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support switch case in the generator 

The implementation is rather simple:
When a <case> is used instead of a <bitcase>
then operator "==" is used instead of "&" in the if-condition.

So it creates a series of "if" statements
(instead of a switch-case statement in C )

In practice this does not matter because a good
optimizing compiler will create the same code
as for a switch-case.

With this simple implementation we get additional
flexibility in the following forms:
* a case value may appear in multiple case branches.
  for example:
	case C1 will be selected by values 1, 4, or 5
	case C2 will be selected by values 3, 4, or 7

* mixing of bitcase and case is possible
	(this will usually make no sense but there may
	be protocol specs where this is needed)

details of the impl:
* replaced "is_bitcase" with "is_case_or_bitcase" in all places
  so that cases are treated like bitcases.

* In function "_c_serialize_helper_switch": write operator "=="
  instead of operator "&" if it is a case.
This commit is contained in:
Christian Linhart 2014-08-19 15:57:34 +02:00 committed by Peter Harris
parent 966fba6ba4
commit 355d4d6ab9
1 changed files with 33 additions and 22 deletions
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55
src/c_client.py
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@ -358,7 +358,7 @@ def _c_type_setup(self, name, postfix):
field.c_pointer = '*' field.c_pointer = '*'
field.c_field_const_type = 'const ' + field.c_field_type field.c_field_const_type = 'const ' + field.c_field_type
self.c_need_aux = True self.c_need_aux = True
elif not field.type.fixed_size() and not field.type.is_bitcase: elif not field.type.fixed_size() and not field.type.is_case_or_bitcase:
self.c_need_sizeof = True self.c_need_sizeof = True
field.c_iterator_type = _t(field.field_type + ('iterator',)) # xcb_fieldtype_iterator_t field.c_iterator_type = _t(field.field_type + ('iterator',)) # xcb_fieldtype_iterator_t
@ -407,7 +407,7 @@ def _c_type_setup(self, name, postfix):
# no list with switch as element, so no call to # no list with switch as element, so no call to
# _c_iterator(field.type, field_name) necessary # _c_iterator(field.type, field_name) necessary
if not self.is_bitcase: if not self.is_case_or_bitcase:
if self.c_need_serialize: if self.c_need_serialize:
if self.c_serialize_name not in finished_serializers: if self.c_serialize_name not in finished_serializers:
finished_serializers.append(self.c_serialize_name) finished_serializers.append(self.c_serialize_name)
@ -437,7 +437,7 @@ def _c_helper_absolute_name(prefix, field=None):
prefix_str += name prefix_str += name
if '' == sep: if '' == sep:
sep = '->' sep = '->'
if ((obj.is_bitcase and obj.has_name) or # named bitcase if ((obj.is_case_or_bitcase and obj.has_name) or # named bitcase
(obj.is_switch and len(obj.parents)>1)): (obj.is_switch and len(obj.parents)>1)):
sep = '.' sep = '.'
prefix_str += sep prefix_str += sep
@ -470,7 +470,7 @@ def _c_helper_field_mapping(complex_type, prefix, flat=False):
all_fields[f.field_name] = (fname, f) all_fields[f.field_name] = (fname, f)
if f.type.is_container and flat==False: if f.type.is_container and flat==False:
if f.type.is_bitcase and not f.type.has_name: if f.type.is_case_or_bitcase and not f.type.has_name:
new_prefix = prefix new_prefix = prefix
elif f.type.is_switch and len(f.type.parents)>1: elif f.type.is_switch and len(f.type.parents)>1:
# nested switch gets another separator # nested switch gets another separator
@ -493,10 +493,10 @@ def _c_helper_resolve_field_names (prefix):
name, sep, obj = p name, sep, obj = p
if ''==sep: if ''==sep:
# sep can be preset in prefix, if not, make a sensible guess # sep can be preset in prefix, if not, make a sensible guess
sep = '.' if (obj.is_switch or obj.is_bitcase) else '->' sep = '.' if (obj.is_switch or obj.is_case_or_bitcase) else '->'
# exception: 'toplevel' object (switch as well!) always have sep '->' # exception: 'toplevel' object (switch as well!) always have sep '->'
sep = '->' if idx<1 else sep sep = '->' if idx<1 else sep
if not obj.is_bitcase or (obj.is_bitcase and obj.has_name): if not obj.is_case_or_bitcase or (obj.is_case_or_bitcase and obj.has_name):
tmp_prefix.append((name, sep, obj)) tmp_prefix.append((name, sep, obj))
all_fields.update(_c_helper_field_mapping(obj, tmp_prefix, flat=True)) all_fields.update(_c_helper_field_mapping(obj, tmp_prefix, flat=True))
@ -689,18 +689,29 @@ def _c_serialize_helper_switch(context, self, complex_name,
for b in self.bitcases: for b in self.bitcases:
len_expr = len(b.type.expr) len_expr = len(b.type.expr)
compare_operator = '&'
if b.type.is_case:
compare_operator = '=='
else:
compare_operator = '&'
for n, expr in enumerate(b.type.expr): for n, expr in enumerate(b.type.expr):
bitcase_expr = _c_accessor_get_expr(expr, None) bitcase_expr = _c_accessor_get_expr(expr, None)
# only one <enumref> in the <bitcase> # only one <enumref> in the <bitcase>
if len_expr == 1: if len_expr == 1:
code_lines.append(' if(%s & %s) {' % (switch_expr, bitcase_expr)) code_lines.append(
' if(%s %s %s) {' % (switch_expr, compare_operator, bitcase_expr))
# multiple <enumref> in the <bitcase> # multiple <enumref> in the <bitcase>
elif n == 0: # first elif n == 0: # first
code_lines.append(' if((%s & %s) ||' % (switch_expr, bitcase_expr)) code_lines.append(
' if((%s %s %s) ||' % (switch_expr, compare_operator, bitcase_expr))
elif len_expr == (n + 1): # last elif len_expr == (n + 1): # last
code_lines.append(' (%s & %s)) {' % (switch_expr, bitcase_expr)) code_lines.append(
' (%s %s %s)) {' % (switch_expr, compare_operator, bitcase_expr))
else: # between first and last else: # between first and last
code_lines.append(' (%s & %s) ||' % (switch_expr, bitcase_expr)) code_lines.append(
' (%s %s %s) ||' % (switch_expr, compare_operator, bitcase_expr))
b_prefix = prefix b_prefix = prefix
if b.type.has_name: if b.type.has_name:
@ -710,7 +721,7 @@ def _c_serialize_helper_switch(context, self, complex_name,
code_lines, temp_vars, code_lines, temp_vars,
"%s " % space, "%s " % space,
b_prefix, b_prefix,
is_bitcase = True) is_case_or_bitcase = True)
code_lines.append(' }') code_lines.append(' }')
# if 'serialize' == context: # if 'serialize' == context:
@ -834,7 +845,7 @@ def _c_serialize_helper_fields_fixed_size(context, self, field,
code_lines, temp_vars, code_lines, temp_vars,
space, prefix): space, prefix):
# keep the C code a bit more readable by giving the field name # keep the C code a bit more readable by giving the field name
if not self.is_bitcase: if not self.is_case_or_bitcase:
code_lines.append('%s /* %s.%s */' % (space, self.c_type, field.c_field_name)) code_lines.append('%s /* %s.%s */' % (space, self.c_type, field.c_field_name))
else: else:
scoped_name = [p[2].c_type if idx==0 else p[0] for idx, p in enumerate(prefix)] scoped_name = [p[2].c_type if idx==0 else p[0] for idx, p in enumerate(prefix)]
@ -951,7 +962,7 @@ def _c_serialize_helper_fields_variable_size(context, self, field,
def _c_serialize_helper_fields(context, self, def _c_serialize_helper_fields(context, self,
code_lines, temp_vars, code_lines, temp_vars,
space, prefix, is_bitcase): space, prefix, is_case_or_bitcase):
count = 0 count = 0
need_padding = False need_padding = False
prev_field_was_variable = False prev_field_was_variable = False
@ -963,7 +974,7 @@ def _c_serialize_helper_fields(context, self,
# switch/bitcase: fixed size fields must be considered explicitly # switch/bitcase: fixed size fields must be considered explicitly
if field.type.fixed_size(): if field.type.fixed_size():
if self.is_bitcase or self.c_var_followed_by_fixed_fields: if self.is_case_or_bitcase or self.c_var_followed_by_fixed_fields:
if prev_field_was_variable and need_padding: if prev_field_was_variable and need_padding:
# insert padding # insert padding
# count += _c_serialize_helper_insert_padding(context, code_lines, space, # count += _c_serialize_helper_insert_padding(context, code_lines, space,
@ -989,7 +1000,7 @@ def _c_serialize_helper_fields(context, self,
continue continue
else: else:
# switch/bitcase: always calculate padding before and after variable sized fields # switch/bitcase: always calculate padding before and after variable sized fields
if need_padding or is_bitcase: if need_padding or is_case_or_bitcase:
count += _c_serialize_helper_insert_padding(context, code_lines, space, count += _c_serialize_helper_insert_padding(context, code_lines, space,
self.c_var_followed_by_fixed_fields) self.c_var_followed_by_fixed_fields)
@ -1003,7 +1014,7 @@ def _c_serialize_helper_fields(context, self,
code_lines.append('%s%s' % (space, value)) code_lines.append('%s%s' % (space, value))
if field.type.fixed_size(): if field.type.fixed_size():
if is_bitcase or self.c_var_followed_by_fixed_fields: if is_case_or_bitcase or self.c_var_followed_by_fixed_fields:
# keep track of (un)serialized object's size # keep track of (un)serialized object's size
code_lines.append('%s xcb_block_len += %s;' % (space, length)) code_lines.append('%s xcb_block_len += %s;' % (space, length))
if context in ('unserialize', 'unpack', 'sizeof'): if context in ('unserialize', 'unpack', 'sizeof'):
@ -1461,7 +1472,7 @@ def _c_accessors_field(self, field):
# special case: switch # special case: switch
switch_obj = self if self.is_switch else None switch_obj = self if self.is_switch else None
if self.is_bitcase: if self.is_case_or_bitcase:
switch_obj = self.parents[-1] switch_obj = self.parents[-1]
if switch_obj is not None: if switch_obj is not None:
c_type = switch_obj.c_type c_type = switch_obj.c_type
@ -1529,7 +1540,7 @@ def _c_accessors_list(self, field):
# the reason is that switch is either a child of a request/reply or nested in another switch, # the reason is that switch is either a child of a request/reply or nested in another switch,
# so whenever we need to access a length field, we might need to refer to some anchestor type # so whenever we need to access a length field, we might need to refer to some anchestor type
switch_obj = self if self.is_switch else None switch_obj = self if self.is_switch else None
if self.is_bitcase: if self.is_case_or_bitcase:
switch_obj = self.parents[-1] switch_obj = self.parents[-1]
if switch_obj is not None: if switch_obj is not None:
c_type = switch_obj.c_type c_type = switch_obj.c_type
@ -1561,7 +1572,7 @@ def _c_accessors_list(self, field):
for p in parents[2:] + [self]: for p in parents[2:] + [self]:
# the separator between parent and child is always '.' here, # the separator between parent and child is always '.' here,
# because of nested switch statements # because of nested switch statements
if not p.is_bitcase or (p.is_bitcase and p.has_name): if not p.is_case_or_bitcase or (p.is_case_or_bitcase and p.has_name):
prefix.append((p.name[-1], '.', p)) prefix.append((p.name[-1], '.', p))
fields.update(_c_helper_field_mapping(p, prefix, flat=True)) fields.update(_c_helper_field_mapping(p, prefix, flat=True))
@ -2364,7 +2375,7 @@ def _man_request(self, name, cookie_type, void, aux):
# special case: switch # special case: switch
switch_obj = self if self.is_switch else None switch_obj = self if self.is_switch else None
if self.is_bitcase: if self.is_case_or_bitcase:
switch_obj = self.parents[-1] switch_obj = self.parents[-1]
if switch_obj is not None: if switch_obj is not None:
c_type = switch_obj.c_type c_type = switch_obj.c_type
@ -2392,7 +2403,7 @@ def _man_request(self, name, cookie_type, void, aux):
# the reason is that switch is either a child of a request/reply or nested in another switch, # the reason is that switch is either a child of a request/reply or nested in another switch,
# so whenever we need to access a length field, we might need to refer to some anchestor type # so whenever we need to access a length field, we might need to refer to some anchestor type
switch_obj = self if self.is_switch else None switch_obj = self if self.is_switch else None
if self.is_bitcase: if self.is_case_or_bitcase:
switch_obj = self.parents[-1] switch_obj = self.parents[-1]
if switch_obj is not None: if switch_obj is not None:
c_type = switch_obj.c_type c_type = switch_obj.c_type
@ -2424,7 +2435,7 @@ def _man_request(self, name, cookie_type, void, aux):
for p in parents[2:] + [self]: for p in parents[2:] + [self]:
# the separator between parent and child is always '.' here, # the separator between parent and child is always '.' here,
# because of nested switch statements # because of nested switch statements
if not p.is_bitcase or (p.is_bitcase and p.has_name): if not p.is_case_or_bitcase or (p.is_case_or_bitcase and p.has_name):
prefix.append((p.name[-1], '.', p)) prefix.append((p.name[-1], '.', p))
fields.update(_c_helper_field_mapping(p, prefix, flat=True)) fields.update(_c_helper_field_mapping(p, prefix, flat=True))