mirror of
https://github.com/ProgramSnail/pass_strategy_synthesis.git
synced 2026-03-11 18:47:08 +00:00
263 lines
11 KiB
OCaml
263 lines
11 KiB
OCaml
|
(*
|
||
|
|
* Samlpe: Ostap sample.
|
||
|
|
* Copyright (C) 2006-2009
|
||
|
|
* Dmitri Boulytchev, St.Petersburg State University
|
||
|
|
*
|
||
|
|
* This software is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU Library General Public
|
||
|
|
* License version 2, as published by the Free Software Foundation.
|
||
|
|
*
|
||
|
|
* This software is distributed in the hope that it will be useful,
|
||
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
||
|
|
*
|
||
|
|
* See the GNU Library General Public License version 2 for more details
|
||
|
|
* (enclosed in the file COPYING).
|
||
|
|
*)
|
||
|
|
|
||
|
|
(* This module serves as Ostap tutorial. The important part is expression in the
|
||
|
|
form ostap (...) (see below), which specified the parsers using a certain
|
||
|
|
syntax extension
|
||
|
|
*)
|
||
|
|
open Ostap
|
||
|
|
open Matcher
|
||
|
|
|
||
|
|
[@@@warning "-26-27-32-33-34-35-36-37-38-39-60-66-67"]
|
||
|
|
|
||
|
|
(* Supplementary wrapper: takes a parser, a printer, a string, parses the
|
||
|
|
string with the parser, and prints the result (if any) with the printer
|
||
|
|
*)
|
||
|
|
let parse p pr s =
|
||
|
|
match Util.parse
|
||
|
|
(* Makes some default stream with minimal entries *)
|
||
|
|
(object
|
||
|
|
inherit Matcher.t s
|
||
|
|
inherit Util.Lexers.decimal s
|
||
|
|
inherit Util.Lexers.ident [] s
|
||
|
|
inherit! Util.Lexers.skip [
|
||
|
|
Matcher.Skip.whitespaces " \t\n";
|
||
|
|
Matcher.Skip.lineComment "--";
|
||
|
|
Matcher.Skip.nestedComment "(*" "*)"
|
||
|
|
] s
|
||
|
|
end)
|
||
|
|
(ostap (p -EOF))
|
||
|
|
with
|
||
|
|
| `Ok p -> Printf.printf "Parsed : %s\n" @@ pr p
|
||
|
|
| `Fail er -> Printf.printf "Syntax error: %s\n" er
|
||
|
|
|
||
|
|
(* Supplementary printer combinators *)
|
||
|
|
let id x = x
|
||
|
|
let pair f g (x, y) = f x ^ g y
|
||
|
|
let triple f g h (x, y, z) = f x ^ g y ^ h z
|
||
|
|
let list f x = List.fold_left (^) "" @@ List.map f x
|
||
|
|
let option f = function None -> "None" | Some x -> "Some " ^ f x
|
||
|
|
|
||
|
|
(* An overview of the basic combinators:
|
||
|
|
- sequencing
|
||
|
|
- attaching semantics
|
||
|
|
- alternation
|
||
|
|
- optionality
|
||
|
|
- iteration
|
||
|
|
*)
|
||
|
|
let _ =
|
||
|
|
(* Sequencing *)
|
||
|
|
parse (ostap ("a" "b" "c")) (* several items in a row return a tuple of parse values *)
|
||
|
|
(triple Token.repr Token.repr Token.repr)
|
||
|
|
"abc";
|
||
|
|
parse (ostap ("a" "b" "d")) (* should be parsing error --- "d" is expected, but "c" specified *)
|
||
|
|
(triple Token.repr Token.repr Token.repr)
|
||
|
|
"abc";
|
||
|
|
parse (ostap ("a" -"b" "c")) (* an item can be skipped from the result by preceding it with "-" *)
|
||
|
|
(pair Token.repr Token.repr)
|
||
|
|
"abc";
|
||
|
|
parse (ostap ("a" -"b" "c")) (* but the skipped item nevertheless important for parsing *)
|
||
|
|
(pair Token.repr Token.repr)
|
||
|
|
"adc";
|
||
|
|
parse (ostap (-"(" "a" -")")) (* it is quite usefule to omit a non-important symbols from *)
|
||
|
|
(* being returned as a result *)
|
||
|
|
Token.repr
|
||
|
|
"(a)";
|
||
|
|
parse (ostap (-"(" "a" -"b" -")")) (* by the way, whitespaces are allowed anywhere (due to a proper *)
|
||
|
|
(* stream definition, see object ... end expression above *)
|
||
|
|
Token.repr
|
||
|
|
" ( a (* comment *) b (* comment again *) ) ";
|
||
|
|
parse (ostap ("a" "b" "c" {"nothing"})) (* now, a semantics can be specified; it replaces the default *)
|
||
|
|
(* return value *)
|
||
|
|
id
|
||
|
|
"a b c";
|
||
|
|
parse (ostap (x:"a" y:"b" z:"c" {"Something: " ^ (Token.repr x) ^ (Token.repr y) ^ (Token.repr z)})) (* the semantics can make use of a bindings *)
|
||
|
|
id
|
||
|
|
"a b c";
|
||
|
|
parse (ostap ("a" | "b")) (* besides sequencing, there is an alternation *)
|
||
|
|
Token.repr
|
||
|
|
"a";
|
||
|
|
parse (ostap ("a" | "b")) (* both branches are matched *)
|
||
|
|
Token.repr
|
||
|
|
"b";
|
||
|
|
parse (ostap (x:("a" | "b") {"Something: " ^ Token.repr x})) (* grouping is allowed *)
|
||
|
|
id
|
||
|
|
"a";
|
||
|
|
parse (ostap ("a"?)) (* optional parsing *)
|
||
|
|
(option Token.repr)
|
||
|
|
"a";
|
||
|
|
parse (ostap ("a"?)) (* optional parsing *)
|
||
|
|
(option Token.repr)
|
||
|
|
"";
|
||
|
|
parse (ostap (x:"a"? {match x with None -> "None" | Some s -> "Some " ^ Token.repr s})) (* bindings for optional return option type *)
|
||
|
|
id
|
||
|
|
"a";
|
||
|
|
parse (ostap ("a"*)) (* greedy iteration (zero-or-more) *)
|
||
|
|
(list Token.repr)
|
||
|
|
"aaa";
|
||
|
|
parse (ostap ("a"+)) (* greedy iteration (one-or-more) *)
|
||
|
|
(list Token.repr)
|
||
|
|
"aaa";
|
||
|
|
parse (ostap (("a" | "b" | "c")+)) (* of course any parser can be specified as an argument *)
|
||
|
|
(list Token.repr)
|
||
|
|
"aa";
|
||
|
|
parse (ostap (!(Util.list)[ostap ("a" | "b" | "c")])) (* parsers can be parameterized; ostap expressions can be nested; arbitrary expression can be emdedded *)
|
||
|
|
(* via the !(...) construct; there are some useful combinators in the Util module --- this one for *)
|
||
|
|
(* non-empty lists *)
|
||
|
|
(list Token.repr)
|
||
|
|
"a, a, b, c, a, b";
|
||
|
|
parse (ostap (!(Util.listBy)[ostap (";")][ostap ("a" | "b" | "c")])) (* another useful one: a list with explicitly specified delimiter *)
|
||
|
|
(list Token.repr)
|
||
|
|
"a; a; b; c; a; b";
|
||
|
|
parse (ostap (x:("a" | "b" | "c") - $(Token.repr x) {"two " ^ Token.repr x ^ "'s"})) (* a $(<string-expression>) can be used to parse a dynamically-evaluated *)
|
||
|
|
(* string; we used "-" to omit the second occurrence of x from being *)
|
||
|
|
(* returned; note a space between the "-" and the "$(...)" *)
|
||
|
|
id
|
||
|
|
"aa";;
|
||
|
|
|
||
|
|
(* This completes the basic combinators overview *)
|
||
|
|
|
||
|
|
(* Among the expression ostap (...) there is a structure item ostap (...) *)
|
||
|
|
(* to specify a set of mutally-recirsive definitions: *)
|
||
|
|
|
||
|
|
ostap (
|
||
|
|
animal : "zeboro" | "cat" | "rabbit" | "giraffe";
|
||
|
|
location: "pool" | "bank" | "cafe" | "theater";
|
||
|
|
action : "playing" | "eating" | "swimming" | "working";
|
||
|
|
phrase : "A" animal "is" action "in" "a" location {"parsed"}
|
||
|
|
)
|
||
|
|
|
||
|
|
let _ = List.iter (parse phrase id) ["A zeboro is playing in a theater";
|
||
|
|
"A cat is eating in a cafe";
|
||
|
|
"A rabbit is eating a cat"];;
|
||
|
|
|
||
|
|
(* Now some "real" parsers *)
|
||
|
|
type expr = Mul of expr * expr | Add of expr * expr | Var of string
|
||
|
|
|
||
|
|
let rec expr_to_string = function
|
||
|
|
| Var s -> s
|
||
|
|
| Mul (x, y) -> "(" ^ expr_to_string x ^ " * " ^ expr_to_string y ^ ")"
|
||
|
|
| Add (x, y) -> "(" ^ expr_to_string x ^ " + " ^ expr_to_string y ^ ")"
|
||
|
|
|
||
|
|
(* Expressions with right-associative binaries *)
|
||
|
|
module RightAssoc =
|
||
|
|
struct
|
||
|
|
|
||
|
|
ostap (
|
||
|
|
expr : addi;
|
||
|
|
addi : x:mulli "+" y:addi {Add (x, y)} | mulli;
|
||
|
|
mulli : x:primary "*" y:mulli {Mul (x, y)} | primary;
|
||
|
|
primary: x:IDENT {Var x} | -"(" expr -")"
|
||
|
|
)
|
||
|
|
|
||
|
|
let _ = List.iter (parse expr expr_to_string) ["a"; "a+b"; "a+b+c"; "a+b*c"; "a+b*c+d"; "(a+b)*c"]
|
||
|
|
|
||
|
|
end
|
||
|
|
|
||
|
|
(* Expressions with left-associative binaries *)
|
||
|
|
module LeftAssoc =
|
||
|
|
struct
|
||
|
|
|
||
|
|
[@@@ocaml.warning "-8"]
|
||
|
|
ostap (
|
||
|
|
expr : addi;
|
||
|
|
addi : <x::xs> :!(Util.listBy)[ostap ("+")][mulli] {List.fold_left (fun x y -> Add (x, y)) x xs}; (* note the use of a pattern for bindings; *)
|
||
|
|
mulli : <x::xs> :!(Util.listBy)[ostap ("*")][primary] {List.fold_left (fun x y -> Mul (x, y)) x xs}; (* note a space between the "<...>" and the ":" *)
|
||
|
|
primary: x:IDENT {Var x} | -"(" expr -")"
|
||
|
|
)
|
||
|
|
|
||
|
|
let _ = List.iter (parse expr expr_to_string) ["a"; "a+b"; "a+b+c"; "a+b*c"; "a+b*c+d"; "(a+b)*c"]
|
||
|
|
|
||
|
|
end
|
||
|
|
|
||
|
|
(* But better use a custom combinator Util.expr: *)
|
||
|
|
module ExprExample =
|
||
|
|
struct
|
||
|
|
|
||
|
|
ostap (
|
||
|
|
expr:
|
||
|
|
!(Util.expr (* The combinator Util.expr takes three arguments: *)
|
||
|
|
(fun x -> x) (* --- a function, used to transform each parsed subexpression into something; often just an id *)
|
||
|
|
[| (* --- an array of binary operator specifiers, ordered by the priority in increasing order *)
|
||
|
|
`Lefta , [ostap ("+"), fun x y -> Add (x, y)]; (* --- each specifier describes the associativity at given priority (one of `Lefta, `Righta, `Nona) *)
|
||
|
|
`Righta, [ostap ("*"), fun x y -> Mul (x, y)]; (* --- and the list of pairs: *)
|
||
|
|
|] (* --- the parser for the operator's infix and two-argument function to construct AST node *)
|
||
|
|
primary (* --- a parser for the primary (simplest form of the expression) *)
|
||
|
|
);
|
||
|
|
|
||
|
|
primary: x:IDENT {Var x} | -"(" expr -")"
|
||
|
|
)
|
||
|
|
|
||
|
|
let _ = List.iter (parse expr expr_to_string) ["a"; "a+b"; "a+b+c"; "a+b*c"; "a+b*c*e+d"; "(a+b)*c"]
|
||
|
|
|
||
|
|
end
|
||
|
|
|
||
|
|
(* And now some "real-world" example *)
|
||
|
|
module ShallowLanguageImplemenation =
|
||
|
|
struct
|
||
|
|
|
||
|
|
let empty x = failwith @@ "Undefined variable " ^ x
|
||
|
|
let update x v s y = if x = y then v else s y
|
||
|
|
|
||
|
|
let runParser p s =
|
||
|
|
match Util.parse
|
||
|
|
(object
|
||
|
|
inherit Matcher.t s
|
||
|
|
inherit Util.Lexers.decimal s
|
||
|
|
inherit Util.Lexers.ident ["if"; "then"; "else"; "fi"; "while"; "do"; "done"] s
|
||
|
|
inherit! Util.Lexers.skip [
|
||
|
|
Matcher.Skip.whitespaces " \t\n";
|
||
|
|
Matcher.Skip.lineComment "--";
|
||
|
|
Matcher.Skip.nestedComment "(*" "*)"
|
||
|
|
] s
|
||
|
|
end)
|
||
|
|
(ostap (p -EOF))
|
||
|
|
with
|
||
|
|
| `Ok p -> p
|
||
|
|
| `Fail er -> failwith @@ Printf.sprintf "Syntax error: %s\n" er
|
||
|
|
|
||
|
|
[@@@ocaml.warning "-8"]
|
||
|
|
ostap (
|
||
|
|
expr:
|
||
|
|
!(Util.expr
|
||
|
|
(fun x -> x)
|
||
|
|
[|
|
||
|
|
`Nona , [ostap ("=="), (fun x y s -> if x s = y s then 1 else 0)];
|
||
|
|
`Lefta , [ostap ("+" ), (fun x y s -> x s + y s); ostap ("-"), (fun x y s -> x s - y s)];
|
||
|
|
`Lefta , [ostap ("*" ), (fun x y s -> x s * y s); ostap ("/"), (fun x y s -> x s / y s)]
|
||
|
|
|]
|
||
|
|
primary
|
||
|
|
);
|
||
|
|
|
||
|
|
primary: x:IDENT {fun s -> s x} | n:DECIMAL {fun s -> n} | -"(" expr -")";
|
||
|
|
|
||
|
|
simpleStmt:
|
||
|
|
x:IDENT ":=" e:expr {fun s -> update x (e s) s}
|
||
|
|
| "if" c:expr "then" s1:stmt "else" s2:stmt "fi" {fun s -> (if c s = 0 then s2 else s1) s}
|
||
|
|
| "while" c:expr "do" s1:stmt "done" {fun s -> let rec w s = if c s = 0 then s else w (s1 s) in w s};
|
||
|
|
|
||
|
|
stmt: <s::ss> : !(Util.listBy)[ostap (";")][simpleStmt] {List.fold_left (fun s ss d -> ss @@ s d) s ss}
|
||
|
|
)
|
||
|
|
|
||
|
|
let fact =
|
||
|
|
let f = runParser stmt "result := 1; while 1 - (n == 0) do result := result * n; n := n - 1 done" in
|
||
|
|
fun n -> (f @@ update "n" n empty) "result"
|
||
|
|
|
||
|
|
let _ = List.iter (fun n -> Printf.printf "fact %d = %d\n" n (fact n)) [1; 2; 3; 4; 5; 6; 7]
|
||
|
|
|
||
|
|
end
|