literal 1.0.0

Quick overview

import literal

@literal.py
def unpack_octet(x, payload, offset, unpack_from):
    x <<= unpack_from('B', payload, offset)
    offset += 1

print(unpack_octet())

Gives:

x = unpack_from('B', payload, offset)
offset += 1

Or another example used to create argument unpackers for the AMQP protocol:

def unpack(method):

    @literal.py
    def body(p, payload, offset, unpack_from, argtuple, ssize):
        fields = method.fields
        names = p.tuple(*self.field_names)

        for i, fset in enumerate(fields):
            if len(fset) == 1:
                for field in fset:
                    name = p.var(field.name)
                    if field.format == '*':
                        # This is a string payload,
                        # don't have to unpack
                        name <<= payload[offset:offset + ssize]
                        offset += ssize
                    else:
                        # A single field to unpack
                        name <<= unpack_from(struct_format(field.format),
                                            payload, offset)[0]
                        offset += field.size
            else:
                # A list of field to unpack
                these = p.tuple(*fset.names)
                these <<= unpack_from(struct_format(fset.format),
                                    payload, offset)
                offset += sum(f.size for f in fset)
            return names

        return body().as_fun(lambda payload, offset: 1,
                            method.name)

Would generate the following code for the AMQP method basic_deliver:

def deliver(payload, offset):
    ssize = unpack_from('B', payload, offset)[0]
    offset += 1
    consumer_tag = payload[offset:offset + ssize]
    offset += ssize
    delivery_tag, redelivered, ssize = unpack_from('QBB', payload, offset)
    offset += 10
    exchange = payload[offset:offset + ssize]
    offset += ssize
    ssize = unpack_from('B', payload, offset)[0]
    offset += 1
    routing_key = payload[offset:offset + ssize]
    offset += ssize
    return (consumer_tag, delivery_tag, redelivered,
            exchange, routing_key)

More documentation to come.