Module Sexplib.Path

Types
type el =
| Pos of int

Pos n denotes nth element in a tuple

| Match of string * int

Match (tag, n) denotes nth argument of sum matching tag

| Rec of string

Rec name denotes the record field having name

Type of substitution elements

type t = el list

Type of substitution paths

High-level functions
val parse : string -> t

parse str

returns

a substitution path represented by string str.

Syntax:

"." -> separates path elements; must be present at start of string.

"[4]" -> specifies the 4th element in a tuple.

"some_tag[4]" -> tries to match some_tag, then denotes its 4th argument.

"name" -> denotes record field having name

Example from test code:

".t.x.B1" -> choose record field with name t, then subfield x. Match this value against B, and denote its first argument.

raises Failure

if the path is syntactically invalid.

val get : ?⁠path:t -> ?⁠str:string -> Sexp.t -> Sexp.t

get ?path ?str sexp if path is provided, use it as path. Otherwise, if str is provided, parse it as a path. If neither is provided, assume an empty path.

returns

the sub-expression from S-expression sexp denoted by the path.

raises Failure

if path is syntactically invalid or if the path structure clashes with the structure of the data.

val replace : ?⁠path:t -> ?⁠str:string -> Sexp.t -> subst:Sexp.t -> Sexp.t

replace ?path ?str sexp ~subst like get, but does not extract a sub-expression but substitutes it with subst.

returns

resulting S-expression.

raises Failure

if path is syntactically invalid or if the path structure clashes with the structure of the data.

val replace_no_path : str:string -> Sexp.t -> subst:Sexp.t -> Sexp.t

replace_no_path ~str sexp ~subst like replace, but does not take optional arguments. str must be specified.

raises Failure

if path is syntactically invalid or if the path structure clashes with the structure of the data.

val subst_path : Sexp.t -> t -> (Sexp.t -> Sexp.t) * Sexp.t

subst_path sexp path

returns

the tuple (subst, sub), where subst is a function that returns an S-expression in which the subexpression denoted by path in sexp has been substituted by its argument. sub is the denoted subexpression. Note that subst sub = sexp.

raises Failure

if path is syntactically invalid or if the path structure clashes with the structure of the data.

Low-level functions
val extract_pos : int -> Sexp.t -> (Sexp.t option -> Sexp.t) * Sexp.t

extract_pos n sexp

returns

the tuple (subst, sub), where subst is a function that returns an S-expression in which the subexpression denoted at position n in sexp, which must be a list, has been substituted by value if the optional argument is Some value, or removes the denoted subexpression if the optional argument is None. sub is the denoted subexpression. Note that subst (Some sub) = sexp.

raises Failure

if the position cannot be resolved within the given S-expression.

val extract_match : string -> int -> Sexp.t -> (Sexp.t option -> Sexp.t) * Sexp.t

extract_match tag n sexp

returns

the tuple (subst, sub), where subst is a function that returns an S-expression in which the subexpression denoted by matching tag and taking its nth argument in sexp has been substituted by value if the argument is Some value, or removes the denoted subexpression if the optional argument is None. sub is the denoted subexpression. Note that subst (Some sub) = sexp.

raises Failure

if the S-expression does not represent a sum tag.

val extract_rec : string -> Sexp.t -> (Sexp.t -> Sexp.t) * Sexp.t

extract_rec name sexp

returns

the tuple (subst, sub), where subst is a function that returns an S-expression in which the subexpression denoted by matching field name name in sexp has been substituted by its argument. sub is the denoted subexpression. Note that subst (Some sub) = sexp.

raises Failure

if the S-expression does not represent a record.