Parses META files
`BaseDef
refers to META definitions using the "=" operator,
and `Appendix
refers to definitions using the "+=" operator.
#
def_var
| : string | ; | (* | The name of the defined variable | *) |
#
def_flav
| : flavour | ; | (* | The flavour of the definition | *) |
#
def_preds
| : formal_pred list | ; | (* | The formal predicates of the def | *) |
#
def_value
| : string | ; | (* | The value assigned to the variable | *) |
A pkg_definition
is expressed by the syntax
var(p1,p2,...) = "value"
(flavour `BaseDef), or the syntax
var(p1,p2,...) += "value"
(flavour `Appendix) in the META file. The list of predicates may be omitted. Predicates may be negated by using "-", e.g. "-x".
#
pkg_defs
| : pkg_definition list | ; | |||
#
pkg_children
| : (string * pkg_expr) list | ; |
A value of type pkg_expr
denotes the contents of a META file.
The component pkg_defs
are the variable definitions.
The component pkg_children
contains
the definitions of the subpackages.
parse ch:
scans and parses the file connected with channel ch
. The file must
have a syntax compatible with the META format. The return value
contains the found definitions for the package and all subpackages.
exception Stream.Error of string:
is
raised on syntax errors. The string explains the error.
print ch expr
:
Outputs the package expression to a channel.
lookup variable_name predicate_list def
:
Returns the value of variable_name
in def
under the assumption
that the predicates in predicate_list
hold, but no other predicates.
The rules are as follows: In the step (A), only the `BaseDef
definitions are considered. The first base definition is determined where
all predicates are satisfied and that has the longest predicate list.
In the step (B) only the `Appendix
definitions are considered.
All definitions are determined where all predicates are satisfied.
The final result is the concatenation of the single result of (A)
and all results of (B) (in the order they are defined). A space
character is inserted between two concatenated strings.
When step (A) does not find any matching definition, the exception
Not_found
is raised.
predicate_exists variable_name def
:
Whether variable_name
is explicitly mentioned in def
.