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generator: sumof with nested expression 

Support sumof with a nested expression.
The nested expression is computed for every list-element
and the result of the computation is added to the sum.

This way, sumof can be applied to a list of structs,
and, e.g., compute the sum of a specific field of that struct.

example:
<struct name="SumofTest_Element">
   <field type="CARD16" name="foo" />
   <field type="CARD16" name="bar" />
</struct>

<struct name="SumofTest_FieldAccess">
   <field type="CARD32" name="len" />
   <list type="SumofTest_Element" name="mylist1">
	   <fieldref>len</fieldref>
   </list>
   <list type="CARD16" name="mylist2">
	<sumof ref="mylist1">
		<fieldref>bar</fieldref>
	</sumof>
   </list>
</struct>

generated tmpvar:
    int xcb_pre_tmp_1; /* sumof length */
    int xcb_pre_tmp_2; /* sumof loop counter */
    int64_t xcb_pre_tmp_3; /* sumof sum */
    const xcb_input_sumof_test_element_t* xcb_pre_tmp_4; /* sumof list ptr */

generated code:
    /* mylist2 */
    /* sumof start */
    xcb_pre_tmp_1 = _aux->len;
    xcb_pre_tmp_3 = 0;
    xcb_pre_tmp_4 = xcb_input_sumof_test_field_access_mylist_1(_aux);
    for ( xcb_pre_tmp_2 = 0; xcb_pre_tmp_2 < xcb_pre_tmp_1; xcb_pre_tmp_2++) {
        xcb_pre_tmp_3 += xcb_pre_tmp_4->bar;
        xcb_pre_tmp_4++;
    }
    /* sumof end. Result is in xcb_pre_tmp_3 */
    xcb_block_len += xcb_pre_tmp_3 * sizeof(uint16_t);

changes for V2 of this patch:
* explicitely set the member access operator in the prefix-tuple
  passed to function _c_helper_field_mapping.
  This enables us to simplify function "_c_helper_absolute_name"
  (which will be renamed "_c_helper_fieldaccess_expr" soon)

V3: Changed style and formatting according to suggestions from Ran Benita

Signed-off-by: Christian Linhart <chris@DemoRecorder.com>
Reviewed-by: Ran Benita <ran234@gmail.com>

Message-ID: <54562798.8040500@DemoRecorder.com>
Patch-Thread-Subject: [Xcb] [PATCHSET] ListInputDevices revision 2
Patch-Set: ListInputDevices
Patch-Number: libxcb 5/9
Patch-Version: V3
This commit is contained in:
Christian Linhart 2014-11-02 13:46:16 +01:00 committed by Christian Linhart
parent 4a915c0dba
commit 51a0d57acc
1 changed files with 24 additions and 1 deletions
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23
src/c_client.py
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@ -1646,7 +1646,30 @@ def _c_accessor_get_expr(expr, field_mapping):
_c_pre.code("%s = %s;", listvar, list_name)
_c_pre.code("for (%s = 0; %s < %s; %s++) {", loopvar, loopvar, lengthvar, loopvar)
_c_pre.indent()
if expr.rhs is None:
_c_pre.code("%s += *%s;", sumvar, listvar)
else:
# sumof has a nested expression which has to be evaluated in
# the context of this list element
# field mapping for the subexpression needs to include
# the fields of the list-member type
scoped_field_mapping = field_mapping.copy()
scoped_field_mapping.update(
_c_helper_field_mapping(
field.type.member,
[(listvar, '->', field.type.member)]))
# cause pre-code of the subexpression be added right here
_c_pre.end()
# compute the subexpression
rhs_expr_str = _c_accessor_get_expr(expr.rhs, scoped_field_mapping)
# resume with our code
_c_pre.start()
# output the summation expression
_c_pre.code("%s += %s;", sumvar, rhs_expr_str)
_c_pre.code("%s++;", listvar)
_c_pre.pop_indent()
_c_pre.code("}")