--- a/doc/book/en/annexes/rql/implementation.rst Mon Jul 06 17:39:35 2015 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,159 +0,0 @@
-
-
-Implementation
---------------
-
-BNF grammar
-~~~~~~~~~~~
-
-The terminal elements are in capital letters, non-terminal in lowercase.
-The value of the terminal elements (between quotes) is a Python regular
-expression.
-::
-
- statement ::= (select | delete | insert | update) ';'
-
-
- # select specific rules
- select ::= 'DISTINCT'? E_TYPE selected_terms restriction? group? sort?
-
- selected_terms ::= expression ( ',' expression)*
-
- group ::= 'GROUPBY' VARIABLE ( ',' VARIABLE)*
-
- sort ::= 'ORDERBY' sort_term ( ',' sort_term)*
-
- sort_term ::= VARIABLE sort_method =?
-
- sort_method ::= 'ASC' | 'DESC'
-
-
- # delete specific rules
- delete ::= 'DELETE' (variables_declaration | relations_declaration) restriction?
-
-
- # insert specific rules
- insert ::= 'INSERT' variables_declaration ( ':' relations_declaration)? restriction?
-
-
- # update specific rules
- update ::= 'SET' relations_declaration restriction
-
-
- # common rules
- variables_declaration ::= E_TYPE VARIABLE (',' E_TYPE VARIABLE)*
-
- relations_declaration ::= simple_relation (',' simple_relation)*
-
- simple_relation ::= VARIABLE R_TYPE expression
-
- restriction ::= 'WHERE' relations
-
- relations ::= relation (LOGIC_OP relation)*
- | '(' relations')'
-
- relation ::= 'NOT'? VARIABLE R_TYPE COMP_OP? expression
- | 'NOT'? R_TYPE VARIABLE 'IN' '(' expression (',' expression)* ')'
-
- expression ::= var_or_func_or_const (MATH_OP var_or_func_or_const) *
- | '(' expression ')'
-
- var_or_func_or_const ::= VARIABLE | function | constant
-
- function ::= FUNCTION '(' expression ( ',' expression) * ')'
-
- constant ::= KEYWORD | STRING | FLOAT | INT
-
- # tokens
- LOGIC_OP ::= ',' | 'OR' | 'AND'
- MATH_OP ::= '+' | '-' | '/' | '*'
- COMP_OP ::= '>' | '>=' | '=' | '<=' | '<' | '~=' | 'LIKE'
-
- FUNCTION ::= 'MIN' | 'MAX' | 'SUM' | 'AVG' | 'COUNT' | 'UPPER' | 'LOWER'
-
- VARIABLE ::= '[A-Z][A-Z0-9]*'
- E_TYPE ::= '[A-Z]\w*'
- R_TYPE ::= '[a-z_]+'
-
- KEYWORD ::= 'TRUE' | 'FALSE' | 'NULL' | 'TODAY' | 'NOW'
- STRING ::= "'([^'\]|\\.)*'" |'"([^\"]|\\.)*\"'
- FLOAT ::= '\d+\.\d*'
- INT ::= '\d+'
-
-
-Internal representation (syntactic tree)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The tree research does not contain the selected variables
-(e.g. there is only what follows "WHERE").
-
-The insertion tree does not contain the variables inserted or relations
-defined on these variables (e.g. there is only what follows "WHERE").
-
-The removal tree does not contain the deleted variables and relations
-(e.g. there is only what follows the "WHERE").
-
-The update tree does not contain the variables and relations updated
-(e.g. there is only what follows the "WHERE").
-
-::
-
- Select ((Relationship | And | Or)?, Group?, Sort?)
- Insert (Relations | And | Or)?
- Delete (Relationship | And | Or)?
- Update (Relations | And | Or)?
-
- And ((Relationship | And | Or), (Relationship | And | Or))
- Or ((Relationship | And | Or), (Relationship | And | Or))
-
- Relationship ((VariableRef, Comparison))
-
- Comparison ((Function | MathExpression | Keyword | Constant | VariableRef) +)
-
- Function (())
- MathExpression ((MathExpression | Keyword | Constant | VariableRef), (MathExpression | Keyword | Constant | VariableRef))
-
- Group (VariableRef +)
- Sort (SortTerm +)
- SortTerm (VariableRef +)
-
- VariableRef ()
- Variable ()
- Keyword ()
- Constant ()
-
-
-Known limitations
-~~~~~~~~~~~~~~~~~
-
-- The current implementation does not support linking two relations of type 'is'
- with an OR. I do not think that the negation is supported on this type of
- relation (XXX to be confirmed).
-
-- missing COALESCE and certainly other things...
-
-- writing an rql query requires knowledge of the used schema (with real relation
- names and entities, not those viewed in the user interface). On the other
- hand, we cannot really bypass that, and it is the job of a user interface to
- hide the RQL.
-
-
-Topics
-~~~~~~
-
-It would be convenient to express the schema matching
-relations (non-recursive rules)::
-
- Document class Type <-> Document occurence_of Fiche class Type
- Sheet class Type <-> Form collection Collection class Type
-
-Therefore 1. becomes::
-
- Document X where
- X class C, C name 'Cartoon'
- X owned_by U, U login 'syt'
- X available true
-
-I'm not sure that we should handle this at RQL level ...
-
-There should also be a special relation 'anonymous'.