sxp.py

xen虚拟机源代码安装包

        out.write(k_list_open)
        i = 0
        for x in sxpr:
            if i: out.write(' ')
            show(x, out)
            i += 1
        out.write(k_list_close)
    elif isinstance(sxpr, (types.IntType, types.FloatType)):
        out.write(str(sxpr))
    elif isinstance(sxpr, types.StringType) and atomp(sxpr):
        out.write(sxpr)
    else:
        out.write(repr(str(sxpr)))

def show_xml(sxpr, out=sys.stdout):
    """Print an sxpr in XML syntax.
    """
    if isinstance(sxpr, (types.ListType, types.TupleType)):
        element = name(sxpr)
        out.write('<%s' % element)
        for attr in attributes(sxpr):
            out.write(' %s=%s' % (attr[0], attr[1]))
        out.write('>')
        i = 0
        for x in children(sxpr):
            if i: out.write(' ')
            show_xml(x, out)
            i += 1
        out.write('</%s>' % element)
    elif isinstance(sxpr, types.StringType) and atomp(sxpr):
        out.write(sxpr)
    else:
        out.write(str(sxpr))

def elementp(sxpr, elt=None):
    """Check if an sxpr is an element of the given type.

    sxpr sxpr
    elt  element type
    """
    return (isinstance(sxpr, (types.ListType, types.TupleType))
            and len(sxpr)
            and (None == elt or sxpr[0] == elt))

def name(sxpr):
    """Get the element name of an sxpr.
    If the sxpr is not an element (i.e. it's an atomic value) its name
    is None.

    sxpr

    returns name (None if not an element).
    """
    val = None
    if isinstance(sxpr, types.StringType):
        val = sxpr
    elif isinstance(sxpr, (types.ListType, types.TupleType)) and len(sxpr):
        val = sxpr[0]
    return val

def attributes(sxpr):
    """Get the attribute list of an sxpr.

    sxpr

    returns attribute list
    """
    val = []
    if isinstance(sxpr, (types.ListType, types.TupleType)) and len(sxpr) > 1:
        attr = sxpr[1]
        if elementp(attr, k_attr_open):
            val = attr[1:]
    return val

def attribute(sxpr, key, val=None):
    """Get an attribute of an sxpr.

    sxpr sxpr
    key  attribute key
    val  default value (default None)

    returns attribute value
    """
    for x in attributes(sxpr):
        if x[0] == key:
            val = x[1]
            break
    return val

def children(sxpr, elt=None):
    """Get children of an sxpr.

    sxpr sxpr
    elt  optional element type to filter by

    returns children (filtered by elt if specified)
    """
    val = []
    if isinstance(sxpr, (types.ListType, types.TupleType)) and len(sxpr) > 1:
        i = 1
        x = sxpr[i]
        if elementp(x, k_attr_open):
            i += 1
        val = sxpr[i : ]
    if elt:
        def iselt(x):
            return elementp(x, elt)
        val = filter(iselt, val)
    return val

def child(sxpr, elt, val=None):
    """Get the first child of the given element type.

    sxpr sxpr
    elt  element type
    val  default value
    """
    for x in children(sxpr):
        if elementp(x, elt):
            val = x
            break
    return val

def child_at(sxpr, index, val=None):
    """Get the child at the given index (zero-based).

    sxpr  sxpr
    index index
    val   default value
    """
    kids = children(sxpr)
    if len(kids) > index:
        val = kids[index]
    return val

def child0(sxpr, val=None):
    """Get the zeroth child.
    """
    return child_at(sxpr, 0, val)

def child1(sxpr, val=None):
    """Get the first child.
    """
    return child_at(sxpr, 1, val)

def child2(sxpr, val=None):
    """Get the second child.
    """
    return child_at(sxpr, 2, val)

def child3(sxpr, val=None):
    """Get the third child.
    """
    return child_at(sxpr, 3, val)

def child4(sxpr, val=None):
    """Get the fourth child.
    """
    return child_at(sxpr, 4, val)

def child_value(sxpr, elt, val=None):
    """Get the value of the first child of the given element type.
    Assumes the child has an atomic value.

    sxpr sxpr
    elt  element type
    val  default value
    """
    kid = child(sxpr, elt)
    if kid:
        val = child_at(kid, 0, val)
    return val

def has_id(sxpr, id):
    """Test if an s-expression has a given id.
    """
    return attribute(sxpr, 'id') == id

def with_id(sxpr, id, val=None):
    """Find the first s-expression with a given id, at any depth.

    sxpr   s-exp or list
    id     id
    val    value if not found (default None)

    return s-exp or val
    """
    if isinstance(sxpr, (types.ListType, types.TupleType)):
        for n in sxpr:
            if has_id(n, id):
                val = n
                break
            v = with_id(n, id)
            if v is None: continue
            val = v
            break
    return val

def child_with_id(sxpr, id, val=None):
    """Find the first child with a given id.

    sxpr   s-exp or list
    id     id
    val    value if not found (default None)

    return s-exp or val
    """
    if isinstance(sxpr, (types.ListType, types.TupleType)):
        for n in sxpr:
            if has_id(n, id):
                val = n
                break
    return val

def elements(sxpr, ctxt=None):
    """Generate elements (at any depth).
    Visit elements in pre-order.
    Values generated are (node, context)
    The context is None if there is no parent, otherwise
    (index, parent, context) where index is the node's index w.r.t its parent,
    and context is the parent's context.

    sxpr   s-exp

    returns generator
    """
    yield (sxpr, ctxt)
    i = 0
    for n in children(sxpr):
        if isinstance(n, (types.ListType, types.TupleType)):
            # Calling elements() recursively does not generate recursively,
            # it just returns a generator object. So we must iterate over it.
            for v in elements(n, (i, sxpr, ctxt)):
                yield v
        i += 1

def merge(s1, s2):
    """Merge sxprs s1 and s2.
    Returns an sxpr containing all the fields from s1 and s2, with
    entries in s1 overriding s2. Recursively merges fields.

    @param s1 sxpr
    @param s2 sxpr
    @return merged sxpr
    """
    if s1 is None:
        val = s2
    elif s2 is None:
        val = s1
    elif elementp(s1):
        name1 = name(s1)
        (m1, v1) = child_map(s1)
        (m2, v2) = child_map(s2)
        val = [name1]
        for (k1, f1) in m1.items():
            merge_list(val, f1, m2.get(k1, []))
        for (k2, f2) in m2.items():
            if k2 in m1: continue
            val.extend(f2)
        val.extend(v1)
    else:
        val = s1
    return val

def merge_list(sxpr, l1, l2):
    """Merge element lists l1 and l2 into sxpr.
    The lists l1 and l2 are all element with the same name.
    Values from l1 are merged with values in l2 and stored in sxpr.
    If one list is longer than the other the excess values are used
    as they are.

    @param sxpr to merge into
    @param l1 sxpr list
    @param l2 sxpr list
    @return modified sxpr
    """
    n1 = len(l1)
    n2 = len(l2)
    nmin = min(n1, n2)
    for i in range(0, nmin):
        sxpr.append(merge(l1[i], l2[i]))
    for i in range(nmin, n1):
        sxpr.append(l1[i])
    for i in range(nmin, n2):
        sxpr.append(l2[i])
    return sxpr

def child_map(sxpr):
    """Get a dict of the elements in sxpr and a list of its values.
    The dict maps element name to the list of elements with that name,
    and the list is the non-element children.

    @param sxpr
    @return (dict, list)
    """
    m = {}
    v = []
    for x in children(sxpr):
        if elementp(x):
            n = name(x)
            l = m.get(n, [])
            l.append(x)
            m[n] = l
        else:
            v.append(x)
    return (m, v)

def to_string(sxpr):
    """Convert an sxpr to a string.

    sxpr sxpr
    returns string
    """
    io = StringIO()
    show(sxpr, io)
    io.seek(0)
    val = io.getvalue()
    io.close()
    return val

def from_string(s):
    """Create an sxpr by parsing a string.

    s string
    returns sxpr
    """
    if s == '':
        return []

    io = StringIO(s)
    vals = parse(io)
    if vals is []:
        return None
    else:
        return vals[0]
    

def all_from_string(s):
    """Create an sxpr list by parsing a string.

    s string
    returns sxpr list
    """
    io = StringIO(s)
    vals = parse(io)
    return vals

def parse(io):
    """Completely parse all input from 'io'.

    io	input file object
    returns list of values, None if incomplete
    raises ParseError on parse error
    """
    pin = Parser()
    while 1:
        buf = io.readline()
        pin.input(buf)
        if len(buf) == 0:
            break
    if pin.ready():
        val = pin.get_all()
    else:
        val = None
    return val
   

if __name__ == '__main__':
    print ">main"
    pin = Parser()
    while 1:
        buf = sys.stdin.read(1024)
        #buf = sys.stdin.readline()
        pin.input(buf)
        while pin.ready():
            val = pin.get_val()
            print
            print '****** val=', val
        if len(buf) == 0:
            break