'|'-'|'~'|'&'|typecast|sizeof) factor | power

def p_factor(s):
    sy = s.sy
    if sy in ('+', '-', '~'):
        op = s.sy
        pos = s.position()
        s.next()
        return ExprNodes.unop_node(pos, op, p_factor(s))
    elif sy == '&':
        pos = s.position()
        s.next()
        arg = p_factor(s)
        return ExprNodes.AmpersandNode(pos, operand = arg)
    elif sy == "<":
        return p_typecast(s)
    elif sy == 'IDENT' and s.systring == "sizeof":
        return p_sizeof(s)
    else:
        return p_power(s)

def p_typecast(s):
    # s.sy == "<"
    pos = s.position()
    s.next()
    base_type = p_c_base_type(s)
    declarator = p_c_declarator(s, empty = 1)
    s.expect(">")
    operand = p_factor(s)
    return ExprNodes.TypecastNode(pos, 
        base_type = base_type, 
        declarator = declarator,
        operand = operand)

def p_sizeof(s):
    # s.sy == ident "sizeof"
    pos = s.position()
    s.next()
    s.expect('(')
    if looking_at_type(s):
        base_type = p_c_base_type(s)
        declarator = p_c_declarator(s, empty = 1)
        node = ExprNodes.SizeofTypeNode(pos, 
            base_type = base_type, declarator = declarator)
    else:
        operand = p_simple_expr(s)
        node = ExprNodes.SizeofVarNode(pos, operand = operand)
    s.expect(')')
    return node

#power: atom trailer* ('**' factor)*

def p_power(s):
    n1 = p_primitive(s)
    if s.sy == '**':
        pos = s.position()
        s.next()
        n2 = p_factor(s)
        n1 = ExprNodes.binop_node(pos, '**', n1, n2)
    return n1

def p_primitive(s):
    n = p_atom(s)
    while s.sy in ('(', '[', '.'):
        n = p_trailer(s, n)
    return n

#trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME

def p_trailer(s, node1):
    pos = s.position()
    if s.sy == '(':
        return p_call(s, node1)
    elif s.sy == '[':
        return p_index(s, node1)
    else: # s.sy == '.'
        s.next()
        name = p_ident(s)
        return ExprNodes.AttributeNode(pos, 
            obj = node1, attribute = name)

# arglist:  argument (',' argument)* [',']
# argument: [test '='] test       # Really [keyword '='] test

def p_call(s, function):
    # s.sy == '('
    pos = s.position()
    s.next()
    positional_args = []
    keyword_args = []
    star_arg = None
    starstar_arg = None
    while s.sy not in ('*', '**', ')'):
        arg = p_simple_expr(s)
        if s.sy == '=':
            s.next()
            if not arg.is_name:
                s.error("Expected an identifier before '='",
                    pos = arg.pos)
            keyword = ExprNodes.StringNode(arg.pos, 
                value = arg.name)
            arg = p_simple_expr(s)
            keyword_args.append((keyword, arg))
        else:
            if keyword_args:
                s.error("Non-keyword arg following keyword arg",
                    pos = arg.pos)
            positional_args.append(arg)
        if s.sy <> ',':
            break
        s.next()
    if s.sy == '*':
        s.next()
        star_arg = p_simple_expr(s)
        if s.sy == ',':
            s.next()
    if s.sy == '**':
        s.next()
        starstar_arg = p_simple_expr(s)
        if s.sy == ',':
            s.next()
    s.expect(')')
    if not (keyword_args or star_arg or starstar_arg):
        return ExprNodes.SimpleCallNode(pos,
            function = function,
            args = positional_args)
    else:
        arg_tuple = None
        keyword_dict = None
        if positional_args or not star_arg:
            arg_tuple = ExprNodes.TupleNode(pos, 
                args = positional_args)
        if star_arg:
            star_arg_tuple = ExprNodes.AsTupleNode(pos, arg = star_arg)
            if arg_tuple:
                arg_tuple = ExprNodes.binop_node(pos, 
                    operator = '+', operand1 = arg_tuple,
                    operand2 = star_arg_tuple)
            else:
                arg_tuple = star_arg_tuple
        if keyword_args:
            keyword_dict = ExprNodes.DictNode(pos,
                key_value_pairs = keyword_args)
        return ExprNodes.GeneralCallNode(pos, 
            function = function,
            positional_args = arg_tuple,
            keyword_args = keyword_dict,
            starstar_arg = starstar_arg)

#lambdef: 'lambda' [varargslist] ':' test

#subscriptlist: subscript (',' subscript)* [',']

def p_index(s, base):
    # s.sy == '['
    pos = s.position()
    s.next()
    subscripts = p_subscript_list(s)
    if len(subscripts) == 1 and len(subscripts[0]) == 2:
        start, stop = subscripts[0]
        result = ExprNodes.SliceIndexNode(pos, 
            base = base, start = start, stop = stop)
    else:
        indexes = make_slice_nodes(pos, subscripts)
        if len(indexes) == 1:
            index = indexes[0]
        else:
            index = ExprNodes.TupleNode(pos, args = indexes)
        result = ExprNodes.IndexNode(pos,
            base = base, index = index)
    s.expect(']')
    return result

def p_subscript_list(s):
    items = [p_subscript(s)]
    while s.sy == ',':
        s.next()
        if s.sy == ']':
            break
        items.append(p_subscript(s))
    return items

#subscript: '.' '.' '.' | test | [test] ':' [test] [':' [test]]

def p_subscript(s):
    # Parse a subscript and return a list of
    # 1, 2 or 3 ExprNodes, depending on how
    # many slice elements were encountered.
    pos = s.position()
    if s.sy == '.':
        expect_ellipsis(s)
        return [ExprNodes.EllipsisNode(pos)]
    else:
        start = p_slice_element(s, (':',))
        if s.sy <> ':':
            return [start]
        s.next()
        stop = p_slice_element(s, (':', ',', ']'))
        if s.sy <> ':':
            return [start, stop]
        s.next()
        step = p_slice_element(s, (':', ',', ']'))
        return [start, stop, step]

def p_slice_element(s, follow_set):
    # Simple expression which may be missing iff
    # it is followed by something in follow_set.
    if s.sy not in follow_set:
        return p_simple_expr(s)
    else:
        return None

def expect_ellipsis(s):
    s.expect('.')
    s.expect('.')
    s.expect('.')

def make_slice_nodes(pos, subscripts):
    # Convert a list of subscripts as returned
    # by p_subscript_list into a list of ExprNodes,
    # creating SliceNodes for elements with 2 or
    # more components.
    result = []
    for subscript in subscripts:
        if len(subscript) == 1:
            result.append(subscript[0])
        else:
            result.append(make_slice_node(pos, *subscript))
    return result

def make_slice_node(pos, start, stop = None, step = None):
    if not start:
        start = ExprNodes.NoneNode(pos)
    if not stop:
        stop = ExprNodes.NoneNode(pos)
    if not step:
        step = ExprNodes.NoneNode(pos)
    return ExprNodes.SliceNode(pos,
        start = start, stop = stop, step = step)

#atom: '(' [testlist] ')' | '[' [listmaker] ']' | '{' [dictmaker] '}' | '`' testlist '`' | NAME | NUMBER | STRING+

def p_atom(s):
    pos = s.position()
    sy = s.sy
    if sy == '(':
        s.next()
        if s.sy == ')':
            result = ExprNodes.TupleNode(pos, args = [])
        else:
            result = p_expr(s)
        s.expect(')')
        return result
    elif sy == '[':
        return p_list_maker(s)
    elif sy == '{':
        return p_dict_maker(s)
    elif sy == '`':
        return p_backquote_expr(s)
    elif sy == 'INT':
        value = s.systring
        s.next()
        return ExprNodes.IntNode(pos, value = value)
    elif sy == 'LONG':
        value = s.systring
        s.next()
        return ExprNodes.LongNode(pos, value = value)
    elif sy == 'FLOAT':
        value = s.systring
        s.next()
        return ExprNodes.FloatNode(pos, value = value)
    elif sy == 'IMAG':
        value = s.systring[:-1]
        s.next()
        return ExprNodes.ImagNode(pos, value = value)
    elif sy == 'STRING' or sy == 'BEGIN_STRING':
        kind, value = p_cat_string_literal(s)
        if kind == 'c':
            return ExprNodes.CharNode(pos, value = value)
        else:
            return ExprNodes.StringNode(pos, value = value)
    elif sy == 'IDENT':
        name = s.systring
        s.next()
        if name == "None":
            return ExprNodes.NoneNode(pos)
        elif name == "new" and s.sy == 'IDENT':
            return p_new_call(s)
        else:
            return p_name_atom(s, name)
    elif sy == 'NULL':
        s.next()
        return ExprNodes.NullNode(pos)
    else:
        s.error("Expected an identifier or literal")

def p_new_call(s):
    node = p_primitive(s)
    if isinstance(node, ExprNodes.SimpleCallNode):
        node.is_new = 1
    else:
        error(s.position(), "'new' must be followed by a C++ constructor call")
    return node

def p_name(s):
    if s.sy == 'IDENT':
        pos = s.position()
        name = s.systring
        s.next()
        return ExprNodes.NameNode(pos, name = name)
    else:
        s.error("Expected a variable name")

def p_name_atom(s, name):
    pos = s.position()
    if not s.compile_time_expr:
        try:
            value = s.compile_time_env.lookup_here(name)
        except KeyError:
            pass
        else:
            rep = repr(value)
            if isinstance(value, int):
                return ExprNodes.IntNode(pos, value = rep)
            elif isinstance(value, long):
                return ExprNodes.LongNode(pos, value = rep)
            elif isinstance(value, float):
                return ExprNodes.FloatNode(pos, value = rep)
            elif isinstance(value, str):
                return ExprNodes.StringNode(pos, value = rep[1:-1])
            else:
                error(pos, "Invalid type for compile-time constant: %s"
                    % value.__class__.__name__)
    return ExprNodes.NameNode(pos, name = name)

def p_cat_string_literal(s):
    # A sequence of one or more adjacent string literals.
    # Returns (kind, value) where kind in ('', 'c', 'r')
    kind, value = p_string_literal(s)
    if kind <> 'c':
        strings = [value]
        while s.sy == 'STRING' or s.sy == 'BEGIN_STRING':
            next_kind, next_value = p_string_literal(s)
            if next_kind == 'c':
                self.error(
                    "Cannot concatenate char literal with another string or char literal")
            strings.append(next_value)
        value = ''.join(strings)
    return kind, value

def p_opt_string_literal(s):
    if s.sy == 'STRING' or s.sy == 'BEGIN_STRING':
        return p_string_literal(s)
    else:
        return None

def p_string_literal(s):
    # A single string or char literal.
    # Returns (kind, value) where kind in ('', 'c', 'r')
    if s.sy == 'STRING':
        value = unquote(s.systring)
        s.next()
        return value
    # s.sy == 'BEGIN_STRING'
    pos = s.position()
    #is_raw = s.systring[:1].lower() == "r"
    kind = s.systring[:1].lower()
    if kind not in "cr":
        kind = ''
    chars = []
    while 1:
        s.next()
        sy = s.sy
        #print "p_string_literal: sy =", sy, repr(s.systring) ###
        if sy == 'CHARS':
            systr = s.systring
            if len(systr) == 1 and systr in "'\"\n":
                chars.append('\\')
            chars.append(systr)
        elif sy == 'ESCAPE':
            systr = s.systring
            if kind == 'r':
                if systr == '\\\n':
                    chars.append(r'\\\n')
                elif systr == r'\"':
                    chars.append(r'\\\"')
                elif systr == r'\\':
                    chars.append(r'\\\\')
                else:
                    chars.append('\\' + systr)
            else:
                c = systr[1]
                if c in "'\"\\abfnrtv01234567":
                    chars.append(systr)
                elif c == 'x':
                    chars.append('\\x0' + systr[2:])
                elif c == '\n':
                    pass
                else:
                    chars.append(r'\\' + systr[1:])
        elif sy == 'NEWLINE':
            chars.append(r'\n')
        elif sy == 'END_STRING':
            break
        elif sy == 'EOF':
            s.error("Unclosed string literal", pos = pos)
        else:
            s.error(
                "Unexpected token %r:%r in string literal" %
                    (sy, s.systring))
    s.next()
    value = join(chars, '')
    #print "p_string_literal: value =", repr(value) ###
    return kind, value

def unquote(s):
    is_raw = 0
    if s[:1].lower() == "r":
        is_raw = 1
        s = s[1:]
    q = s[:3]
    if q == '"""' or q == "'''":
        s = s[3:-3]
    else:
        s = s[1:-1]
    if is_raw:
        s = s.replace('\\', '\\\\')
        s = s.replace('\n', '\\\n')
    else:
        # Split into double quotes, newlines, escape sequences 
        # and spans of regular chars
        l1 = re.split(r'((?:\\[0-7]{1,3})|(?:\\x[0-9A-Fa-f]{2})|(?:\\.)|(?:\\\n)|(?:\n)|")', s)
        print "unquote: l1 =", l1 ###
        l2 = []
        for item in l1:
            if item == '"' or item == '\n':
                l2.append('\\' + item)
            elif item == '\\\n':
                pass
            elif item[:1] == '\\':
                if len(item) == 2:
                    if item[1] in '"\\abfnrtv':
                        l2.append(item)
                    else:
                        l2.append(item[1])
                elif item[1:2] == 'x':
                    l2.append('\\x0' + item[2:])
                else:
                    # octal escape
                    l2.append(item)
            else:
                l2.append(item)
        s = "".join(l2)
    return s
        
def p_list_maker(s):
    # s.sy == '['
    pos = s.position()
    s.next()
    exprs = p_simple_expr_list(s)
    s.expect(']')
    return ExprNodes.ListNode(pos, args = exprs)

#dictmaker: test ':' test (',' test ':' test)* [',']

def p_dict_maker(s):
    # s.sy == '{'
    pos = s.position()
    s.next()
    items = []
    while s.sy <> '}':
        key = p_simple_expr(s)
        s.expect(':')
        value = p_simple_expr(s)
        items.append((key, value))
        if s.sy <> ',':
            break
        s.next()
    s.expect('}')
    return ExprNodes.DictNode(pos, key_value_pairs = items)

def p_backquote_expr(s):
    # s.sy == '`'
    pos = s.position()
    s.next()
    arg = p_expr(s)
    s.expect('`')
    return ExprNodes.BackquoteNode(pos, arg = arg)

#testlist: test (',' test)* [',']

def p_simple_expr_list(s):
    exprs = []
    while s.sy not in expr_terminators:
        exprs.append(p_simple_expr(s))
        if s.sy <> ',':
            break
        s.next()
    return exprs

def p_expr(s):
    pos = s.position()
    expr = p_simple_expr(s)
    if s.sy == ',':
        s.next()
        exprs = [expr] + p_simple_expr_list(s)
        return ExprNodes.TupleNode(pos, args = exprs)
    else:
        return expr

expr_terminators = (')', ']', '}', ':', '=', 'NEWLINE')

#-------------------------------------------------------
#
#   Statements
#
#-------------------------------------------------------

def p_global_statement(s):
    # assume s.sy == 'global'
    pos = s.position()
    s.next()
    names = p_ident_list(s)
    return Nodes.GlobalNode(pos, names = names)

inplace_operators = ('+=', '-=', '*=', '/=', '%=', '**=',
    '<<=', '>>=', '&=', '^=', '|=')

def p_expression_or_assignment(s):
    pos = s.position()
    expr = p_expr(s)
    if s.sy in inplace_operators:
        return p_inplace_operation(s, expr)
    elif s.sy <> '=':
        if isinstance(expr, ExprNodes.StringNode):
            return Nodes.PassStatNode(expr.pos)
        else:
            return Nodes.ExprStatNode(expr.pos, expr = expr)
    else:
        expr_list = [expr]
        while s.sy == '=':
            s.next()
            expr_list.append(p_expr(s))
        expr_list_list = []
        flatten_parallel_assignments(expr_list, expr_list_list)
        nodes = []
        for expr_list in expr_list_list:
            lhs_list = expr_list[:-1]
            rhs = expr_list[-1]
            if len(lhs_list) == 1:
                node = Nodes.SingleAssignmentNode(rhs.pos, 
                    lhs = lhs_list[0], rhs = rhs)
            else:
                node = Nodes.CascadedAssignmentNode(rhs.pos,
                    lhs_list = lhs_list, rhs = rhs)
            nodes.append(node)
        if len(nodes) == 1:
            return nodes[0]
        else:
            return Nodes.ParallelAssignmentNode(nodes[0].pos, stats = nodes)

def p_inplace_operation(s, lhs):
    pos = s.position()
    op = s.sy
    s.next()
    rhs = p_expr(s)
    return Nodes.AugmentedAssignmentNode(pos, lhs = lhs, operator = op, rhs = rhs)

def flatten_parallel_assignments(input, output):
    #  The input is a list of expression nodes, representing 
    #  the LHSs and RHS of one (possibly cascaded) assignment 
    #  statement. If they are all sequence constructors with 
    #  the same number of arguments, rearranges them into a
    #  list of equivalent assignments between the individual 
    #  elements. This transformation is applied recursively.
    size = find_parallel_assignment_size(input)
    if size >= 0:
        for i in range(size):
            new_exprs = [expr.args[i] for expr in input]
            flatten_parallel_assignments(new_exprs, output)
    else:
        output.append(input)

def find_parallel_assignment_size(input):
    #  The input is a list of expression nodes. If 
    #  they are all sequence constructors with the same number
    #  of arguments, return that number, else return -1.
    #  Produces an error message if they are all sequence
    #  constructors but not all the same size.
    for expr in input:
        if not expr.is_sequence_constructor:
            return -1
    rhs = input[-1]
    rhs_size = len(rhs.args)
    for lhs in input[:-1]:
        lhs_size = len(lhs.args)
        if lhs_size <> rhs_size:
            error(lhs.pos, "Unpacking sequence of wrong size (expected %d, got %d)"
                % (lhs_size, rhs_size))
            return -1
    return rhs_size

def p_print_statement(s):
    # s.sy == 'print'
    pos = s.position()
    s.next()
    if s.sy == '>>':
        s.error("'print >>' not yet implemented")
    args = []
    ewc = 0
    if s.sy not in ('NEWLINE', 'EOF'):
        args.append(p_simple_expr(s))
        while s.sy == ',':
            s.next()
            if s.sy in ('NEWLINE', 'EOF'):
                ewc = 1
                break
            args.append(p_simple_expr(s))
    return Nodes.PrintStatNode(pos, 
        args = args, ends_with_comma = ewc)

def p_del_statement(s):
    # s.sy == 'del'
    pos = s.position()
    s.next()
    args = p_simple_expr_list(s)
    return Nodes.DelStatNode(pos, args = args)

def p_pass_statement(s, with_newline = 0):
    pos = s.position()
    s.expect('pass')
    if with_newline:
        s.expect_newline("Expected a newline")
    return Nodes.PassStatNode(pos)

def p_break_statement(s):
    # s.sy == 'break'
    pos = s.position()
    s.next()
    return Nodes.BreakStatNode(pos)

def p_continue_statement(s):
    # s.sy == 'continue'
    pos = s.position()
    s.next()
    return Nodes.ContinueStatNode(pos)

def p_return_statement(s):
    # s.sy == 'return'
    pos = s.position()
    s.next()
    if s.sy not in statement_terminators:
        value = p_expr(s)
    else:
        value = None
    return Nodes.ReturnStatNode(pos, value = value)

def p_raise_statement(s):
    # s.sy == 'raise'
    pos = s.position()
    s.next()
    exc_type = None
    exc_value = None
    exc_tb = None
    if s.sy not in statement_terminators:
        exc_type = p_simple_expr(s)
        if s.sy == ',':
            s.next()
            exc_value = p_simple_expr(s)
            if s.sy == ',':
                s.next()
                exc_tb = p_simple_expr(s)
    if exc_type or exc_value or exc_tb:
        return Nodes.RaiseStatNode(pos, 
            exc_type = exc_type,
            exc_value = exc_value,
            exc_tb = exc_tb)
    else:
        return Nodes.ReraiseStatNode(pos)

def p_import_statement(s):
    # s.sy in ('import', 'cimport')
    pos = s.position()
    kind = s.sy
    s.next()
    items = [p_dotted_name(s, as_allowed = 1)]
    while s.sy == ',':
        s.next()
        items.append(p_dotted_name(s, as_allowed = 1))
    stats = []
    for pos, target_name, dotted_name, as_name in items:
        if kind == 'cimport':
            stat = Nodes.CImportStatNode(pos, 
                module_name = dotted_name,
                as_name = as_name)
        else:
            if as_name and "." in dotted_name:
                name_list = ExprNodes.ListNode(pos, args = [
                    ExprNodes.StringNode(pos, value = "*")])
            else:
                name_list = None
            stat = Nodes.SingleAssignmentNode(pos,
                lhs = ExprNodes.NameNode(pos, 
                    name = as_name or target_name),
                rhs = ExprNodes.ImportNode(pos, 
                    module_name = ExprNodes.StringNode(pos,
                        value = dotted_name),
                    name_list = name_list))
        stats.append(stat)
    return Nodes.StatListNode(pos, stats = stats)

def p_from_import_statement(s, ctx):
    # s.sy == 'from'
    pos = s.position()
    s.next()
    (dotted_name_pos, _, dotted_name, _) = \
        p_dotted_name(s, as_allowed = 0)
    if s.sy in ('import', 'cimport'):
        kind = s.sy
        s.next()
    else:
        s.error("Expected 'import' or 'cimport'")
    if kind == 'cimport' and ctx.level not in ('module', 'module_pxd'):
        s.error("cimport statement not allowed in this context")
    if s.sy == '*':
        s.error("'import *' not supported")
    is_cimport = kind == 'cimport'
    imported_names = [p_imported_name(s, is_cimport)]
    while s.sy == ',':
        s.next()
        imported_names.append(p_imported_name(s, is_cimport))
    if kind == 'cimport':
        for imp in imported_names:
            local_name = imp.as_name or imp.name
            s.add_type_name(local_name)
        return Nodes.FromCImportStatNode(pos,
            module_name = dotted_name,
            imported_names = imported_names)
    else:
        imported_name_strings = []
        items = []
        for imp in imported_names:
            imported_name_strings.append(
                ExprNodes.StringNode(imp.pos, value = imp.name))
            items.append(
                (imp.name,
                 ExprNodes.NameNode(imp.pos, 
                   name = imp.as_name or imp.name)))
        import_list = ExprNodes.ListNode(
            imported_names[0].pos, args = imported_name_strings)
        return Nodes.FromImportStatNode(pos,
            module = ExprNodes.ImportNode(dotted_name_pos,
                module_name = ExprNodes.StringNode(dotted_name_pos,
                    value = dotted_name),
                name_list = import_list),
            items = items)

class ImportedName(object):
    #  pos
    #  name
    #  as_name
    #  kind     'class', 'struct', 'union', None
    
    def __init__(self, pos, name, as_name, kind):
        self.pos = pos
        self.name = name
        self.as_name = as_name
        self.kind = kind

imported_name_kinds = ('class', 'struct', 'union')

def p_imported_name(s, is_cimport):
    pos = s.position()
    kind = None
    if is_cimport and s.systring in imported_name_kinds:
        kind = s.systring
        s.next()
    name = p_ident(s)
    as_name = p_as_name(s)
    return ImportedName(pos, name, as_name, kind)

def p_dotted_name(s, as_allowed):
    pos = s.position()
    target_name = p_ident(s)
    as_name = None
    names = [target_name]
    while s.sy == '.':
        s.next()
        names.append(p_ident(s))
    if as_allowed:
        as_name = p_as_name(s)
    return (pos, target_name, join(names, "."), as_name)

def p_as_name(s):
    if s.sy == 'IDENT' and s.systring == 'as':
        s.next()
        return p_ident(s)
    else:
        return None

def p_assert_statement(s):
    # s.sy == 'assert'
    pos = s.position()
    s.next()
    cond = p_simple_expr(s)
    if s.sy == ',':
        s.next()
        value = p_simple_expr(s)
    else:
        value = None
    return Nodes.AssertStatNode(pos, cond = cond, value = value)

statement_terminators = (';', 'NEWLINE', 'EOF')

def p_if_statement(s):
    # s.sy == 'if'
    pos = s.position()
    s.next()
    if_clauses = [p_if_clause(s)]
    while s.sy == 'elif':
        s.next()
        if_clauses.append(p_if_clause(s))
    else_clause = p_else_clause(s)
    return Nodes.IfStatNode(pos,
        if_clauses = if_clauses, else_clause = else_clause)

def p_if_clause(s):
    pos = s.position()
    test = p_simple_expr(s)
    body = p_suite(s)
    return Nodes.IfClauseNode(pos,
        condition = test, body = body)

def p_else_clause(s):
    if s.sy == 'else':
        s.next()
        return p_suite(s)
    else:
        return None

def p_while_statement(s):
    # s.sy == 'while'
    pos = s.position()
    s.next()
    test = p_simple_expr(s)
    body = p_suite(s)
    else_clause = p_else_clause(s)
    return Nodes.WhileStatNode(pos, 
        condition = test, body = body, 
        else_clause = else_clause)

def p_for_statement(s):
    # s.sy == 'for'
    pos = s.position()
    s.next()
    expr = p_for_expr(s)
    if s.sy == 'in':
        return p_standard_for_statement(s, expr)
    elif s.sy in inequality_relations:
        return p_integer_for_statement(s, expr)
    elif s.sy == 'from':
        #warning(pos, "Old-style integer for-loop is deprecated, use 'for x < i < y' instead")
        return p_old_style_integer_for_statement(s, expr)
    else:
        s.error("Expected 'in' or an inequality relation")

def p_standard_for_statement(s, target):
    # s.sy == 'in'
    s.next()
    iterator = p_for_iterator(s)
    body = p_suite(s)
    else_clause = p_else_clause(s)
    return Nodes.ForInStatNode(target.pos, 
        target = target,
        iterator = iterator,
        body = body,
        else_clause = else_clause)

def p_integer_for_statement(s, bound1):
    rel1 = s.sy
    s.next()
    name_pos = s.position()
    target = p_name(s)
    rel2_pos = s.position()
    rel2 = p_inequality_relation(s)
    bound2 = p_bit_expr(s)
    if rel1[0] <> rel2[0]:
        error(rel2_pos,
            "Relation directions in integer for-loop do not match")
    body = p_suite(s)
    else_clause = p_else_clause(s)
    return Nodes.IntegerForStatNode(bound1.pos,
        bound1 = bound1,
        relation1 = rel1,
        target = target,
        relation2 = rel2,
        bound2 = bound2,
        body = body,
        else_clause = else_clause)

def p_old_style_integer_for_statement(s, target):
    # s.sy == 'for'
    s.next()
    bound1 = p_bit_expr(s)
    rel1 = p_inequality_relation(s)
    name2_pos = s.position()
    name2 = p_ident(s)
    rel2_pos = s.position()
    rel2 = p_inequality_relation(s)
    bound2 = p_bit_expr(s)
    if not target.is_name:
        error(target.pos, 
            "Target of for-from statement must be a variable name")
    elif name2 <> target.name:
        error(name2_pos,
            "Variable name in for-from range does not match target")
    if rel1[0] <> rel2[0]:
        error(rel2_pos,
            "Relation directions in for-from do not match")
    body = p_suite(s)
    else_clause = p_else_clause(s)
    return Nodes.IntegerForStatNode(bound1.pos,
        bound1 = bound1,
        relation1 = rel1,
        target = target,
        relation2 = rel2,
        bound2 = bound2,
        body = body,
        else_clause = else_clause)

def p_inequality_relation(s):
    if s.sy in inequality_relations:
        op = s.sy
        s.next()
        return op
    else:
        s.error("Expected one of '<', '<=', '>' '>='")

inequality_relations = ('<', '<=', '>', '>=')

def p_for_expr(s):
    # Target of standard for-statement or first bound of integer for-statement
    pos = s.position()
    expr = p_bit_expr(s)
    if s.sy == ',':
        s.next()
        exprs = [expr]
        while s.sy <> 'in':
            exprs.append(p_bit_expr(s))
            if s.sy <> ',':
                break
            s.next()
        return ExprNodes.TupleNode(pos, args = exprs)
    else:
        return expr

def p_for_iterator(s):
    pos = s.position()
    expr = p_expr(s)
    return ExprNodes.IteratorNode(pos, sequence = expr)

def p_try_statement(s):
    # s.sy == 'try'
    pos = s.position()
    s.next()
    body = p_suite(s)
    except_clauses = []
    else_clause = None
    if s.sy in ('except', 'else'):
        while s.sy == 'except':
            except_clauses.append(p_except_clause(s))
        if s.sy == 'else':
            s.next()
            else_clause = p_suite(s)
        return Nodes.TryExceptStatNode(pos,
            body = body, except_clauses = except_clauses,
            else_clause = else_clause)
    elif s.sy == 'finally':
        s.next()
        finally_clause = p_suite(s)
        return Nodes.TryFinallyStatNode(pos,
            body = body, finally_clause = finally_clause)
    else:
        s.error("Expected 'except' or 'finally'")

def p_except_clause(s):
    # s.sy == 'except'
    pos = s.position()
    s.next()
    exc_type = None
    exc_value = None
    tb_value = None
    if s.sy <> ':':
        exc_type = p_simple_expr(s)
        if s.sy == ',':
            s.next()
            exc_value = p_simple_expr(s)
            if s.sy == ',':
                s.next()
                tb_value = p_simple_expr(s)
    body = p_suite(s)
    return Nodes.ExceptClauseNode(pos,
        pattern = exc_type, exc_target = exc_value, tb_target = tb_value, body = body)

def p_include_statement(s, ctx):
    pos = s.position()
    s.next() # 'include'
    _, include_file_name = p_string_literal(s)
    s.expect_newline("Syntax error in include statement")
    if s.compile_time_eval:
        include_file_path = s.context.find_include_file(include_file_name, pos)
        if include_file_path:
            s.included_files.append(include_file_name)
            f = open(include_file_path, "rU")
            s2 = PyrexScanner(f, include_file_path, parent_scanner = s)
            try:
                tree = p_statement_list(s2, ctx)
            finally:
                f.close()
            return tree
        else:
            return None
    else:
        return Nodes.PassStatNode(pos)

def p_with_statement(s):
    pos = s.position()
    s.next() # 'with'
#  if s.sy == 'IDENT' and s.systring in ('gil', 'nogil'):
    if s.sy == 'IDENT' and s.systring == 'nogil':
        state = s.systring
        s.next()
        body = p_suite(s)
        return Nodes.GILStatNode(pos, state = state, body = body)
    else:
        s.error("Only 'with nogil' implemented")
    
def p_simple_statement(s, ctx):
    if s.sy == 'global':
        node = p_global_statement(s)
    elif s.sy == 'print':
        node = p_print_statement(s)
    elif s.sy == 'del':
        node = p_del_statement(s)
    elif s.sy == 'break':
        node = p_break_statement(s)
    elif s.sy == 'continue':
        node = p_continue_statement(s)
    elif s.sy == 'return':
        node = p_return_statement(s)
    elif s.sy == 'raise':
        node = p_raise_statement(s)
    elif s.sy == 'cimport':
        if ctx.level not in ('module', 'module_pxd'):
            s.error("cimport statement not allowed in this context")
        node = p_import_statement(s)
    elif s.sy == 'import':
        node = p_import_statement(s)
    elif s.sy == 'from':
        node = p_from_import_statement(s, ctx)
    elif s.sy == 'assert':
        node = p_assert_statement(s)
    elif s.sy == 'pass':
        node = p_pass_statement(s)
    else:
        node = p_expression_or_assignment(s)
    return node

def p_simple_statement_list(s, ctx):
    # Parse a series of simple statements on one line
    # separated by semicolons.
    stat = p_simple_statement(s, ctx)
    if s.sy == ';':
        stats = [stat]
        while s.sy == ';':
            s.next()
            if s.sy in ('NEWLINE', 'EOF'):
                break
            stats.append(p_simple_statement(s, ctx))
        stat = Nodes.StatListNode(stats[0].pos, stats = stats)
    s.expect_newline("Syntax error in simple statement list")
    return stat

def p_compile_time_expr(s):
    old = s.compile_time_expr
    s.compile_time_expr = 1
    expr = p_expr(s)
    s.compile_time_expr = old
    return expr

def p_DEF_statement(s):
    pos = s.position()
    denv = s.compile_time_env
    s.next() # 'DEF'
    name = p_ident(s)
    s.expect('=')
    expr = p_compile_time_expr(s)
    value = expr.compile_time_value(denv)
    #print "p_DEF_statement: %s = %r" % (name, value) ###
    denv.declare(name, value)
    s.expect_newline()
    return Nodes.PassStatNode(pos)

def p_IF_statement(s, ctx):
    pos = s.position()
    saved_eval = s.compile_time_eval
    current_eval = saved_eval
    denv = s.compile_time_env
    result = None
    while 1:
        s.next() # 'IF' or 'ELIF'
        expr = p_compile_time_expr(s)
        s.compile_time_eval = current_eval and bool(expr.compile_time_value(denv))
        body = p_suite(s, ctx)
        if s.compile_time_eval:
            result = body
            current_eval = 0
        if s.sy <> 'ELIF':
            break
    if s.sy == 'ELSE':
        s.next()
        s.compile_time_eval = current_eval
        body = p_suite(s, ctx)
        if current_eval:
            result = body
    if not result:
        result = Nodes.PassStatNode(pos)
    s.compile_time_eval = saved_eval
    return result

def p_statement(s, ctx):
    pos = s.position()
    cdef_flag = ctx.cdef_flag
    if s.sy == 'ctypedef':
        if ctx.level not in ('module', 'module_pxd'):
            s.error("ctypedef statement not allowed here")
        #if ctx.api:
        #  error(s.pos, "'api' not allowed with 'ctypedef'")
        return p_ctypedef_statement(s, ctx)
    elif s.sy == 'DEF':
        return p_DEF_statement(s)
    elif s.sy == 'IF':
        return p_IF_statement(s, ctx)
    else:
        if s.sy == 'cdef':
            cdef_flag = 1
            s.next()
            if s.sy == '+':
                ctx = ctx(cplus_flag = 1)
                s.next()
        if cdef_flag:
            if ctx.level not in ('module', 'module_pxd', 'function', 'c_class', 'c_class_pxd'):
                s.error('cdef statement not allowed here')
            return p_cdef_statement(s, ctx)
        else:
            if ctx.api:
                error(s.pos, "'api' not allowed with this statement")
            if s.sy == 'def':
                if ctx.level not in ('module', 'class', 'c_class', 'property'):
                    s.error('def statement not allowed here')
                return p_def_statement(s)
            elif s.sy == 'class':
                if ctx.level <> 'module':
                    s.error("class definition not allowed here")
                return p_class_statement(s)
            elif s.sy == 'include':
                #if ctx.level not in ('module', 'module_pxd'):
                #  s.error("include statement not allowed here")
                return p_include_statement(s, ctx)
            elif ctx.level == 'c_class' and s.sy == 'IDENT' and s.systring == 'property':
                return p_property_decl(s)
            elif s.sy == 'pass' and ctx.level <> 'property':
                return p_pass_statement(s, with_newline = 1)
            else:
                if ctx.level in ('c_class', 'c_class_pxd', 'property'):
                    s.error("Executable statement not allowed here")
                if s.sy == 'if':
                    return p_if_statement(s)
                elif s.sy == 'while':
                    return p_while_statement(s)
                elif s.sy == 'for':
                    return p_for_statement(s)
                elif s.sy == 'try':
                    return p_try_statement(s)
                elif s.sy == 'with':
                    return p_with_statement(s)
                else:
                    return p_simple_statement_list(s, ctx)

def p_statement_list(s, ctx):
    # Parse a series of statements separated by newlines.
    pos = s.position()
    stats = []
    while s.sy not in ('DEDENT', 'EOF'):
        stats.append(p_statement(s, ctx))
    if len(stats) == 1:
        return stats[0]
    else:
        return Nodes.StatListNode(pos, stats = stats)

def p_suite(s, ctx = Ctx(), with_doc = 0, with_pseudo_doc = 0):
    pos = s.position()
    s.expect(':')
    doc = None
    stmts = []
    if s.sy == 'NEWLINE':
        s.next()
        s.expect_indent()
        if with_doc or with_pseudo_doc:
            doc = p_doc_string(s)
        body = p_statement_list(s, ctx)
        s.expect_dedent()
    else:
        if ctx.api:
            error(s.pos, "'api' not allowed with this statement")
        if ctx.level in ('module', 'class', 'function', 'other'):
            body = p_simple_statement_list(s, ctx)
        else:
            body = p_pass_statement(s)
            s.expect_newline("Syntax error in declarations")
    if with_doc:
        return doc, body
    else:
        return body

def p_c_base_type(s, self_flag = 0):
    # If self_flag is true, this is the base type for the
    # self argument of a C method of an extension type.
    if s.sy == '(':
        return p_c_complex_base_type(s)
    else:
        return p_c_simple_base_type(s, self_flag)

def p_calling_convention(s):
    if s.sy == 'IDENT' and s.systring in calling_convention_words:
        result = s.systring
        s.next()
        return result
    else:
        return ""

calling_convention_words = ("__stdcall", "__cdecl", "__fastcall")

def p_c_complex_base_type(s):
    # s.sy == '('
    pos = s.position()
    s.next()
    base_type = p_c_base_type(s)
    declarator = p_c_declarator(s, empty = 1)
    s.expect(')')
    return Nodes.CComplexBaseTypeNode(pos, 
        base_type = base_type, declarator = declarator)

def p_c_simple_base_type(s, self_flag):
    #print "p_c_simple_base_type: self_flag =", self_flag
    is_basic = 0
    signed = 1
    longness = 0
    module_path = []
    pos = s.position()
    if looking_at_base_type(s):
        #print "p_c_simple_base_type: looking_at_base_type at", s.position()
        is_basic = 1
        signed, longness = p_sign_and_longness(s)
        if s.sy == 'IDENT' and s.systring in basic_c_type_names:
            name = s.systring
            s.next()
        else:
            name = 'int'
    elif s.looking_at_type_name() or looking_at_dotted_name(s):
        #print "p_c_simple_base_type: looking_at_type_name at", s.position()
        name = s.systring
        s.next()
        while s.sy == '.':
            module_path.append(name)
            s.next()
            name = p_ident(s)
    else:
        #print "p_c_simple_base_type: not looking at type at", s.position()
        name = None
    return Nodes.CSimpleBaseTypeNode(pos, 
        name = name, module_path = module_path,
        is_basic_c_type = is_basic, signed = signed,
        longness = longness, is_self_arg = self_flag)

def looking_at_type(s):
    return looking_at_base_type(s) or s.looking_at_type_name()

def looking_at_base_type(s):
    #print "looking_at_base_type?", s.sy, s.systring, s.position()
    return s.sy == 'IDENT' and s.systring in base_type_start_words

def looking_at_dotted_name(s):
    if s.sy == 'IDENT':
        name = s.systring
        s.next()
        result = s.sy == '.'
        s.put_back('IDENT', name)
        return result
    else:
        return 0

basic_c_type_names = ("void", "char", "int", "float", "double") #,
    #"size_t", "Py_ssize_t")

sign_and_longness_words = ("short", "long", "signed", "unsigned")

base_type_start_words = \
    basic_c_type_names + sign_and_longness_words

def p_sign_and_longness(s):
    signed = 1
    longness = 0
    while s.sy == 'IDENT' and s.systring in sign_and_longness_words:
        if s.systring == 'unsigned':
            signed = 0
        elif s.systring == 'signed':
            signed = 2
        elif s.systring == 'short':
            longness = -1
        elif s.systring == 'long':
            longness += 1
        s.next()
    return signed, longness

def p_opt_cname(s):
    literal = p_opt_string_literal(s)
    if literal:
        _, cname = literal
    else:
        cname = None
    return cname

def p_c_declarator(s, ctx = Ctx(), empty = 0, is_type = 0, cmethod_flag = 0, nonempty = 0,
        calling_convention_allowed = 0):
    # If empty is true, the declarator must be empty. If nonempty is true,
    # the declarator must be nonempty. Otherwise we don't care.
    # If cmethod_flag is true, then if this declarator declares
    # a function, it's a C method of an extension type.
    pos = s.position()
    if s.sy == '(':
        s.next()
        if s.sy == ')' or looking_at_type(s):
            base = Nodes.CNameDeclaratorNode(pos, name = "", cname = None)
            result = p_c_func_declarator(s, pos, ctx, base, cmethod_flag)
        else:
            result = p_c_declarator(s, ctx, empty = empty, is_type = is_type,
                cmethod_flag = cmethod_flag, nonempty = nonempty,
                calling_convention_allowed = 1)
            s.expect(')')
    else:
        result = p_c_simple_declarator(s, ctx, empty, is_type, cmethod_flag, nonempty)
    if not calling_convention_allowed and result.calling_convention and s.sy <> '(':
        error(s.position(), "%s on something that is not a function"
            % result.calling_convention)
    while s.sy in ('[', '('):
        pos = s.position()
        if s.sy == '[':
            result = p_c_array_declarator(s, result)
        else: # sy == '('
            s.next()
            result = p_c_func_declarator(s, pos, ctx, result, cmethod_flag)
        cmethod_flag = 0
    return result

def p_c_array_declarator(s, base):
    pos = s.position()
    s.next() # '['
    if s.sy <> ']':
        dim = p_expr(s)
    else:
        dim = None
    s.expect(']')
    return Nodes.CArrayDeclaratorNode(pos, base = base, dimension = dim)

def p_c_func_declarator(s, pos, ctx, base, cmethod_flag):
    #  Opening paren has already been skipped
    args = p_c_arg_list(s, ctx, cmethod_flag = cmethod_flag,
        nonempty_declarators = 0)
    ellipsis = p_optional_ellipsis(s)
    s.expect(')')
    nogil = p_nogil(s)
    exc_val, exc_check = p_exception_value_clause(s)
    with_gil = p_with_gil(s)
    return Nodes.CFuncDeclaratorNode(pos, 
        base = base, args = args, has_varargs = ellipsis,
        exception_value = exc_val, exception_check = exc_check,
        nogil = nogil or ctx.nogil or with_gil, with_gil = with_gil)

def p_c_simple_declarator(s, ctx, empty, is_type, cmethod_flag, nonempty):
    pos = s.position()
    calling_convention = p_calling_convention(s)
    if s.sy == '*':
        s.next()
        base = p_c_declarator(s, ctx, empty = empty, is_type = is_type,
            cmethod_flag = cmethod_flag, nonempty = nonempty)
        result = Nodes.CPtrDeclaratorNode(pos, 
            base = base)
    elif s.sy == '**': # scanner returns this as a single token
        s.next()
        base = p_c_declarator(s, ctx, empty = empty, is_type = is_type,
            cmethod_flag = cmethod_flag, nonempty = nonempty)
        result = Nodes.CPtrDeclaratorNode(pos,
            base = Nodes.CPtrDeclaratorNode(pos,
                base = base))
    else:
        if s.sy == 'IDENT':
            name = s.systring
            if is_type:
                s.add_type_name(name)
            if empty:
                error(s.position(), "Declarator should be empty")
            s.next()
            cname = p_opt_cname(s)
        else:
            if nonempty:
                error(s.position(), "Empty declarator")
            name = ""
            cname = None
        result = Nodes.CNameDeclaratorNode(pos,
            name = name, cname = cname)
    result.calling_convention = calling_convention
    return result

def p_nogil(s):
    if s.sy == 'IDENT' and s.systring == 'nogil':
        s.next()
        return 1
    else:
        return 0

def p_with_gil(s):
    if s.sy == 'with':
        s.next()
        s.expect_keyword('gil')
        return 1
    else:
        return 0

def p_exception_value_clause(s):
    exc_val = None
    exc_check = 0
    if s.sy == 'except':
        s.next()
        if s.sy == '*':
            exc_check = 1
            s.next()
        else:
            if s.sy == '?':
                exc_check = 1
                s.next()
            exc_val = p_simple_expr(s)
    return exc_val, exc_check

c_arg_list_terminators = ('*', '**', '.', ')')

def p_c_arg_list(s, ctx = Ctx(), in_pyfunc = 0, cmethod_flag = 0, nonempty_declarators = 0,
        kw_only = 0):
    #  Comma-separated list of C argument declarations, possibly empty.
    #  May have a trailing comma.
    args = []
    is_self_arg = cmethod_flag
    while s.sy not in c_arg_list_terminators:
        args.append(p_c_arg_decl(s, ctx, in_pyfunc, is_self_arg,
            nonempty = nonempty_declarators, kw_only = kw_only))
        if s.sy <> ',':
            break
        s.next()
        is_self_arg = 0
    return args

def p_optional_ellipsis(s):
    if s.sy == '.':
        expect_ellipsis(s)
        return 1
    else:
        return 0

def p_c_arg_decl(s, ctx, in_pyfunc, cmethod_flag = 0, nonempty = 0, kw_only = 0):
    pos = s.position()
    allow_none = None
    #not_none = 0
    default = None
    base_type = p_c_base_type(s, cmethod_flag)
    declarator = p_c_declarator(s, ctx, nonempty = nonempty)
    if s.sy in ('or', 'not'):
        or_not = s.sy
        s.next()
        if s.sy == 'IDENT' and s.systring == 'None':
            s.next()
        else:
            s.error("Expected 'None'")
        if not in_pyfunc:
            error(pos, "'%s None' only allowed in Python functions" % or_not)
        allow_none = or_not == 'or'
    if s.sy == '=':
        s.next()
        default = p_simple_expr(s)
    return Nodes.CArgDeclNode(pos,
        base_type = base_type,
        declarator = declarator,
        allow_none = allow_none,
        default = default,
        kw_only = kw_only)

def p_api(s):
    if s.sy == 'IDENT' and s.systring == 'api':
        s.next()
        return 1
    else:
        return 0

def p_cdef_statement(s, ctx):
    ctx = ctx(cdef_flag = 1)
    pos = s.position()
    ctx.visibility = p_visibility(s, ctx.visibility)
    ctx.api = ctx.api or p_api(s)
    if ctx.api:
        if ctx.visibility not in ('private', 'public'):
            error(pos, "Cannot combine 'api' with '%s'" % visibility)
    if ctx.visibility == 'extern' and s.sy == 'from':
        return p_cdef_extern_block(s, pos, ctx)
    if p_nogil(s):
        ctx.nogil = 1
    if s.sy == ':':
        return p_cdef_block(s, ctx)
    elif s.sy == 'class':
        if ctx.level not in ('module', 'module_pxd'):
            error(pos, "Extension type definition not allowed here")
        #if api:
        #  error(pos, "'api' not allowed with extension class")
        return p_c_class_definition(s, pos, ctx)
    elif s.sy == 'IDENT' and s.systring in struct_union_or_enum:
        if ctx.level not in ('module', 'module_pxd'):
            error(pos, "C struct/union/enum definition not allowed here")
        #if ctx.visibility == 'public':
        #  error(pos, "Public struct/union/enum definition not implemented")
        #if ctx.api:
        #  error(pos, "'api' not allowed with '%s'" % s.systring)
        if s.systring == "enum":
            return p_c_enum_definition(s, pos, ctx)
        else:
            return p_c_struct_or_union_definition(s, pos, ctx)
    elif s.sy == 'pass':
        node = p_pass_statement(s)
        s.expect_newline('Expected a newline')
        return node
    else:
        return p_c_func_or_var_declaration(s, pos, ctx)

def p_cdef_block(s, ctx):
    return p_suite(s, ctx(cdef_flag = 1))

def p_cdef_extern_block(s, pos, ctx):
    include_file = None
    s.expect('from')
    if s.sy == '*':
        s.next()
    else:
        _, include_file = p_string_literal(s)
    ctx = ctx(cdef_flag = 1, visibility = 'extern', extern_from = True)
    if p_nogil(s):
        ctx.nogil = 1
    body = p_suite(s, ctx)
    return Nodes.CDefExternNode(pos,
        include_file = include_file,
        body = body)

struct_union_or_enum = (
    "struct", "union", "enum"
)

def p_c_enum_definition(s, pos, ctx):
    # s.sy == ident 'enum'
    s.next()
    if s.sy == 'IDENT':
        name = s.systring
        s.next()
        s.add_type_name(name)
        cname = p_opt_cname(s)
    else:
        name = None
        cname = None
    items = None
    s.expect(':')
    items = []
    if s.sy <> 'NEWLINE':
        p_c_enum_line(s, items)
    else:
        s.next() # 'NEWLINE'
        s.expect_indent()
        while s.sy not in ('DEDENT', 'EOF'):
            p_c_enum_line(s, items)
        s.expect_dedent()
    return Nodes.CEnumDefNode(pos, name = name, cname = cname, items = items,
        typedef_flag = ctx.typedef_flag,
        visibility = ctx.visibility,
        in_pxd = ctx.level == 'module_pxd')

def p_c_enum_line(s, items):
    if s.sy <> 'pass':
        p_c_enum_item(s, items)
        while s.sy == ',':
            s.next()
            if s.sy in ('NEWLINE', 'EOF'):
                break
            p_c_enum_item(s, items)
    else:
        s.next()
    s.expect_newline("Syntax error in enum item list")

def p_c_enum_item(s, items):
    pos = s.position()
    name = p_ident(s)
    cname = p_opt_cname(s)
    value = None
    if s.sy == '=':
        s.next()
        value = p_simple_expr(s)
    items.append(Nodes.CEnumDefItemNode(pos, 
        name = name, cname = cname, value = value))

def p_c_struct_or_union_definition(s, pos, ctx):
    # s.sy == ident 'struct' or 'union'
    ctx.cplus_check(pos)
    kind = s.systring
    s.next()
    module_path, name = p_qualified_name(s)
    bases = []
    if s.sy == '(':
        s.next()
        while s.sy == 'IDENT':
            bases.append(p_qualified_name(s))
            if s.sy <> ',':
                break
            s.next()
        s.expect(')')
    if bases and not ctx.cplus_flag:
        error(s, "Only C++ struct may have bases")
    cname = p_opt_cname(s)
    s.add_type_name(name)
    attributes = None
    if s.sy == ':':
        s.next()
        s.expect('NEWLINE')
        s.expect_indent()
        attributes = []
        body_ctx = Ctx()
        while s.sy <> 'DEDENT':
            if s.sy <> 'pass':
                attributes.append(p_c_func_or_var_declaration(s,
                    s.position(), body_ctx))
            else:
                s.next()
                s.expect_newline("Expected a newline")
        s.expect_dedent()
    else:
        s.expect_newline("Syntax error in struct or union definition")
    return Nodes.CStructOrUnionDefNode(pos, 
        name = name, cname = cname, module_path = module_path,
        kind = kind, attributes = attributes,
        typedef_flag = ctx.typedef_flag,
        visibility = ctx.visibility,
        in_pxd = ctx.level == 'module_pxd',
        cplus_flag = ctx.cplus_flag,
        bases = bases)

def p_visibility(s, prev_visibility):
    pos = s.position()
    visibility = prev_visibility
    if s.sy == 'IDENT' and s.systring in ('extern', 'public', 'readonly'):
        visibility = s.systring
        if prev_visibility <> 'private' and visibility <> prev_visibility:
            s.error("Conflicting visibility options '%s' and '%s'"
                % (prev_visibility, visibility))
        s.next()
    return visibility

def p_c_func_or_var_declaration(s, pos, ctx):
    cmethod_flag = ctx.level in ('c_class', 'c_class_pxd')
    base_type = p_c_base_type(s)
    declarator = p_c_declarator(s, ctx, cmethod_flag = cmethod_flag, nonempty = 1)
    if s.sy == ':':
        if ctx.level not in ('module', 'c_class'):
            s.error("C function definition not allowed here")
        suite = p_suite(s, Ctx(level = 'function'), with_pseudo_doc = 1)
        result = Nodes.CFuncDefNode(pos,
            visibility = ctx.visibility,
            base_type = base_type,
            declarator = declarator, 
            body = suite,
            api = ctx.api)
    else:
        #if api:
        #  error(pos, "'api' not allowed with variable declaration")
        declarators = [declarator]
        while s.sy == ',':
            s.next()
            if s.sy == 'NEWLINE':
                break
            declarator = p_c_declarator(s, ctx, cmethod_flag = cmethod_flag, nonempty = 1)
            declarators.append(declarator)
        s.expect_newline("Syntax error in C variable declaration")
        result = Nodes.CVarDefNode(pos, 
            visibility = ctx.visibility,
            base_type = base_type, 
            declarators = declarators,
            in_pxd = ctx.level == 'module_pxd',
            api = ctx.api)
    return result

def p_ctypedef_statement(s, ctx):
    # s.sy == 'ctypedef'
    pos = s.position()
    s.next()
    visibility = p_visibility(s, ctx.visibility)
    api = p_api(s)
    ctx = ctx(typedef_flag = 1, visibility = visibility)
    if api:
        ctx.api = 1
    if s.sy == 'class':
        return p_c_class_definition(s, pos, ctx)
    elif s.sy == 'IDENT' and s.systring in ('struct', 'union', 'enum'):
        if s.systring == 'enum':
            return p_c_enum_definition(s, pos, ctx)
        else:
            return p_c_struct_or_union_definition(s, pos, ctx)
    else:
        base_type = p_c_base_type(s)
        declarator = p_c_declarator(s, ctx, is_type = 1, nonempty = 1)
        s.expect_newline("Syntax error in ctypedef statement")
        return Nodes.CTypeDefNode(pos,
            base_type = base_type, declarator = declarator,
            visibility = ctx.visibility,
            in_pxd = ctx.level == 'module_pxd')

def p_def_statement(s):
    # s.sy == 'def'
    pos = s.position()
    s.next()
    name = p_ident(s)
    #args = []
    s.expect('(');
    args = p_c_arg_list(s, in_pyfunc = 1, nonempty_declarators = 1)
    star_arg = None
    starstar_arg = None
    if s.sy == '*':
        s.next()
        if s.sy == 'IDENT':
            star_arg = p_py_arg_decl(s)
        if s.sy == ',':
            s.next()
            args.extend(p_c_arg_list(s, in_pyfunc = 1,
                nonempty_declarators = 1, kw_only = 1))
        elif s.sy <>')':
            s.error("Syntax error in Python function argument list")
    if s.sy == '**':
        s.next()
        starstar_arg = p_py_arg_decl(s)
    s.expect(')')
    if p_nogil(s):
        error(s.pos, "Python function cannot be declared nogil")
    doc, body = p_suite(s, Ctx(level = 'function'), with_doc = 1)
    return Nodes.DefNode(pos, name = name, args = args, 
        star_arg = star_arg, starstar_arg = starstar_arg,
        doc = doc, body = body)

def p_py_arg_decl(s):
    pos = s.position()
    name = p_ident(s)
    return Nodes.PyArgDeclNode(pos, name = name)

def p_class_statement(s):
    # s.sy == 'class'
    pos = s.position()
    s.next()
    class_name = p_ident(s)
    if s.sy == '(':
        s.next()
        base_list = p_simple_expr_list(s)
        s.expect(')')
    else:
        base_list = []
    doc, body = p_suite(s, Ctx(level = 'class'), with_doc = 1)
    return Nodes.PyClassDefNode(pos,
        name = class_name,
        bases = ExprNodes.TupleNode(pos, args = base_list),
        doc = doc, body = body)

def p_qualified_name(s):
    path = []
    name = p_ident(s)
    while s.sy == '.':
        s.next()
        path.append(name)
        name = p_ident(s)
    return path, name

class CClassOptions:

    objstruct_cname = None
    typeobj_cname = None
    no_gc = 0


def p_c_class_definition(s, pos, ctx):
    # s.sy == 'class'
    s.next()
    module_path, class_name = p_qualified_name(s)
    if module_path and s.sy == 'IDENT' and s.systring == 'as':
        s.next()
        as_name = p_ident(s)
    else:
        as_name = class_name
    s.add_type_name(as_name)
    options = CClassOptions()
    base_class_module = None
    base_class_name = None
    if s.sy == '(':
        s.next()
        base_class_path, base_class_name = p_qualified_name(s)
        if s.sy == ',':
            s.error("C class may only have one base class")
        s.expect(')')
        base_class_module = ".".join(base_class_path)
    if s.sy == '[':
        p_c_class_options(s, ctx, options)
    if s.sy == ':':
        if ctx.level == 'module_pxd':
            body_level = 'c_class_pxd'
        else:
            body_level = 'c_class'
        doc, body = p_suite(s, Ctx(level = body_level), with_doc = 1)
    else:
        s.expect_newline("Syntax error in C class definition")
        doc = None
        body = None
    if ctx.visibility == 'extern':
        if not module_path:
            error(pos, "Module name required for 'extern' C class")
        if options.typeobj_cname:
            error(pos, "Type object name specification not allowed for 'extern' C class")
    elif ctx.visibility == 'public':
        if not options.objstruct_cname:
            error(pos, "Object struct name specification required for 'public' C class")
        if not options.typeobj_cname:
            error(pos, "Type object name specification required for 'public' C class")
    else:
        if ctx.api:
            error(pos, "Only 'public' C class can be declared 'api'")
    return Nodes.CClassDefNode(pos,
        visibility = ctx.visibility,
        typedef_flag = ctx.typedef_flag,
        api = ctx.api,
        module_name = ".".join(module_path),
        class_name = class_name,
        as_name = as_name,
        base_class_module = base_class_module,
        base_class_name = base_class_name,
        options = options,
        in_pxd = ctx.level == 'module_pxd',
        doc = doc,
        body = body)

def p_c_class_options(s, ctx, options):
    s.expect('[')
    while 1:
        if s.sy <> 'IDENT':
            break
        if s.systring == 'object':
            if ctx.visibility not in ('public', 'extern'):
                error(s.position(), "Object name option only allowed for 'public' or 'extern' C class")
            s.next()
            options.objstruct_cname = p_ident(s)
        elif s.systring == 'type':
            if ctx.visibility not in ('public', 'extern'):
                error(s.position(), "Type name option only allowed for 'public' or 'extern' C class")
            s.next()
            options.typeobj_cname = p_ident(s)
        elif s.systring == 'nogc':
            s.next()
            options.no_gc = 1
        else:
            s.error("Unrecognised C class option '%s'" % s.systring)
        if s.sy <> ',':
            break
        s.next()
    s.expect(']', "Expected a C class option")

def p_property_decl(s):
    pos = s.position()
    s.next() # 'property'
    name = p_ident(s)
    doc, body = p_suite(s, Ctx(level = 'property'), with_doc = 1)
    return Nodes.PropertyNode(pos, name = name, doc = doc, body = body)

def p_doc_string(s):
    if s.sy == 'STRING' or s.sy == 'BEGIN_STRING':
        _, result = p_cat_string_literal(s)
        if s.sy <> 'EOF':
            s.expect_newline("Syntax error in doc string")
        return result
    else:
        return None

def p_module(s, pxd):
    s.add_type_name("object")
    pos = s.position()
    doc = p_doc_string(s)
    if pxd:
        level = 'module_pxd'
    else:
        level = 'module'
    body = p_statement_list(s, Ctx(level = level))
    if s.sy <> 'EOF':
        s.error("Syntax error in statement [%s,%s]" % (
            repr(s.sy), repr(s.systring)))
    return ModuleNode(pos, doc = doc, body = body)

#----------------------------------------------
#
#   Debugging
#
#----------------------------------------------

def print_parse_tree(f, node, level, key = None):  
    ind = "  " * level
    if node:
        f.write(ind)
        if key:
            f.write("%s: " % key)
        t = type(node)
        if t == TupleType:
            f.write("(%s @ %s\n" % (node[0], node[1]))
            for i in xrange(2, len(node)):
                print_parse_tree(f, node[i], level+1)
            f.write("%s)\n" % ind)
            return
        elif isinstance(node, Node):
            try:
                tag = node.tag
            except AttributeError:
                tag = node.__class__.__name__
            f.write("%s @ %s\n" % (tag, node.pos))
            for name, value in node.__dict__.items():
                if name <> 'tag' and name <> 'pos':
                    print_parse_tree(f, value, level+1, name)
            return
        elif t == ListType:
            f.write("[\n")
            for i in xrange(len(node)):
                print_parse_tree(f, node[i], level+1)
            f.write("%s]\n" % ind)
            return
    f.write("%s%s\n" % (ind, node))

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