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Module Fl_metascanner

module Fl_metascanner: sig .. end

Parses META files

type formal_pred = [ `NegPred of string | `Pred of string ] 
type flavour = [ `Appendix | `BaseDef ]

`BaseDef refers to META definitions using the "=" operator, and `Appendix refers to definitions using the "+=" operator.

type pkg_definition = {
   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".

type pkg_expr = {
   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.

val parse : Stdlib.in_channel -> pkg_expr

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.

val parse2 : Stdlib.in_channel -> pkg_expr
val parse2_lexing : Stdlib.Lexing.lexbuf -> pkg_expr
val parse_lexing : Stdlib.Lexing.lexbuf -> pkg_expr
val print_def : Stdlib.out_channel -> pkg_definition -> unit

print_def ch def: Outputs the definition to a channel.

val print : Stdlib.out_channel -> pkg_expr -> unit

print ch expr: Outputs the package expression to a channel.

val lookup : string -> string list -> pkg_definition list -> string

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.

val lookup_2 : string ->
       string list ->
       pkg_definition list ->
       string * formal_pred list

Like lookup, but also returns the list of predicates that had to be considered to select the particular variable definition.

val predicate_exists : string -> pkg_definition list -> bool

predicate_exists variable_name def:

Whether variable_name is explicitly mentioned in def.

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